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Some properties of thermal muds of some spas in Turkey
Applied Clay Science 48 (2010) 531–537
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Applied Clay Science j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / c l a y
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Some properties of thermal muds of some spas in Turkey Muazzez Çelik Karakaya a,⁎, Necati Karakaya a, Şerife Sarıoğlan b,1, Murat Koral b,1 a b
Selçuk Üniversitesi Muh.-Mim. Fak. Jeoloji Mühendisliği Bölümü, Konya, 42079, Turkey TUBITAK Marmara Araştırma Merkezi, Kimya Enstitüsü, 41470, Gebze, Kocaeli, Turkey
a r t i c l e
i n f o
Article history: Received 12 November 2009 Received in revised form 4 February 2010 Accepted 9 February 2010 Available online 16 February 2010 Keywords: Clay Pelotherapy Thermal mud Turkey
a b s t r a c t In Turkey, over thirty spa centers use local, naturally occurring thermal muds for therapeutic, aesthetic, and pharmaceutical purposes. Mineralogical, chemical, and technological properties of thermal muds from nine different spas were investigated to identify the most suitable materials for pelotherapy. The muds consisted of smectite, illite, illite–smectite, quartz, feldspar, some calcite, amorphous silica, and rarely halite. The Na2O/CaO ratio of the muds was lower than 0.09, representing non-swelling bentonites. Some mud samples contained higher levels of hazardous chemical elements, including As, Cd, Hg, Pb, Tl, Th and U, and some less dangerous elements, including Co, Cr, Cs, Ni, Sr, Zr, and REE, compared to argillaceous sediments and shales. In general, particle sizes of muds larger than 2 μm, and cation-exchange capacity and specific surface areas are lower than the standard value. Properties of a few thermo-mineral waters were also analyzed. The low swelling index, Na2O/CaO ratio, plasticity, and specific surface area (due to the low content of the b 2 μm clay fraction), as well as the high content of non-clay minerals and exchange capacity of the muds, make them unsuitable for therapeutic and aesthetic applications. These results indicate that there is a need to develop suitable standards for thermal muds in relation to their use for therapeutic, pharmaceutical, and aesthetic medicine purposes. Appropriate materials can be obtained from the bentonite deposits at very low cost, and the material can be maturated using thermal–mineral water in different compositions for different types of applications. © 2010 Elsevier B.V. All rights reserved.
1. Introduction The therapeutic effects of peloids have been extensively studied, particularly in the fields of rheumatology and dermatology (Nappi et al., 1996; Bellometti et al., 2000; Beer et al., 2003; Argenziano et al., 2004; Codish et al., 2005). In pharmaceutical formulations, they are used as gastrointestinal protectors, oral laxatives, anti-diarrheals, dermatological protectors, and cosmetics. The main factors that determine the nature of a peloid and its suitability for pelotherapeutic applications are low cooling rate, high absorption capacity, high cation-exchange capacity (CEC), good adhesiveness, ease of handling, and a pleasant feeling when applied to the skin (Carretero et al., 2006; Veniale et al., 2007). The composition and granulometry of the initial form of the clay and the composition of the mineral water used for the mixture are also important (Curini et al., 1990; Veniale et al., 1999; Carretero, 2002; Sánchez et al., 2002; Carretero et al., 2006, 2007; Gomes and Silva, 2007; Tateo and Summa, 2007; Veniale et al., 2007; Tateo et al., 2009). The use of a clay mineral for any specific application depends on both its type of structure (1:1 or 2:1 layer type) and its chemical composition. Textural differences between structurally and chemically identical minerals also
⁎ Corresponding author. Tel./fax: + 90 332410555. E-mail address: [email protected] (M. Çelik Karakaya). 1 Tel./fax: + 90 332410555. 0169-1317/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.clay.2010.02.005
affect their adsorptive and rheological properties (Lagaly, 1989; Murray and Keller, 1993; Viseras, 1997; Yebra, 2000). In Turkey (Fig. 1), thermal water has been used in over fifty spas, and thermal muds have been used for a long time in over twenty spas for therapeutic and aesthetic purposes. However, no detailed analyses of these muds have ever been conducted. This study was conducted to define the properties of the thermal muds from select sources. The chemical, mineralogical and technological properties of the muds were measured and compared with the mud of the well-known Italian Benetutti spa (Thermal Mud: T.M.) and a commercial peloid (C.P.) (Cara et al., 2000). 2. Materials and methods The mud samples were collected from the most popular spa centers (Fig. 2). All mud samples were homogenized, dried and then ground for 5 min in a porcelain ball mill for X-ray diffraction and chemical analysis. The mineralogical analyses of the samples were performed on randomly oriented samples (total fraction) and clay fraction (N2 μm) using an X-ray diffraction (XRD) equipment with a scanning speed of 1° 2θ/min and Cu-Kα radiation from 2° to 70° 2θ (40 kV, 20 mA). After removing non-silicate minerals from the claysized fractions (b2 µm), clay minerals were identified from three XRD patterns. In the first step, the clay-sized fractions were extracted by the standard sedimentation technique in deionized water. Oriented
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Fig. 1. Location of young tectonic lines and location of warm and mineralized spring waters of Turkey. After Şimşek, 2007.
preparations of the clay fractions were obtained by vacuum filtration of the clay suspension and transferred to glass plates. Next, samples were air-dried at 25 °C, finally the samples were ethylene-glycolated and heated at 490 °C for 4 h. Grain-size analyses were carried out using a Malvern MasterSizer2000 laser particle sizer, with 45 mm and 100 mm lenses, which identifies grain-size intervals from 0.02 to 2000 μm. Samples were dispersed in distilled water for 30 min, stirred, and immersed in an ultrasonic bath to completely disperse the aggregates. After filtering the water with a 0.45-μm Millipore filter, the temperature, pH, Eh, and conductivity were determined on site using WTW Multi 340i instruments and electrodes (pH, SenTix ORP, DO) with automatic temperature compensation. The pH electrode was used after stabilization in a buffer solution at pH 4 and 7 for 24 h, followed by in-situ calibration (buffers: pH 4, 7, and 10). The measured Eh was converted to a standard H electrode using ZoBell's solution and a Pt-calomelane combined electrode. BET analyses were made on samples that were dried, homogenized and then dispersed. Dispersion was performed by hand in an agate mortar. The BET surface areas of the samples were determined using an Autosorb-1 Quantachrome volumetric gas adsorption instrument. Plasticity was calculated on the basis of Atterberg limits, following UNE 7-377-75
and UNE 103-104-93 standards. CEC, filtration loss, swelling index, grain size of the peloids, DTA-TG, specific surface area, and oil and water absorption were determined at the Turkish Scientific and Technical Researches Council Marmara Research Center (MAM). The CECs of the bentonite samples were determined by the methylene blue (MB) method (Hang and Brindley, 1970; Rytwo et al., 1991). The total abundances of the major oxides and minor elements analyses were performed by ACME Laboratories (Canada). 3. Results Grain-size analyses of seven mud samples are shown in Table 1. The granulometric curves revealed that the mud samples consisted mostly of grain sizes less than 20 and 10 μm, around 80.77% and 69%, respectively. The thermal mud samples were composed of calcite, quartz, and smectite, with illite, kaolinite and rarely feldspar in subordinate quantities, whereas dolomite, amorphous silica, zeolite, pyrite, and halite are rare (Table 2, Fig. 3A). The samples showed a low content of clay minerals in the total fraction (between 30 and 60%) with characteristic reflections at 14.73 Å, 10.04 Å, 7.10 Å, 5.35 Å, 5.06 Å, and 1.501 Å (Fig. 3B). The last d-value, which corresponds to d (060) reflection, clearly shows that the clay minerals are dioctahedral, except in sample KC-9. These data revealed that the muds are composed mainly from three minerals, and content of the non-swelling phase is high for KC-4 and KC-5. Treatment with ethylene glycol caused this reflection to shift to 17.40 Å,
Table 1 Grain size of some thermal muds.
Fig. 2. Location of sample locations.
