Catalytic ozonation of an azo-dye using a natural aluminosilicate

Journal Pre-proof Catalytic ozonation of an azo-dye using a natural aluminosilicate ˇ N. Inchaurrondo, C. di Luca, G. Zerjav, J.M. Grau, A. Pintar, P. Haure

PII:

S0920-5861(19)30668-6

DOI:

https://doi.org/10.1016/j.cattod.2019.12.019

Reference:

CATTOD 12597

To appear in:

Catalysis Today

Received Date:

30 September 2019

Revised Date:

5 December 2019

Accepted Date:

14 December 2019

ˇ Please cite this article as: Inchaurrondo N, di Luca C, Zerjav G, Grau JM, Pintar A, Haure P, Catalytic ozonation of an azo-dye using a natural aluminosilicate, Catalysis Today (2019), doi: https://doi.org/10.1016/j.cattod.2019.12.019

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Catalytic ozonation of an azo-dye using a natural aluminosilicate

N. Inchaurrondoa* [email protected], C. di Lucaa, G. Žerjavb, J.M. Grauc, A. Pintarb, P. Haurea

a

Dpto. de Ing. Química/Div. Catalizadores y Superficies-INTEMA-CONICET/UNMdP, Mar

del Plata, Argentina Laboratory for Environmental Sciences and Engineering, Department of Inorganic Chemistry

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b

and Technology, National Institute of Chemistry, SI-1001 Ljubljana, Slovenia c

Instituto de Investigaciones en Catálisis y Petroquímica “Ing. José Miguel Parera”- INCAPE

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(FIQ, UNL-CONICET), Santa Fe, Argentina

*

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Corresponding author.

Graphical abstract

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CATALYTI C OZONATI ON O3 HO•

HCl H2SO4

Mn

Orange II

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(acidic pH, over 20 h)

↑ Si:Al ratio ↑ Surface area ↓Fe and Mn %

XTOC = 88% (acidic pH)

active sites

XTOC = 91%

ACI D TREATMENT

Montanit300 ® Natural aluminosilicate

 Mild activity at neutral pH  Quick deactivation (reversible)

Highlights 

Cost-effective natural aluminosilicate for catalytic ozonation of Orange II.

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

Acid treatment modified surface area, hydrophobicity, acidity, pHPZC, composition.



Natural catalyst reached remarkable 90 % mineralization.



Catalytic activity sustained over 4 cycles (20 h.).



Activity related to Mn traces.

Abstract - Catalytic ozonation of Orange II (100 mg/L) was studied using aluminosilicate Montanit300® (M) modified with H2SO4 (MS) and HCl (MH). Characterization of these

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samples was performed through several techniques: SEM/EDX, FTIR, XRD, FRX, TPD

pyridine, surface area, pHPZC. Acid treatment increased surface area, Si:Al ratio and quantity of acid sites, but reduced pHPZC and Fe and Mn content.

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Ozonation experiments achieved complete decoloration and remarkable TOC conversions of 66, 65, 88 and 91% by single ozonation and catalytic ozonation with MH, MS and M,

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respectively. Higher M and MS activity under acidic pH was attributed to Mn leaching.

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Decreased mineralization efficiency in the presence of tert-butanol suggested a radical mechanism. At neutral pH, M showed no activity, while MS presented mild activity owing to

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its enlarged hydrophobicity.

The M sample sustained mineralization levels over 20 h. Lower O3 dose caused quick MS deactivation. However, it was reversed through calcination and prevented with a higher oxidant dose.

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Mn is naturally found in Montanit300®, thus making it an inexpensive catalyst. The development of a dynamic cycle combining reduced and oxidized forms of Mn was key to the outstanding activity observed.

