Synthesis Of Organoclays Research Articles

Purification of Iranian bentonite for organoclay synthesis for use in clay–polymer composites

Abstract Polymer-based composites modified with organoclay are economically beneficial candidates for a variety of applications. Different types of impurities accompany montmorillonite phases in various bentonites, which impact the quality and cost of organoclays and final composites. To obtain organoclays for clay composite applications, eight Iranian raw bentonites from different geographical locations were selected as the candidates and characterized by X-ray diffraction (XRD). Sample IB was chosen due to its high purity and lower cristobalite content than the other samples. It was purified by centrifugation or sedimentation methods using a sodium hexametaphosphate (NaHMP) dispersant. The cation-exchange capacity (CEC) was measured for bentonite before and after purification by sedimentation, and it showed a significant increase from 6.944 to 12.128 eq g–1, confirming successful purification. Organoclays were prepared using purified bentonite (sedimentation method) with two surfactants (cetyltrimethylammonium bromide and octadecylamine), and the amount of octadecylamine was optimized. Purified bentonite and organoclay were characterized by XRD, scanning electron microscopy (SEM) and X-ray fluorescence. The results indicate that most of the impurities were removed after purification, and the interlayer space of organoclays increased to 35 Å in the optimized sample prepared with an amount of octadecylamine that was twice the CEC in purified bentonite. The prepared organoclay was used to improve low-density polyethylene (LDPE) polymer properties. The clay–polymer composite properties were studied by field emission SEM, thermogravimetric analysis and tensile strength tests. The organoclay was fully dispersed in the LDPE matrix and in the sample with 5 wt.% of organoclay, where Ti (the temperature at which 10% of the sample is decomposed) and T50% (the midpoint of degradation) were 17°C and 13°C greater than those of polyethylene, respectively. Additionally, the sample residue with 5 wt.% of organoclay at 600°C was 43.4%. The tensile strength of polyethylene increased from 8.67 to 9.03 MPa in the sample with 4 wt.% of organoclay.

Gamma radiation-induced synthesis of organoclays based polyaniline and ilmenite clay minerals for cesium ions removal from aqueous solutions

In this study, new eco-friendly organoclays sorbents-based bentonite clay (bentonite/polyaniline OC1 and bentonite/polyaniline/ilmenite OC2) were prepared by gamma radiation. Characterization of the prepared materials was done using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD), and energy dispersive X-ray analysis (EDX). The results show that polyaniline molecules and ilmenite penetrate the bentonite host material at montmorillonite sites. The synthesized sorbents were tested to remove cesium ions from the aqueous solutions. The parameters affecting the adsorption of cesium were also investigated, such as contact time, pH, the initial metal ion concentration, and the adsorbent dosage. The regeneration tests reflect the long-term stability of the prepared sorbent up to 5 cycles. The optimum conditions for adsorption of cesium ions using the mentioned sorbents were found at a contact time of 120 min and pH of 6–7 and 0.05 g dose weight. The maximum adsorption capacity of Cs+ reached about 24.7 mg/g and 34.4 mg/g for the prepared bentonite/polyaniline and bentonite/polyaniline/ilmenite at 25°C, respectively. The desorption experiment indicates that 0.1 M NaOH and 0.1 M HCl were chosen as the best eluents for loaded cesium on OC1 and OC2, with desorption rates of 45% and 15%, respectively. The thermodynamic investigation suggested the exothermic and spontaneous nature of the adsorption process. The removal efficiency of Cs+ from simulated aqueous mixture was found to fellow this order Cs+ > Co++ > Na+ > K+ ≫ Cr+6 this behavior reflects the selectivity of the synthesized adsorbents based bentonite towards Cs ions. Furthermore, this unique, cost-effective, and environmentally bentonite/polyaniline/ilmenite organoclay has good merits and can be utilized to separate pollutants for wastewater treatment applications.

