Bentonite Surface Research Articles

Synthesis of Magnetic Modified Organobentonite as Adsorbent for Degradation of Orange II

Magnetic modified organobentonite (Fe3O4/CTAB–Bent) was synthesized by chemical co-precipitation method in which CTAB–Bent was firstly achieved via ion–exchange.The composite materials have been characterized by powder X–ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR) and Scanning electron microscopy (SEM) . The results revealed that basal spacing of bentonite was increased through organic modification and the Fe3O4 particles synthesized which covering the surfaces of bentonite .Compared with natural bentonite, the adsorption capacity of Fe3O4/CTAB–Bent for Orange II was greatly enhanced and can be easily separated from the reaction medium by an external magnetic field after the treatment.

A green synthesis of magnetic bentonite material and its application for removal of microcystin-LR in water

A simple and green method has been developed for in situ assembly of magnetic Fe3O4 on the pillared bentonite by a solvothermal reaction. Fe3O4 nanopaticles have a nearly uniform size of about 200nm, and they create the homogeneous structures distributed on the bentonite surface. The resulting magnetic material (Fe3O4@Al-B) has a surface area of 110 m2/g and a saturation magnetization of 36.18emu/g. At the same time, Fe3O4@Al-B has a strong surface affinity toward microcystin-LR (MC-LR) both in Mili-Q water and river water samples. Adsorption of MC-LR on Fe3O4@Al-B increases with pH decrease, with a maximum adsorption at pH 2.1. The equilibrium adsorption data are also analyzed by using the Langmuir and Freundlich models to evaluate the adsorption capacity of Fe3O4@Al-B and a result of 161.29mg/g is achieved. The pseudo-second-order kinetic model provides the best correlation of the experimental data. Therefore, Fe3O4@Al-B is an effective technology and has a great potential in removing MC-LR from drinking water resources.

Sorption behavior of U(VI) onto Chinese bentonite: Effect of pH, ionic strength, temperature and humic acid

Herein, a local bentonite from Huangshan county (Anhui province, China) was purified and the purge bentonite sample was characterized by using FTIR and XRD to determine its chemical constituents and microstructures. The sample was chosen as an adsorbent to remove uranium ions from aqueous solutions as a function of various environmental parameters such as contact time, pH, ionic strength, foreign ions, humic acid and temperature under ambient conditions. The results indicated that the sorption of U(VI) on the bentonite was strongly dependent on pH and ionic strength. At pH<6.5, the sorption of U(VI) on the bentonite increased with increasing pH, whereas the sorption of U(VI) on bentonite decreased with increasing pH at pH>6.5. The presence of humic acid (HA) enhanced the sorption of U(VI) on bentonite obviously at low pH while it reduced the U(VI) sorption on bentonite at high pH values. The enhancement of U(VI) sorption on HA-bentonite hybrids at low pH was attributed to the strong surface complexation of surface adsorbed HA with U(VI) on bentonite surface, whereas the decrease of U(VI) sorption on bentonite at high pH was attributed to the formation of free HA-U complexes in solution. The Langmuir, Freundlich and D–R models were applied to simulate the sorption isotherms of U(VI) at three different temperatures of 298, 318 and 338K, respectively. The thermodynamic parameters (i.e., ∆H0, ∆S0 and ∆G0) calculated from the temperature dependent sorption isotherms indicated that the sorption process of U(VI) on bentonite was an endothermic and spontaneous process. At low pH, the sorption of U(VI) was mainly dominated by outer-sphere surface complexation and ion exchange with H+/Na+ on bentonite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH values. Based on the experimental results, bentonite is a very suitable material for the preconcentration and solidification of U(VI) ions from large volumes of aqueous solutions in U(VI) pollution cleanup.

Adsorptive removal of La(III) from aqueous solutions with 8-hydroxyquinoline immobilized GMZ bentonite

Due to the low permeability, high swelling capacity and good retardation properties, bentonite has been considered as the main component of buffer/backfill material for high level radioactive wastes repository all over the world. The adsorptions of metal ion were widely investigated recently. In this presentation, we provide an easy-to-use method to immobilize 8-hydroxyquinoline onto the surface of bentonite for the use of adsorption studies of La(III) from the aqueous solution. The effects of various parameters such as contact time, pH of the solution, ionic strength and metal ion concentration on the adsorption were investigated by the batch experiments. The biggest adsorption capacity is 41.7 mg/g, higher than the value reported by our previous work which is performed by the raw bentonite. Langmuir isotherm fits the experimental data well and the adsorption follows pseudo-second-order kinetic model. In summary, 8-hydroxyquinoline immobilized GMZ bentonite is an effective adsorbent for the removal of La(III) from aqueous solutions.

