Montmorillonite- hydrothermal carbon nanocomposites: Synthesis, characterization and evaluation of pesticides retention for potential treatment of agricultural wastewater

1 Montmorillonitehydrothermal carbon nanocomposites: synthesis, characterization and evaluation of pesticides retention for potential treatment of agricultural wastewater M.E. Zelaya Souléa, M.A. Fernándeza, M.L. Montesb, F. Suárez-Garcíac, R.M. Torres Sáncheza and J.M. D. Tascónc aCentro de Tecnología de Recursos Minerales y Cerámica. CETMIC, CIC-CONICET CCT-La Plata, Camino Centenario y 506M.B. Gonnet, Argentina. bIFLP, CONICET CCT-La Plata, UNLP, La Plata, Argentina. cInstituto Nacional del Carbón, INCAR-CSIC, Francisco Pintado Fe, 26, 33011, Oviedo, España. emizelayasou[email protected], [email protected], mlucia[email protected]om, [email protected], ro[email protected]om, ta[email protected] Abstract Montmorillonite (M) was modified by addition of hydrothermal carbon (HC) in order to obtain pesticide adsorbent materials. Carbohydrates were used as carbon source, and in some cases, also phosphoric acid was applied as activation agent. The M-HC hybrids maintain the negative electrical surface charge of their precursors (between -35 mV and -15 mV), while lower specific surface areas (around 6 m2 g-1) than that of M sample (66 m2 g-1) were found. The loss of specific surface could be assigned to the carbon location on both the external and the interlayer surface of the M sheets, as was confirmed by FTIR, zeta potential measurements and XRD analysis. For M-HC products obtained by acid treatment, despite their structure alteration, the specific surface values remained similar to that of M sample (around 70 m2 g-1). The M-HC products with or without acid treatment retain almost 100 % adsorption of chlorpyrifos (CPF) and thiabendazole (TBZ) as that obtained for M sample, under the tested conditions. Coagulation studies revealed that M-HC products evaluated showed better precipitation property than that of M sample, which would preclude the typical montmorillonite gel formation that usually block filters and reactors. Keywords: hydrothermal carbon, montmorillonite, thiabendazole, chlorpyrifos 2 1. Introduction Human activity generates wastewaters that cause environmental pollution. In particular, farming activities use pesticides for crops, achieving groundwater or surface water-bodies by runoff, infiltration and/or containers washing (Regaldo et al., 2018). The water contamination with pesticides and possible damage of living beings’ health has raised scientific concern, revealing the need of remediation of the polluted water through water purification systems. In this sense, the optimization and development of advanced technologies are crucial to meet the current and future water needs (Geise et al., 2010) The low cost and easy access of clay minerals allow their use as adsorbents of a wide variety of pollutants. Among them, montmorillonite clay (M) stands out because in addition to its laminar structure, presents large surface area and cation exchange capacity (Lagaly et al., 2006). Nevertheless, its use as filter is controversial due to its swelling property, which produces an increase in filter resistance by gel formation (Basnayaka et al., 2018). Besides in batch conditions, the M relatively low coagulation property difficult its recuperation from the treatment reactors (Santiago et al., 2016). The surface modification of M sample by some carbon coating would change some of its properties, as swelling capacity decrease (as reported for a Nigerian bentonite modified by dodecyltrimethylammonium bromide (Chikwe et al., 2018)) or coagulation increase, allowing its use in filters and reactors, without losing or even increasing the adsorption capacity of both. Several methods were employed for the treatment of wastewater intended for agricultural use, based on adsorption processes, such as filters and batch processes (Capra and Scicolone, 2004; Gottschall et al., 2007; Jiménez et al., 1999). While for the treatment of agricultural wastewater, the use of M and organo-montmorillonites as adsorbents has proven successful (Gamba et al., 2017, 2015; Gu et al., 2015; Nir et al., 2000). Activated carbon materials have a well-developed internal pore structure and various functional groups on their surface, which allowed them to be widely used as adsorbents, catalysts and catalyst carriers (Liu et al., 2010). A cheaper alternative and environmentally