Raw Montmorillonite Research Articles

Induced π–complexation properties of smectites impregnated by Ni, Cu and Ag transition metals: The highly efficient styrene uptake

Two natural smectite minerals (montmorillonite and beidellite) differing in structural charge location were impregnated with varying amounts of transition metals: Ni(II), Cu(I) or Ag(I). The modification aimed to increase the affinity of the minerals towards styrene vapors. The structure, texture, chemical composition and surface chemistry of the materials were studied by XRD, FTIR, Raman, N2 adsorption/desorption, XRF and XPS. The experiments examined the influence of the starting smectite and the type of introduced metal on styrene adsorption efficiency. The styrene uptake mechanisms were investigated through solid state analysis and supported by DFT calculations. The study demonstrated that the small content of introduced metals (<2% wt.) substantially increased styrene uptake (∼200–350% wt.) surpassing values reported for surfactant-intercalated smectites (∼40–80% wt.) and activated carbons (∼30% wt.). This enhancement was attributed to the π-complexation between dispersed d-block metals and π-electron-rich styrene molecules, subsequently leading to polystyrene formation. The DFT calculations were consistent with experimental findings, indicating a higher affinity of the raw beidellite towards styrene than the raw montmorillonite connected to the charge location. Moreover, the observed trends in calculated adsorption energies and lengths of weak hydrogen bonds allowed to explain a significant adsorption increase observed for the Ni- and Cu-impregnated montmorillonite-based materials.

Preparation of Melamine Formaldehyde Foam and a Melamine-Formaldehyde-Organo-Clay Nanocomposite and Hybrid Composites

Mineral fillers can be added to thermoset polymers to improve thermal conductivity and deformation behavior, shrinkage, impact strength, dimensional stability and molding cycle time. This study aims to prepare various hybrid composites (MFHCs) using melamine formaldehyde foam (MF), a melamine formaldehyde organo-clay nanocomposite (MFNC) and also pumice as primary filler, and gypsum, kaolinite and a hollow glass sphere as secondary filler. It also focuses on the study of some mechanical properties and thermal conductivities, as well as their microscopic and spectroscopic characterization. For this, firstly, organo-clay was prepared with the solution intercalation method using montmorillonite, a cationic surfactant and long-chain hydrocarbon material, and then was produced using a melamine formaldehyde nanocomposite with in situ synthesis using a melamine formaldehyde pre-polymer and organo-clay. Finally, hybrid composites were prepared by blending various minerals and the produced nanocomposite. For morphological and textural characterization, both FTIR spectroscopy and XRD spectra, as well as SEM and HRTEM images of the raw montmorillonite (MMT), organo-montmorillonite (OMMT), pure polymer (MF) and prepared hybrid composites, were used. Spectroscopic and microscopic analyses have shown that materials with different textural arrangements and properties are obtained depending on effective adhesion interactions between polymer–clay nanocomposite particles and filler grains. Mechanical and thermal conductivity test results showed that melamine-formaldehyde-organo-clay nanocomposite foam (MFCNC) exhibited a very good thermal insulation performance despite its weak mechanical strength (λ: 0.0640 W/m K). On the other hand, among hybrid composites, it has been determined that the hybrid composite containing hollow glass beads (MFCPHHC) is a material with superior properties in terms of thermal insulation and mechanical strength (λ: 0.642 W/m K, bulk density: 0.36 g/cm3, bending strength: 228.41 Mpa, modulus of elasticity: 2.22 Mpa and screw holding resistance: 3.59 N/mm2).

Raw and Purified Clay Minerals for Drug Delivery Applications.