Sample number/grain size (in %)
KC-1
KC-3
KC-5
KC-6
KC-7
KC-8
KC-9
+ 100 μm − 100 μm − 63 μm − 20 μm − 10 μm − 2 μm
18.00 82.00 99.25 91.85 79.00 22.80
3.22 96.78 99.50 87.58 64.85 16.20
12.27 87.83 95.80 55.72 26.60 5.30
14.90 85.10 99.70 92.95 77.42 22.10
14.80 85.20 95.40 70.25 50.69 21.86
2.84 97.16 95.40 70.82 50.60 12.03
25.96 74.04 99.90 93.96 74.50 20.10
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Table 2 Mineralogical composition of thermal muds from some spa centers.
Quartz Calcite Dolomite Feldspar Illite Kaolinite Smectite A. Silica Halite Pyrite Zeolite Gypsum
KC-1
KC-2
KC-3
KC-4
KC-5
KC-6
KC-7
KC-8
KC-9
KC-10
C.P.
+++ ++ − + + ± +++ + − − − −
− ++++ − − − − − − − − − −
++ + − + + − +++ + + − − ±
++ + + ++ ++ + − − − − − −
+ ++++ − + + ± ± − − − − −
+ ++ ± + + + +++ − − − − −
++ ++++ − + + + + − − − − −
+ ++ − + + + +++ + − + + −
++ +++ + + + + +++ + + − + −
++ ++ ± + + + + − − − − −
+
+
+++
C.P.: Commercial peloid (Cara et al., 2000), +: shows relative abundances.
Fig. 3. A. X-ray diffraction pattern of random powder patterns of studied bulk samples showing the main reflections (Å) and minerals identified of some thermal muds. B. X-ray diffraction pattern of b2 μm fraction oriented in natural condition, after it was heated at 490 °C and solvated in ethylene glycol atmosphere. S. Smectite, I. Illite, K. Kaolinite of KC-6.
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Table 3A Major element analyses (in %) of some thermal mud samples.
KC-1 KC-3 KC-5 KC-6 KC-7 KC-8 KC-9 T.M. C.P.* D.L.
SiO2
Al2O3
Fe2O3
MgO
CaO
Na2O
K2O
TiO2
P2O5
MnO
TOT/C
TOT/S
LOI
Total
Na2O/CaO
41.44 50.79 28.56 41.62 37.19 44.10 33.49 58.93 55.39 0.01
9.58 13.34 7.34 12.82 6.53 12.18 6.24 18.00 19.78 0.01
5.49 3.10 3.20 5.13 3.62 5.13 5.40 4.43 7.28 0.04
1.74 2.18 1.65 1.92 3.39 2.16 9.95 2.41 3.01 0.01
16.99 5.90 29.69 13.93 23.04 12.54 16.70 3.37 0.89 0.01
1.02 3.39 0.75 0.84 0.53 1.07 1.26 0.99 1.95 0.01
1.40 2.30 0.97 2.93 1.11 2.11 1.03 1.65 1.19 0.01
0.48 0.35 0.36 0.65 0.44 0.66 0.38 0.48 0.85 0.01
0.19 0.08 0.12 0.20 0.19 0.18 0.06 0.06 0.10 0.01
0.10 0.09 0.05 0.19 0.06 0.09 0.15 0.13 0.17 0.01
4.17 2.6 6.96 3.54 6.44 4.73 4.75 n.g. n.g.
0.06 0.44 0.28 0.11 0.33 0.73 0.13 n.g. n.g.
21.4 18.3 27.1 19.3 23.7 19.5 24.9 9.50 7.39 0.10
99.84 99.87 99.85 99.55 99.78 99.77 99.73 99.95 98.00
0.06 0.58 0.03 0.06 0.02 0.09 0.08 0.29 2.19
Note: T.M.: thermal muds of Benetutti; C.P.: commercial peloid (Cara et al., 2000); n.g.: was not given. D.L.: Detection limits of major elements and LOI (in %) and trace elements (in ppm).
a shoulder near 4.30 Å) and a weaker reflection at 2.50 Å in the XRD patterns (KC-1, 3, 8 and 9, Fig. 3A, Table 2). Chemical analyses were made from some of the samples in which the clay mineral content was high, except KC-5 (Tables 3A and 3B). A high Na2O/CaO ratio indicates the presence of swelling 2:1 clay minerals (1b Na2O/CaOb 3), while a low ratio (Na2O/CaOb 1) is typical for nonswelling 2:1 clay minerals (Ravaglioli et al., 1989). Na2O/CaO ratios in all samples were found to be below than those of C.P. and T.M. (Cara et al., 2000). The CaO content of all samples was higher than that of C.P. and T.M., while the SiO2 and Al2O3 contents were lower. The Fe2O3 content was found to be lower in 3 and higher in 4 samples. The thermal muds contained a little smectite, so major element oxides were low in comparison to C.P. and T.M., except for CaO and Fe2O3 in some samples. Comparatively, the values of the liquid and plastic limits were similar for three muds, KC-1, KC-3, and KC-8, but rather lower than
which revealed a 2:1 swelling clay mineral. Heating at 490 °C revealed a shift in reflection to 10.4 Å. This is consistent with a structural collapse process in a mineral where the interlayer space is occupied by hydrated exchangeable ions. The subordinated clay mineral showed no changes of the basal spacing after heating to 490 °C. The reflection remained at around 9.9 Å, which identifies this mineral as illite. The illite 001 reflection (d=10 Å) was broadened, suggesting poor crystallinity, with a Kubler index of 0.27° 2θ. The second subordinated clay mineral showed no changes in the basal spacing at 7.16 Å after reaction with ethylene glycol, and the disappearance of the reflection after heating at 490 °C indicates amorphization of the mineral. Traces of irregular illite–smectite mixed layer minerals were also identified. Amorphous silica in accessory quantities, found in nature as biogenic silica (e.g., diatomaceous earth) and/or as silica glass, was observed by XRD and SEM observations. Opal-A was identified by the diffuse band centered at approximately 4.04 Å (with
Table 3B Trace and RE elements (ppm) of some thermal muds and mean values of argillaceous sediments and shales.a Sample/element
KC-1
KC-3
KC-5
KC-6
KC-7
KC-8
KC-9
D.L.
A.S.a
Shalesa
Ag As Au (ppb) Ba Be Bi Cd Co Cr Cs Cu Ga Hf Hg Mo Nb Ni Pb Rb Sb Sc Se Sr Ta Th TI U V W Y Zn Zr REE
b0.1 11.2 39.5 309 1.0 0.1 0.2 16.4 123.2 3.6 32.2 11.2 3.1 0.02 0.2 10.2 105 6.9 57.2 b 0.1 11 b 0.5 424.8 0.7 7.0 b 0.1 1.5 87 0.9 16.3 40 117.8 90.82
b0.1 5.1 7.3 225 5.0 0.7 0.2 9.1 61.6 16.0 12.4 18.2 4.5 0.04 1.2 26.7 27 33.7 175.1 0.2 10 b 0.5 214.3 3.3 13.3 0.5 6.3 55 1.9 32.3 38 116.8 108.06
b0.1 45.8 3.5 263 3.0 0.4 0.2 11.0 95.8 39.8 18.7 8.3 2.7 0.05 0.4 8.3 86 20.8 49.8 1.0 7 b 0.5 349.7 0.6 7.8 0.1 3.5 66 3.1 17.6 45 95.1 85.49
b 0.1 62.6 1.9 1153 5.0 0.4 0.1 15.2 73.3 14.8 30.3 17.1 7.2 0.02 0.7 25.8 40 32.3 146 0.4 10 b0.5 1540.4 1.4 28.0 0.6 5.5 95 3.6 24.2 50 274.5 277.7
b 0.1 15.3 5 212 1.0 0.1 0.1 19.3 390.0 9.8 15.3 8.7 4.4 0.02 0.4 10.7 202 8.7 50.4 0.4 7 b0.5 787 0.7 7.3 0.1 1.8 60 1.2 18.5 33 150 95.32
0.1 39.3 38.5 708 2.0 0.5 0.2 16.8 109.5 35.6 30.8 14.2 3.7 0.15 0.6 13.6 56 38.2 115.8 1.2 12 b 0.5 442.5 1.0 15.0 1.6 2.8 92 3.1 22.1 56 117.2 152.26
b 0.1 11.6 b 0.5 110 1.0 b 0.1 0.1 54.5 547.4 4.2 24.1 7.9 2.1 0.02 0.2 8.0 671 7.9 38.7 b0.1 11 0.7 464.1 0.6 4.2 0.1 1.0 69 0.6 13.3 40 67.3 65.89
0.1 1.0 0.5 1.0 0.2 0.1 0.1 0.2 0.002 0.1 0.1 0.5 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 1.0 0.5 0.5 0.1 0.2 0.1 0.1 8.0 0.5 0.1 1.0 0.1
0.007 13 3–4 500–800 2–6 0.05–0.40 0.3 14–20 80–120 5–10 40–60 19–25 2.8–6.0 0.02–0.04 2.0–2.6 15–20 40–90 20–40 120–200 1.2–2 12–15 0.4–0.6 300–450 0.8–1.5 9.6–13 0.5–1.5 3–4 80–130 1.8–2.0 25–35 80–120 160–200 140–245
0.007–0.01 5–13 2.5–4 500–800 2–5 0.05–0.50 0.22–0.3 11–20 60–100 6–8 40 15–25 2.8–4.0 0.018–0.04 0.7–2.6 15–20 50–70 18–25 140–160 0.8–1.5 10–15 0.6 300 1–2 12 0.5–2.0 3.0–4.1 100–130 1.8–2.0 30–40 80–120 150–200 109–224
Note: A.S.: argillaceous sediments. Above and lower values from the mean values were shown in bold and italic, respectively. a Represents mean values of shales and A.S. from Kabata-Pendias and Mukherjee (2009).