1. Introduction

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Large volumes of wastewater are produced by dyeing and washing processes in the textile industry reducing light radiation penetration into water and therefore affecting the photosynthetic function of plants [1]. Due to the low removal efficiency of dyes in conventional biological installations, the treatment through Advanced Oxidation Processes (AOPs) has received increasing attention in recent years [2]. Azo compounds are the most widely used dyes and account for 60% of the total dye structures known to be manufactured [3]. In the present study, Orange II (OII) was selected as a model compound for evaluation in

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catalytic ozonation experiments, since due to its azo character it is representative of a high number of dyes in the textile industry.

Among the AOPs, the catalytic ozonation process is a promising option for treatment of

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industrial effluents due to its ability to oxidize refractory compounds [4]. The mechanism of oxidation by ozone is a complex process that takes place by two routes: direct reaction with

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dissolved ozone or indirect oxidation through the formation of radicals (OH•). The intensity of

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both mechanisms depends on factors like the nature of the pollutant, ozone dose and pH. Normally, under acidic conditions (pH<4) direct ozonation prevails while at pH>9, the indirect route is the most important [5]. Ozonation carried out in the presence of a catalyst

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may present several advantages, such as: (i) enhances the effective generation of hydroxyl radicals even at low pH values; (ii) reduces ozone requirement; (iii) decreases bromate formation, and (iv) reduces the action of radical inhibitors [5].

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In order to enhance performance without increasing costs, many authors have proposed the use of natural catalysts, especially clays, zeolites and natural oxides [6-8]. In this context, we propose to evaluate the performance of a natural aluminosilicate, Montanit300®, from Montana Žalec, Slovenia, in the catalytic ozonation of the azo-compound, OII. The use of this abundant, inexpensive natural material may optimize the ozonation process with a lower cost and environmental impact compared to synthetic materials. In addition, the raw Montanit300®

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was previously studied in a different AOP, the Fenton-like oxidation of OII, showing good mineralization levels (70%) at 70ºC and pH=3 [9]. However, the extent of Fe leaching resulted too high (7 mg/L). Therefore, the evaluation of Montanit300® in the ozonation of OII will be performed searching for a higher mineralization level and reduced leaching at lower temperature, in contrast to the Fenton process. While several publications reported the advantages of catalytic ozonation, there is a lack of understanding about reaction mechanism and catalyst deactivation [10]. Some authors stated

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that Brönsted or Lewis acid sites present on the surface of the catalysts play an important role in ozone decomposition and production of radicals [5, 7, 11]. Valdés et al. [7] reported that acid treated zeolites present a higher amount of Brönsted acid sites, which promotes ozone

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decomposition into hydroxyl radicals and therefore pollutants oxidation. On the other hand,

activity has also been attributed to the direct reaction between adsorbed ozone and pollutants,

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which in zeolites is directly related to the silica-to-alumina ratio [12-16]. Acid activation can

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also increase the density of silanol groups (increases Si:Al ratio) and therefore the hydrophobic character of the surface, promoting the catalytic activity of the material. Taking into account these previous studies, we also propose to modify Montanit300® with HCl and

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H2SO4 treatments, and according to the characterization results choose the material with the most appropriate characteristics (surface area, acid sites, Si/Al ratio, Fe/Mn content) to be evaluated in the ozonation of OII.

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Montanit300® was previously evaluated as a catalyst for the depolymerization of polyethylene by our collaborative Slovenian group [18], and as mentioned before, as a natural catalyst for the Fenton-like reaction [9]. Both studies showed promising results regarding the catalytic properties of this aluminosilicate. Therefore, the novelty of this study lies in the extension of application possibilities of this profitable material to different processes. In addition, reaction and catalyst deactivation mechanisms on this type of processes is still under discussion and

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this study will contribute on this subject using a material of natural origin. Performance in terms of stability, leached species, homogeneous contribution and presence of radical scavengers will be evaluated.