In this study, the aim was to prepare drug-releasing clay mineral particles using raw (CaMt) and purified (PMt) montmorillonite and to compare and determine the effects of purification on the properties of montmorillonite. Montmorillonite clay minerals are used in several pharmaceutical and cosmetic products due to their many favorable properties, such as cation exchange capacity, adsorption capability, high specific surface area, and biocompatibility. Recently, several types of clay minerals have been widely studied for drug delivery applications due to their unique properties. The purification of montmorillonite is considered as a potentially useful step which may decrease the toxicity of impurities but which may increase the adsorption capacity of the montmorillonite. However, the effects on the toxicity and drug-release properties of purified montmorillonite have never been compared to that of raw montmorillonite. Montmorillonite was purified through decomposition of carbonates, dissolution of hydroxides, oxidation of organic materials, dialysis, and sedimentation. The raw and the purified montmorillonite were characterized using XRD, FTIR, and cation exchange capacities. Then, the cytotoxicity of raw and purified montmorillonite on normal hFOB cells was investigated to assess their biocompatibility in vitro. Finally, the efficacy of montmorillonite as a drug-delivering agent was investigated in vitro using cytotoxicity assays with the MCF7 cell line. The antitumor drug doxorubicin was loaded onto particles through electrostatic forces at 97.99% for CaMt and 96.79% for PMt. The drug-loading efficiency and release behavior of both clay minerals were determined. Results showed that both raw and purified montmorillonite did not significantly reduce the viability of normal cells at low concentrations (<500 μg/mL). At high concentrations, both raw and purified montmorillonite showed significant toxicity and the effect of impurities on toxicity were also more pronounced. Although drug loading was successful for both clay minerals there were differences in their controlled drug-release behavior. Doxorubicin-loaded raw and purified clay minerals significantly reduced MCF7 cell viability similar to pure DOX.

Removal of color and COD from textile dyeing effluent by adsorption technique using montmorillonite clay

AbstractThe study involves the removal of color and COD from textile dyeing effluents using the method of adsorption. Montmorillonite clay is used as an adsorbent. The surface area of the adsorbent is increased using acid treatment techniques with Para Toluene Sulfonic Acid (PTSA) and Phenol Di‐Sulfonic Acid (PDSA) solutions. In addition, the dosage of adsorbent for maximum removal of color and COD, the effect of contact time on adsorption, and the treatment cost of montmorillonite clay with PTSA and PDSA were determined. From the results, the surface area of montmorillonite clay increased from 30 to 119 m2/g and 246 m2/g upon treating it with PTSA and PDSA solutions, respectively. Raw montmorillonite clay was able to adsorb 89% of acid dye with a dosage of 1.8 g/100 ml and 93% of basic dye with a dosage of 1.0 g/100 ml for a dye having an initial concentration of 2000 mg/L. With an increase in the surface area of modified montmorillonite clay, it was able to adsorb about 95% of acid dye with a dosage of 1.2 g/100 ml and 96% of basic dye with a dosage of 0.5 g/100 ml. Concerning Acid Blue1 dye, about 86%, 90%, and 93% of the dye were adsorbed in the initial 2 min for raw montmorillonite clay, modified montmorillonite clay treated with PTSA, and PDSA solution, respectively. In the case of Basic Yellow2 dye, about 86% of the dye was adsorbed in the initial 2 min for raw montmorillonite clay and the clay treated with PTSA solution, whereas about 96% of the dye was adsorbed onto clay treated with PDSA. Regarding Basic Violet1, about 98%, 96%, and 99% of the dye were adsorbed in the initial 2 min for raw montmorillonite clay, clay treated with PTSA, and clay treated with PDSA solution, respectively. The cost of treatment of clay with PTSA and PDSA solutions is found to be Rs. 1.70/g or 0.023 $ per gram and Rs. 6.6/g or 0.089 $ per gram of clay, respectively. Therefore, considering the cost of treatment, clay treated with PTSA is preferred over clay treated with PDSA solution.