M. Çelik Karakaya et al. / Applied Clay Science 48 (2010) 531–537 Table 4 Representative technological properties for some thermal muds of Turkey. Sample number
Liquid limit (%)
Plastic limit (%)
Plasticity index
Soil type
pH
Eh (mV)
EC (mS/cm)
KC-1 KC-2 KC-3 KC-4 KC-5 KC-6 KC-7 KC-8 KC-9 KC-10 V.C.
67.58 n.m. 69.35 45.12 n.m. 66.33 30.50 64.80 49.48 67.70 180
31.88 n.m. 36.81 23.3 n.m. 28.6 n.d. 30.98 28.27 28.14 27
35.7 n.m. 32.54 21.82 n.m. 37.73 n.d. 33.10 21.21 39.46 153
HPC NP MPC LC n.d. HPC n.d. HPC LPC/HPC HPC HPC
7.94 8.45 8.29 9.39 8.50 8.48 8.56 8.27 7.73 8.71 9.90
92 160 129 − 340 86 105 104 − 151 106 90
455 489 8760 1640 280 341 397 848 6310 443
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Table 6 Some physicochemical characteristics of mineral waters of the studied spas (after Şimşek, 2007).
KC-1 KC-2 KC-3 KC-4 KC-5 KC-6 KC-7 KC-8 KC-9 KC-10
T (°C)
pH
Na + K
Ca + Mg
SO4
HCO3
CO3
Cl
B
45 73 84 74 50 67 73 30 42 70
8.4 7.6 8.7 7.2 7.6 6.6 7.6 8.7 6.8 6.5
2375 75 415 1625 222 259 295 71 9130 809
45 217 33 86 49 212 217 84 1850 192
209 651 185 52 40 485 654 144 2748 490
4654 544 561 2210 534 561 544 329 317 573
287 b10 60 n.d. 54 n.l. b10 n.d. b10 10
693 55 210 1440 37 92 55 16 17 107
99 63 13 45 16 n.l. 63 1 4 13
Note: n.l.: under detection limit, n.d.: could not be determined.
V.C.: virgin clay (Veniale et al., 2004), n.m. not measured, n.d.: could not be determined. HPC: high plastic clay, NP: non-plastic, MPC: moderately plastic clay, LC: low plastic clay.
those of the virgin clay of Veniale et al. (2004). Their plasticity index, or the difference between the liquid and plastic limits, is lower than that of the clay, due to the slightly higher specific surface area of the samples (Tables 4 and 5). The smallest specific surface area was observed in KC-7, which had a calcite and/or CaO (23.04%) content higher than those of the other samples, except KC-5. The CEC values of KC-5, KC-7 and KC-10 were similar and lower than the others. The lowest liquid limits were observed for KC-7, and KC-4. KC-9 showed medium plasticity while liquid limits of the other samples ranged from 64.08 to 69.35, indicating high plasticity (Grabowska-Olszewska, 1998). The CEC values of the samples were similar (b35 meq/100 g). Oil and water absorption values were similar in all samples, except KC-5, which had higher values than the others. The pH of the thermal muds was similar and varies between 7.73 and 8.71. The lowest pH was recorded for KC-1 and KC-9, while the lowest pH values were found for KC-6 and KC-9 at the thermal waters (Tables 4 and 6). The muds were classified as neutral to weakly alkaline, whereas the thermal water was weakly acidic to neutral. The influence of the thermal water on the pH of peloid muds did not seem to be significant.
4. Discussion The samples can be classified as silty clay according to Sheppard (1954), with a low fraction of clay-size particles. The lowest clay fractions were observed for KC-5 and KC-8, whose calcite and nonclay mineral contents were high. The thermal mud contained calcite, quartz, and smectite, with illite, kaolinite, and feldspar in subordinate quantities, while dolomite, amorphous silica, zeolite, pyrite, and halite are rare. The muds used in Turkish spas contain higher amounts of residual minerals, mainly quartz and feldspar, whereas the C.P. was mainly composed of montmorillonite (N95%; Cara et al., 2000) (Table 2).
The plasticity indexes, i.e., the difference between the liquid and plastic limits, of the samples were between 39 and 21, and swelling varies from 67 to 163 (Fig. 4, Table 5). The mechanical properties, i.e., hardness, plasticity, grain size and swelling, affect handling properties of the peloid. The mud samples had low and medium plasticities, together with a low content of clay-size particles, high content of quartz and feldspars and low swelling. These properties resulted in handling difficulties, as the mud had a thick consistency and worse thermal behavior due to a low level of hygroscopic water. This also affects adhering properties of the muds to the skin, and the mud may cause scratches or cuts to the skin during pelotherapy. The mud reacts with water to a minimal extent, in contrast to smectites, which are regarded as hydrophilic. Illite reacts with water to a limited extent (Pająk-Komorowska, 2003). Pastes consisting of bentonite/mineral water mixtures are the best materials for thermal pelotherapy applications (Morandi, 1999; Novelli, 2000). The lowest swelling values were observed for KC-5, KC-7, and KC-9. These samples had higher TOT/C contents than the other mud samples. The CaCO3 content in excess of 28 to 30% may inhibit swelling, but nothing is reported in the literature regarding the effects this has on pelotherapy behavior (Harris, 1996). Kaolinite and illite presented low CECs (3–22 and 20–50 meq/100 g, respectively) and specific surface areas (7–30 and 65–100 m2/g, respectively). In the case of smectites with high cation-exchange capacities (80–150 meq/100 g) and surface areas (280–800 m2/g), these properties are related to the interlayer spaces commonly occupied by hydrated exchangeable cations (Kabata-Pendias and Pendias, 2001; López-Galindo et al., 2007). The highest CEC was observed for KC-1 and the lowest KC-5 and KC-7. The highest surface areas were found in KC-6, KC-5, and KC-1, and the lowest in KC-8. Both CEC and surface areas were much lower than normal smectite values (Table 5). High sand content of the mud reduces its stickiness on the skin, and reduces the CEC and swelling values. Thus, a higher swelling value corresponds to higher water
Table 5 Some technological properties of some thermal muds. KC-1
KC-3
Oil absorption 27.70 27.83 (ml/100 g) Water absorption 33.54 31.70 (ml/100 g) CEC meq/100 g 32.26 23.24 Filtration loss 7.5 ml 91.30 77.90 Filtration loss 7.5 ml 188.6 156.5 Specific surface area 51.00 43.01 (m2/g) Swelling index % 128.2 129.9 Loss of hygroscopic 6.42 5.71 water
KC-5
KC-6
KC-7
KC-8
KC-9
65.92
21.74 27.94
35.45
27.76
79.37
31.59 29.76
39.95
25.93
9.55 254.9 n.d. 54.15
27.96 65.10 136.3 66.46
72.50 4.44
129.4 67.00 163.5 5.84 1.48 4.73
V.C.