Adsorption of sulfur and nitrogen compounds on hydrophobic bentonite

The successful synthesis of hydrophobic magnetic composites formed by carbon filaments on bentonite surface has been obtained via chemical vapor deposition of ethanol and studied by electron microscopy, XRD, Mössbauer spectroscopy, Raman, and thermal analysis measurements. Bentonite clay was impregnated with different concentrations of iron salt and subjected to a chemical vapor deposition using ethanol as carbon source. The results suggest the reaction of iron on the surface of bentonite with ethanol leading to the formation of reduced iron phases and carbon. The carbon deposited is present as graphite, amorphous and filaments and the resulting materials show hydrophobic behavior besides magnetic properties conferred by the iron phases. This magnetic property is very interesting and allows the materials to be easily removed from the system. The hydrophobic bentonite was used as adsorbent of sulfur and nitrogen compounds, important contaminants in fuels, showing adsorption capacity of 38.7mgg−1 and 54.5mgg−1 for nitrogen and sulfur compounds respectively, a very high adsorption capacity compared with other materials with carbon presented in the literature.

Determination The Effect of ZnO on Iraqi Bentonite Surface Properties

Bentonite is widely used in industrial applications. The present study reports the effect of adding different weights of ZnO to the Iraqi bentonite, on surface area, pore volume and real density. These surface properties were evaluated for pure and modified bentonite. The modification was made by adding different ZnO weights such as; ( 0.5%, 1%, 5%, 10% ). The effect of heat exposing for all modified clay samples at 500 ?C have been also evaluated. The results show that the addition of 0.5% ZnO leads to increase the surface area percentage about 36%, increase pore volume percentage about 5.48% and increase the real density percentage about 27.116%. When the samples exposed to 500 ?C, their surface area and pore volumes have been decreased and the real density increased in compared with non-heat exposed samples.

Determination The Effect of ZnO on Iraqi Bentonite Surface Properties

Bentonite is widely used in industrial applications. The present study reports the effect of adding different weights of ZnO to the Iraqi bentonite, on surface area, pore volume and real density. These surface properties were evaluated for pure and modified bentonite. The modification was made by adding different ZnO weights such as; ( 0.5%, 1%, 5%, 10% ). The effect of heat exposing for all modified clay samples at 500 ?C have been also evaluated. The results show that the addition of 0.5% ZnO leads to increase the surface area percentage about 36%, increase pore volume percentage about 5.48% and increase the real density percentage about 27.116%. When the samples exposed to 500 ?C, their surface area and pore volumes have been decreased and the real density increased in compared with non-heat exposed samples.

Study on the adsorption behavior and mechanism of dimethyl sulfide on silver modified bentonite by in situ FTIR and temperature-programmed desorption

A high-performance adsorbent was developed by loading silver on bentonite for the adsorption of dimethyl sulfide (DMS) from liquid hydrocarbon streams under ambient conditions. It demonstrated a high saturated sulfur capacity of 80mg S/g adsorbent when the bentonite was loaded with 8wt% Ag+ and calcined at 150°C. The prepared adsorbents were characterized by adsorption of nitrogen (BET), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), pyridine Fourier transform infrared spectroscopy (pyridine-FTIR) and Thermogravimetric Analysis (TG). The results showed that the silver species dispersed on the surface of bentonite had an important role in determining the DMS removal performance while the surface acid sites of adsorbent had little correlation with the DMS removal performance. Combined techniques of temperature programmed desorption of DMS (DMS-TPD) and in situ Fourier transform infrared spectroscopy (in situ FTIR) were used to investigate the adsorption mechanism of DMS on raw bentonite and Ag+ modified bentonite, respectively. The results revealed that three interaction patterns were existed between the adsorbed DMS and raw bentonite while two interaction patterns were observed between adsorbed DMS and Ag+ modified bentonite. The DMS molecules hardly entered into the interlayer of Ag+ modified bentonite due to the strong interactions between DMS molecules and silver cations.