friendly method to attain carbon has been developed recently by hydrothermal carbonization (HTC) treatment of biomass saturated with water, at mild reaction conditions (≤ 350 °C and ≤ 20 MPa) (Guo et al., 2016; Titirici and Antonietti, 2010). During the treatment, oxygen functional groups decomposed, leading to dehydration and increasing the heating value (Zheng et al., 2017). The hydrothermal treatment of carbohydrates produces their aromatization, generating products in the form of micrometric spheres with a large number of OHand CO= groups (Liu et al., 2010). Hydrothermal carbonizaton has been carried out in the presence of e.g. graphene oxide (GO) nanosheets (Martín-Jimeno et al., 2015), more recently in the presence of montmorillonite (Li et al., 2014), zeolites (Gao et al., 2005) and silica gel (Gun’ko et al., 2004). In the first case, GO acted as a morphology-directing agent and a hybrid HC-GO material formed by a thin layer of hydrothermal carbon was obtained on the CO sheets. In the second case, a composite material of hydrothermal carbon nanospheres supported on montmorillonite was prepared. Besides, several works conclude that parameters as temperature, time and acid type and concentration are relevant in the achieved characteristic of the synthetized materials (Chham et al., 2018; Kausar et al., 2018; Mansouri et al., 2018; Toor and Jin, 2012). Several chemical agents are used to safeguard agricultural commodities against fungi, insects and herbs (Abbas et al., 2018), although various studies highlighted their genotoxic and mutagenic effects (Abbas et al., 2018; Iqbal, 2016). In particular, the wide use in Argentina of the insecticide chlorpyrifos (CPF) for crop protection (Hunt et al., 2016; Marino and Ronco, 2005), and the fungicide thiabendazole (TBZ) for fruit protection (Lombardi et al., 2003), generates an important environmental concern. Particularly, to obtain a good dispersion of this insecticide, 3 it is sprayed as fine particles suspended in an aqueous medium. Its application by spraying in the atmosphere generates by means of rain or irrigation its leachate below the root zone, reaching and contaminating groundwater and / or surface water (Haynes et al., 2000; Schipper et al., 2008), making its removal very difficult. While residues from the washes of insecticides containers, and the application of fungicides in fruit packing plants (Gamba et al., 2017) can accumulate in their effluents as a source of point pollution, which can be treated before they reach water bodies. The treatment of these effluents could be solved technologically with filtering materials where low cost is usually one of the main limiting factors. In this study, montmorillonite-carbon nanocomposites (M-HC) were produced by hydrothermal carbonization of carbohydrates in presence of M sample. In a previous work, authors reported that similar M-HC materials showed higher reutilization capacity than that of M for norfloxacin (NOR) sorption (Zelaya Soulé et al., 2019). This behavior indicated that a deeper research on the synthesis conditions will be needed in order to improve the adsorption capacity of M-HC materials. Besides, the possible posterior microbiological treatment of the resultant M-HC-NOR materials could be favored in comparison to raw M samples (Yue et al., 2019). The M-HC hybrids synthesis on the present work was performed at various temperatures, times and using different types and concentrations of carbohydrates, as well as adding phosphoric acid at two concentrations as activating agent. SEM, porous texture characterization, XRD and FTIR analysis and zeta potential measurements, were used to characterize selected products and to evaluate structural and electrical surface charge changes produced by the synthesis conditions. Some materials were also chosen to study the chlorpyrifos (CPF) and thiabendazole (TBZ) adsorption capacity, and coagulation was also evaluated in order to assess their potential use as filters or reactors. 