Al-pillared Bentonite Research Articles

Active sites regulation and adsorption performance of Al-pillared bentonite for the removal of lead from aqueous phase

Developing an environmentally friendly adsorbent with high adsorption capacity and economic benefits is crucial for the treatment of lead-contaminated wastewater. In this study, active clay (A-bent) and Al pillared acid-activated clay (A-AlPILC) were prepared using natural bentonite as the carrier via acidification and pillar-supported technology. The samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption experiments, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray fluorescence spectrometer (XRF). The results showed that the amended clay exhibited an increase in specific surface area (SSA) from 39.37 m2/g to 175.28 m2/g and 245.42 m2/g compared to raw bentonite. The interlayer spacing and total pore volume rose respectively. The adsorption technique achieved an impressive removal rate of 90.6 % for Pb(II). Adsorption data were fitted by adsorption kinetics and adsorption isotherm model. Based on the response surface method (RSM), and analysis of variance (ANOVA) showed that the influence of these variables was significant. The simulation of lead ions showed that the acidic functional groups and ligands promote adsorption more than they inhibit it. Using the density function theory (DFT) calculation, the bentonite cycle model was established to demonstrate the interaction between bentonite and lead, with a binding energy of −0.369 eV. Similarly, the density and energy band structure of the state were computed to explore the mechanism of heavy metal adsorption by clay minerals.

Lead (II) removal from aqueous solution over Al-pillared bentonite as low-cost adsorbent and optimization

This study focuses on the optimization of lead ion (Pb2+) removal from aqueous solution by modified Aceh natural bentonite using response surface methodology (RSM). The modification process involves sodium ion (Na+) from NaCl intercalation and pillarization with aluminum ion (Al+) from AlCl3. The composition of natural and modified bentonite was examined via X-ray fluorescence (XRF). The surface area of the samples was characterized by Brunauer Emmett and Teller surface area (BET) analysis. In addition, the experiments were conducted based on Box-Behnken Design (BBD). Furthermore, adsorption characteristics were investigated as a function of three independent factors comprising bentonite mass (1.0–2.0 g), agitation time (30–200 min), and initial lead concentration (100–500 mg/l). Analysis of variance (ANOVA) depicted the influence of these variables is very significant. Also, optimization equations were developed for the natural, intercalated, and pillared samples. Based on the RSM model, the optimized conditions were found at 1.93 g bentonite mass, 176.42 min agitation time, 367.44 mg/l of its initial adsorbate concentrations viz. 250.264 mg/l (NB), 253.902 mg/l (IB), and 260.768 mg/l at approximately 1.00 desirability. Therefore, Pb2+ adsorption capacity onto the pillared bentonite (PB) appears greater compared to the intercalated and natural materials. Al-pillared bentonite appears to be a promising candidate for the adsorbent of Pb2+ from an aqueous solution.

Catalytic Oxidation of Ponceau 4R in Aqueous Solution using Iron-impregnated Al-pillared Bentonite: Optimization of the Process

The application of the Fenton-like process for the oxidation of an aqueous solution of Ponceau 4R dye, using an aluminum pillared clay impregnated with iron (Fe(wt%)/Al-PILC) as catalyst, was investigated. The Response Surface Methodology (RSM), based on a Central Composite Design (CCD) was used to evaluate and optimize the oxidation process of a Ponceau 4R solution. Three independent variables were studied in the experimental design: the amount of H2O2 expressed in multiples of times of stoichiometry dose, iron concentration incorporated by impregnation onto aluminum pillared clay (Fe(wt%)), and amount of catalyst (Fe(wt%)/Al-PILC). The response variables were decolorization and total organic carbon (TOC) removal. The significance of independent variables and their interactions were tested by means of analysis of variance (ANOVA), with a 95% confidence level. With low stoichiometric dose of H2O2 (0.96 and 1.54 times), medium amount of catalyst (374.4 and 391.3 mg) and high Fe concentration impregnated in pillared clay (9.3 and 7.7 wt%), the total decolorization and high TOC removal were achieved. Under multi-objective optimization conditions (3.0 times the stoichiometric dose of H2O2, 420 mg Fe(wt%)/Al-PILC and 5.5 wt% Fe impregnated in Al-PILC), it was possible to achieve 86.18% decolorization and 66.81% TOC removal after 5 h of reaction at 25 °C, with the additional advantage of showing an iron leaching of less than 0.10 mg/L. The established models' soundness is confirmed by a good fit between predictive models and experimental results. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Nickel catalysts promoted with lanthanum for ethanol steam reforming: Influence of support and treatment on activity