Synthesis, characterization, and challenges faced during the preparation of zirconium pillared clays

In this study, Zr-pillared montmorillonite clays (Zr-PILCs) were synthesized using two different precursor materials: raw montmorillonite (CM) and sodium ion-saturated montmorillonite (Na-CM) at different Zr/clay ratios (2.5, 5 and 10 mmol/g). To study the effect of Zr concentration and clay pre-treatment with NaCl on pillaring, the modified clay samples were characterized in detail using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy (STEM-EDX). The XRD analysis showed the increase of basal spacing of Zr-PILCs prepared from both precursor materials: from 1.26 to 1.74 nm in the case of CM, and from 1.13 to 1.93 nm for Na-CM. Results from FT-IR revealed new bands ascribed to Zr-O bonds in the range of 400–500 cm −1 in Zr-pillared samples obtained from Na-CM at Zr/clay ratios of 2.5 and 5 mmol/g. The distribution and nature of Zr species in between the silicate layers were studied using STEM-EDX and HAADF imaging. They were found to be separated by a distance of 1.5–3 nm and their thickness lies in the range of 1–2 nm. Pillared clays prepared from pre-treatment with NaCl were more thermally stable at higher temperatures.

The influence of montmorillonite on the flame‐retarding properties of intumescent bio‐based PLA composites

AbstractBiobased flame‐retardant polylactic acid composites were prepared using ammonium polyphosphate (AP), lignin, and a raw montmorillonite (ANa) as the intumescent formulation. The concentration of AP and of ANa was varied in order to study its influence on the flammability properties of the composites. The samples were submitted to cone calorimeter test, thermogravimetric analysis coupled to Fourier‐transform infrared spectroscopy (TGA‐FTIR), limiting oxygen index (LOI), and UL‐94 vertical burn. The cone calorimeter residues were analysed through scanning electronic microscopy, X‐ray diffraction, and FTIR. The results show that the combined addition of the intumescent formulation and the ANa leads to an improvement in the fire behavior of the composites, compared with that of the neat polymer. The best fire‐retardant performance was achieved by using the highest AP concentration (17%) and the lowest ANa concentration (1.2%), reaching a LOI value of 39%.

Al30 polycation pillared montmorillonite preparation and phosphate adsorption removal from water

Phosphorus removal from surface water is a key to control eutrophication issues. Among phosphorus removal strategies, clay adsorption materials have been studied widely due to various advantages. Yet, raw montmorillonite (MMT) has limited adsorption capacity for phosphate. In order to improve the adsorption performance of MMT for phosphate, aluminum polycation Al30 was used as a pillaring agent to modify MMT material, and response surface method was used to optimize the preparation process. The optimal conditions were obtained as: [OH−]/[Al3+] molar ratio of 2.4:1, Al/MMT ratio of 4:1, curing time of 12 h, reaction temperature of 77.5 °C, and alkali adding rate of 1.55 mL/min. After modification, the properties of MMT were improved obviously and the adsorption of phosphate in solution was enhanced. Investigation results indicate that the acid environment is more favorable for the adsorption of phosphate by Al30-MMT. The adsorption of phosphate by Al30-MMT accords with Langmuir model with maximum adsorption of 62.5 mg/g at 318 K and pseudo-second order kinetic model. The main adsorption mechanisms of Al30-MMT in the process of phosphate removal include electrostatic physical adsorption and anion exchange.

Effect of montmorillonite addition (modified and unmodified) on the structural, mechanical, thermal, and morphological properties of nanocomposites based poly (vinyl chloride)