ADSORPTION STUDY OF RHODAMIN B DYE ON IRAQI BENTONITE AND MODIFIED BENTONITE BY NANOCOMPOUNDS TIO&lt;sub&gt;2&lt;/sub&gt;, ZNO, AL&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; AND SODIUM DODECYL SULFATE

The adsorption of Rhodamin B on Iraqi bentonite at the concentration range from 50 to 250 µg mL-1 was studied, Nano compounds; ZnO, TiO2, Al2O3 m and SDS in different amounts 0.01-0.1 g 10-1 g of Bentonite were used to modified the adsorption capacity of bentonite to remove the Rhodamin B from aqueous solutions. The study indicated that using 0.05 g and 0.1 of Sodium Dodecyl Sulfate (SDS) lead to increase the percentage removal (%R) from 79.3% for pure bentonite to 99.3%. While using 0.05 g TiO2 lead to increase the %R to 98.9%, 0.05 of ZnO to 98.6%. The other amount additives and Al2O3 using was not success to increase the %R for the Rhodamin B on bentonite surface. SEM measurement was achieved to discover the Nanoparticl exists in the bentonite surfaces.

Catalytic degradation of microcystin-LR using bentonite supported bimetallic Fe/Pd nanoparticles

In this paper,bentonite supported bimetallic Fe/Pd nanoparticles(B-Fe/Pd) was explored to use for degradation of microcystin-LR(MC-LR).96.86% of MC-LR was degraded after 180 min with an initial MC-LR concentration of 5mg L-1(pH 6.86) using 0.1g B-Fe/Pd.UV-Vis and HPLC-UV showed that the peak of MC-LR at 238 nm was disappeared after B-Fe/Pd react with MC-LR.SEM-EDS,XRD,FTIR and XPS used for characterization of B-Fe/Pd before and after reaction with MC-LR revealed the formation of iron oxide and iron hydroxides after degradation of MC-LR.The degradation of MC-LC using B-Fe/Pd fitted well the pseudo-first kinetic order model with an activation energy was 12.77 kJ mol-1.Degradation mechanism of MC-LR was proposed,which was based on firstly MC-LR adsorded in the surface of bentonite and iron nanoparticles-palladium particles,secondly iron nanoparticles reacted with water to produce hydrogen,and the formation of hydrogen radical by the Pd catalysis,finally MC-LR was reduced by hydrogen radical,where the most toxic conjugated double bond of MC-LR was broken by the reduction.

Comparative Study of Laterite and Bentonite Based Organoclays: Implications of Hydrophobic Compounds Remediation from Aqueous Solutions

Four cost effective organoclays were synthesized, characterized, and studied for the sorption of hydrophobic compounds (edible oil/grease and hydrocarbon oil) from aqueous solutions. Organoclays were prepared by cation exchange reaction of lattice ions (present onto the surface of laterite and bentonite clay minerals) with two surfactants, hexadecyl trimethyl ammonium chloride (HDTMA-Cl) and tetradecyl trimethyl ammonium bromide (TDTMA-Br). Fourier transform infrared spectroscopy and scanning electron microscopy were used for the characterization of synthesized organoclays. It was found that the amount of surfactant loading and the nature of the surfactant molecules used in the syntheses of organoclay strongly affect the sorption capacity of the clay mineral. Further, it was found that both the laterite and bentonite based organoclays efficiently removed the edible and hydrocarbon oil content from lab prepared emulsions; however, the adsorption capacity of clay mineral was greatly influenced by the nature of hydrophobic compounds as well.

Synthesis and characterization of clay/polyaniline nanofiber hybrids

AbstractA modified interfacial polymerization was used to prepare polyaniline (PANI) nanohybrids. The influence of the synthetic route, amounts of bentonite, and the surfactant on the structure, morphology, and optical properties of the as‐synthesized nanocomposite were investigated. These materials were characterized by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction, ultraviolet–visible spectroscopy, thermogravimetric analysis, and rheometer. The results show that PANI could be intercalated into the interlayer of the bentonite. The interlayer space increased from 1.25 to 1.486 nm. Then, the hexadecyl trimethyl ammonium bromide was used to modify the surface of bentonite, which was helpful in hybridizing with PANI for its hydrophobic properties. Both the intercalated and coating structure were found in the bentonite/PANI nanohybrid. The TEM and SEM images verified that the surface of the bentonite plate was coated by PANI nanofibers. In addition, for the study of the electroresponsive behavior, the composite was dispersed in silicone oil, and its electrorheological characteristics were examined via both an optical microscope and a rheometer equipped with a high‐voltage power source. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effect of a mixed anionic-nonionic surfactant adsorption on bentonite structure and on distribution of pentachlorophenol

