Enhanced removal efficiency of acid red 18 from aqueous solution using wheat bran modified by multiple quaternary ammonium salts

Chemical Physics Letters 710 (2018) 193–201

Contents lists available at ScienceDirect

Chemical Physics Letters journal homepage: www.elsevier.com/locate/cplett

Research paper

Enhanced removal efficiency of acid red 18 from aqueous solution using wheat bran modified by multiple quaternary ammonium salts

T

⁎

Wei-Xing Zhanga, Lu Laia, , Ping Meia, Yan Lia, Yu-Hang Lia, Yi Liub,c a

College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434023, PR China State Key Laboratory of Virology & Key Laboratory of Analytical Chemistry for Biology and Medicine (MOE), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China c College of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, PR China b

H I GH L IG H T S

quaternary ammonium salts-modified wheat bran for removing anionic dyes. • Multiple equilibrium and kinetic adsorption mechanism were investigated. • The effects of molecular structures of surfactants on the removal efficiency. • The dynamic adsorption studies using the packing column of wheat bran. • The • Potential as biomass adsorbent for the removal of dyes from wastewater.

A R T I C LE I N FO

A B S T R A C T

Keywords: Multiple quaternary ammonium salts Dye removal Wheat bran Adsorption mechanism Surfactant structures

A natural biosorbent prepared from wheat bran (WB) and multiple quaternary ammonium salts (MQAS) was used to remove dye (AR-18) from aqueous solution. The adsorption kinetics and thermodynamic mechanism of the adsorption of AR-18 on MQAS-WB were also examined. Results reveal that adsorption isotherm data can be well described by Langmuir model. The calculated thermodynamic parameters indicate that the adsorption is exothermic and spontaneous. The adsorption kinetics follows the pseudo-second-order model. MQAS-WB shows potential for large-scale wastewater treatment. Dynamic adsorption studies reveal that the dye removal efficiency of the packing column of MQAS-WB is higher than that of raw WB.

1. Introduction Different classes of synthetic dyes are widely used in various industrial fields, including textiles, food, cosmetics, and paper making [1,2]. About 10–15% of dyes are discharged during an industrial process, thereby causing inevitable environmental problems [3]. In general, dyes are so stable that they are difficult to be degraded by light, heat, oxidizing agents, and microorganisms [4]. With strict regulations on water pollution, dye removal from aqueous solution has been extensively explored [5–7]. Various methods, including membrane separation, photocatalysis, biological oxidation, adsorption, ozonation, oxidation, and electrochemical methods, have been employed to remove dye from wastewater [8]. However, these methods have some disadvantages. For example, biological methods are time-consuming and unsatisfactorily effective. Although chemical oxidation possesses a high degradation

⁎

Corresponding author. E-mail address: [email protected] (L. Lai).

https://doi.org/10.1016/j.cplett.2018.09.009 Received 7 July 2018; Accepted 5 September 2018 Available online 06 September 2018 0009-2614/ © 2018 Published by Elsevier B.V.

efficiency, toxic oxidation products are generated. Fenton reactive oxidation, ultrasonic oxidation, ozone-UV combined oxidation and photocatalysis are uneconomic. By comparison, adsorption is an efficient dye removal method when the adsorbent is low-priced and extensive sources [9–12]. Activated carbon is a well-known and widely used adsorbent in daily life and different industrial fields. However, relatively high treatment costs and difficult regeneration of activated carbon have prompted researchers to develop new sorbents [13]. Various nonconventional adsorbents, including clay, guar gumbased hydrogels [14], calcium alginate hydrogel beads [15], wheat bran [16,17], fly ash, walnut shell [18], microalga Spirulina platensis [19], Cucumis sativus peel [20], rice straw [21], crop residues [22], palm ash [23], corncob, barley husk [24], nanomaterials [25,26], Salxi babylonica leaves powder [27] and polymer particles [28], have been employed to remove dye from aqueous solution. Low-cost agricultural residues and byproducts show potential for wastewater treatment

Chemical Physics Letters 710 (2018) 193–201

W.-X. Zhang et al.

(DeTAB), dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (CTAB), and stearyltrimethylammoium bromide (STAB) were also obtained from Aladdin Reagent (Shanghai, China). Bisquaternary ammonium salts (BQAS, 12-2-12) and multiple quaternary ammonium salts (MQAS) were synthesized in our laboratory according to Ref. [36] and [37], respectively. All of the cationic surfactants were recrystallized thrice from acetone and alcohol. All of the other reagents were analytical grade.