9.20 23.90 10.00 63 260.0 97.30 75.90 n.d. 206.31 72.9 16.50 38.50 42.70 92.30 4.18 16.1
Note: n.d.: could not be determined, V.C.: virgin clay (Veniale et al., 2004).
Fig. 4. Casagrande's chart modified by Grabowska-Olszewska (1998) for the evaluation of plasticity of the thermal muds.
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absorption, which improves therapeutic effects. A higher CEC value allows the mud to trap a higher quantity of trace elements, which are essential for therapeutic benefits from the water. The low swelling index and plasticity index, specific surface area (due to the low content of b2 μm clay fraction), and low cationexchange capacity of the mud make them unsuitable for improving the quality of peloid muds. Because smectite content and particle sizes are low, heat capacity and cooling rate are also low. The trace element and Ca2+ content of peloid are important factors during pelotherapy, related to crossing the skin barrier and depositing in the bone. CaO in the thermal muds was originated from their calcite content, not from smectites; so the CEC capacity of the sample muds is much lower than that of the T.M. and C.P. Ca2+ ions in the form of calcite may not cross the skin barrier. However, some of the sand content of the muds originated from biogenic carbonate. Some fragments of ostracods, gastropods and diatoms were observed in the muds. Biogenic carbonate is the active component, and the pH conditioner is responsible for the dissolution and corresponding liberation of Ca, Mg, Sr, and other elements existing in the sand, making them available for adsorption through the skin and passage into the extra-cellular matrix (Gomes and Silva, 2007). Gomes and Silva (2007) pointed out that osteoporosis is not only the lack of Ca in the bone; P, Si, Mg, F, and Sr are the other constituents of bone, and Sr contributes to stabilization of the calcium phosphate structure in the bone. The Sr content of the samples KC-6, KC-7, and KC-9, and partly KC-1 and KC-8, is higher compared to the A.S. and shales (Table 3B), virgin clay (Sr = 397 ppm; Veniale et al., 2004), and shale (Sr = 142 ppm; Gromet et al., 1984). The exchange capability of Sr from the muds is unknown. A number of patients are using these muds to recover from osteoporosis, rheumatism, arthritis, and muscular skeletal traumas. Although some properties of the mud are not suitable for therapy, i.e. size, mineralogical composition, plasticity and CEC, the chemical composition and other features make them useful for treating these illnesses. The total supply of Al from pelotherapy is 0.2 mg/day, so it can be neglected. Lead can be very toxic, and its maximum allowable daily level is about 25 μg/kg body mass/week, even if the observed intake is sometimes higher (WHO, 1996). The lead exposure from pelotherapy is far below the advised amount (2 μg/day). Turkey is one of the top countries in the world in terms of thermal source richness, with almost 1000 thermal springs throughout Anatolia. The temperature of these hot springs varies between 20 and 110 °C (Fig. 1) (Şimşek, 2007). The pH of the thermal waters ranged from 6.60 to 8.70 and temperatures varied from 30 °C to 84 °C (Table 6). The lowest pH values of the thermal water were recorded in KC-6, KC-9, and KC-10, which were classified as weakly acidic to neutral, whereas others were near-neutral to alkaline. KC-1 and KC-4 were rich in HCO3 and alkaline elements. KC-1 was richer in boron ions, while KC-4 was richer in chlorine ions than the other waters. KC-9 is rich in alkali and alkali earth elements, as well as sulfurous water. The CEC, soluble salts, water retention, swelling index, activity, consistency parameters (WL, WP, and PI), thermal behavior, and cooling kinetics are influenced by the geochemistry of mineral waters used for the maturation treatments, with some opposite trends for Br–I–salty water and for sulfurous and Ca-sulfate waters (Veniale et al., 2004). 5. Conclusion We investigated Turkish thermal muds that have been used by local and international visiting patients for pelotherapy since ancient times. We can affirm that the muds we investigated generally contain clay minerals and other minerals. Several properties of the mud samples made them unsuitable for medicinal purposes, even after application of certain improvement or maturation processes. These properties include the low swelling index, low smectite content, low moisture and water absorption, low specific surface area (owing to
the high content of b2 μm clay fraction), exchange capacity, and high CaO contents (in some muds). The muds contain biogenic carbonate, amorphous silica, and some elements (Sr, P, Ca, etc.) that may make them useful for treating some health problems. The heterogeneous variables may play a role in the application of the thermal muds and therapy. Finally, some properties of these thermal muds may be improved by maturation using different types of thermal waters for different applications in thermal pelotherapy. Acknowledgements The authors are indebted to Prof. Gerhard Lagaly for his careful editorial comments and constructive suggestions. We are also grateful to the reviewers for their comments and suggestions, which improved the quality of the manuscript. The author is grateful to Prof. Dr. M. Emin Aydın and Assis. Prof. Dr. Şuayip Kupeli (Selçuk University) for their constructive comments, which significantly improved the quality of the manuscript, and Dr. H. Yüzer for performing some of the analyses at MAM. References Argenziano, G., Delfino, M., Russo, N., 2004. Mud and bath therapy in the acne cure. Clinica Terapeutica 155/4, 121–125. Beer, A.M., Junginger, H.E., Lukanov, J., Sagorchev, P., 2003. Evaluation of the permeation of peat substances through human skin in vitro. International Journal of Pharmaceutics 253/1-2, 169–175. Bellometti, S., Poletto, M., Gregotti, C., Richelmi, P., Berte, F., 2000. Mud bath therapy influences nitric oxide, myeloperoxidase and glutathione peroxidase serum levels in arthritic patients. International Journal of Clinical Pharmacology Research 20/3-4, 69–80. Cara, S., Carcangiu, G., Paladino, G., Palomba, M., Tamanini, M., 2000. The bentonites in pelotherapy: thermal properties of clay pastes from Sardinian (Italy). Applied Clay Science 16, 125–132. Carretero, M.I., 2002. Clay minerals and their beneficial effects upon human health. A review. Applied Clay Science 21, 155–163. Carretero, M.I., Gomes, C., Tateo, F., 2006. Clay minerals and health. In: Bergaya, F., Theng, B., Lagaly, G. (Eds.), Handbook of Clay Science. Elsevier, The Netherlands, pp. 717–741. Carretero, M.I., Pozo, M., Sánchez, C., García, F.J., Medina, J.A., Bernabé, J.M., 2007. Comparison of saponite and montmorillonite behaviour during static and stirring maturation with seawater for pelotherapy. Applied Clay Science 36, 161–173. Codish, S., Abu-Shakra, M., Flusser, D., Friger, M., Sukenik, S., 2005. Mud compress therapy for the hands of patients with rheumatoid arthritis. Rheumatology International 25/1, 49–54. Curini, R., D'Ascenzo, G., Fraioli, A., Lagana, A., Marino, A., Messina, B., 1990. Instrumental multiparametric study of the maturing of therapeutic muds of some Italian spas. Thermochimica Acta 157/2, 377–393. Gomes, C., Silva, J., 2007. Minerals and clay minerals in medical geology. Applied Clay Science 36 (1–3), 4–21. Grabowska-Olszewska, B., 1998. Geologia stosowana. Wlaściwości gruntów nienasyconych. Wyd. Naukowe PWN, Warszawa. Gromet, L.P., Dymek, R.F., Haksin, L.A., Korotev, R.L., 1984. The “North American shale composite”: its compilation, major and trace element characteristics. Geochimica et Cosmochimica Acta 48, 2469–3482. Hang, P.T., Brindley, G.W., 1970. Methylene blue adsorption by clay minerals. Determination of surface areas and cation exchange capacities (clay-organic studies XVIII). Clays and Clay Minerals 18, 203–212. Harris, C.S. (Ed.), 1996. Engineering Geology of the Channel Tunnel. Thomas Telford, London. 496 p. Kabata-Pendias, A., Pendias, H., 2001. Trace Elements in Soil and Plants, 3rd ed. CRC Press, London. 413p. Kabata-Pendias, A., Mukherjee, A.B., 2009. Trace Elements from Soil to Human. Springer, 576p. Lagaly, G., 1989. Principles of flow of kaolin and bentonite dispersions. Applied Clay Science 4, 105–123. López-Galindo, A., Viseras, C., Cerezo, P., 2007. Compositional, technical and safety specifications of clays to be used as pharmaceutical and cosmetic products. Applied Clay Science 36, 51–63. Morandi, N., 1999. Thermal and diffractometric behaviour: decisive parameters for assessing the quality of clays used for healing purposes. In: Veniale, F. (Ed.), Proc. Symp. “Argille per fanghi peloidi termali e per trattamenti dermatologici e cosmetici”. Montecatini Terme/ PT, Gruppo Ital. AIPEA: Mineral. Petrogr. Acta, vol. XLII, pp. 307–316. Murray, H.H., Keller, W.D., 1993. Kaolins, kaolins and kaolins. In: Murray, H., Bundy, W., Harvey, C. (Eds.), Kaolin: Genesis and Utilization. Clay Minerals Society, Boulder, Colorado, pp. 1–24. Nappi, G., Masciocchi, M.M., De Luca, S., Calcaterra, P., Carrubba, I.G., 1996. Le muffe termali solfuree nel tratamento de la psoriasi cutanea. Medicina e Clinica Termale 34, 7–18. Novelli, G., 2000. La bentonite: un'argilla nei secoli al servizio dell'uomo. In: Fiore, S. (Ed.), Incontri Scientifici, vol. II. Ricerche Argille-CNR, Potenza, pp. 207–304.