The adsorption of an anionic–nonionic surfactant mixture and its effect on bentonite structure and the impact of surfactants on pentachlorophenol (PCP) distribution in solid–liquid system were investigated. The aim was to study and explain the high remediating efficiency of ionic–nonionic mixed surfactants for hydrophobic organic compounds (HOCs) — present in contaminated soils and groundwater. The anionic surfactant not only reduced adsorption of nonionic surfactant, but also significantly enhanced PCP desorption from bentonite, as indicated by the apparent distribution coefficients (Kd⁎) of PCP. Surfactant intercalation modified bentonite specific surface area, pore volume, surface roughness and irregularities, as indicated by the fractal dimension calculated by nitrogen adsorption–desorption isotherms. The co-adsorption of the anionic and nonionic surfactants increased ordering conformation of the surfactants on bentonite surface, and improved the thermal stability of the organobentonite system.

Synthesis of nano-MoS2/bentonite composite and its application for removal of organic dye

A nano-MoS2/bentonite composite was synthesized by calcinating MoS3 deposited on bentonite in H2. The obtained composite was characterized using thermogravimetric analysis, X-ray diffractometer, scanning electron microscope and transmission electron microscope. The results show that nano-MoS2 particles are distributed on the surface of bentonite and form layered structures with layer distance of about 0.64 nm. The composite presents an excellent performance for the removal of methyl orange. Some operation conditions affect the removal efficiency of methyl orange, such as dosage of composite, initial concentration of methyl orange, temperature and pH value. However, light source does not influence the removal efficiency. The removal mechanism is attributed to the adsorption of methyl orange on the nano-MoS2/bentonite composite. The adsorption of methyl orange on the composite is in accordance with the pseudo-second-order kinetic model.

Evaluation of Turkish bentonite for removal of dyes from textile wastewaters

Removal of reactive dyes from textile industry wastewaters is a great economic and environmental challenge. In this study, systematic adsorption tests were carried out using natural and modified bentonites to remove a textile dye, Procion Navy HEXL. The results indicated an optimum at 0.1% solids concentration and 4 h of mixing time. The modified bentonite (hexadecyltrimethylammonium bromide, HTAB) had a 12-fold increase in the adsorption capacity compared to the natural bentonite. The zeta potential experiments revealed that the negative surface charge of natural bentonite at all pH values became positive upon modification with HTAB. These results clearly indicated that the negatively charged dye can adsorb onto bentonite surface via electrostatic attraction. In addition, adsorption isotherm models (Langmuir, Freundlich and Dubinin-Radushkevich) were used to analyze the adsorption in the dye-bentonite system. It is concluded that bentonite after surface modification can be conveniently used in the abatement of reactive azo dyes in textile wastewaters.

The Effection of Copper Chloride on the Surface of Bentonite in Adsorption of Propylmercaptan

In this article, dynamic tests and static tests were carried out at room temperature to test the propylmercaptan adsorption of original bentonite and different modified bentonites. With the increasing of Cu loading, the capacity of adsorption increased, but it was decreased by the increasing of roast temperature. The bentonites were characterized by solubility tests, X-ray diffraction, thermal analysis, and nitrogen adsorption. They reveal that chloride compounds on the surface of bentonite with a roast temperature of 150°C may be present mostly in the form of CuCl2. But with the rise of the roast temperature, CuCl and CuO will replace CuCl2, and it is not good for propylmercaptan adsorption. Also, it shows that the compounds may exist as amorphous materials.