applications because of their economic efficiency, eco-friendliness, and resource sustainability [13]. In north China, wheat is an important and abundant crop. However, the disposal of its byproduct wheat bran is considered a serious environmental problem. Wheat bran is wheat grain’s outer shell, that can be obtained as an argicultural byproduct from a flour mill. Wheat bran accounts for 40% of wheat grain weight [29]. In terms of structure, wheat bran consists of an outer pericarp, an inner pericarp, a testa, and hyaline and aleurone layers [29]. The major constituent of wheat bran includes cellulose (32.1%), hemicellulose (29.2%), lignin (16.4%) and extractives (22.3%). Wheat bran can be utilized as an effective adsorbent to remove hazardous materials. For anionic dyes, wheat bran exhibits a low adsorption efficiency because of numerous hydroxyl groups that exist in cellulose, hemicellulose, and lignin structures. The surface modification of wheat bran is practical and effective to enhance its adsorption effeciency for anionic dye. Yue et al. introduced amine groups to the structure of wheat bran through chemical modification to obtain a positive adsorbent [16]. Lee et al. modified rice hull by using ethylenediamine to remove aionic and cationic dyes from aqueous solution [17]. In another study, wheat straw is modified with polyethyleneimine to improve the adsorption capacity for anionic dyes [30]. Magnetic graphene oxide and Fe3O4 nanoparticles have been loaded on the surface of wheat bran [31,32] to improve the reusability and recovery of adsorbents. Cationic surfactants are used to modify the surface of adsorbents and obtain a cationic adsorbent. Surfactant modification is a simple, low-cost, and environmentally friendly method. For example, Malek et al. used quaternary ammonium salts (hexadecyltrimethylammonium bromide, CTAB) to modify pineapple leaf powder [33]. Lafi et al. also enhanced the adsorption capacity of a commercial coffee waste by using cetylpyridinium chloride (CPC) [32]. With the special molecular structures, Gemini surfactants possess remarkably low critical micellization concentration, interesting rheological properties, and abundant microscopic aggregates [34,35]. Cationic Gemini surfactants (12-2-12) improve the adsorption capacity of wheat bran because they have two cationic head groups [29]. As a new type of cationic Gemini surfactants, multiple quaternary ammonium salts (MQAS) have three positive hydrophilic head groups and two hydrophobic alkyl chains. Owing to great performance in the printing and dyeing process, AR-18 becomes a typical kind of azo dye widely used in industrial fields, including textiles, food. In terms of its molecular structure, most importantly, it has three sulfonate groups indicating it owns good solubility and more negative charges helpful to the electrostatic interaction during adsorption process. Considering its wide application and ideal characteristic in molecular structure, AR-18 is chosen as a representative research target for our study. In this study, a natural biosorbent prepared from wheat bran and MQAS was used to remove textile dye (AR-18) from aqueous solution. The removal efficiency of the biosorbent for AR-18 was examined by varying the initial dye concentration, pH, dosage, contact time and temperature. The adsorption kinetics and thermodynamic mechanism of the adsorption of AR-18 on the biosorbent were evaluated. Eight different surfactants were utilized to modify the surface of wheat bran and to understand the effects of molecular structures of cationic surfactants on the removal efficiency. The corresponding adsorption properties of these biosorbents were then evaluated. The dynamic adsorption properties of the packing column of MQAS-WB were analyzed.

2.2. Wheat bran adsorbent preparation Raw wheat bran (RWB) obtained from a flour mill (Shandong, China) was ground to a particle size of 75–100 mesh. Ultrafine wheat bran powders of wheat bran were washed with distilled water thrice to remove dust and soluble impurities. The powders were dried for 12 h at 65 °C under air and were stored in a glass dryer. The cationic surfactantmodified wheat bran was prepared by mixing RWB with a cationic surfactant solution (1 mmol⋅L−1) at a ratio (RWB weight [g]: surfactant solution volume [mL]) of 1: 50. The mixtures were stirred for 24 h at 30 °C, and filtrated to obtain the cationic surfactant-modified WB powders. The powders were washed with distilled water thrice to remove unconjugated surfactant molecules, dried again for 12 h at 65 °C and stored in a glass dryer to preserve the reserve. 2.3. Characterization of adsorbent The morphological characteristics of the adsorbent were observed using a scanning electron microscope (SEM; S-4800, Hitachi, Japan). The samples were mounted on metal grids and coated with platinum in a vacuum evaporator before observation, and the accumulation voltage was 5.0 kV. FT-IR spectra were recorded on a Nicolet 6700 FT-IR spectrometer (Thermo Nicolet, USA). The water contact angle of wheat bran surfaces were measured using a DSA 30 Drop Shape Analysis system (Krüss, Germany). The measurements of contact angle have been repeated ten times. 2.4. Adsorption and desorption studies Appropriate wheat bran powders and 15 mL of dye solution (50 mg⋅L−1) were mixed in a glass flask. The pH of the dye solution was measured using a pH meter (PB-10, Sartorius, German) and adjusted to 3.0 with 0.1 mol·L−1 HCl solution, and the experimental temperature was set at 25 °C. After the resulting solution was stirred for 12 h at 200 rpm, the wheat bran powders were separated from the dye solution through centrifugation at 5000×g for 10 min. The concentration of the dye solution was determined using a UV–vis spectrophotometer (TU1810, Puxi Analytic Instrument Ltd., Beijing, China) equipped with 1.0 cm quartz cells. The maximum adsorbance values of AR-18 solutions were examined at 505 nm. The removal efficiency (%) can be obtained using Eq. (1),

Removal efficiency (%) = −1

c0−ce × 100 c0

(1)

−1

where c0 (mg⋅L ) and ce (mg⋅L ) are the initial concentration and the equilibrium concentration of the dye solution, respectively. The adsorption capacity (Q) of wheat bran powders can be calculated by Eq. (2),

2. Experimental

Q= 2.1. Materials

c0−ce ×V m

(2)

where V (L) and m (g) are the volume of the dye solution and the weight of wheat bran, respectively. Different amounts of wheat bran ranging from 0 g⋅L−1 to 2.4 g⋅L−1 at an interval of 0.2 g⋅L−1 were added to the dye solution to examine the effects of wheat bran dosage on the adsorption of dye. The effects of

Acid Red 18 (AR-18, C.I. 16255) were purchased from Aladdin Reagent (Shanghai, China). The chemical structures of the cationic surfactants used to modify wheat bran are shown in Fig. 1. Sodium dodecyl sulfate (SDS), decyltrimethylammonium bromide 194

Chemical Physics Letters 710 (2018) 193–201

W.-X. Zhang et al.