2. Experimental

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2.1. Catalyst characterization

Characterization methodology by DRIFTS technique, emission scanning electron microscope and energy-dispersive X-ray analysis (SEM/EDX), and N2 Physisorption were reported in a

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previous study by Djinović et al. [17]. Characterization methodology of point of zero charge (pHPZC), powder X-ray diffraction (XRD) and X-ray fluorescence (XRF) were reported by

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Inchaurrondo et al. [9]. The amount of acid sites was assessed by means of temperature

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programmed desorption (TPD) of pyridine as reported by Inchaurrondo et al. [9] for fresh samples and as reported by di Luca et al. [18], for comparison between fresh and used samples.

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Leached species were measured by Inductively Coupled Plasma Mass Spectrometry, ICP-MS (Agilent Technologies, model 7500 Series).

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2.2. Oxidation tests

The catalytic ozonation of OII (c0=100 mg/L) was performed during 4 or 5 h in a 1 L semibatch stirred-tank reactor at T=25ºC, O3 dose = 7 or 14 mg·min-1 L-1, ccatalyst = 1 g/L and pH0=6. Ozone was generated from pure oxygen with an Enaly KNT24 generator and O3 concentration in the gas phase was monitored using a BMT64 sensor.

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The OII solution decoloration was evaluated at =485 nm using a Shimadzu UV-1800 spectrophotometer. Total organic carbon (TOC) content was determined by means of a TOC analyser (Shimadzu, model TOC-VCPN). Reported values are the average of at least two measurements and error bars represent the standard deviation.

2.3. Chemical treatment of Montanit300®

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The modified zeolites were prepared from a naturally-occurring aluminosilicate (Montanit300®, Montana Žalec, Slovenia), labelled M, as reported in a previous study by

Djinović et al. [17] (see Table S1). Samples were digested with boiling acid, under reflux,

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using H2SO4 (MS) and HCl (MH) with a weight ratio m(Montanit300®):m(acid solution) of

1:10 in all cases. MS samples were treated with different sulfuric acid concentrations (10 and

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80 wt.%: samples 10MS, 80MS) for 6 h, while the digestion with hydrochloric acid (5 mol/L)

dried.

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3. Results and discussion

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was performed during 45 min (sample 5MH45). Treated samples were filtered, washed and

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3.1.Catalyst characterization

Montanit300® was characterized thoroughly in previous studies as a catalyst for the Fentonlike reaction and for the depolymerization of polyethylene [9, 17]. Characterization by SEM-EDX was performed (Figs. S1-S4) and revealed a chemical weight composition with a medium degree of homogeneity in each sample (Table S1, Fig. S5). SiO2 was identified as a major compound, together with other mineral compounds, i.e. Al, Fe, K,

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Ca and Mg. Acid leaching decreased the concentration of all metallic cations, which are present as impurities or charge-balancing cations [17]. XRF results indicated the presence of Mn in only sample M (Table S3). According to XRD measurements, the M sample is mostly composed of quartz and zeolites heulandite and clinoptilolite (Fig. S6). The zeolite structure presents an open framework containing six-membered rings of silica and alumina tetrahedral, joined in parallel planes. Although chemical formula varies with composition, a typical representation is given by

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(Na2K2Ca)3Al6Si30O72·24H2O [17]. This is usually present as plate-like crystals (Fig. S1). Morphological properties of samples are presented in Table 1. The acid treatment increased the BET surface area and pore volume, probably due to dissolution of its framework.

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According to DRIFTS results (Figs. S7), the drastic acid treatment increased the Si/Al ratio, which relates to the disappearance of Si-O-Al bending (520 cm-1) and a progressive shift of

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the Si-O-Si absorption band from about 1010 cm−1to higher wavenumbers.