M. Çelik Karakaya et al. / Applied Clay Science 48 (2010) 531–537 Pająk-Komorowska, A., 2003. Swelling, expansion and shrinkage properties of selected clays in the Mazowsze province, central Poland. Geological Quarterly 47/1, 55–62. Ravaglioli, A., Fiori, C., Fabbri, B., 1989. In: Faenza (Ed.) Materia Prime Ceramiche. Argille, materiali non argillosi e sottoprodotti industriali. Biblioteca Tecnica Ceramica, 392 p. Rytwo, G., Serben, C., Nir, S., Margulies, L., 1991. Use of methylene blue and crystal violet for determination of exchangeable cations in montmorillonite. Clays and Clay Minerals 39, 551–555. Sánchez, C.J., Parras, J., Carretero, M.I., 2002. The effect of maturation upon the mineralogical and physicochemical properties of illitic–smectitic clays for pelotherapy. Clay Minerals 37, 457–463. Shepard, F.P., 1954. Nomenclature based on sand–silt–clay ratios. Journal of Sedimentary Petrology 24, 151–158. Şimşek, Ş., 2007. Dünya'da ve Türkiye'de jeotermal gelişmeler. Ülkemizdeki Doğal Kaynakların Enerji Üretimindeki Önemi ve Geleceği Sempozyumu, 15 Mayıs, İzmir. Tateo, F., Summa, V., 2007. Element mobility in clays for healing use. Applied Clay Science 36, 64–76. Tateo, F., Ravaglioli, A., Andreoli, C., Bonina, F., Coiro, V., Degetto, S., Giaretta, A., Menconi Orsini, A., Puglia, C., Summa, V., 2009. The in-vitro percutaneous migration of chemical elements from a thermal mud for healing use. Applied Clay Science 44, 83–94.
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Note
Some properties of thermal muds of some spas in Turkey Muazzez Çelik Karakaya a,⁎, Necati Karakaya a, Şerife Sarıoğlan b,1, Murat Koral b,1 a b
Selçuk Üniversitesi Muh.-Mim. Fak. Jeoloji Mühendisliği Bölümü, Konya, 42079, Turkey TUBITAK Marmara Araştırma Merkezi, Kimya Enstitüsü, 41470, Gebze, Kocaeli, Turkey
a r t i c l e
i n f o
Article history: Received 12 November 2009 Received in revised form 4 February 2010 Accepted 9 February 2010 Available online 16 February 2010 Keywords: Clay Pelotherapy Thermal mud Turkey
a b s t r a c t In Turkey, over thirty spa centers use local, naturally occurring thermal muds for therapeutic, aesthetic, and pharmaceutical purposes. Mineralogical, chemical, and technological properties of thermal muds from nine different spas were investigated to identify the most suitable materials for pelotherapy. The muds consisted of smectite, illite, illite–smectite, quartz, feldspar, some calcite, amorphous silica, and rarely halite. The Na2O/CaO ratio of the muds was lower than 0.09, representing non-swelling bentonites. Some mud samples contained higher levels of hazardous chemical elements, including As, Cd, Hg, Pb, Tl, Th and U, and some less dangerous elements, including Co, Cr, Cs, Ni, Sr, Zr, and REE, compared to argillaceous sediments and shales. In general, particle sizes of muds larger than 2 μm, and cation-exchange capacity and specific surface areas are lower than the standard value. Properties of a few thermo-mineral waters were also analyzed. The low swelling index, Na2O/CaO ratio, plasticity, and specific surface area (due to the low content of the b 2 μm clay fraction), as well as the high content of non-clay minerals and exchange capacity of the muds, make them unsuitable for therapeutic and aesthetic applications. These results indicate that there is a need to develop suitable standards for thermal muds in relation to their use for therapeutic, pharmaceutical, and aesthetic medicine purposes. Appropriate materials can be obtained from the bentonite deposits at very low cost, and the material can be maturated using thermal–mineral water in different compositions for different types of applications. © 2010 Elsevier B.V. All rights reserved.
1. Introduction The therapeutic effects of peloids have been extensively studied, particularly in the fields of rheumatology and dermatology (Nappi et al., 1996; Bellometti et al., 2000; Beer et al., 2003; Argenziano et al., 2004; Codish et al., 2005). In pharmaceutical formulations, they are used as gastrointestinal protectors, oral laxatives, anti-diarrheals, dermatological protectors, and cosmetics. The main factors that determine the nature of a peloid and its suitability for pelotherapeutic applications are low cooling rate, high absorption capacity, high cation-exchange capacity (CEC), good adhesiveness, ease of handling, and a pleasant feeling when applied to the skin (Carretero et al., 2006; Veniale et al., 2007). The composition and granulometry of the initial form of the clay and the composition of the mineral water used for the mixture are also important (Curini et al., 1990; Veniale et al., 1999; Carretero, 2002; Sánchez et al., 2002; Carretero et al., 2006, 2007; Gomes and Silva, 2007; Tateo and Summa, 2007; Veniale et al., 2007; Tateo et al., 2009). The use of a clay mineral for any specific application depends on both its type of structure (1:1 or 2:1 layer type) and its chemical composition. Textural differences between structurally and chemically identical minerals also
⁎ Corresponding author. Tel./fax: + 90 332410555. E-mail address: [email protected] (M. Çelik Karakaya). 1 Tel./fax: + 90 332410555. 0169-1317/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.clay.2010.02.005
affect their adsorptive and rheological properties (Lagaly, 1989; Murray and Keller, 1993; Viseras, 1997; Yebra, 2000). In Turkey (Fig. 1), thermal water has been used in over fifty spas, and thermal muds have been used for a long time in over twenty spas for therapeutic and aesthetic purposes. However, no detailed analyses of these muds have ever been conducted. This study was conducted to define the properties of the thermal muds from select sources. The chemical, mineralogical and technological properties of the muds were measured and compared with the mud of the well-known Italian Benetutti spa (Thermal Mud: T.M.) and a commercial peloid (C.P.) (Cara et al., 2000). 2. Materials and methods The mud samples were collected from the most popular spa centers (Fig. 2). All mud samples were homogenized, dried and then ground for 5 min in a porcelain ball mill for X-ray diffraction and chemical analysis. The mineralogical analyses of the samples were performed on randomly oriented samples (total fraction) and clay fraction (N2 μm) using an X-ray diffraction (XRD) equipment with a scanning speed of 1° 2θ/min and Cu-Kα radiation from 2° to 70° 2θ (40 kV, 20 mA). After removing non-silicate minerals from the claysized fractions (b2 µm), clay minerals were identified from three XRD patterns. In the first step, the clay-sized fractions were extracted by the standard sedimentation technique in deionized water. Oriented
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Fig. 1. Location of young tectonic lines and location of warm and mineralized spring waters of Turkey. After Şimşek, 2007.