O

O-

Na+

Na+

O

S

O

OS

O N

N

Na+ OO S O

CH3 H2n+1Cn

+ N

CH3 Br- (n=10, 12, 14,16, 18)

CH3

HO AR-18

(DeTAB, DTAB, TTAB, CTAB and STAB) CH3

CH3

+ + CnH2n+1- N - CH2CH2 - N - Cn H2n+1 2Br

CH3

CH3

+ + + CnH2n+1- N - CH2 CHCH2NCH2 CHCH2 - N-CnH2n+1 3Cl-

CH3

CH3

C2H5

CH3

BQAS

OH

C2H5 OH

CH3

MQAS

Fig. 1. Molecular structure of AR-18 and cationic surfactants used to wheat bran modification.

alkyl chains of surfactant molecules and the hydrophobic regions of WB surface.

pH on dye adsorption were investigated at an adsorbent dosage of 1 g⋅L−1, and an initial dye concentration of 50 mg⋅L−1. The pH of the dye solution was adjusted using NaOH (0.1 mol·L−1) and HCl (0.1 mol·L−1) solution. Different amounts of NaCl were added to 50 mg⋅L−1 dye solution at an adsorbent dosage of 1 g⋅L−1 to examine the effects of ionic strength on dye adsorption. The pH of the solution was adjusted to 3.0 by using 0.1 mol·L−1 HCl solution. The adsorption isotherms were determined at different temperatures of 303, 313, and 323 K, while the initial concentrations of the dye solution range from 0 mg⋅L−1 to 50 mg⋅L−1. The other parameters were kept constant. The adsorption kinetics of AR-18 on wheat bran was investigated at different temperatures of 303, 313, 323, and 333 K. The adsorbent dosage was 1 g⋅L−1, and the initial dye concentration was 50 mg⋅L−1. The specific procedures of desorption and dynamic adsorption studies were depicted in Supporting Information.

3.2. Effects of adsorbent dosage on adsorption behavior The effects of MQAS-WB dosage on its adsorption capacity and removal efficiency for AR-18 are shown in Fig. 4. As the MQAS-WB dosage increases, the adsorption capacity of MQAS-WB decreases. At 2.4 g⋅L−1, the adsorption capacity of MQAS-WB for AR-18 is 20.61 mg⋅g−1. By contrast, the removal efficiency of AR-18 increases as MQAS-WB dosage increases. At > 1.0 g⋅L−1, the removal efficiency of AR-18 increases insignificantly, and the removal efficiency reaches 98.91%. Therefore, the MQAS-WB dosage of 1 g⋅L−1 is chosen for further studies. 3.3. Effects of pH on adsorption behavior Fig. S1 shows the effects of initial pH on the adsorption of AR-18 on MQAS-WB and RWB. For RWB, as pH decreases from 9.0 to 2.0, the adsorption capacity of RWB for AR-18 gradually increases. A similar adsorption curve can be observed in MQAS-WB, but the adsorption capacity of MQAS-WB reaches the maximum when pH is reduced to 3.0. Huang et al. also found similar adsorption results [29]. The changes in the pH of the solution can result in the variation of the surface charges of the adsorbent and the ionization degree of the adsorbate [38]. Therefore, the pH of dye solution plays a key factor in adsorption. In this study, raw wheat bran modified by cationic surfactants is employed to remove anionic dye. Thus electrostatic attraction controls adsorption [16]. Low pH enhances the electrostatic attraction between wheat bran modified by a cationic surfactant and anionic dye molecule, thereby increasing the adsorption capacity. In the following experiments, pH is set at 3.0.

3. Results and discussion 3.1. Characterization of the adsorbent Second derivative analysis is generally used to analyze the changes in the infrared spectra and to resolve the overlaps of the infrared spectral features of the complex biological samples. The second derivative spectra of RWB and MQAS-WB based on infrared analysis are shown in Fig. 2(a) and (b). For wheat bran, the peaks at 2924 and 2852 cm−1 can be attributed to the strong stretching vibration of C-H. Aromatic skeleton vibrations occur at 1511 and 1463 cm−1, while the band at 1161 cm−1 represents the C-O-C stretching vibrations. The modification of MQAS on wheat bran results in an increase in the intensity of some bands such as 2962 and 2852 cm−1. These bands indicate the vibrations of aliphatic groups, which are the main functional groups in the molecule structure of MQAS. The SEM images of RWB and MQAS-WB are shown in Fig. 2(c). The SEM images of MQAS-WB were characterized by a rough surface texture compared with those of RWB. In order to acknowledge the effects of surfactant modification on the surface wettability of wheat bran, the water contact angles of WB and MQAS-WB were examined. As shown in Fig. 3(a), the water contact angles of RWB is about 105 °, indicating the slight hydrophobicity of RWB surface. After the surface modification with MQAS, the water contact angle of MQAS-WB decreases to ∼60°. This decrease is attributed to the hydrophobic interaction between the

3.4. Effect of ionic strength on the adsorption behavior Ionic strength can affect the adsorption behavior of dye [24] because of the electrostatic attraction between adsorbent and the adsorbate. Dye wastewater possesses high ionic strength. Fig. S2 shows the effects of the addition of NaCl on the adsorption of AR-18 on MQASWB. As the NaCl concentration increases from 0 mol⋅L−1 to 0.4 mol⋅L−1, the removal efficiency of AR-18 gradually decreases from 98.21% to 77.96%. With the addition of inorganic salts, the thickness of double electrode layers on the adsorbent surface is reduced, and the 195

Chemical Physics Letters 710 (2018) 193–201

W.-X. Zhang et al.

MQAS-WB

(b)

RWB

3050

MQAS-WB

RWB

Second derivative

Second derivative

(a)

3000 2950

2900 2850

2800

2750

1800

1600

1400

1200

1000

800

-1

-1

Wavenumber (cm )

Wavenumber (cm )

Fig. 2. Characterization of RWB and MQAS-WB based on infrared analysis and SEM. The second derivative spectra of RWB and MQAS-WB: (a) spectrum results between 3050 cm−1 and 2750 cm−1; (b) spectrum results between 1800−1 and 800−1; (c) SEM images of RWB (left) and MQAS-WB (right).

surface charges are decreased [39]. As a result, the electrostatic attraction between the cationic adsorbent and anionic dye weakens. The corresponding removal efficiency of AR-18 decreases as ionic strength increases.