Interaction of Indigo carmine with naturally occurring clay minerals: An approach for the synthesis of nanopigments

Dyes are organic colorants used in textile, paint, printing and many more industries for different purposes, especially to make the products more attractive. However, these organic compounds can not be removed easily from water bodies due to their non-biodegradable nature. In this context, this paper aims at the application of clay minerals and their organo forms which were used to remove the anionic dye, Indigo Carmine from aqueous media at different conditions such as pH, contact time and initial concentration by employing batch extraction method. Synthesis of organo clay was done through ion-exchange method using cationic surfactant (Cetylpyridinium chloride). The adsorbents (before and after adsorption of dye) were characterized using different analytical techniques like X – Ray diffraction, Fourier Transform Infra-Red spectroscopy, UV–vis spectroscopy. During the study, it was found that the efficiency for uptake of anionic dye was more for organo clay (Organo Montmorillonite − 330 mg g−1 and Organo Bentonite − 468 mg g−1) at favorable acidic condition as the surface of Montmorillonite and Bentonite become positively charged after interaction with surfactant results in electrostatic interaction between dye and organo clays. As there was no significant change in diffraction peak of adsorbent after interaction with dye suggested the surface interaction of dye which was further supported by FT-IR studies.

The Synthesis of Organoclays Based on Clay Minerals with Different Structural Expansion Capacities

An important goal in environmental research for industrial activity and sites is the investigation and development of effective adsorbents for chemical pollutants that are widespread, inexpensive, unharmful to the environment, and have the required adsorption selectivity. Organoclays are adsorption materials that can be obtained by modifying clays and clay minerals with various organic compounds through intercalation and surface grafting. Organoclays have important practical applications as adsorbents of a wide range of organic pollutants and some inorganic contaminants. The traditional raw materials for the synthesis of organoclays are phyllosilicates with the expanding structural cell of the smectite group, such as montmorillonite. Moreover, other phyllosilicates and inosilicates are used to synthesize organoclay to a limited extent. The purpose of this review was to analyze the possibility of using minerals of other groups with different abilities to expand the structure and structural charge for the adsorption of chemical environmental pollutants. The structural characteristics of various groups of phyllosilicates and chain minerals that affect their ability to modify organic surfactants and the adsorption properties of prepared organoclays were reviewed.

Improvement of glyphosate adsorption using new composites based on Ghassoul and chitosan: Kinetics and equilibrium study

Clay materials combined with other compounds are intensely used in several fields. The present study focuses on the synthesis of organoclays and nanocomposites based on the intercalation of surfactant and biopolymer into swelling Moroccan clay. The produced materials were used in the removal of glyphosate from the aqueous medium. The organoclay was obtained by the intercalation of cetyltrimethylammonium bromide (CTAB) in the interlamellar space of stevensite, and the nanocomposite was fabricated by the direct interaction between the stevensite and chitosan. These materials were characterized by mean X-Ray Diffraction, Fourier Transform Infra-Red Spectroscopy (FTIR), Thermal Analysis and Transmission Electron Microscopy (TEM). The results showed that the stevensite is the dominant clay mineral of Ghassoul and confirmed that the nanocomposite has an intercalated clay structure. The batch mode was accomplished to quantify the glyphosate removal capacity from aqueous solution by these materials. The enhancement of hydrophobic properties has promoted the retention of the herbicide. The pseudo-second-order kinetic model of adsorption was the most suitable to describe the process of adsorption and the Freundlich isotherm equation fitted satisfactory the adsorption isotherm data. The capacity of adsorption was more outstanding for the nanocomposite chitosan/Ghassoul and reached a significant value of 159.10 mg.g-1. The nanocomposites based on chitosan/Ghassoul could be considered as promising materials for treatments of pesticide-contaminated water.

Remediation of Phenol-contaminated Aqueous Solutions by Synthesized Organoclay

Phenol and its metabolites are among the hazardous organic compounds, due to their carcinogenicity, toxicity, long term persistence in the environment. The purposes of this study are the synthesis of organoclay as an adsorbent with high physicochemical stability, environmental compatibility and its application for remediation of aqueous solutions contaminated with phenol. In this research, organoclay was synthesized by the combination of sodium bentonite and Cetyl Trimethyl Ammonium Bromide (CTAB) surfactant with three different Cation Exchange Capacities (CECs). As well as, adsorption capacity of synthesized organoclay was determined during reuse until saturation. The results revealed that the removal efficiencies of phenol at concentrations of 100, 1000, 2000, and 3000 mg/L were 68, 84, 82, and 80%, respectively. In general, the use of organoclay can be an alternative to the complex and expensive systems for the removal of phenol from aqueous solutions with respect to its simplicity, high performance, and cost-effectiveness.