Poly (vinyl chloride)/ montmorillonite nanocomposites were prepared using a melt mixing technique. For this purpose, three montmorillonite samples (MMT) namely, raw montmorillonite (R-MMT), sodium montmorillonite (Na+-MMT) and organically modified montmorillonite (O-MMT) were used with different contents (0, 1, 3, 5, 7 and 9 phr) in the presence of dioctyl phthalate (DOP). X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC), and mechanical testing were used to investigate the physical properties of nanocomposites (PVC/MMT). The results of XRD show that macromolecule chains of PVC may be intercalated or exfoliated into the gallery of modified montmorillonite (Na+-MMT and O-MMT). Microcomposites structure is formed on the PVC/R-MMT nanocomposites when the unmodified montmorillonite (R-MMT) content is added from 1 to 9 phr. However, the glass transition temperature (Tg) of PVC/O-MMT nanocomposites is shifted slightly to lower temperatures. Furthermore, O-MMT plays the role of an internal plasticizer hence increases the distance between macromolecule chains of the polymer. Consequently, the degree of interactions between the chains decreases inducing a decrease in Tg. Synergy effect is also observed on the PVC/O-MMT nanocomposites with the increase in the amount of O-MMT. The morphological study by AFM shows a reduction in surface roughness under the effect of montmorillonite modified, and particularly with (1 phr) of O-MMT.

Technology for Preparation of Hybrid Sorbents Based on Plant Raw Materials and Montmorillonite

The possibility of preparation of hybrid nanocomposites, based on Burdock Arctium Lappa L biomass, modified with enzymes and montmorillonite, was substantiated. It was founded that bio-modification allowing releasing pectin into the biomass Burdock structure that allow fixing clay mineral particles onto biomass. It was found that the increase of pore spaces occurs at the expense of increasing mesopore spaces to 93 %. It allows increasing the adsorption capacity of hybrid nanocomposites to zinc ions and methylene blue to 52.2 and 166.9 mg g-1 respectively; that is 3.5 and 9 times more than adsorption capacityfor initial plant Burdock

Adsorption of Eriochrome black-T from aqueous environment by raw Montmorillonite

ABSTRACT The present study aimed to investigate the removal of the azo dye, Eriochrome black-T (EBT) from the synthesised effluents using the Montmorillonite (MM) raw clay. MM is a soft phyllosilicate group of minerals and has been used as a low-cost adsorbent for the removal of pollutants from the environment. In this regard, the effect of several factors, such as contact time, pH, adsorbent dose, initial dye concentration, solution ion strength, and temperature in the batch system was assessed. Fourier transformed infrared (FTIR) spectroscopy and X-ray diffractometer (XRD) techniques were also employed to examine the MM. Adsorption capacity of EBT in equilibrium time equal to 20 min was attained 57.88 mg/g. Removal of EBT by the MM illustrated that the data had a good fit with the models of pseudo-second-order and Freundlich isotherm. The contact time and pH were also optimised at 20 min and pH = 3, respectively. The maximum adsorption capacity (72.71 mg/g) was obtained for pH value of 3. Based on the value of RL in this study (RL = 0.70), the adsorption process of EBT removal using MM was favourable. The results from this study confirmed the effectiveness of MM as an inexpensive and eco-friendly option for the adsorption and removal of EBT from polluted water.

Synthesis of C21H38ClN Assisted Si Pillared Clays and the Effects of CeO2 Addition on Its Supported Palladium Catalyst for Benzene Oxidation

Mesoporous silica-pillared clays (SPC) were prepared with C21H38ClN cationic surfactant as template and supported PdOx catalysts were prepared by impregnation method. The influence of addition of CeO2 on benzene combustion was evaluated. The samples were characterized by N2 adsorption–desorption, XRD, XPS, HRTEM and TPSR. Compared with the raw montmorillonite, the d001 value of SPC increased from 0.96 to 3.45 nm. Furthermore, the surface area was increased from 30 to 835 m2/g and the pore volume was increased from 0.11 to 1.30 cm3/g, respectively. The addition of CeO2 increased oxygen vacancies and improved the dispersion of PdOx on SPC, and the optimal addition of CeO2 was 10%. Therefore, of all the catalysts, 0.3%Pd/10%Ce/SPC could completely oxidize benzene at 280 °C, showing the highest catalytic activity. This catalyst showed high activity for benzene oxidation in wet conditions with or without Cl− displaying good durability, which should be related to the presence of Ce3+ on the surface of catalyst after reaction. The excellent pore structure of SPC, improved dispersion of PdOx and high concentration of Ce3+ on the catalyst surface were the key factors for the high catalytic activity of 0.3%Pd/10%Ce/SPC. Mesoporous silica-pillared clays (SPC) were synthesized and SPC supported CeO2 and PdO catalysts were prepared by impregnation method. The 0.3% Pd/10% Ce/SPC catalyst displayed the highest activity for benzene combustion.