The effect of support nature on the catalytic performance of Ni-based catalysts for ethanol steam reforming (ESR) was investigated. Nickel catalysts supported on lanthanum-modified Al2O3, TiO2, Al2O3-TiO2 and Al-pillared bentonite (denoted as Clay) were prepared by impregnation, characterized by X-ray diffraction (XRD), N2 adsoption-desorption, IR spectroscopy of acetonitrile adsorption and thermogravimetric analysis (TGA), and evaluated at 500 °C under atmospheric pressure. Both Ni/La-Al2O3 and Ni/La-TiO2-Al2O3 exhibited the best stability, whereas Ni/La-TiO2 and Ni/La-Clay deactivated quickly but with similar or higher H2 production. Catalyst deactivation was caused by carbon deposition, which formation was related to strong Brønsted sites. Efficiency of lanthanum as inhibitor of carbon deposition depended on the support nature.Oxidative regeneration allowed recovering initial activity of all used catalysts and even improving the performance of the latter two catalysts. This unexpected improvement can be due to change of nickel centres nature, caused by local overheating during the deposited carbon combustion.

Synthesis and Characterization of Al-Pillared Bentonite for Remediation of Chlorinated Pesticide-Contaminated Water

AbstractThe removal of pesticide contaminants from water is a key priority in environmental remediation, and requires intensive effort; this necessitates modification of the properties of pillared clays (PILCs) such as porosity, pore-volume, surface area, and synthesis methods. The purpose of the present study was to test the ability of Al-pillared bentonite (Al-PILB), using [Al13O4(OH)24(H2O)12]7+ and [Al30O8(OH)56(H2O)24]18+ (keggin cations, Al13 and Al30) as pillars, to adsorb chlorinated pesticides from contaminated water. In order to maximize intercalation and uniformity of layer stacking, various ratios of the nitrate forms of the synthesized keggin cations were intercalated into the natural bentonite (BT). The synthesized materials (Al-PILBs) were characterized by various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Fourier-transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy, and N2 adsorption-desorption measurements. Increases in basal spacing, surface area, and pore volume were observed. The adsorption capacity of the Al-PILBs for 17 types of chlorinated pesticides from contaminated water was better than using the BT alone, e.g. for heptachlor epoxide, dieldrin, and endrin at natural pH, the maximum adsorptions obtained at equilibrium solution concentrations of 16, 20, and 20 μg/L, respectively, were 59.2, 59.15, and 60 μg/g, whereas corresponding values using pristine BT were 34.68, 39.45, and 38.9, respectively. The data were best described by the Freundlich adsorption model.

Green synthesis of gold nanoparticles supported in Al-pillared bentonite using aqueous leaf extracts of Dracaena angustifolia and their use for reductive degradation of methyl orange

We obtained the green synthesis of gold nanoparticles (AuNPs) using suji leaf extract (Dracaena angustifolia) and used the AuNPs to reduce methyl orange. The active substance in suji leaf extract was determined using phytochemical tests to identify components such as terpenoid, steroid, alkaloid, polyphenol, flavonoid, and saponin. The catalyst Al–bentonite@AuNP was prepared by immobilizing HAuCl4 in Al–pillared bentonite, which was then reduced using various concentrations of suji leaf extract [0.1 %–1 % (w/v)]. The AuNPs were characterized using UV–vis spectroscopy and transmission electron microscopy, and the Al–bentonite@AuNP catalyst was characterized using Fourier transform infrared spectroscopy and X-ray diffraction. The application of Al–bentonite@AuNP as catalyst in the reductive degradation of methyl orange yields a degradation percent of up to 34.5 %.

Synthesizing and characterizing the mixed Al,Cu-pillared and copper doped Al-pillared bentonite for electrocatalytic reduction of CO2

Aluminum copper mixed Al,Cu-PILCs and copper dopped Cu@Al-PILC have been prepared. X-ray diffraction (XRD), N2 adsorption-desorption, fourier transformed infrared spectroscopy (FTIR), and Field Emission Scanning Electron Microscope (FESEM) have been used to characterize the samples. It was found that they are porous materials with high specific surface area and Cu specimens situated at the interlayer of bentonite. Basal spacing and specific surface area in bentonite were 1.1 nm and 33 m2/g respectively that increased to 1.98 nm and 296 m2/g by pillaring. Electrocatalytic behavior of these samples for CO2 reduction were studied by cyclic voltammetry. The voltammograms with and without CO2 indicate that PILCs is capable of catalyzing electrochemical reduction of CO2 with high current density. The results show that Cu@Al-PILC enjoys more acceptable electrocatalytic activities than other samples.