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The loss of Al3+ cations led to an increased hydrophobic character (Table 1). Zeolites are basically hydrophilic, but they turn hydrophobic when the Si/Al ratio reaches eight or ten. Zeolites with high Si/Al ratios are called high silica zeolites and are known to have good

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adsorption properties for organic molecules [19-20]. In the TPD-pyridine experiments, the pyridine chemisorbed on centers of different acidic strength is desorbed as the temperature increases. Thus, the desorption curve quantifies the

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total amount of acid sites (weak, medium and strong acid sites) of each sample. The bridging OH group linking Si to Al, both tetrahedrally coordinated in zeolite frameworks is certainly the most studied Brønsted site on solid acids and its acidic properties have been shown to depend on the zeolite structure, aluminium content and distribution, and on the environment defined by the zeolite channels and/or cages geometry [21]. It has been reported that acid treatment and dealumination could lead to a higher quantity of active acid sites on zeolite

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surface [7, 21-23]. Barrer and Peterson [23], reported aluminium expulsion in a soluble form and its replacement by a nest of four hydroxyl groups. However, in most of our acid treated samples the quantity of acid sites is almost the same as in the original sample with a slight increase in 5MH45 (Table 1). During the severe treatment with 80% wt. of H2SO4, dissolution and high dealumination of M was observed, resulting in a chemical composition approaching that of SiO2. Therefore, the amount of acid sites in 80MS sample resulted much lower (Fig. 1).

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After acid digestions, the pHPZC decreased dramatically (Table 1). The M sample presents a much higher pHPZC, which would favor electrostatic interactions between the catalyst surface and dissociated anionic pollutants. The surface charge of M sample is positive at pH<9, while

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the surface charge of 5MH45 and 80MS solids is negative at pH>3.2.

According to the characterization results, 5MH45, 80MS and untreated M samples were

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selected to be tested during ozonation experiments. The 5MH45 and 80MS samples were

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chosen as they presented the highest specific surface area, additionally 5MH45 showed slightly higher quantity of acidic sites and 80MS showed higher hydrophobicity (Si:Al ratio). However, according to EDX and XRF results, these samples also showed lower Fe and Mn

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content, elements which have been linked to catalytic activity in ozonation [5]. Therefore, sample M, which presents a higher amount of Fe and Mn, was also selected to be evaluated.

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3.2. Orange II oxidation tests

3.2.1. Decoloration and mineralization of OII After 240 min, complete decoloration and TOC conversions of 66, 91, 65 and 88% were achieved by means of single ozonation and catalytic ozonation with M, 5MH45 and 80MS samples, respectively (Fig. 2). The pH value of the reaction medium decreased from 6 to 3-3.5

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after 30 min, due to generation and accumulation of carboxylic acids (Fig. S8). The mineralization rate was enhanced in the presence of M and 80MS samples. During the decoloration step (approximately 30 to 60 min, Fig. S9), the presence of the catalyst did not accelerate either the decoloration or the mineralization rate. Azo dyes are highly sensitive to molecular ozone due to its high selectivity towards N=N unsaturated bonds [24]. The highest mineralization levels obtained (88-91 %) represented total carbon concentrations

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around 5 to 2 mg/L with no aromaticity (254 nm), according to the UV-Vis spectra. The relationship between aromaticity and toxicity (determined by several techniques) for

degradation of OII by Fenton related processes (analogous AOP) was suggested by several

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authors [25-26]. According to these studies, the toxicity level of our highly mineralized treated samples is expected to be negligible.

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The use of 5MH45 sample had no effect on the reaction. One more test was performed with

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an increased load of this solid (8 g/L) and the same outcome was obtained. Therefore, the higher surface area and slight increment of acidic sites on 5MH45 sample did not play a crucial role in the catalytic ozonation of this pollutant. However, in the case of 80MS, which

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presented a much more pronounced hydrophobic character (higher Si:Al ratio) than 5MH45, TOC profiles indicated a better performance in terms of mineralization rate than single ozonation but worse than sample M. Then, further studies were performed to elucidate the

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cause of this activity.

3.2.2. Tert-butanol as radical scavenger Tert-butanol (TBA) is a common and efficient hydroxyl radical scavenger, usually used to confirm a mechanism based on radicals. Catalytic ozonation tests in the presence of TBA (40

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mg/L) were performed with samples M and 80MS. The mineralization rate was reduced, indicating the scavenging of radicals in solution (see Fig. S10).