2. Materials and Methods 2.1 Materials Na-montmorillonite (84%) labelled as M, was provided by Castiglioni Pes and Cia. (Lago Pellegrini deposit, Rio Negro, North Patagonia, Argentina) and used as received. The structural formula obtained from the chemical analysis was [(Si3.89Al0.11)(Al1.43Fe3+0.28Mg0.30)O10(OH)2]Na+0.41 and its main properties were: isoelectric point (IEP) pH = 2.7, total specific surface area (TSSA) = 621 m2 g-1 , cationic exchange capacity (CEC) = 0.825 mmol g-1 (Gamba et al., 2015), and 31.4 cm3 of swelling capacity (Magnoli et al., 2008) Dextrose (D), cellulose (C) and cornstarch (AM) were used as carbon sources. All of them were analytical grade reagents, purchased from Anedra, MERCK, and Sigma Aldrich, respectively. C is a biopolymer of D. The H3PO4 (85%) was analytical grade from Chicarelli Lab., chosen as activating agent due to the low cost, the fact that is more environmental friendly than alkali hydroxide, by its possible industrial recovery after their use (Wang et al., 2011) and the better obtained material when it is used instead of H2SO4 (Mansouri et al., 2018). Thiabendazole (TBZ) was from Fluka (Buchs, Switzerland) (98%). It´s IUPAC chemical formula is 2-(thiazol4-yl) benzimidazole. Chlorpyrifos (CPF) was purchase at Clorfox Company (48%). All drugs were use as received without further purification. The structure schema of both pesticides is shown in Fig. 1. 4 Fig. 1 Structure scheme of: A) Thiabendazole (TBZ) and B) Chlorpyrifos (CPF) pesticides. 2.2. Methods 2.2.1 Carbon synthesis by hydrothermal carbonization In order to synthetize the M-HC hybrid, 50 mL of a suspension of 10 mg mL-1 of M sample in deionized water was sonicated for 3 h, and then a specific amount (to achieve a 5, 10 or 25 mg mL-1 concentration) of the selected carbohydrate (D, C or AM) was added. After, the suspension was heated (180 or 210 ºC) into a Teflon-lined autoclave during 16 or 24 h. The solid products were filtered and dried at 60 ºC overnight, ground and stored for further analysis. In some cases, acid activation was performed by the H3PO4 addition (0.17 or 0.33 % V/V, which were identified adding ac1 and ac2 labels, respectively) into the Teflon-lined autoclave before heat treatment. In order to evaluate the thermal and acid treatments effect on the carbohydrates and on M sample, same procedures indicated previously were performed on some carbohydrates (HC) without M sample and on M sample in absence of HC. The products were labeled with the following code: M, indicating the clay presence, followed by the carbohydrate and concentration used, and the acid presence when corresponded (ac1 or ac2). Finally, the temperature and the time of the synthesis process were included. For example, the name MD10ac1-210-24 indicates that the synthesis was performed in presence of Montmorillonite with 10 mg mL-1 of Dextrose and phosphoric acid at 0.16% V/V at 210 °C for 24 h. 2.2.2. Samples characterization The FE-SEM was performed on a Quanta FEG 650 microscope (FEI Company). Samples were fixed to 10mm metal mounts using carbon tape, and sputter coated with iridium under low pressure argon atmosphere. Porous texture characterization was obtained from N2 adsorption-desorption isotherms (>99.9995% pure) at - 196 ºC and up to 1 atm measured in a volumetric apparatus ASAP-2010 (Micromeritics). Prior to the measurements, all samples were degassed overnight at 130 ºC under vacuum. The repeatability of the isotherms between different runs was better than 1.5%. The specific surface area was calculated applying the BET equation. Total pore volume (TPV) was calculated from the adsorbed amount at the relative pressure of 0.975. X-ray diffraction (XRD) patterns were collected on powder samples using a Philips PW 1710 diffractometer operated at 40 kV and 35 mA with CuKα radiation, in the range 3° < 2θ < 70°, with counting time of 2 s/step and step width of 0.040° (2θ). Fourier transform infrared spectra (FTIR) were acquired using Nicolet 8700 Fourier Transformer Infrared Spectrometer with DTGS and MCT Detectors by averaging 64 scans in the 4000-400 cm-1 spectral range. Electrokinetic potentials were determined using Brookhaven 90Plus/Bi-MAS with the electrophoretic mobility function. The electrophoretic mobility was converted into zeta potential values automatically using the 5 Smoluchowski equation. For each determination, sample suspensions (1 g/L) were done on KCl 10-3 M solutions used as inert electrolyte and the pH value was adjusted to 4.5. 