3.5. Adsorption kinetics The effects of contact time on the amount adsorbed of MQAS-WB for AR-18 were investigated to obtain the adsorption kinetic parameters. In Fig. 5, the amount adsorbed of MQAS-WB initially increases as the contact time is prolonged, and gradually reaches equilibrium. At 303 K, adsorption approaches an equilibrium state at a contact time of 4 h. As the experimental temperature increases, equilibrium time is shortened, and the equilibrium amount adsorbed of MQAS-WB decreases. At 333 K, the equilibrium time is reduced to 30 min, while the equilibrium amount adsorbed is decreased to 43.47 mg⋅g−1. The adsorption of AR18 on MQAS-WB is a rapid process. Five kinetic models (pseudo-firstorder, pseudo-second-order, Elovich, intra-particle diffusion, and liquid film diffusion model) are employed to fit the experimental data and to elaborate the kinetic mechanism for the adsorption of AR-18 on MQASWB [40]. These kinetic models can be expressed as follows [41],

Fig. 3. Photographs of water contact angle measurement of RWB (a) and MQAS-WB (b); (c) The corresponding statistical results of left and right water contact angle (CAL and CAR) measurement of RWB and MQAS-WB.

ln(Qe−Qt ) = −k1 t + ln Qe

196

(1)

Chemical Physics Letters 710 (2018) 193–201

W.-X. Zhang et al.

105 80

Q (mg . g -1 )

70

90

Q Removal efficiency

60

75

50

60

40

45

30

30

20

Removal efficiency (%)

(c)

Fig. 4. (a) Photographs of the MQAS-WB before and after the adsorption of AR-18 from aqueous solution; (b) photographs of the dye solution before and after the adsorption process; (c) the effects of adsorbent dosage on the adsorption capacity (mg⋅g−1) and removal efficiency (%) for the adsorption of AR-18 on MQAS-WB (initial dye concentration: 50 mg⋅L−1; experiment temperature: 303 K; contact time: 12 h; the pH: 3.0).

15 0.0

0.5

1.0

1.5

2.0

2.5 -1

Wheat bran dosage (g.L ) 50

Table 1 Kinetic parameters for the adsorption of AR-18 on MQAS-WB.

Q (mg/g)

45

Kinetic model

40 35

303K 313K 323K 333K

30 25

0

2

4

6

Contact time (h)

8

10

Fig. 5. Adsorption kinetics of AR-18 on MQAS-WB at different temperatures (initial pH: 3.0; adsorbent dosage: 1 g⋅L−1; initial dye concentration: 50 mg⋅L−1).

t t 1 = + Qt Qe k2 Qe2

Qt =

1 1 ln(αβ ) + ln t β β

(2)

Parameters

Temperatures

−1

303 K

313 K

323 K

333 K

Pseudo-first-order

Qe,exp (mg⋅g ) Qe,cal (mg⋅g−1) k1(min−1) R2

49.12 18.93 0.021 0.954

48.20 14.08 0.026 0.941

45.96 11.57 0.035 0.964

43.47 7.199 0.051 0.947

Pseudo-second-order

Qe,exp (mg⋅g−1) Qe,cal (mg⋅g−1) k2 (g⋅mg−1⋅min−1) R2

49.12 49.51 0.003 0.999

48.20 48.89 0.005 0.999

47.06 47.37 0.009 0.999

43.47 44.13 0.015 0.999

Elovich

α (mg⋅g−1⋅min−1) β (g⋅mg−1) R2

78.99 0.149 0.984

369.9 0.184 0.962

1148 0.216 0.929

1381 0.219 0.937

Intra-particle diffusion

Intercept ki1(mg⋅g−1⋅min-0.5) R2 Intercept ki2(mg⋅g−1⋅min−0.5) R2

17.71 4.236 0.981 34.42 1.243 0.926

22.63 3.762 0.954 38.84 0.829 0.859

23.66 3.685 0.907 39.71 0.629 0.922

26.69 3.065 0.919 41.86 0.158 0.968

Liquid film diffusion

Intercept kfd(min−1) R2

0.952 0.021 0.959

1.229 0.026 0.947

1.429 0.024 0.931

1.566 0.058 0.977

(3) 3.6. Adsorption thermodynamics

Qt = k i t 1/2 + C

(4)

Q ln ⎛1− t ⎞ = - k fd t ⎝ Qe ⎠

(5)

⎜

The plots of the equilibrium adsorption capacity with the dye concentration at different temperatures are shown in Fig. 6. At low dye concentrations, the adsorption capacity increases sharply, and attains the maximum value as the dye concentration further increases. In this study, Langmuir, Freundlich, and Redlich-Peterson models are employed to fit the variation of the adsorption capacity of MQAS-WB with the equilibrium concentration of the dye [42]. These isotherm equations are expressed as follows [43],

⎟

where Qe and Qt are the amount adsorbed at equilibrium time and at time t, respectively; k1 is the pseudo-first-order rate constant; k2 is the pseudo-second-order rate constant; α and β are the initial adsorption rate and the desorption constant, respectively; k i is the rate constant of intra-particle diffusion model, while C is a constant related to the thickness of boundary layer; k fd is the liquid film diffusion constant. The corresponding kinetic parameters can be obtained by fitting the experimental data with these five models (Table 1). The fitting curves are shown in Figs. S3–S7. The correlation coefficient indicates that the experimental data are consistent with the pseudo-second-order model at different experimental temperatures (R2 = 0.999). Therefore, the adsorption of AR-18 on MQAS-WB is a chemical adsorption process and controlled by electrostatic attraction [40]. The plots of lnk versus 1/T are illustrated in Fig. S8. As the experimental temperature increases, the rate constant of adsorption increases gradually. According to Arrhenius equation, the activation energy of adsorption is 42.96 kJ⋅mol−1.