preparations of the clay fractions were obtained by vacuum filtration of the clay suspension and transferred to glass plates. Next, samples were air-dried at 25 °C, finally the samples were ethylene-glycolated and heated at 490 °C for 4 h. Grain-size analyses were carried out using a Malvern MasterSizer2000 laser particle sizer, with 45 mm and 100 mm lenses, which identifies grain-size intervals from 0.02 to 2000 μm. Samples were dispersed in distilled water for 30 min, stirred, and immersed in an ultrasonic bath to completely disperse the aggregates. After filtering the water with a 0.45-μm Millipore filter, the temperature, pH, Eh, and conductivity were determined on site using WTW Multi 340i instruments and electrodes (pH, SenTix ORP, DO) with automatic temperature compensation. The pH electrode was used after stabilization in a buffer solution at pH 4 and 7 for 24 h, followed by in-situ calibration (buffers: pH 4, 7, and 10). The measured Eh was converted to a standard H electrode using ZoBell's solution and a Pt-calomelane combined electrode. BET analyses were made on samples that were dried, homogenized and then dispersed. Dispersion was performed by hand in an agate mortar. The BET surface areas of the samples were determined using an Autosorb-1 Quantachrome volumetric gas adsorption instrument. Plasticity was calculated on the basis of Atterberg limits, following UNE 7-377-75
and UNE 103-104-93 standards. CEC, filtration loss, swelling index, grain size of the peloids, DTA-TG, specific surface area, and oil and water absorption were determined at the Turkish Scientific and Technical Researches Council Marmara Research Center (MAM). The CECs of the bentonite samples were determined by the methylene blue (MB) method (Hang and Brindley, 1970; Rytwo et al., 1991). The total abundances of the major oxides and minor elements analyses were performed by ACME Laboratories (Canada). 3. Results Grain-size analyses of seven mud samples are shown in Table 1. The granulometric curves revealed that the mud samples consisted mostly of grain sizes less than 20 and 10 μm, around 80.77% and 69%, respectively. The thermal mud samples were composed of calcite, quartz, and smectite, with illite, kaolinite and rarely feldspar in subordinate quantities, whereas dolomite, amorphous silica, zeolite, pyrite, and halite are rare (Table 2, Fig. 3A). The samples showed a low content of clay minerals in the total fraction (between 30 and 60%) with characteristic reflections at 14.73 Å, 10.04 Å, 7.10 Å, 5.35 Å, 5.06 Å, and 1.501 Å (Fig. 3B). The last d-value, which corresponds to d (060) reflection, clearly shows that the clay minerals are dioctahedral, except in sample KC-9. These data revealed that the muds are composed mainly from three minerals, and content of the non-swelling phase is high for KC-4 and KC-5. Treatment with ethylene glycol caused this reflection to shift to 17.40 Å,
Table 1 Grain size of some thermal muds.
Fig. 2. Location of sample locations.
Sample number/grain size (in %)
KC-1
KC-3
KC-5
KC-6
KC-7
KC-8
KC-9
+ 100 μm − 100 μm − 63 μm − 20 μm − 10 μm − 2 μm
18.00 82.00 99.25 91.85 79.00 22.80
3.22 96.78 99.50 87.58 64.85 16.20
12.27 87.83 95.80 55.72 26.60 5.30
14.90 85.10 99.70 92.95 77.42 22.10
14.80 85.20 95.40 70.25 50.69 21.86
2.84 97.16 95.40 70.82 50.60 12.03
25.96 74.04 99.90 93.96 74.50 20.10
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Table 2 Mineralogical composition of thermal muds from some spa centers.
Quartz Calcite Dolomite Feldspar Illite Kaolinite Smectite A. Silica Halite Pyrite Zeolite Gypsum
KC-1
KC-2
KC-3
KC-4
KC-5
KC-6
KC-7
KC-8
KC-9
KC-10
C.P.
+++ ++ − + + ± +++ + − − − −
− ++++ − − − − − − − − − −
++ + − + + − +++ + + − − ±
++ + + ++ ++ + − − − − − −
+ ++++ − + + ± ± − − − − −
+ ++ ± + + + +++ − − − − −
++ ++++ − + + + + − − − − −
+ ++ − + + + +++ + − + + −
++ +++ + + + + +++ + + − + −
++ ++ ± + + + + − − − − −
+
+
+++
C.P.: Commercial peloid (Cara et al., 2000), +: shows relative abundances.
Fig. 3. A. X-ray diffraction pattern of random powder patterns of studied bulk samples showing the main reflections (Å) and minerals identified of some thermal muds. B. X-ray diffraction pattern of b2 μm fraction oriented in natural condition, after it was heated at 490 °C and solvated in ethylene glycol atmosphere. S. Smectite, I. Illite, K. Kaolinite of KC-6.
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Table 3A Major element analyses (in %) of some thermal mud samples.
KC-1 KC-3 KC-5 KC-6 KC-7 KC-8 KC-9 T.M. C.P.* D.L.
SiO2
Al2O3
Fe2O3
MgO
CaO
Na2O
K2O
TiO2
P2O5
MnO
TOT/C
TOT/S
LOI
Total
Na2O/CaO
41.44 50.79 28.56 41.62 37.19 44.10 33.49 58.93 55.39 0.01
9.58 13.34 7.34 12.82 6.53 12.18 6.24 18.00 19.78 0.01
5.49 3.10 3.20 5.13 3.62 5.13 5.40 4.43 7.28 0.04
1.74 2.18 1.65 1.92 3.39 2.16 9.95 2.41 3.01 0.01
16.99 5.90 29.69 13.93 23.04 12.54 16.70 3.37 0.89 0.01
1.02 3.39 0.75 0.84 0.53 1.07 1.26 0.99 1.95 0.01
1.40 2.30 0.97 2.93 1.11 2.11 1.03 1.65 1.19 0.01
0.48 0.35 0.36 0.65 0.44 0.66 0.38 0.48 0.85 0.01
0.19 0.08 0.12 0.20 0.19 0.18 0.06 0.06 0.10 0.01
0.10 0.09 0.05 0.19 0.06 0.09 0.15 0.13 0.17 0.01
4.17 2.6 6.96 3.54 6.44 4.73 4.75 n.g. n.g.
0.06 0.44 0.28 0.11 0.33 0.73 0.13 n.g. n.g.