Evaluation of the influence of manufacture parameters during organoclay synthesis

Abstract The aim of this study was to evaluate the influences of synthesis parameters on the organophilization of a sodium bentonite clay via interlayer cation exchange by organocations. The parameters analyzed were: stirring time, rest time and surfactant concentration. The novelty of this study, when compared to others reported on the literature data, is the evaluation of different stirring and rest times, which is usually used as 20 min and 24 h, respectively. The organoclays obtained were characterized via X-ray diffraction, Fourier transform infrared spectroscopy and Foster swelling test performed in water and hexane. The results allowed to observe the intercalation of the surfactant between the bentonite layers, the low influence of stirring and resting times on basal interplanar distance, and that the increase of the resting time resulted in higher efficiency on the organophilization process. The Foster swelling test evidenced the organophilic character of the obtained clay.

Preparations of Organoclay Using Cationic Surfactant and Characterization of PVC/ (Bentonite and Organoclay) Composite Prepared via Melt Blending Method

Calcium-Montmorillonite (bentonite) [Ca-MMT] has been prepared via cation exchange reaction using benzalkonium chloride [quaternary ammonium] as a surfactant to produce organoclay which is used to prepare polymer composites. Functionalization of this filler surface is very important factor for achieving good interaction between filler and polymer matrix. Basal spacing and functional groups identification of this organoclay were characterized using X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy respectively. The (XRD) results showed that the basal spacing of the treated clay (organoclay) with the benzalkonium chloride increased to 15.17213 0A, this represents an increment of about 77.9% in the basal spacing. FTIR spectra illustrate that benzalkonium chloride compound was successfully intercalated in to clay layers. The results confirm the effectiveness of the synthesis of organoclay with similar characteristics compared to those ones observed in the bentonite. The features were obtained by a simple process and enable interaction with organic compounds (polymers and plastic). PVC/bentonite composite and PVC/organoclay composite were prepared by the melt intercalation method .The results have been analyzed and compared for PVC samples with (3wt%, 7wt% and 12wt %) bentonite and organoclay micro filler .Mechanical properties, thermal properties, flammability and water absorption percentage of prepared samples were tested. Mechanical characteristic such as tensile strength, elongation at break, hardness and impact strength (charpy type) were measured for all samples, where the tensile strength and elongation at break of PVC composites increased with increasing organoclay loading compared with unmodified bentonite. Also, the hardness and impact strength of the composites increase with increase in filler content. Thermal properties of PVC/ (bentonite, organoclay) composites were characterized using Differential Scanning Calorimeter (DSC) and thermal conductivity analyzer. The results showed Tg shifted toward higher temperature for all type of filler compared to neat PVC. Also, thermal conductivity measurement values illustrated that PVC/bentonite composites have a good thermal insulation at 12wt%, thermal conductivity was decreased from 0.222 W/m.K for neat PVC to 0.11 W/m.K at 12wt% PVC/bentonite composites. Organoclay give the best possible water absorbability of the PVC, with other word making it moisture resistant .The higher the filler content the higher burning time, the lower rate of burning and the lower height of the flame which are evident at 12wt% for all fillers.

Remediation of distilleries wastewater using chitosan immobilized Bentonite and Bentonite based organoclays

Organic⿿inorganic nanocomposite, namely chitosan immobilized Bentonite (CIB) with chitosan content of 5% was synthesized in an acetic acid solution (2%). Organically modified CIB and Bentonite (mbent.) were prepared by intercalating cetyl trimethylammonium bromide (CTAB) as a cationic surfactant at doses equivalent to 1.5 and 3 times the cation exchange capacity (CEC) of clay. The prepared samples were characterized using FTIR, XRD and SEM to explore the interlayer structure and morphology of the resultant nanocomposites. The remediation of distilleries (vinasse) wastewater process was carried out using different adsorbents including CIB, modified CIB (mCIB), Bentonite (bent.), modified Bentonite (mbent.) and chitosan at different contact time. The results showed that the packing density of surfactant used in the synthesis of organoclays strongly affects the sorption capacity of the clay mineral and also showed that (mCIB)3 was found to be the most effective sorbent in the purification of distilleries wastewater with 83% chemical oxygen demand (COD) reduction and 78% color removal.