Ce C 1 = e + Qe Qm Qm KL

ln Qe = ln KF +

Qe =

KR Ce 1 + αR Ceβ

RL =

1 1 + KL C0

1 ln Ce n

(6) (7)

(8)

(9) −1

where Qe (mg⋅g ) is the adsorption capacity of MQAS-WB for AR-18 at the equilibrium time; Qm (mg⋅g−1) is the maximum monolayer 197

Chemical Physics Letters 710 (2018) 193–201

W.-X. Zhang et al.

65

65

60

60

Q e (mg. g-1)

(b) 70

Q e (mg. g-1)

(a) 70

55 50

303K 313K 323K

45 40 35

0

10

20

30

Ce (mg.L-1)

55 50

40

40

35

50

65

60

60

experimental 313K Langmuir Freundlich Redlich-Peterson

45 40 35

0

10

20

30

Ce (mg.L )

40

50

Q e(mg. g-1)

65

Q e(mg. g-1)

(d) 70

55

0

10

20

30

40

50

Ce (mg.L-1)

(c) 70

50

experimental 303K Langmuir Freundlich Redlich-Peterson

45

Fig. 6. Adsorption isotherms of AR-18 on MQAS-WB at different temperatures. The black squares represent the experimental results. The red solid line, green dash line, and blue dash line represent the curves simulated by Langmuir, Freundlich, and Redlich-Peterson models, respectively. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

55 50

experimental 323K Langmuir Freundlich Redlich-Peterson

45 40 35

-1

0

10

20

30

40

50

Ce (mg.L-1)

Table 2 Adsorption parameters obtained from different isotherm models. Adsorption isotherms

Parameters

Temperatures 303 K

313 K

323 K

Langmuir

KL (L⋅mg−1) Qmax (mg⋅g−1) R2 RL

1.748 65.41 0.999 0.005–0.014

1.131 64.64 0.999 0.008–0.022

0.728 64.31 0.999 0.012–0.033

Freundlich

KF ((mg⋅g−1)(L⋅mg−1)1/n) 1/n R2

48.29 0.087 0.845

45.41 0.097 0.815

42.16 0.112 0.758

Redlich-Peterson

KRP (L⋅g−1) aRP ((L⋅mg−1)β) β R2

276.3 4.912 0.962 0.976

129.2 2.244 0.971 0.947

44.36 0.605 1.035 0.947

adsorption capacity; Ce (mg⋅L−1) is the equilibrium concentration of AR-18 solution; KL (L⋅mg−1) is the Langmuir adsorption constant; KF (mg⋅g−1) and n are the Freundlich constants, which are related to the relative adsorption capacity and adsorption intensity, respectively; KR and αR are Redlich-Peterson constants, and the values of β is between 0 and 1. For the Langmuir isotherm equation, Eq. (9) can be used to calculate the dimensionless separation factor (RL ). The values of RL suggest whether the adsorption isotherm is consistent with the Langmuir isotherm equation. The corresponding adsorption parameters obtained from different isotherm models are present in Table 2. Langmuir model yields R2 of 0.999 at different temperatures, whereas Freundlich and Redlich-Peterson models obtain relatively low R2. Therefore, Langmuir model is suitable to describe the adsorption behavior of AR-18 on the surface of MQAS-WB. This finding indicates that the adsorption of MQAS-WB for AR-18 is a monolayer adsorption, and the surface of MQAS-WB is homogeneous [44]. The maximum adsorption capacities of MQAS-WB for AR-18 are 65.41, 64.64, and 64.31 mg⋅g−1 at 303, 313, and 323 K, respectively.

Gibbs free energy (ΔG ), enthalpy change (ΔH ), and entropy change (ΔS ) for the adsorption of AR-18 on MSWB can be calculated using Equations (10) and (11), respectively.

ΔG = −RT ln K

(10)

ΔS ΔH − R RT

(11)

ln K =

ΔG , ΔH , and ΔS obtained at different temperatures are shown in Table 3. The calculated thermodynamic parameters indicate that Table 3 Thermodynamic parameters for the adsorption of AR-18 on MQAS-WB.

198

T (K)

ΔG (kJ mol−1)

ΔH (kJ⋅mol−1)

ΔS (J⋅mol−1⋅K−1)

303 K 313 K 323 K

−1.458 −0.321 0.852

−36.460

−115.500

Chemical Physics Letters 710 (2018) 193–201

W.-X. Zhang et al.

(b) Removal of dye (%)

Removal of dye (%)

(a) 100 80 60 40 20

100 80 60 40 20 0

0

RWB

SDS-WB

DTAB-WB

RWB DeTAB DTAB TTAB CTAB STAB -WB -WB -WB -WB -WB

Removal of dye (%)

(c) 100

Fig. 7. (a) The removal efficiency of wheat bran (WB) modified by opposite charged surfactants for AR-18 (adsorbent dosage: initial dye concentration: 1 g⋅L−1; 50 mg⋅L−1; pH value: 3.0; experiment temperature: 303 K; contact time: 12 h); (b) the removal efficiency of WB modified by cationic surfactants with different alkyl chains for AR-18 (adsorbent dosage: 1 g⋅L−1; initial dye concentration: 50 mg⋅L−1; pH value: 3.0; experiment temperature: 303 K; contact time: 12 h); (c) the removal efficiency of WB modified by single quaternary ammonium salts, bisquaternary ammonium salts, and multiple quaternary ammonium salts for AR-18 (adsorbent dosage: 1 g⋅L−1; initial dye concentration: 50 mg⋅L−1; pH value: 3.0; experiment temperature: 303 K; contact time: 12 h).