3.2.3. Contribution of leached species ICP measurements of leached species in supernatants obtained after 240 min of ozonation indicated the presence of 0.95, 0.50 and 0.80 mg/L of Fe and 0.066, 0.0037 and 0.0074 mg/L of Mn in samples M, 5MH45 and 80MS, respectively. For M sample, leached Mn was

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measured at two different reaction times, then, concentrations of 0.22 and 0.066 mg/L were registered at 150 and 240 min, respectively. Hence, it is possible that only a fraction of Mn was lost as soluble MnO4- or Mn2+, and part of it could have been recovered as insoluble

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MnO2 precipitated onto the catalyst surface.

Fe and Mn homogeneous contributions were evaluated by carrying out ozonation tests with

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2.5 mg/L of Fe3+ (Fe(NO3)3) at pH0=3, and 0.5 mg/L of Mn2+ (MnSO4) at pH0=6 (Fig. S11). In the experiment with Fe3+, the same TOC and OII evolution was obtained as in the non-

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catalytic ozonation experiment. In the case of Mn2+, a TOC conversion of 71% was obtained in only 180 min with a final value of 94% (4 h). During this reaction, a dark precipitate

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appeared due to the oxidation of Mn2+ to Mn(OH)3 or MnO2 and at the end of the test a strong pink color appeared due to further oxidation and formation of permanganate (MnO4-). Additionally, the contribution of leached species from M and 80MS was also evaluated

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through a two-step experiment. First, a catalytic ozonation test was performed during 90 min. At this point, pH value decreased down to 3.3 due to the generation of carboxylic acids. Then, the catalyst was filtered and in a second step the supernatant was used in a single ozonation experiment of 150 min. Fig. 2 shows the mineralization evolution of standard catalytic oxidation tests in contrast to the two-step experiment in which the solid catalysts were filtered. As it can be observed, the mineralization evolution resulted the same in both

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experiments, for both samples. Therefore, the increased mineralization levels obtained with M and 80MS samples under the given operating conditions could be attributed to leached species, especially Mn. The content of Mn leached from M was an order of magnitude higher than from 5MH45 and 80MS. Moreover, after 150 min of reaction with sample M a strong pink coloration appeared in the reaction medium, which can be attributed to the formation of MnO4- (Fig. S12). Mn was mostly removed during the acid treatment of 5MH45 sample. The amount leached

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from this sample during ozonation experiments was half the amount leached from 80MS. It is important to highlight that only a small trace of Mn present in a natural material could be

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the key of an outstanding activity.

3.2.4. Adsorption tests and pH effect

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OII adsorption was evaluated under the same conditions as in ozonation studies (but in

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absence of O2/O3) and it resulted to be negligible for all samples. In order to evaluate the contribution of the adsorption of reaction intermediates in TOC conversion values, the supernatant of single ozonation tests (90 and 240 min long, TOC0 of 42 and 22 mg/L,

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respectively) at pH=3.2 and pH=7.5, were contacted with 1 g/L of samples M, 5MH45 and 80MS, in the absence of ozone, during 120 min. In the given range of operating conditions, adsorption values around 1 mgTOC/gsample were obtained for all samples, under acidic and

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neutral pH, for both supernatants (90 and 240 min). Therefore, it can be concluded that the contribution of adsorption on measured data was negligible. The pH effect was evaluated using the supernatant obtained in 90-min single ozonation assays (TOC0 42 mg/L). The pH value of the supernatant was brought to neutral and experiments were performed with single ozonation and samples M, 5MH45 and 80MS, under the conditions considered previously. Outcomes are presented in Fig. 3. In all tests, the pH value