Adsorption of two β-blocker pollutants on modified montmorillonite with environment-friendly cationic surfactant containing amide group: Batch adsorption experiments and Multiwfn wave function analysis

The novel environment-friendly hexadecanoamide propyltrimethy lammonium chloride (NQAS16-3) surfactant with different amounts (0.2, 0.4, 0.6, 0.8, 1.0, 1.2 CEC) was firstly used to modify montmorillonite, and the obtained organomontmorillonite (N-Mt) with the amount of surfactant equal to 1.0 CEC was utilized to adsorb two β-blocker pollutants- Atenolol (ATE) and acebutolol (ACE). The experimental results indicated that the equilibrium adsorption capacity of N-Mt(the organo-montmorillonite that the amount of modifier was 1.0 CEC) for ATE and ACE was 93.47 mg/g and 84.55 mg/g, respectively, which was more than twice that of raw montmorillonite for two pollutants, the adsorption was better fitted with the pseudo-second-order model and Langmuir isotherms model, and the adsorption was the spontaneous and exothermic process. Moreover, combining with the Zeta potential values of N-Mt, and with the help of Multiwfn wave function program based on density functional theory (DFT), the electrostatic interaction and the hydrophobic partitioning between N-Mt and two pollutant molecules were verified, p-π/π interaction between NQAS16-3 and ATE (or ACE) may be contributed to the increasing adsorption capacity of N-Mt for two β-blocker pollutants. The work provided novel organomontmorillonite for the removal of non-degradable β-blocker pollutants and the insight of the adsorption mechanism from the atomic level.

Capture effect of Pb, Zn, Cd and Cr by intercalation-exfoliation modified montmorillonite during coal combustion

Raw montmorillonite (MMT) was modified by intercalation-exfoliation method to improve the capture capacity of heavy metals (Pb, Zn, Cr and Cd) during coal combustion. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) Spectroscopy and Brunner-Emmett-Teller (BET) indicated that intercalation agents cetyltrimethylammonium bromide (CTAB) and sodium dodecyl benzene sulfonate (SDBS) could be successfully inserted into the interlayer of MMT during the intercalation step, additionally exfoliation process could peel off the MMT into fine flakes. The co-combustion of coal and MMTs was conducted in a tube furnace from 900 to 1300 °C. Results indicated that with the increase of temperature, the retention ratio of Pb, Zn and Cd gradually decreased, especially higher than 1200 °C with a great capture capacity reduction, whereas for Cr, it rose first and then decreased. The capture performance of modified MMT on Pb, Zn and Cr was obviously improved. However, for Cd, adverse effect was observed, of which the capacity was even worse than that of raw MMT in some cases. According to the mechanism analysis, the intercalation-exfoliation modification of MMT primarily enhances the chemisorption of heavy metals by exposing more active sites, which facilitates the fixation of heavy metals in the form of aluminosilicates.