80 60 40 20 0 RWB

DTAB-WB BQAS-WB MQAS-WB

efficiency are hardly changed (∼98%) with the volume of the dye solution increases from 100 mL to 5000 mL. The equilibrium adsorption capacities of MQAS-WB for AR-18 remain unchanged (∼ 49 mg⋅g−1). This condition indicates that the decrease in removal efficiency is not observed as the volume of dye solution increases. Therefore, MQAS-WB shows potential for large-scale wastewater treatment.

adsorption is exothermic and spontaneous, while the negative ΔS corresponds to a decrease in the disorder degree of adsorption. 3.7. Effects of the molecular structure of cationic surfactants The surface modification of wheat bran by using cationic surfactants is a practical and effective approach to enhance the adsorption efficiency of wheat bran for anionic dye [29]. Therefore, we aim to determine whether the molecular structures of surfactants cause detectable effects on the adsorption capacity of wheat bran for anionic dyes. To investigate the effects of the molecular structure of cationic surfactants, we use eight different surfactants to modify the surface of wheat bran. SDS and DTAB have opposite charged headgroups and same length of alkyl chain. In Fig. 7 (a), the dye removal efficiency of DTABWB (cationic adsorbent) is higher than that of SDS-WB (anionic adsorbent), indicating that the electrostatic attraction between the cationic adsorbent and the anionic dye is essential for adsorption. Besides the charge of hydrophilic headgroups, the length of alkyl chain plays a key factor in the interfacial properties of surfactants [34]. In Fig. 7(b), the removal efficiency of dye initially increases and then remains unchanged as the length of alkyl chains increase. This finding indicates the interaction between raw wheat bran and cationic surfactants becomes weak when the alkyl chain of surfactants is relatively short, resulting in the decrease in the dye removal efficiency. Furthermore, single quaternary ammonium salts, bisquaternary ammonium salts, and multiple quaternary ammonium salts were used to modify wheat bran. In Fig. 7(c), the removal efficiency of surfactant-modified wheat bran for AR-18 increases as the number of cationic headgroups of surfactant molecules increases. Under the same condition, MQAS-WB possesses the highest dye removal efficiency.

3.9. Desorption behavior of AR-18 from MQAS-WB The effects of pH, experimental temperatures, and the ethanol addition on the desorption behavior of AR-18 from the MQAS-WB surface were examined to study the recovery of MQAS-WB. In Fig. S12(a), as the pH of the solution increases, the desorption efficiency of the dye from MQAS-WB increases. In particular, the desorption efficiency of the dye increases to 48.61% at pH 10.0. At pH 7.0, the increase in temperature enhances the desorption efficiency of dye [Fig. S12(b)]. At 333 K, the desorption efficiency of dye reaches 72.39%. In Fig. S12(c), the desorption efficiency of dye initially increases and then decreases when the volume fraction of ethanol increases. When the volume fraction of ethanol is 75%, the maximum desorption efficiency of the dye is reached the maximum (78.68%). Therefore, alkaline environment, temperature increase, and ethanol addition contribute to the desorption of dye from MQAS-WB. 3.10. Dynamic adsorption behavior of MQAS-WB for AR-18 The dynamic adsorption properties of RWB and MQAS-WB for AR18 have been examined. Fig. 8(a) and (b) show the photographs of column separation and dye solution after column separation by using the packing column of MQAS-WB at different times, respectively. According to the concentration of the dye solution passing through the packing column, the removal efficiency of RWB and MQAS-WB for AR18 at different times is shown in Fig. 8(c). For the packing column of RWB, the removal efficiency of dye gradually decreases as separation time is prolonged. When the separation time is more than 160 min, the

3.8. Effects of the treatment volume of dye solution The effects of the treatment volume of dye solution on the removal efficiency of dye were examined. Fig. S11 shows that the removal 199

Chemical Physics Letters 710 (2018) 193–201

W.-X. Zhang et al.

(a)

Removal efficiency (%)

(c)

(b)

Fig. 8. (a) Photograph of the column separation process; (b) photograph of the dye solution after the column separation using the packing column of MQAS-WB at different times; (c) the dynamic removal efficiency of RWB and MQAS-WB for AR-18 (adsorbent dosage: 0.5 g; initial dye concentration: 50, 70, and 90 mg⋅L−1; pH value: 3.0; flow rate: 60 mL⋅h−1).

100 80 60 40

RWB, 50 mg/L MQAS-WB, 50 mg/L MQAS-WB, 70 mg/L MQAS-WB, 90 mg/L

20 0

0

80

160

240

320

400

t (min) online version, at https://doi.org/10.1016/j.cplett.2018.09.009.

removal efficiency decreases sharply. When the separation time is extended to 320 min, the packing column of RWB is almost unable to remove the dye. By contrast, the packing column of MQAS-WB exhibits a high removal efficiency. At a dye concentration of 50 mg⋅L−1, the dye can be completely removed from the aqueous solution by using the packing column of MQAS-WB when the separation time is less than 4 h. The removal efficiency gradually decreases as the separation time is prolonged. When the separation time is extended to 7 h, the packing column of MQAS-WB cannot efficiently remove the dye from the flowing solution. When the concentration of dye solution increases, the dynamic adsorption properties of MQAS-WB for AR-18 moderately decrease. These dynamic adsorption properties are conducive to the application of agricultural residues and by-products as biosorbent.