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fluctuated identically from 6.7 to 7.3 and the same TOC evolution was obtained with single ozonation and samples M and 5MH45. According to these results, under neutral pH value, the activity of M is decreased, since the electrostatic interaction between the catalyst surface and dissociated anionic compounds is reduced, inhibiting Mn leaching. Sample 80MS showed only mild activity and a slightly higher mineralization rate compared to single O3. Final TOC conversions of 58 and 47% were obtained for 80MS and single O3, respectively. This activity at neutral pH value can be related to its higher hydrophobicity

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(higher Si:Al ratio), which may have enhanced the interaction between the catalyst surface and ozone/pollutants [27]. It has been reported that ozone is stabilized in high-silica zeolites due to its non-polar properties and affinity towards non-polar phases [15]. Then, as reported

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by Gonzalez-Olmos et al. [28] and Fujita et al. [15], a high degree of adsorptive enrichment of the pollutant and ozone in the vicinity of the catalytically active centers would have a positive

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influence on the probability of collisions between reactive species and contaminant

3.2.5. Stability tests

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molecules.

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In order to evaluate the long-term stability of M and 80MS, the catalyst load was retained and used again in successive runs without any treatment of samples between tests, only drying at room temperature for 48 h and at 60ºC for 24 h.

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With sample M, oxidation tests were performed with an ozone dose of 7 mg·min-1·L-1 (half the employed in the previous tests). The M sample was used in four consecutive oxidation runs of five hours each. Fig. 4 shows that the final TOC conversions of all tests remained close to 90%. The initial rate mostly declined after the first usage; however, between runs 2 and 4 initial rates remained constant. An average leaching of 0.036 mg/L Mn was observed at

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the end of each test. However, as mentioned before, a fraction of leached Mn could have been recovered as insoluble MnO2 precipitated over the catalyst surface. For 80MS, two consecutive oxidation runs were performed (Fig. 5). Two ozone doses were evaluated: 14 mg·min-1·L-1(test A) and 7 mg·min-1·L-1 (test B), in experiments of 240 and 300 min, respectively. With the lower ozone dose, the activity drastically decayed after the first usage (80MS-2A), obtaining TOC conversion values of 87, 68 and 50 % with the fresh sample, used sample (80MS-2A) and single O3, respectively. With the higher dose, the TOC

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conversion rate was only reduced 10%. Blockage of active sites involved in ozone decomposition into radicals could be a possible explanation. In order to further study this

behaviour, the 80MS sample used twice in test A was calcined (500ºC, during 1 h). After the

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treatment, the sample recovered its full activity (Fig. 5). Therefore, under acidic pH, the

activity of 80MS sample connected to Mn may be related to a surface initiation step involving

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the interaction between organic intermediates, ozone and the catalyst surface, which could be

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inhibited by the eventual blockage of active sites.

TPD curves (Fig. 1) of used samples (M4 and 80MS-2A) displayed smaller desorption peaks than fresh samples, clearly indicating that in successive reaction cycles the catalysts lose acid

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strength. This could be connected to the loss of Fe, Al and Mn, and the possibility of blockage related to adsorption, especially in the 80MS sample, which presented a higher Si:Al ratio (hydrophobicity). The area of the desorption peak of M sample was reduced 35 % after 4

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usages. In the case of 80MS, the desorption peak was drastically reduced (60 %) in only 2 usages (Fig. 1).

3.2.6. The role of Mn The role of Mn(II) on the catalytic ozonation of organic pollutants has been reported by other authors [29-32]. Thus, according to results described previously, the catalytic activity of M

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and 80MS samples under acidic conditions could be mainly related to the dosification of Mn into the solution. Ma et al. [29] studied the manganese catalyzed ozonation of atrazine and observed that a relatively low amount of Mn(II) (0.3 mg/L) was able to catalyze the decomposition of ozone via intermediate manganese species, generating radical species. Andreozzi et al. [30] studied the use of MnO2 for the catalytic ozonation of oxalic acid and observed catalytic effect at moderately acidic pH values, since the electrostatic attraction with the protonated surface