Synthesis of organoclays: A critical review and some unresolved issues

The synthesis of organoclays (OC) by intercalation of quaternary ammonium cation (QAC) into expanding clay minerals, notably montmorillonite (Mt), has attracted a great deal of attention during the past two decades. The OC have also found applications in the manufacture of clay polymer nanocomposites (CPN) and environmental remediation. Despite the wealth of information that exists on the formation and properties of OC, some problems remain to be resolved. The present contribution is an attempt at clarifying two outstanding issues, based on the literature and experimental data obtained by the authors over the past years. The first issue concerns the relationship between the cation exchange capacity (CEC) of the Mt and the basal spacing of the OC which, in turn, is dependent on the concentration and the nature of the added QAC. At a concentration less than 1 CEC, organo-Mt (OMt) formed using the QAC with a short alkyl chain length with nc<16 (e.g., dodecyl trimethylammonium) gives basal spacings of 1.4–1.6nm that are essentially independent of the CEC. However, for long-chain QAC with nc≥16 (e.g., hexadecyl trimethylammonium), the basal spacing varies with the QAC concentration. For Mt with a CEC of 80–90meq/100g, the basal spacing of the OC increases gradually with the CEC and shows a sudden (stepwise) increase to 3.2–3.8nm at a QAC concentration of 1.5 CEC and to 3.5–4.0nm at a concentration of 2.0 CEC. The second issue pertains to the “locking” effect in QAC- and silane-modified pillared interlayered clays (PILC) and Mt. For silylated Mt, the “locking” effect results from the covalent bonding of silane to two adjacent layers within a single clay mineral particle. The same mechanism can operate in silane-grafted PILC but in this case, the “locking” effect may primarily be ascribed to the pillaring of adjacent basal surfaces by metal hydr(oxides).

Physical and chemical organoclay synthesis features for adsorption of chromium

Although the wide range of publications devoted to obtaining sorbents by modification of the clay mineral montmorillonite by cationic surfactants to remove chromium (VI) from an aqueous solutions, by this time little attention was given to physical and chemical features of the process of synthesis. In the present paper was first shown the influence of different factors in the process of modifying montmorillonite by hexadecyltrimethylammonium bromide on the absorption characteristics using X-ray diffraction, macroelectrophoresis analysis and sorption methods. Revealed that the change of pH in range 4-10 and choosing contact time in a wide range slightly affect the final properties of the resulting sorbent. Proved that increasing the ratio of surfactant in the reaction medium towards montmorilonite, lowering the temperature and the absence of ethanol in the reaction medium significantly increase the adsorption properties of modified montmorillonite towards ions of chromium (VI). Results of the research can be used to obtain sorbents for the removal of chromium (VI) from contaminated water.

Synthesis of organoclays and their application for the adsorption of phenolic compounds from aqueous solution

Organoclays were synthesized by exchanging inorganic cations between layers in Thanh Hoa bentonite using organic cations including benzylhexadecyldimethylammonium (BHDDM+), dimethyldioctadecylammonium (DMDOD+) and benzylstearyldimethylammonium (BSDM+). Inserting organic cations increases material interlayer distance significantly (from 15Å to 40Å) and simultaneously enhances affinity of materials toward organic pollutants. The results show that adsorption capacity of organics on organoclays strongly depends on affinity between organic substances and ammonium cations rather than on interlayer distance of organoclays. This means that the sorption of organoclays for organic contaminants was significantly influenced by the nature of the surfactants added to the clay.

A thermoanalytical assessment of an organoclay

High resolution thermogravimetric analysis (TG) has attracted much attention in the synthesis of organoclays and its applications. In this study, organoclays were synthesised through ion exchange of a single cationic surfactant for sodium ions, and characterised by methods including X-ray diffraction (XRD) and TG. The changes of surface properties in montmorillonite (MMT) and organoclays intercalated with surfactant were determined using XRD through the changes in the basal spacing. The TG was applied in this study to investigate more information of the configuration and structural changes in the organoclays with thermal decomposition. There are four different decompositions steps in differential thermogravimetric curves. The obtained TG steps are relevant to the arrangement of the surfactant molecules intercalated in MMT and the thermal analysis indicates the thermal stability of surfactant modified clays. This investigation provides new insights into the properties of organoclays and is important in the synthesis and processing of organoclays for environmental applications.

Studies on the Suitability of Iron-rich Indian Bentonites for Synthesis of Organoclays by Intercalation

In the present study intercalation behaviour of two bentonites from Indian origin were compared with a high-puritycommercial montmorillonite. Experimental bentonites of Indian origin showed low cation exchange capacity (CEC) due to limited Mg2+ substitution. Infra-red spectral study revealed the presence of Fe3+ in octahedral positions. Organic loading of intercalated clays increased with CEC.