References [1] H.A. Shindy, Fundamentals in the chemistry of cyanine dyes: a review, Dyes Pigment. 145 (2017) 505–513. [2] J.L. Bricks, A.D. Kachkovskii, Y.L. Slominskii, A.O. Gerasov, S.V. Popov, Molecular design of near infrared polymethine dyes: a review, Dyes Pigment. 121 (2015) 238–255. [3] G. Boczkaj, A. Fernandes, Wastewater treatment by means of advanced oxidation processes at basic pH conditions: a review, Chem. Eng. J. 320 (2017) 608–633. [4] A. Asghar, A.A.A. Raman, W. Daud, Advanced oxidation processes for in-situ production of hydrogen peroxide/hydroxyl radical for textile wastewater treatment: a review, J. Clean Prod. 87 (2015) 826–838. [5] A. Pettignano, N. Tanchoux, T. Cacciaguerra, T. Vincent, L. Bernardi, E. Guibal, F. Quignard, Sodium and acidic alginate foams with hierarchical porosity: preparation, characterization and efficiency as a dye adsorbent, Carbohydr. Polym. 178 (2017) 78–85. [6] R. Pourfaraj, S.J. Fatemi, S.Y. Kazemi, P. Biparva, Synthesis of hexagonal mesoporous MgAl LDH nanoplatelets adsorbent for the effective adsorption of Brilliant Yellow, J. Colloid Interface Sci. 508 (2017) 65–74. [7] M. Tanzifi, S.H. Hosseini, A.D. Kiadehi, M. Olazar, K. Karimipour, R. Rezaiemehr, I. Ali, Artificial neural network optimization for methyl orange adsorption onto polyaniline nano-adsorbent: kinetic, isotherm and thermodynamic studies, J. Mol. Liq. 244 (2017) 189–200. [8] V.K. Gupta, Suhas, Application of low-cost adsorbents for dye removal – a review, J. Environ. Manage. 90 (8) (2009) 2313–2342. [9] S.B. Wang, Y.L. Peng, Natural zeolites as effective adsorbents in water and wastewater treatment, Chem. Eng. J. 156 (1) (2010) 11–24. [10] A. Zahir, Z. Aslam, M.S. Kamal, W. Ahmad, A. Abbas, R.A. Shawabkeh, Development of novel cross-linked chitosan for the removal of anionic Congo red dye, J. Mol. Liq. 244 (2017) 211–218. [11] U.A. Qureshi, Z. Khatri, F. Ahmed, A.S. Ibupoto, M. Khatri, F.K. Mahar, R.Z. Brohi, I.S. Kim, Highly efficient and robust electrospun nanofibers for selective removal of acid dye, J. Mol. Liq. 244 (2017) 478–488. [12] R.P.F. Melo, E.L.B. Neto, S.K.S. Nunes, T.N.C. Dantas, A.A.D. Neto, Removal of Reactive Blue 14 dye using micellar solubilization followed by ionic flocculation of surfactants, Sep. Purif. Technol. 191 (2018) 161–166. [13] G.M. Gadd, Biosorption: critical review of scientific rationale, environmental importance and significance for pollution treatment, J. Chem. Technol. Biotechnol. 84 (1) (2009) 13–28. [14] N. Thombare, U. Jha, S. Mishra, M.Z. Siddiqui, Borax cross-linked guar gum hydrogels as potential adsorbents for water purification, Carbohydr. Polym. 168 (2017) 274–281. [15] X. Vecino, R. Devesa-Rey, J.M. Cruz, A.B. Moldes, Study of the physical properties of calcium alginate hydrogel beads containing vineyard pruning waste for dye removal, Carbohydr. Polym. 115 (2015) 129–138. [16] Q.Q. Zhong, Q.Y. Yue, Q.A. Li, X. Xu, B.Y. Gao, Preparation, characterization of modified wheat residue and its utilization for the anionic dye removal, Desalination 267 (2–3) (2011) 193–200. [17] S.T. Ong, C.K. Lee, Z. Zainal, Removal of basic and reactive dyes using ethylenediamine modified rice hull, Bioresour. Technol. 98 (15) (2007) 2792–2799. [18] R.X. Tang, C. Dai, C. Li, W.H. Liu, S.T. Gao, C. Wang, Removal of methylene blue from aqueous solution using agricultural residue walnut shell: equilibrium, kinetic, and thermodynamic studies, J. Chem. (2017). [19] F. Deniz, R.A. Kepekci, Equilibrium and kinetic studies of azo dye molecules biosorption on phycocyanin-extracted residual biomass of microalga Spirulina platensis, Desalin. Water Treat. 57 (26) (2016) 12257–12263. [20] L.Y. Lee, S.Y. Gan, M.S.Y. Tan, S.S. Lim, X.J. Lee, Y.F. Lam, Effective removal of Acid Blue 113 dye using overripe Cucumis sativus peel as an eco-friendly biosorbent from agricultural residue, J. Clean Prod. 113 (2016) 194–203. [21] S. Chowdhury, S. Chakraborty, P. Das, Adsorption of crystal violet from aqueous

4. Conclusions The removal of AR-18 from aqueous solution by using wheat bran modified with multiple quaternary ammonium salts was investigated. The optimum pH for the adsorption of AR-18 on MQAS-WB is 3.0. As temperature increases, the adsorption capacity decreases. The adsorption capacity of MQAS-WB for AR-18 also decreases as the NaCl concentration increases. The adsorption isotherm data can be well described by Langmuir model, while the adsorption kinetics follows the pseudo-second-order model. The calculated thermodynamic parameters indicate that the adsorption of AR-18 on MAQS-WB is exothermic and spontaneous. The amount of cationic headgroups remarkably influences the removal efficiency of dye because the adsorption of AR-18 on MQAS-WB is controlled by the electrostatic attraction. The removal efficiency of AR-18 is maintained at about 98% when the volume of the dye solution increases from 100 mL to 5000 mL, indicating that MQASWB shows potential for large-scale wastewater treatments. Alkaline environment, temperature increase, and the ethanol addition contribute to the desorption of dye from MQAS-WB. The results of dynamic adsorption studies reveal that the dye removal efficiency of the packing column of MQAS-WB is higher than that of RWB. Funding The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China (grant no. 21403017, 21473125) and the Bagui Scholar Program of Guangxi (2016). Conflict of interest: The authors declare that they have no conflict of interest. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the 200

Chemical Physics Letters 710 (2018) 193–201

W.-X. Zhang et al.