Characterization of natural- and organobentonite by XRD, SEM, FT-IR and thermal analysis techniques and its adsorption behaviour in aqueous solutions

AbstractIn this study, natural bentonite was modified with hexadecyltrimethylammonium (HDTMA) bromide to obtain organobentonite (HDTMA-bentonite). Bentonite and HDTMA-bentonite were then characterized using XRD, XRF, SEM, FT-IR, thermogravimetric (TG) analysis, elemental analysis and Brunauer-Emmett-Teller (BET) surface area techniques. The HDTMA+ cation was found to be located on the surface and enters the interlayer spaces of smectite according to the XRD and SEM results. FT-IR spectra indicated the existence of HDTMA functional groups on the bentonite surface. The BET surface area significantly decreased after the modification due to the coverage of the pores of natural bentonite. After the characterization, the adsorption of a textile dye, Reactive Blue 19 (RB19), onto bentonite and HDTMA-bentonite was investigated. The maximum adsorption capacity of HDTMA-bentonite for RB19 was 502 mg g-1 at 20°C. The adsorption process followed a pseudo-second-order kinetic model and it was exothermic and physical in nature.

Removal of Hg(II) from an Aqueous Medium by Adsorption onto Natural and Alkyl-Amine Modified Brazilian Bentonite

AbstractMercury ion removal from waste-waters has been the subject of extensive research. The aim of the present investigation was to report the incorporation of the n-alkylamine molecules onto a bentonite surface and the capacities of these new chelating moieties on this modified bentonite surface for mercury removal from water. Bentonite collected from the Amazon region, Brazil, was used in an intercalation process with polar n-alkylamine molecules of general formula H3C(CH2)n-NH2 (n = 1 to 4) in 1,2-dichloroethane. The natural and modified bentonite samples were characterized by elemental analysis, Xray diffraction, helium picnometry, mercury porosimetry, and 29Si, 27Al, and 13C nuclear magnetic resonance spectroscopy. Because of the increasing size of the molecules attached to the pendant chains, the metal-adsorption capability of the final chelating materials was measured in each case. The adsorption of Hg(II) on natural and modified bentonites was determined under different conditions. The effects of concentration of Hg(II), contact time, and pH were investigated; batch and dynamic adsorption experiments of Hg(II) were conducted on bentonite samples under various conditions. The ability of these materials to remove Hg(II) from aqueous solution was assessed by means of a series of adsorption isotherms at room temperature and pH 4.0. In order to evaluate the bentonite samples as adsorbents in a dynamic system, a glass column was filled with clay samples (1.0 g each) and fed with 1.8 × 10−4 mol dm−3 Hg(II) at pH 4.0. The energetic effects caused by adsorption of metal cations were determined by means of calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such Hg(II)-nitrogen interactions.

Structural analysis of naproxen-intercalated bentonite (Unye)

The difference in the basal spacing (8.79 Å) and a higher mass loss (6.2%) in the temperature range of 200–750 °C of naproxen-bentonite (N-bentonite) comparing to that of Unye bentonite (UB) signified the existence of thermally stable organic species in the interlamellar space of the bentonite clay. The asymmetric OCO − stretching band (1607 cm −1) of N-bentonite became stronger in the temperature interval of 100–400 °C as a result of binding via the C O group of the ligand to exchangeable cation and/or water molecule whereas the OH bending peak of water (1633 cm −1) and the C C stretching vibration of aromatic ring (1531 cm −1) became weaker on thermal treatment. The effect of ionic strength on the desorption of naproxen species and the related kinetic data revealed that the release mechanism at pH = 7.4 is unrestricted diffusion controlled and governed by the repulsive interactions between the bentonite surface and the negatively charged species. The pore structure characteristics of the bentonite samples corresponding to the surface area, pore volume and pore size were determined by using the conventional analysis of the nitrogen adsorption–desorption isotherms.

Preparation and characterization of a quaternized chitosan

A novel method was developed to obtain N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride (HTCC) using glycidyl trimethyl ammonium chloride (GTMAC) and chitosan in a homogeneous system. The factors affecting the degree of substitution (DS) of HTCC, including the amount of perchloric acid, the reaction temperature, and the reaction time, were especially investigated. Under optimal conditions (i.e., with 2.0, 1.9, and 15 g of chitosan, perchloric acid, and GTMAC, respectively), chitosan was pre-reacted with GTMAC at 60 °C, and then the reaction was continued at 80 °C for 8 h. The as-produced HTCC had a DS of 86.9%. Its structure was characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance. Moreover, it had a good solubility in water within a wide pH range. Besides, the composite was formed from HTCC loaded on bentonite surface.