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facilitated the adsorption of oxalic acid. The catalytic effect was based on the formation of a surface manganese-oxalic acid complex to form an intermediate product that was more easily degraded by ozone. Also, the complex formation, followed by a “one electron” exchange step,

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could cause the detachment of the reduced surface center and leaching of Mn. Manganese catalyzed the decomposition of ozone generating hydroxyl radicals and at the same time

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Mn(II) was oxidized by ozone to form higher valent manganese oxide. Depending on the ozone concentration and the presence of reducing compounds (Fe(II), reaction intermediates),

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insoluble MnO2 as well as soluble Mn(II) or MnO4-, recognizable by its pink color, could be obtained [33]. One should note that during the ozonation reaction the occurrence of a dynamic

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cycle combining Mn2+, MnO2 and MnO4- is possible, and at the end of each test a fraction of Mn could have been recovered as a precipitate MnO2 over the catalyst surface, explaining the

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long-term stability of M sample over several cycles.

4. Conclusions

 Montanit300® (M) was modified by acid treatments, resulting in samples with increased surface area and Si:Al ratio, reduced pHPZC and loss of labile Fe and Mn

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species. The quantity of acid sites was mostly conserved, with only a slight increment in sample 5MH45.  Samples were used in the catalytic ozonation of OII at different pH values. Best results were obtained at lower values.  Complete decoloration and mineralization levels of 66, 65, 88 and 91% were observed for ozonation and catalytic ozonation with 5MH45, 80MS and M samples, respectively. Adsorption contribution was negligible in all cases.

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 The activity of M and 80MS was associated to Mn leaching promoted by the interaction between the catalyst surface and carboxylic acids.

 The reaction mechanism was based on a dynamic cycle involving reduced and

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oxidized forms of Mn, which depends on the oxidant dose and nature of the reaction

mechanism involving radicals.

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intermediates. Tert-butanol decreased the mineralization level suggesting a reaction

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 At neutral pH values, M showed no activity and 80MS showed moderate activity, which could be associated to the enhanced interaction between the catalyst surface and ozone/pollutants, due to its higher Si: Al ratio (hydrophobicity).

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 A low O3 dose caused quick 80MS deactivation. However, it was reversed through calcination and prevented using a higher oxidant dose.  For M sample the mineralization level was mostly sustained over the four runs

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studied. A fraction of Mn leached could have been recovered as precipitated MnO2.

Authors Contribution Statement

Inchaurrondo N.: Conceptualization, Methodology, Investigation, Validation, Resources, Writing original draft, Funding acquisition

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di Luca C.: Investigation, Reviewing and Editing, Visualization. Žerjav G.: Methodology, Investigation, Reviewing and Editing. Grau J. M.: Investigation. Pintar A.: Resources, Reviewing and Editing, Funding acquisition Haure P.: Reviewing and Editing, Supervision, Funding acquisition

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Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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Acknowledgements - Financial support from CONICET. UNMdP. ANPCyT (PICT 2322-

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2017) (Argentina). G. Žerjav and A. Pintar acknowledge the financial support from the

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Slovenian Research Agency (research core funding No. P2-0150).

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[14] N.A.S. Amin, J. Akhtar, H.K. Rai, Chem. Eng. J. 158 (2010) 520-527. [15] H. Fujita, J. Izumi, M. Sagehashi, T. Fujii, A. Sakoda, Wat. Res. 38 (2004) 159-165. [16] F. Boudissa, D. Mirilà, V.-A. Arus, T. Terkmani, S. Semaan, M. Proulx, I.D. Nistor, R. Roy, A. Azzouz, J. Hazard. Mater. 15 (2019) 356-366. [17] P. Djinović, T. Tomše, J. Grdadolnik, Š. Božič, B. Erjavec, M. Zabilskiy, A. Pintar, Catal. Today 258 (2) (2015) 648-659.