Synthesis of Organoclays with Controlled Particle Size and Whiteness from Chemically Treated Indian Bentonite

Organoclays or nanoclays have gained increased attention from industry as well as academia during the past 11/2 decades. These clays are prepared from natural clays which invariably have other minerals as impurities. It is of prime significance to remove impurities from organoclays which find applications in polymer nanocomposites, paints, cosmetics, and medicinal formulations. The Indian bentonites were treated with sulfuric acid, hydrochloric acid, hydrogen peroxide, oxalic acid, citric acid, and sodium dithionite to remove impurities invariably present in natural clays. Treatment with both minerals and organic acid could remove both interlayer and structural iron and improve the whiteness with breaking up layered structure. However, sodium dithionite treatment is observed to be more suited to remove iron impurities from bentonite and improve whiteness to 11% without any effect on the structure of the clay. Chemically treated bentonites were used for preparing organoclays in a single step to eliminate t...

Preparation of polystyrene/montmorillonite nanocomposites: optimization by response surface methodology (RSM)

Preparation of polystyrene (PS)-montmorillonite nanocomposites was carried out in 3 steps: purification and determination of the cation exchange capacity (CEC) of clay, synthesis of organoclay, and preparation of nanocomposites. In organoclay synthesis, 3 types of surfactants, long-chained (cetyltrimethylammonium bromide (CTAB)), short-chained (tetraethylammonium bromide (TEAB)), and ringed (benzyltriethylammonium bromide (BTEAB)), were used. Gallery distances of pure clay and organoclays (CTAB-O, TEAB-O, and BTEAB-O) were determined by X-ray diffraction (XRD) analysis as 1.25, 2.09, 1.52, and 1.63 nm, respectively. Preparation of nanocomposites was carried out by in situ polymerization. Composites, containing 2%, 4%, and 6% organoclay by mass, were characterized by XRD, thermogravimetric analysis (TGA), gel permeation chromatography (GPC), and transmission electron microscope (TEM). The synthesized nanocomposites showed an exfoliated structure and a higher decomposition temperature in comparison with pure PS. A new approach was tried in nanocomposite preparation using response surface methodology (RSM).

Synthesis of organoclays using non-ionic surfactants: Effect of time, temperature and concentration

The objective of the present research was to investigate the intercalation of three different polymer-based surfactants, namely polyethylene-glycol 1500 and 4000 (PEG 1500 and PEG 4000) and polyethylene-oxide (BRIJ 78), inside the interlayer of STx-1 montmorillonite. The effect of three parameters, such as time (30, 60, 90 min), temperature (30 and 60 °C) and initial concentrations in solution (45, 90, and 180 mM) was studied. A full microstructural characterization of the synthesized organoclays by XRD, FT-IR, and TG-DTA was performed. The quantification of polymer intercalated was estimated by COD (Chemical Oxygen Demand) analysis of the residual amount in solution. The intercalation was successful, as showed by the basal expansions detected by XRD, and confirmed by FT-IR, showing the typical C–H-stretching bands in the spectra of the synthesized clays. TG-DTA was not a reliable technique for the quantification of polymer intercalated, while COD correctly quantified such amounts. The role of temperature and time appeared to be uninfluent for intercalating the polymer inside the interlayer of STx-1 montmorillonite, while the driving parameter ruling the amount of intercalated polymer was the initial concentration in solution.

Adsorption of hydrocarbons on organo-clays—Implications for oil spill remediation

Organo-clays synthesised by the ion exchange of sodium in Wyoming Na-montmorillonite (SWy-2-MMT) with three surfactants: (a) octadecyltrimethylammonium bromide (ODTMA), formula C 21H 46NBr; (b) dodecyldimethylammonium bromide (DDDMA), formula C 22H 48BrN; and (c) di(hydrogenated tallow)dimethylammonium chloride were tested for hydrocarbon adsorption. Using diesel, hydraulic oil, and engine oil an evaluation was made of the effectiveness of the sorbent materials for a range of hydrocarbon products that are likely to be involved in land-based oil spills. It was found that the hydrocarbon sorption capacity of the organo-clays depended upon the materials and surfactants used in the organo-clay synthesis. Greater adsorption was obtained if the surfactant contained two or more hydrocarbon long chains. Extensive utilisation of chemometrics principally with the aid of MCDM methods, produced models which consistently ranked the organo-clays well above any of the competitors including commercial benchmark materials. Thus, the use of organo-clays for cleaning up oil spills is feasible due to its many desirable properties such as high hydrocarbon sorption and retention capacities, hydrophobicity. The negative effects of the use of organo-clays for oil-spill cleanup are the cost, the biodegradability, and recyclability of the organo-clays.