21.4 18.3 27.1 19.3 23.7 19.5 24.9 9.50 7.39 0.10
99.84 99.87 99.85 99.55 99.78 99.77 99.73 99.95 98.00
0.06 0.58 0.03 0.06 0.02 0.09 0.08 0.29 2.19
Note: T.M.: thermal muds of Benetutti; C.P.: commercial peloid (Cara et al., 2000); n.g.: was not given. D.L.: Detection limits of major elements and LOI (in %) and trace elements (in ppm).
a shoulder near 4.30 Å) and a weaker reflection at 2.50 Å in the XRD patterns (KC-1, 3, 8 and 9, Fig. 3A, Table 2). Chemical analyses were made from some of the samples in which the clay mineral content was high, except KC-5 (Tables 3A and 3B). A high Na2O/CaO ratio indicates the presence of swelling 2:1 clay minerals (1b Na2O/CaOb 3), while a low ratio (Na2O/CaOb 1) is typical for nonswelling 2:1 clay minerals (Ravaglioli et al., 1989). Na2O/CaO ratios in all samples were found to be below than those of C.P. and T.M. (Cara et al., 2000). The CaO content of all samples was higher than that of C.P. and T.M., while the SiO2 and Al2O3 contents were lower. The Fe2O3 content was found to be lower in 3 and higher in 4 samples. The thermal muds contained a little smectite, so major element oxides were low in comparison to C.P. and T.M., except for CaO and Fe2O3 in some samples. Comparatively, the values of the liquid and plastic limits were similar for three muds, KC-1, KC-3, and KC-8, but rather lower than
which revealed a 2:1 swelling clay mineral. Heating at 490 °C revealed a shift in reflection to 10.4 Å. This is consistent with a structural collapse process in a mineral where the interlayer space is occupied by hydrated exchangeable ions. The subordinated clay mineral showed no changes of the basal spacing after heating to 490 °C. The reflection remained at around 9.9 Å, which identifies this mineral as illite. The illite 001 reflection (d=10 Å) was broadened, suggesting poor crystallinity, with a Kubler index of 0.27° 2θ. The second subordinated clay mineral showed no changes in the basal spacing at 7.16 Å after reaction with ethylene glycol, and the disappearance of the reflection after heating at 490 °C indicates amorphization of the mineral. Traces of irregular illite–smectite mixed layer minerals were also identified. Amorphous silica in accessory quantities, found in nature as biogenic silica (e.g., diatomaceous earth) and/or as silica glass, was observed by XRD and SEM observations. Opal-A was identified by the diffuse band centered at approximately 4.04 Å (with
Table 3B Trace and RE elements (ppm) of some thermal muds and mean values of argillaceous sediments and shales.a Sample/element
KC-1
KC-3
KC-5
KC-6
KC-7
KC-8
KC-9
D.L.
A.S.a
Shalesa
Ag As Au (ppb) Ba Be Bi Cd Co Cr Cs Cu Ga Hf Hg Mo Nb Ni Pb Rb Sb Sc Se Sr Ta Th TI U V W Y Zn Zr REE
b0.1 11.2 39.5 309 1.0 0.1 0.2 16.4 123.2 3.6 32.2 11.2 3.1 0.02 0.2 10.2 105 6.9 57.2 b 0.1 11 b 0.5 424.8 0.7 7.0 b 0.1 1.5 87 0.9 16.3 40 117.8 90.82
b0.1 5.1 7.3 225 5.0 0.7 0.2 9.1 61.6 16.0 12.4 18.2 4.5 0.04 1.2 26.7 27 33.7 175.1 0.2 10 b 0.5 214.3 3.3 13.3 0.5 6.3 55 1.9 32.3 38 116.8 108.06
b0.1 45.8 3.5 263 3.0 0.4 0.2 11.0 95.8 39.8 18.7 8.3 2.7 0.05 0.4 8.3 86 20.8 49.8 1.0 7 b 0.5 349.7 0.6 7.8 0.1 3.5 66 3.1 17.6 45 95.1 85.49
b 0.1 62.6 1.9 1153 5.0 0.4 0.1 15.2 73.3 14.8 30.3 17.1 7.2 0.02 0.7 25.8 40 32.3 146 0.4 10 b0.5 1540.4 1.4 28.0 0.6 5.5 95 3.6 24.2 50 274.5 277.7
b 0.1 15.3 5 212 1.0 0.1 0.1 19.3 390.0 9.8 15.3 8.7 4.4 0.02 0.4 10.7 202 8.7 50.4 0.4 7 b0.5 787 0.7 7.3 0.1 1.8 60 1.2 18.5 33 150 95.32
0.1 39.3 38.5 708 2.0 0.5 0.2 16.8 109.5 35.6 30.8 14.2 3.7 0.15 0.6 13.6 56 38.2 115.8 1.2 12 b 0.5 442.5 1.0 15.0 1.6 2.8 92 3.1 22.1 56 117.2 152.26
b 0.1 11.6 b 0.5 110 1.0 b 0.1 0.1 54.5 547.4 4.2 24.1 7.9 2.1 0.02 0.2 8.0 671 7.9 38.7 b0.1 11 0.7 464.1 0.6 4.2 0.1 1.0 69 0.6 13.3 40 67.3 65.89
0.1 1.0 0.5 1.0 0.2 0.1 0.1 0.2 0.002 0.1 0.1 0.5 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 1.0 0.5 0.5 0.1 0.2 0.1 0.1 8.0 0.5 0.1 1.0 0.1
0.007 13 3–4 500–800 2–6 0.05–0.40 0.3 14–20 80–120 5–10 40–60 19–25 2.8–6.0 0.02–0.04 2.0–2.6 15–20 40–90 20–40 120–200 1.2–2 12–15 0.4–0.6 300–450 0.8–1.5 9.6–13 0.5–1.5 3–4 80–130 1.8–2.0 25–35 80–120 160–200 140–245
0.007–0.01 5–13 2.5–4 500–800 2–5 0.05–0.50 0.22–0.3 11–20 60–100 6–8 40 15–25 2.8–4.0 0.018–0.04 0.7–2.6 15–20 50–70 18–25 140–160 0.8–1.5 10–15 0.6 300 1–2 12 0.5–2.0 3.0–4.1 100–130 1.8–2.0 30–40 80–120 150–200 109–224
Note: A.S.: argillaceous sediments. Above and lower values from the mean values were shown in bold and italic, respectively. a Represents mean values of shales and A.S. from Kabata-Pendias and Mukherjee (2009).
M. Çelik Karakaya et al. / Applied Clay Science 48 (2010) 531–537 Table 4 Representative technological properties for some thermal muds of Turkey. Sample number
Liquid limit (%)
Plastic limit (%)
Plasticity index
Soil type
pH
Eh (mV)
EC (mS/cm)
KC-1 KC-2 KC-3 KC-4 KC-5 KC-6 KC-7 KC-8 KC-9 KC-10 V.C.
67.58 n.m. 69.35 45.12 n.m. 66.33 30.50 64.80 49.48 67.70 180
31.88 n.m. 36.81 23.3 n.m. 28.6 n.d. 30.98 28.27 28.14 27
35.7 n.m. 32.54 21.82 n.m. 37.73 n.d. 33.10 21.21 39.46 153
HPC NP MPC LC n.d. HPC n.d. HPC LPC/HPC HPC HPC
7.94 8.45 8.29 9.39 8.50 8.48 8.56 8.27 7.73 8.71 9.90
92 160 129 − 340 86 105 104 − 151 106 90
455 489 8760 1640 280 341 397 848 6310 443
535
Table 6 Some physicochemical characteristics of mineral waters of the studied spas (after Şimşek, 2007).
KC-1 KC-2 KC-3 KC-4 KC-5 KC-6 KC-7 KC-8 KC-9 KC-10
T (°C)
pH
Na + K
Ca + Mg
SO4
HCO3
CO3
Cl
B
45 73 84 74 50 67 73 30 42 70
8.4 7.6 8.7 7.2 7.6 6.6 7.6 8.7 6.8 6.5
2375 75 415 1625 222 259 295 71 9130 809
45 217 33 86 49 212 217 84 1850 192
209 651 185 52 40 485 654 144 2748 490
4654 544 561 2210 534 561 544 329 317 573
287 b10 60 n.d. 54 n.l. b10 n.d. b10 10
693 55 210 1440 37 92 55 16 17 107
99 63 13 45 16 n.l. 63 1 4 13
Note: n.l.: under detection limit, n.d.: could not be determined.
V.C.: virgin clay (Veniale et al., 2004), n.m. not measured, n.d.: could not be determined. HPC: high plastic clay, NP: non-plastic, MPC: moderately plastic clay, LC: low plastic clay.
those of the virgin clay of Veniale et al. (2004). Their plasticity index, or the difference between the liquid and plastic limits, is lower than that of the clay, due to the slightly higher specific surface area of the samples (Tables 4 and 5). The smallest specific surface area was observed in KC-7, which had a calcite and/or CaO (23.04%) content higher than those of the other samples, except KC-5. The CEC values of KC-5, KC-7 and KC-10 were similar and lower than the others. The lowest liquid limits were observed for KC-7, and KC-4. KC-9 showed medium plasticity while liquid limits of the other samples ranged from 64.08 to 69.35, indicating high plasticity (Grabowska-Olszewska, 1998). The CEC values of the samples were similar (b35 meq/100 g). Oil and water absorption values were similar in all samples, except KC-5, which had higher values than the others. The pH of the thermal muds was similar and varies between 7.73 and 8.71. The lowest pH was recorded for KC-1 and KC-9, while the lowest pH values were found for KC-6 and KC-9 at the thermal waters (Tables 4 and 6). The muds were classified as neutral to weakly alkaline, whereas the thermal water was weakly acidic to neutral. The influence of the thermal water on the pH of peloid muds did not seem to be significant.