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[18] C. di Luca, P. Massa, J.M. Grau, S.G. Marchetti, R. Fenoglio, P. Haure, Appl. Catal. B 237 (2018) 1110-1123. [19] J. Reungoat, J.S. Pic, M.H. Manéro, H. Debellefontaine, Sep. Sci. Technol. 42 (2007) 1447-1463. [20] M. Khalid, G. Joly, A. Renaud, P. Magnoux, Ind. Eng. Chem. Res. 43 (2004) 5275-5280. [21] E.G. Derouane , J.C. Védrine , R. Ramos Pinto , P.M. Borges , L. Costa , M.A.N.D.A. Lemos , F. Lemos, F. Ramôa Ribeiro, Catalysis Reviews: Science and Engineering 55:4

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18

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ur na

lP

re

-p

ro of

[33] D. Gregory, K.H. Carlson, Ozone: Science & Engineering 23 (2001) 149-159.

19

100

200

300

re

-p

ro of

Signal FID (a.u.)

M 80MS M4 80MS-2A

400

500

600

700

ur na

lP

Temperature (°C)

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Fig. 1. Temperature programmed desorption of pyridine of fresh and used samples.

20

O3 5MH45 M 80MS M filtered 80MS filtered

80 60 40

ro of

TOC Conversion (%)

100

20

0

30

60

90

-p

0

120 150 180 210 240

lP

re

Time (min)

Fig. 2. TOC conversion evolution obtained in standard ozonation tests. Operating conditions:

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O3 dose = 14 mg·min-1·L-1, c(OII)0=100 mg/L, Vliq=500 mL, pH0=6, solid load = 1 g/L.

21

O3

80

5MH45 M 80MS

60 40

ro of

TOC Conversion (%)

100

20

0

-p

0 30

60

90

120

lP

re

Time (min)

Fig. 3. TOC conversion evolution obtained at pH=7. The test was performed with supernatant

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from single O3 test of 90 min. Operating conditions: O3 dose = 14 mg·min-1·L-1, Vliq=500 mL,

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pH0=7, solid load = 1 g/L.

22

100 1 2 3 4 Single O3

60 40

ro of

TOC Conversion (%)

80

20

60

120 180 Time (min)

240

300

lP

re

0

-p

0

Fig. 4. Stability tests conducted in the presence of M sample. Operating conditions: O3 dose =

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7 mg·min-1·L-1, c(OII)0=100 mg/L, Vliq=1000 mL, pH0=6, solid load = 1 g/L.

23

100

Single O3-A Single O3-B 80MS-1A 80MS-2A 80MS-calcined A 80MS-1B 80MS-2B

60 40

ro of

TOC Conversion (%)

80

20

60

120 180 Time (min)

240

300

lP

re

0

-p

0

Fig. 5. Stability tests conducted in the presence of 80MS sample. Operating conditions: O3

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dose = 7 mg·min-1·L-1 (A), 14 mg·min-1·L-1 (B), c(OII)0=100 mg/L, Vliq=1000 mL, pH0=6,

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solid load = 1 g/L.

24

Table 1. Summary of characterization results. Sampl SBET

Vtot

e

dpor

Fe

Mn

Si:Al

Acid

Acid

T

pHPZ

e

(EDX)

(XRF)

(EDX)

sites

sites

desorptio

C

density

quantity

n pyridine

(mmol/g)

(oC)

0.14

259

(m2/

(cm3/

(n

g)

g)

m)

M

36

0.07

7.8

5.9

1.6

4.4

0.0038

10MS

127

0.13

4.7

0.8


9.3

0.0012

0.15

233

3.3

80MS

128

0.13

4.7

0.3


26.3

-

-

-

3.3

5MH

150

0.16

4.1

1.1


8.8

0.0013

0.19

242

3.2

(wt.%)

(wt.%)

(mmol/

D.L. - Detection limit.

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a

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lP

re

-p

45

ro of

m2)

25

8.9