[22]

[23] [24]

[25]

[26]

[27]

[28]

[29]

[30]

[31]

[32]

solution by citric acid modified rice straw: equilibrium, kinetics, and thermodynamics, Sep. Sci. Technol. 48 (9) (2013) 1339–1348. R.K. Xu, S.C. Xiao, J.H. Yuan, A.Z. Zhao, Adsorption of methyl violet from aqueous solutions by the biochars derived from crop residues, Bioresour. Technol. 102 (22) (2011) 10293–10298. A.A. Ahmad, B.H. Hameed, N. Aziz, Adsorption of direct dye on palm ash: kinetic and equilibrium modeling, J. Hazard. Mater. 141 (1) (2007) 70–76. T. Robinson, B. Chandran, P. Nigam, Removal of dyes from an artificial textile dye effluent by two agricultural waste residues, corncob and barley husk, Environ. Int. 28 (1–2) (2002) 29–33. P. Zhang, I. Lo, D. O'Connor, S. Pehkonen, H. Cheng, D. Hou, High efficiency removal of methylene blue using SDS surface-modified ZnFe2O4 nanoparticles, J. Colloid Interface Sci. 508 (2017) 39–48. M. Jafari, M.R. Rahimi, M. Ghaedi, H. Javadian, A. Asfaram, Fixed-bed column performances of azure-II and auramine-O adsorption by Pinus eldarica stalks activated carbon and its composite with zno nanoparticles: Optimization by response surface methodology based on central composite design, J. Colloid Interface Sci. 507 (2017) 172–189. A. Khodabandehloo, A. Rahbar-Kelishami, H. Shayesteh, Methylene blue removal using Salix babylonica (Weeping willow) leaves powder as a low-cost biosorbent in batch mode: kinetic, equilibrium, and thermodynamic studies, J. Mol. Liq. 244 (2017) 540–548. M.S. de Luna, R. Castaldo, R. Altobelli, L. Gioiella, G. Filippone, G. Gentile, V. Ambrogi, Chitosan hydrogels embedding hyper-crosslinked polymer particles as reusable broad-spectrum adsorbents for dye removal, Carbohydr. Polym. 177 (2017) 347–354. Y. Zhang, G.H. Huang, C.J. An, X.Y. Xin, X. Liu, M. Raman, Y. Yao, W.X. Wang, M. Doble, Transport of anionic azo dyes from aqueous solution to gemini surfactantmodified wheat bran: synchrotron infrared, molecular interaction and adsorption studies, Sci. Total Environ. 595 (2017) 723–732. Y. Shang, J.H. Zhang, X. Wang, R.D. Zhang, W. Xiao, S.S. Zhang, R.P. Han, Use of polyethyleneimine-modified wheat straw for adsorption of Congo red from solution in batch mode, Desalin. Water Treat. 57 (19) (2016) 8872–8883. A.E. Pirbazari, E. Saberikhah, N.G.A. Gorabi, Fe3O4 nanoparticles loaded onto wheat straw: an efficient adsorbent for Basic Blue 9 adsorption from aqueous solution, Desalin. Water Treat. 57 (9) (2016) 4110–4121. H.Y. Ge, C.C. Wang, S.S. Liu, Z. Huang, Synthesis of citric acid functionalized

[33]

[34]

[35]

[36] [37]

[38]

[39]

[40] [41]

[42]

[43] [44]

201

magnetic graphene oxide coated corn straw for methylene blue adsorption, Bioresour. Technol. 221 (2016) 419–429. A.A. Kamaru, N.S. Sani, N. Malek, Raw and surfactant-modified pineapple leaf as adsorbent for removal of methylene blue and methyl orange from aqueous solution, Desalin. Water Treat. 57 (40) (2016) 18836–18850. L. Lai, P. Mei, X.M. Wu, L. Cheng, Z.H. Ren, Y. Liu, Interfacial dynamic properties and dilational rheology of sulfonate gemini surfactant and its mixtures with quaternary ammonium bromides at the air-water interface, J. Surfactants Deterg. 20 (3) (2017) 565–576. L. Lai, P. Mei, X.M. Wu, L. Chen, Y. Liu, Interfacial dynamic properties and dilational rheology of mixed anionic and cationic Gemini surfactant systems at airwater interface, Colloid Surf. A-Physicochem. Eng. Asp. 509 (2016) 341–350. R. Zana, J. Xia, Gemini Surfactants: Synthesis, Interfacial and Solution-Phase Behavior, and Applications, Marcel Dekker, 2004. T.S. Kim, T. Kida, A. Yohji Nakatsuji, I. Ikeda, Preparation and properties of multiple ammonium salts quaternized by epichlorohydrin, Langmuir 12 (26) (1996) 6304–6308. M. Rahmani, M. Kaykhaii, M. Sasani, Application of Taguchi L16 design method for comparative study of ability of 3A zeolite in removal of Rhodamine B and Malachite green from environmental water samples, Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. 188 (2018) 164–169. K.W. Jung, S. Lee, Y.J. Lee, Synthesis of novel magnesium ferrite (MgFe2O4)/biochar magnetic composites and its adsorption behavior for phosphate in aqueous solutions, Bioresour. Technol. 245 (2017) 751–759. H. Qiu, L. Lv, B.C. Pan, Q.J. Zhang, W.M. Zhang, Q.X. Zhang, Critical review in adsorption kinetic models, J. Zhejiang Univ.-SCI A 10 (5) (2009) 716–724. W. Plazinski, W. Rudzinski, A. Plazinska, Theoretical models of sorption kinetics including a surface reaction mechanism: a review, Adv. Colloid Interface Sci. 152 (1–2) (2009) 2–13. G.Z. Kyzas, E.A. Deliyanni, K.A. Matis, Graphene oxide and its application as an adsorbent for wastewater treatment, J. Chem. Technol. Biotechnol. 89 (2) (2014) 196–205. I. Anastopoulos, G.Z. Kyzas, Agricultural peels for dye adsorption: a review of recent literature, J. Mol. Liquids 200 (2014) 381–389. W.W. Zhao, Y.X. Fan, H. Wang, Y.L. Wang, Coacervate of polyacrylamide and cationic gemini surfactant for the extraction of methyl orange from aqueous solution, Langmuir 33 (27) (2017) 6846–6856.