4. Discussion The samples can be classified as silty clay according to Sheppard (1954), with a low fraction of clay-size particles. The lowest clay fractions were observed for KC-5 and KC-8, whose calcite and nonclay mineral contents were high. The thermal mud contained calcite, quartz, and smectite, with illite, kaolinite, and feldspar in subordinate quantities, while dolomite, amorphous silica, zeolite, pyrite, and halite are rare. The muds used in Turkish spas contain higher amounts of residual minerals, mainly quartz and feldspar, whereas the C.P. was mainly composed of montmorillonite (N95%; Cara et al., 2000) (Table 2).
The plasticity indexes, i.e., the difference between the liquid and plastic limits, of the samples were between 39 and 21, and swelling varies from 67 to 163 (Fig. 4, Table 5). The mechanical properties, i.e., hardness, plasticity, grain size and swelling, affect handling properties of the peloid. The mud samples had low and medium plasticities, together with a low content of clay-size particles, high content of quartz and feldspars and low swelling. These properties resulted in handling difficulties, as the mud had a thick consistency and worse thermal behavior due to a low level of hygroscopic water. This also affects adhering properties of the muds to the skin, and the mud may cause scratches or cuts to the skin during pelotherapy. The mud reacts with water to a minimal extent, in contrast to smectites, which are regarded as hydrophilic. Illite reacts with water to a limited extent (Pająk-Komorowska, 2003). Pastes consisting of bentonite/mineral water mixtures are the best materials for thermal pelotherapy applications (Morandi, 1999; Novelli, 2000). The lowest swelling values were observed for KC-5, KC-7, and KC-9. These samples had higher TOT/C contents than the other mud samples. The CaCO3 content in excess of 28 to 30% may inhibit swelling, but nothing is reported in the literature regarding the effects this has on pelotherapy behavior (Harris, 1996). Kaolinite and illite presented low CECs (3–22 and 20–50 meq/100 g, respectively) and specific surface areas (7–30 and 65–100 m2/g, respectively). In the case of smectites with high cation-exchange capacities (80–150 meq/100 g) and surface areas (280–800 m2/g), these properties are related to the interlayer spaces commonly occupied by hydrated exchangeable cations (Kabata-Pendias and Pendias, 2001; López-Galindo et al., 2007). The highest CEC was observed for KC-1 and the lowest KC-5 and KC-7. The highest surface areas were found in KC-6, KC-5, and KC-1, and the lowest in KC-8. Both CEC and surface areas were much lower than normal smectite values (Table 5). High sand content of the mud reduces its stickiness on the skin, and reduces the CEC and swelling values. Thus, a higher swelling value corresponds to higher water
Table 5 Some technological properties of some thermal muds. KC-1
KC-3
Oil absorption 27.70 27.83 (ml/100 g) Water absorption 33.54 31.70 (ml/100 g) CEC meq/100 g 32.26 23.24 Filtration loss 7.5 ml 91.30 77.90 Filtration loss 7.5 ml 188.6 156.5 Specific surface area 51.00 43.01 (m2/g) Swelling index % 128.2 129.9 Loss of hygroscopic 6.42 5.71 water
KC-5
KC-6
KC-7
KC-8
KC-9
65.92
21.74 27.94
35.45
27.76
79.37
31.59 29.76
39.95
25.93
9.55 254.9 n.d. 54.15
27.96 65.10 136.3 66.46
72.50 4.44
129.4 67.00 163.5 5.84 1.48 4.73
V.C.
9.20 23.90 10.00 63 260.0 97.30 75.90 n.d. 206.31 72.9 16.50 38.50 42.70 92.30 4.18 16.1
Note: n.d.: could not be determined, V.C.: virgin clay (Veniale et al., 2004).
Fig. 4. Casagrande's chart modified by Grabowska-Olszewska (1998) for the evaluation of plasticity of the thermal muds.
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absorption, which improves therapeutic effects. A higher CEC value allows the mud to trap a higher quantity of trace elements, which are essential for therapeutic benefits from the water. The low swelling index and plasticity index, specific surface area (due to the low content of b2 μm clay fraction), and low cationexchange capacity of the mud make them unsuitable for improving the quality of peloid muds. Because smectite content and particle sizes are low, heat capacity and cooling rate are also low. The trace element and Ca2+ content of peloid are important factors during pelotherapy, related to crossing the skin barrier and depositing in the bone. CaO in the thermal muds was originated from their calcite content, not from smectites; so the CEC capacity of the sample muds is much lower than that of the T.M. and C.P. Ca2+ ions in the form of calcite may not cross the skin barrier. However, some of the sand content of the muds originated from biogenic carbonate. Some fragments of ostracods, gastropods and diatoms were observed in the muds. Biogenic carbonate is the active component, and the pH conditioner is responsible for the dissolution and corresponding liberation of Ca, Mg, Sr, and other elements existing in the sand, making them available for adsorption through the skin and passage into the extra-cellular matrix (Gomes and Silva, 2007). Gomes and Silva (2007) pointed out that osteoporosis is not only the lack of Ca in the bone; P, Si, Mg, F, and Sr are the other constituents of bone, and Sr contributes to stabilization of the calcium phosphate structure in the bone. The Sr content of the samples KC-6, KC-7, and KC-9, and partly KC-1 and KC-8, is higher compared to the A.S. and shales (Table 3B), virgin clay (Sr = 397 ppm; Veniale et al., 2004), and shale (Sr = 142 ppm; Gromet et al., 1984). The exchange capability of Sr from the muds is unknown. A number of patients are using these muds to recover from osteoporosis, rheumatism, arthritis, and muscular skeletal traumas. Although some properties of the mud are not suitable for therapy, i.e. size, mineralogical composition, plasticity and CEC, the chemical composition and other features make them useful for treating these illnesses. The total supply of Al from pelotherapy is 0.2 mg/day, so it can be neglected. Lead can be very toxic, and its maximum allowable daily level is about 25 μg/kg body mass/week, even if the observed intake is sometimes higher (WHO, 1996). The lead exposure from pelotherapy is far below the advised amount (2 μg/day). Turkey is one of the top countries in the world in terms of thermal source richness, with almost 1000 thermal springs throughout Anatolia. The temperature of these hot springs varies between 20 and 110 °C (Fig. 1) (Şimşek, 2007). The pH of the thermal waters ranged from 6.60 to 8.70 and temperatures varied from 30 °C to 84 °C (Table 6). The lowest pH values of the thermal water were recorded in KC-6, KC-9, and KC-10, which were classified as weakly acidic to neutral, whereas others were near-neutral to alkaline. KC-1 and KC-4 were rich in HCO3 and alkaline elements. KC-1 was richer in boron ions, while KC-4 was richer in chlorine ions than the other waters. KC-9 is rich in alkali and alkali earth elements, as well as sulfurous water. The CEC, soluble salts, water retention, swelling index, activity, consistency parameters (WL, WP, and PI), thermal behavior, and cooling kinetics are influenced by the geochemistry of mineral waters used for the maturation treatments, with some opposite trends for Br–I–salty water and for sulfurous and Ca-sulfate waters (Veniale et al., 2004). 5. Conclusion We investigated Turkish thermal muds that have been used by local and international visiting patients for pelotherapy since ancient times. We can affirm that the muds we investigated generally contain clay minerals and other minerals. Several properties of the mud samples made them unsuitable for medicinal purposes, even after application of certain improvement or maturation processes. These properties include the low swelling index, low smectite content, low moisture and water absorption, low specific surface area (owing to
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