RSM and ANN-GA modeling of colloidal particles removal from paint wastewater via coagulation method using modified Aguleri montmorillonite clay

In this study, response surface methodology (RSM) and artificial neural network (ANN) based on statistically designed experiments (CCD) were used as tools for simulation and optimization of total dissolved and suspended particles (TDSP)(colloidal particles) removal from paint effluent using coagulation method. A feed forward neural network model with Levenberg - Marquard (LM) back propagating training algorithm was adapted to predict the response (TDSP). The studied input variables were dosage, time and temperature. The raw montmorillonite clay (RMC) and modified montmorillonite (MMC) clay were characterized for elemental/structural elucidation using XRF, FTIR and SEM techniques and the result indicates that RMC is predominantly sodium montmorillonite. The performance of the ANN and RSM model showed adequate prediction of the response with R2 of 0.9504 and 0.9403, respectively. The RSM model predicted an optimal TDSP removal efficiency of 91.9% at 3 ​g/L, 38 ​min and 37 ​°C and validated experimentally as 89.8%. The artificial neural network-genetic algorithm (ANN-GA) predicted optimal TDSP removal of 90% at 3 ​g/L, 25 ​min and 30 ​°C and validated as 90.6%. The results obtained indicate that the ANN-GA was a better and more effective optimization tool than RSM in consideration of its higher R2.

Synergistic Action of Montmorillonite with an Intumescent Formulation: The Impact of the Nature and the Strength of Acidic Sites on the Flame-Retardant Properties of Polypropylene Composites

A raw montmorillonite (Mt) was submitted to different acidic activation times in order to investigate the influence of the strength and the nature (Brønsted and Lewis) of acidic sites on the synergistic action with an intumescent formulation (IF) composed of ammonium polyphosphate (APP) and pentaerythritol (PER) when incorporated into a polypropylene (PP) matrix. The acidity of the Mt samples was quantified by ammonia temperature-programmed desorption (TPD-NH3) and Fourier transform infrared spectroscopy (FTIR) with pyridine adsorption. The mineral clays were also characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), nitrogen adsorption analysis and particle size distribution. Thermogravimetric analysis (TGA), limit oxygen index (LOI) and UL-94 were performed to evaluate the flame-retardant properties and the thermal stability. The TGA results show that the final residue increased 2 to 3 fold in comparison to the values predicted theoretically. The flammability properties achieved a maximum for the system containing an excess of moderate-strength Brønsted sites relative to the Lewis ones, reaching 38% in the LOI test. This result suggests that the presence of these Brønsted acidic sites is important, as they take part in the esterification reaction between APP and PER which gives rise to the char formation. The FTIR-Pyr adsorption and flammability results indicate that both the nature and strength of the acidic sites influence the flame-retardant properties.

Greener adhesives based on UF/soy protein reinforced with montmorillonite clay for wood particleboard

AbstractThere is a global concern about the types of adhesives used for the binding of wood particles, most of which include formaldehyde in their formulation. The aim of this work is to study the effect of raw montmorillonite (Mt) particles on blended urea formaldehyde (UF)/soy protein (SP) adhesives for the manufacture of wood particleboards to reduce the use of this carcinogenic component. Rheology showed that Mt does not alter the viscosity of adhesives at high shear rates, so they can be applied by spray. Thermogravimetric analysis/derivative thermogravimetry (TGA/DTG) analysis revealed an enhancement of their thermal stability due to the presence of clay particles. Polymer–Mt interaction was studied by small amplitude X‐ray scattering and scanning electron microscopy. According to these results, the exfoliated structure of the clay particles was achieved. Wood particleboards were manufactured with UF/SP/Mt adhesives in order to study their mechanical properties. The three‐point bending test showed that Mt particles improved the modulus of both rupture and elasticity. UF/SP/Mt resins proved to be a prominent product for the development of environmentally friendlier particleboards with desirable mechanical properties.

Study on Morphology and Rheological Property of Organoclay Dispersions in Soybean Oil Fatty Acid Ethyl Ester over a Wide Temperature Range.