2.2.3. Adsorption experiments A weighed amount of the respective pesticide was dissolved in deionized water in order to prepare a 25 mg L1 solution. Additional concentrations were obtained by dilution the previous solution in deionized water. The adsorption experiments were carried out in batch conditions with a solid/ solution ratio of 8 g L-1, a contact time of 24 h, at 20 ºC, under continuous stirring (150 rpm) and without pH adjustment. After the equilibration time, the suspensions were centrifuged at 14000 rpm for 15 min to separate the reaction products. The solid phases resulting from the adsorption experiments were rinsed with distilled water, air dried, and stored for further analysis. The concentration of TBZ in the supernatants was determined by a high performance liquid chromatograph (HPLC) coupled to UV–visible ( = 298 nm) detector. The used column was a Shimadzu HPLC C18 (4.6 mm × 250 mm, 4.6 m). The used mobile phase was a 70/30 methanol/water mixture flowing at 0.9 mL min-1. The injected volume was 10 µL. The linear ranges of TBZ concentrations were within 0.5–25 mg/L (R2 = 0.999). The concentration of CPF in the supernatants was analyzed by HPLC equipment described above, at λ= 290 nm. The mobile phase was an 80/20 acetonitrile/water mixture flowing at 0.9 mL min-1. The injected volume was 10 µL. The linear ranges of CPF concentrations were within 0.25–10 mg L-1 (R2 = 0.999). The adsorption percentage of TBZ or CPF was determined according to the following equations: 𝑠𝑜𝑟𝑝𝑡𝑖𝑜𝑛 (%)=𝐶𝑖− 𝐶𝑒 𝐶𝑖 ∗100 𝑒𝑞 (1) where Ci and Ce represent the adsorbate concentration in solution before and after sorption experiments, respectively. 2.2.4. Coagulation experiments The coagulation property was evaluated for M, Mac1-210-24, MD10-210-24 and MD25ac2-210-24 samples. To achieve this, 0.12 g of the indicated sample was suspended in 10 mL of water (Milli-Q), and photographs of the suspensions were taken after 0, 24 and 45 h of contact time. 3. Results and discussion 3.1 Characterization of the hydrothermal carbons Fig. 2 revealed the different colors of the obtained products. Particularly, the light brown of raw M changed to orange and green color for M-210-24 and Mac1-210-24 samples, respectively. These color differences could be attributed to changes in the structural iron oxidation state (Eissa et al., 1994). The M-HC compounds showed dark brown (MC10ac1-180-16 sample) or black color (MD25-180-16 and MAMac1-210-24, samples) which revealed the M surface coating by carbonaceous materials (Zhang et al., 2015). In particular, color of materials obtained at 180 °C from cellulose (C) was gray (Fig. 2 and Fig. S1 in supplementary material), which reveals an unfinished process of carbon formation, probably because this temperature is not enough to produce a complete hydrothermal carbonization of the cellulose biopolymer. On the contrary, samples synthesized from cellulose at 210 °C shown a dark color indicating that carbonization took place. 6 Therefore, in the following syntheses a treatment temperature of 210 °C and 24 h were used for all materials tested to guarantee the complete carbon formation process. Fig. 2 Images of the obtained products. SEM images of some representative samples were shown in Fig. 3. The SEM micrograph of M treated at 180 ºC, M-180-16 sample (Fig. 3a), showed a layered morphology characteristic of clays (Magaña et al., 2008). Composite materials prepared with carbohydrates showed, in general, the same-layered morphology but with greater roughness, probably due to the carbon layer deposited on the clay sheets (Fig. 3b). For samples prepared with carbohydrate concentration of 5 mg mL-1, non-free carbon was observed (figure not shown). When the concentration used was 10 mg mL-1, few carbon microspheres with size around 1 μm can be observed in some samples, e.g. Fig. 3c. The amount and size of these microspheres increase with the carbohydrate concentration used during the synthesis. Thus, carbon microspheres of around 2 μm (Fig. 3d) were observed for all samples prepared with the highest carbohydrate concentration studied here (25 mg mL-1). These microspheres correspond to the expected morphology for hydrothermal carbon prepared by hydrothermal carbonization of carbohydrates (Titirici et al., 2008). Because our interest is to attain a material with the carbon integrates at the M surface, without isolated microspheres, the concentration of carbohydrates choose for the following synthesis was 10 mg mL-1. In figures 3c and d also lower clay sheet than those of the M thermal treated sample (fig.3 a) can be identified, indicative of the M structure attack by the acid treatment (Hisarli, 2005). M M-210-24 Mac1-210-24 MC10ac1-180-16 MD25-180-16 MAMac1-210-24 7 Fig. 3 SEM images of: a) M-180-16, b) MAM10-210-16, c) MD10ac2-210-16 and d) MD25ac2-210-16. The microspheres presence of free hydrochar was indicated within circles. In