This work attempted to establish the relationship between the dispersion morphology and the viscous flow behavior of clay dispersions in soybean oil fatty acid ethyl ester (FAEE) at 2 and 65 °C. The clays used in this study include raw montmorillonite (Mt) and three kinds of organoclays prepared by ion exchange modification of Mt by cetyltrimethylammonium chloride (OC16), dihexadecyldimethylammonium chloride (ODC16), and trihexadecylmethylammonium chloride (OTC16), respectively. The X-ray diffraction and water contact angle results demonstrated that greater alkyl chain number of surfactants led to greater interlayer space and stronger hydrophobicity of organoclays. Due to the good affinity of the surfactant and FAEE, OC16 exhibited the most stable dispersion in FAEE between 2–65 °C, which resulted in the best flat rheological property. The molecular structures of multiple chain surfactants were quite different from that of FAEE, resulting in weak affinity between organoclays (ODC16 and OTC16) and FAEE. The sheets of ODC16 and OTC16 tended to aggregate at 2 °C, forming a gel structure, thus significantly increasing the low shear rate viscosity (LSRV) and yield stress. At 65 °C, with the expansion of FAEE and the stronger thermal motion of sheets, the dispersions of ODC16 and OTC16 were improved, destroying the original gel structure and resulting in significant decreases in LSRV and yield stress. This study confirmed that stable clay/FAEE dispersions tended to exhibit flat rheology, which could serve as a basis for the application of clay/biodiesel dispersion in deep-water drilling.

Adsorption of Methylene Blue by Hydroxyl-Aluminum Pillared Montmorillonite

A purified raw montmorillonite and hydroxy-aluminum pillared montmorillonite have been prepared from a natural bentonite from Maghnia, Algeria. These materials have been analyzed by X-ray fluorescence spectroscopy, X-ray diffraction, Infrared spectroscopy and nitrogen adsorption-desorption measurement. The pillared montmorillonite provided a certain increase of interlayer basal spacing and BET surface area and consequently the improvement of its capacities adsorption and decolorization of Methylene Blue. The adsorption properties of these materials were studied as a function of contact time, solution pH, initial Methylene Blue concentration and temperature. The adsorption kinetics and isotherms were well fitted by pseudo-second order and Freundlich models, respectively. In addition to that, thermodynamic studies showed an exothermic and a spontaneous process.

Adsorption of Methylene Blue by Hydroxyl-Aluminum Pillared Montmorillonite

A purified raw montmorillonite and hydroxy-aluminum pillared montmorillonite have been prepared from a natural bentonite from Maghnia, Algeria. These materials have been analyzed by X-ray fluorescence spectroscopy, X-ray diffraction, Infrared spectroscopy and nitrogen adsorption-desorption measurement. The pillared montmorillonite provided a certain increase of interlayer basal spacing and BET surface area and consequently the improvement of its capacities adsorption and decolorization of Methylene Blue. The adsorption properties of these materials were studied as a function of contact time, solution pH, initial Methylene Blue concentration and temperature. The adsorption kinetics and isotherms were well fitted by pseudo-second order and Freundlich models, respectively. In addition to that, thermodynamic studies showed an exothermic and a spontaneous process.

Effect of acid-treated and hexadecyltrimethylammonium bromide-modified montmorillonites on adsorption performance of mycotoxins.

A series of modified montmorillonites treated by acid and hexadecyltrimethylammonium bromide (HTAB) were prepared and characterized, and their adsorption performances for three mycotoxins (aflatoxin B1, zearalenone, and deoxynivalenol) were evaluated at pH 2.8 and 8.0, respectively. The results indicate that the layers of raw montmorillonite are exfoliated after acid treatment and more active sites for adsorption of weak polar mycotoxins are exposed. While the intercalation of HTAB leads to an obvious increase of the interlamellar spacing and hydrophobic character of montmorillonite. The HTAB-AMMT-3 modified by acid and HTAB exhibits excellent adsorption capacity towards aflatoxin B1 (AFB1) and zearalenone (ZEA) whether in acidic or alkaline conditions compared with raw montmorillonite (MMT). However, all modified montmorillonites have low adsorption capacity for DON due to its poor planarity preventing it from entering into interfacial layer of montmorillonite.