order to evaluate changes in the specific surface and porosity of the studied samples, the BET surface area (Fig. 4) and total pore volume (Fig. 5) were determined. The M used in this work has a BET surface area of 66 m2 g-1. Hydrothermal treatments at 180 and 210 ºC cause the reduction of the BET surface area to 53 and 49 m2 g-1, respectively. This fact is attributed to the collapse of the interlayer space of M (as was corroborated by the absence of the reflection peak corresponding to d001 plane, and will be discussed in following paragraph), which produce a decrease of the available surface (Fernández et al., 2013; Torres Sánchez et al., 2011). Contrary, for an Australian bentonite an increases on specific surface area was observed when heating the samples at 100 ºC or 200 ºC in a muffle furnace (Toor and Jin, 2012). On the other hand, when the hydrothermal treatment at 210 ºC was carried out in the presence of phosphoric acid, an increase in the BET surface area was observed: Mac1 and Mac2 samples had 82 and 81 m2 g-1, respectively, as was also reported for an Australian sodium bentonite obtained by acid treatment (Toor and Jin, 2012). This increase in the surface area after activation of M with acids was assigned to the removal of metal-exchange cation (Mg2+, Fe3+ and Al3+) and proton exchange (Nguetnkam et al., 2005; Wang et al., 2010). In addition, for the Mac1 sample the structure was preserved despite the acid treatment, but not for the Mac2 sample where mainly the leaching of octahedral ions Al3+ modifies the M structure, as will be explained later. The BET surface values of M-HC samples synthetized in the absence of acid were lower than that of M sample. The increase of the initial carbohydrate concentration (evaluated for dextrose, with 5, 10 and 25 mg mL-1, at 180 °C and 16 h of treatment) did not evidence significant changes in the BET values (< 2.5 m2 g-1). This behavior was attributed to the pores obstruction by the HC formation (Zhang et al., 2015). The acid presence in the synthesis of M-HC materials produced higher surface area than those prepared by hydrothermal carbonization without phosphoric acid, increasing with the acid concentration used in the synthesis, and assigned to the partial decay of the lamellar structure of M sample (Wang et al., 2010). The evaluation of the carbohydrates initial content effect, contrarily to that evidenced for products without acid treatment, showed a significant decrease of the surface area (from 64.8 to 42.8 m2 g-1, for MD10ac2-210-16 and MD25ac2-210-16 samples, respectively). It is also worth 8 noting that a time increase of thermal treatment (for 210 ºC) from 16 to 24 h, evaluated in the MHC25ac2 with dextrose as HC source, generated a decrease in the specific surface from 42.4 to 28.7 m2 g-1. The thermal treatment of carbohydrates alone (irrespective of the carbohydrate used) generated products with very low surface values (Titirici and Antonietti, 2010), and the acid treatment seem does not influence this parameter (e.g. HC10-210-24 and HC10ac2-210-24 samples, in Fig. 4), being somewhat larger the surface values attained for HC coming from cellulose than for dextrose or cornstarch. Fig. 4 Specific surface for the indicated samples. Grey zones highlight materials synthetized in acid presence. Symbols indicate: () M and M-HC samples with different carbohydrates () dextrose, () cellulose, and () cornstarch. The Fig. 5 showed the total pore volume, TPV, values for the synthetized samples. The TPV of the montmorillonite decreases with the thermal treatment, as happened for surface area values, mainly originated by the drop of microporosity and collapse of the interlayer (Torres Sánchez et al., 2011). The increase of TPV values with the activation treatment (thermal treatment in the presence of phosphoric acid) could be assigned to the formation of porous silica product, as for the M acid activation with HCl (Temuujin et al., 2004). Unambiguously, the decrease found in the surface area values for M-HC samples, described in the previous section, can be assigned to the pores obstruction of M by HC originating the collapse of the TPV values of these samples (Fig. 5). Furthermore, an increase in the TPV values of all acid activated samples was observed, being higher for products prepared with the highest acid concentration. Thus, both series (M and M-HC samples) showed similar trends. Besides, the lower TPV value obtained for MHC25ac2 than MHC10ac2 samples (Fig. 5) was associated to a high obstruction of its pores due to a greater amount of HC deposited. For HC materials, the existence of small number of micropores (Titirici and Antonietti, 2010) regardless the initial carbohydrate and the used acid, produced the drop observed of TPV values in Fig. 5. In brief, it can be highlighted that the acid treatment recovers the loss of BET and TPV values of the M-HC samples, reaching those obtained for the raw M sample. M M-180-16 M-210-24 Mac1-210-24 Mac2-210-24 HC10-210-24 MHC5-180-16 MHC10-180-16 MHC25-180-16 MHC10-210-16 MHC10-210-24 MHC10ac1-180-16 MHC10ac2-180-16 MHC10ac1-210-16 MHC10ac2-210-16 MHC10ac1-210-24 MHC10ac2-210-24 MHC25ac2-210-16 MHC25ac2-210-24 HC10ac2-210-24 0 20 40 60 80 Specific Surface (m2 g-1) 9 Fig. 5 Total pore volume of indicated samples. Grey zones highlight materials synthetized in acid presence. Symbols indicate: () M and M-HC samples with different carbohydrates () dextrose, () cellulose, and () cornstarch. Total diffraction patterns of some samples (M, AM with thermal treatment, M with AM as HC source and thermal treatment, MAM10-210-24, and acid treatment, MAM10ac2-210-24 samples) were shown in Fig. 6, in order to evidence crystallinity changes among them. Typical X-ray diffractogram was found for M sample with d001 peaks at 6.9º and 6.18º (2θ) corresponding to 1.27 nm and 1.43 nm of the basal space and associated to the Na+ and Ca2+ presence in the interlayer space, respectively. The HC samples, represented by AM10-210-24 sample in Fig. 6, shown an amorphous large peak between 15º to 35º (2θ), which did not overlap the 001 peaks of M, and allowed to follow its shift by changes produced due to the different treatments at the M sample interlayer. The XRD pattern of M sample and its thermal treated products up to 550 ºC was analyzed in previous work, and a decrease of the interlayer space of 0.03 nm resulted as the main structure modification (Torres Sánchez et al., 2011). The structural modification of M sample by phosphoric acid treatment, generate leaching of Al3+ ions from the octahedral sheet bringing a decrease in the intensity of 001 and 100 reflection peaks at 6.9º and 19.7 º(2θ) (or 1.27 and 0.45 nm, respectively). Particularly, the 001 peak shift to lower values indicating the relaxation of the structure in the c direction. In the Mac2-210-24 sample (Fig. S2 in supplementary material) peaks at 20.3; 21.4 y 23.0 º(2θ) (or 0.44, 0.41 and 0.37 nm, respectively) were assigned to tridymite phase (Freiding et al., 2007; Tanaka and Chikazawa, 1999; Xu et al., 1989), which remained in MAM10ac1-210-24 and MAM10ac2-210-24 samples (Fig. 6). Also, the quartz peak at 26.5 º(2θ) (0.34 nm) can be noticed in the acid treated M samples (Fig. 6) by the formation of amorphous silica (Trabelsi and Tlili, 2017) The structural characteristic of M sample, as was indicated previously, remained in the M-HC products after thermal (MAM10-210-24 sample) or ac1 treatment (MAM10ac1-210-24), and similar results were obtained for all M-CH thermal and acid activated products (figures not shown). Particularly, the decrease of 060 reflection peak (62.0 º(2θ)) with increase of acid concentration treatment showed the decay of crystal structure (Torres Sánchez, 1997). M M-180-16 M-210-24 Mac1-210-24 Mac2-210-24 HC10-210-24 MHC5-180-16 MHC10-180-16 MHC25-180-16 MHC10-210-16 MHC10-210-24 MHC10ac1-180-16 MHC10ac2-180-16 MHC10ac1-210-16 MHC10ac2-210-16 MHC10ac1-210-24 MHC10ac2-210-24 MHC25ac2-210-16 MHC25ac2-210-24 HC10ac2-210-24 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 M D C AM Total pore volume (cm3 g-1) 16 References Abbas, M., Adil, M., Ehtisham-ul-Haque, S., Munir, B., Yameen, M., Ghaffar, A., Shar, G.A., Asif Tahir, M., Iqbal, M., 2018. Vibrio fischeri bioluminescence inhibition assay for ecotoxicity assessment: A review. Sci. Total Environ. 626, 1295–1309. https://doi.org/10.1016/j.scitotenv.2018.01.066 Amarasinghe, P.M., Katti, K.S., Katti, D.R., 2009. Nature of organic fluid-montmorillonite interactions: An FTIR spectroscopic study. J. Colloid Interface Sci. 337, 97–105. https://doi.org/10.1016/j.jcis.2009.05.011 Basnayaka, L., Subasinghe, N., Albijanic, B., 2018. Influence of clays on fine particle filtration. Appl. 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Fig. S3: DRX of mixtures of M sonicated during 3 h and indicated carbohydrates (at 10 mg mL-1) 510 15 20 25 30 35 40 45 50 55 60 65 70 ° (2 Theta) Mac2-210-24 20.3 21.4 23.0