Synthesis and Characterization of Mixed Al,Cu-Pillared and Copper Doped Al-Pillared Bentonite

Synthesis and Characterization of Mixed Al,Cu-Pillared and Copper Doped Al-Pillared Bentonite

Development of Mn or Fe sulfides in the interlayer space of raw and Al-pillared bentonite

Preparation of metal sulfide nanoclusters (Mn or Fe) confined in the interlayer space of a bentonite either with or without previous Al2O3-pillaring was investigated by H2S-sulfidization of Mn²⁺- or Fe²⁺-exchanged Al2O3-pillared bentonite as potential strategy to control growth and mean final size of interlayered, MnS or FeS-like polynuclear nanoclusters. The materials were characterized by elemental analysis, cation exchange capacity, low-angle powder X-ray Diffraction, N2 adsorption isotherms, simultaneous thermal analysis (DTA/TGA), diffuse reflectance UV-vis spectroscopy and high-resolution X-ray photoelectron spectroscopy. Interlayered metal sulfides were successfully obtained in pretty short time of reaction (only ~12 h). Optimal set of preparation conditions was established promoting stabilization of the interlayered metal sulfides, whereas preserving typical layered stacking of the starting clay: (i) ratio H2S/M²⁺(incorporated) = 50 mol/mol (M = Mn²⁺ or Fe²⁺); (ii) temperature of sulfidization = 100 °C; (iii) 200 °C for final thermal treatment, irrespective the type of atmosphere used (inert-N2 or oxidizing-air) and (iv) acid-base neutralization prior to thermal treatment did not enhance thermal stability. The most efficient Al-pillaring was achieved with 20 meq Al³⁺/g clay in terms of both higher XRD 001 basal reflection and narrower distribution of alumina-pillars. HR-XPS and DR-UV-vis analyses of the best materials with every transition metal evidenced formation of polysulfide groups and blue-shift of the absorption signal as a consequence of the modification performed on the layered aluminosilicate. Development of Mn or Fe sulfides in the interlayer space of.... Available from: https://www.researchgate.net/publication/323399710_Development_of_Mn_or_Fe_sulfides_in_the_interlayer_space_of_raw_and_Al-pillared_bentonite [accessed Apr 18 2018].

Visible light induced photocatalytic degradation of rhodamine B by magnetic bentonite.

The photocatalytic activity of magnetic bentonite, Fe3O4 nanoparticles decorated Al-pillared bentonite (Fe3O4/Al-B), for the degradation of rhodamine B (RhB) in the presence of H2O2 under visible light (VL) was evaluated. The effects of different reaction parameters such as catalyst dose, dye concentration and externally added H2O2 were also investigated. The magnetic bentonite showed good photocatalytic activity, magnetic separability and stability for repeated use. More than 95% of 40 mg/L RhB was converted within 3 h under VL with a catalyst dose of 0.5 g/L. Suitable mechanisms have been proposed to account for the photocatalytic activities in the presence and absence of H2O2. The efficiency of H2O2 in VL process was much higher than that of the dark process. Results obtained in the current study may be useful to develop a suitable photocatalyst for photocatalytic remediation of different water contaminants including organic dyes.

Uptake of lead by Na-exchanged and Al-pillared bentonite in the presence of organic acids with different functional groups

This study investigated the uptake of lead (Pb) ions by Na-rich bentonite (Na-bentonite) and Al-pillared bentonite (Al-bentonite) in the presence or absence of organic acids containing different functional groups. Na-bentonite was an effective adsorbent for Pb2+ ions. The element was taken up by the mineral through ion exchange mechanism; and the formation of a lead carbonate hydroxide (hydrocerussite) also occurred. Al-bentonite adsorbed a smaller amount of Pb than Na-bentonite. XRD data indicated that the totality of clay interlayers was occupied by the pillaring agent that led to decrease in Pb uptake.The amount of Pb taken up by Na-bentonite decreased with increasing concentration of citric acid both when Pb and organic acid were added together as a mixture, and when citric acid was added 2h before the metal ions. Possible reasons for this were the formation of Pb-citrate complexes which had less affinity to Na-bentonite, and also hydrocerussite dissolution at acidic pH. Citric acid, however, did not change Pb uptake by Al-bentonite.Addition of lysine together with Pb did not have any effect on Pb uptake by Na-bentonite and Al-bentonite, which indicated occupation of different adsorption sites by Pb and lysine compared to citrate. However, lysine addition at 1:1 ratio 2h before Pb decreased the metal uptake, which again may be explained by the effect of lysine in hydrocerussite dissolution. Uptake of Pb in the presence of lysine was also higher when using Na-bentonite compared to Al-bentonite.

Catalytic properties and activity of copper and silver containing Al-pillared bentonite for CO oxidation

Al-pillared bentonite (Al-PB) using bentonite obtained from the Middle Anatolia region (Hançılı) was synthesized, and Cu@Al-PB and Ag@Al-PB were obtained after the second metal impregnation step. Cu/AlPB prepared using a hydrothermal method was obtained with a Cu/(Cu + Al) mole ratio of 0.05. The SEM/EDS, scanning electron microscopy/energy dispersive X-ray spectroscopy analyses indicated that the impregnation method resulted in a higher copper loading in the structure. Based on the XPS, X-ray photoelectron spectroscopy analysis, the aluminum in all of the samples was in the Al2O3 form with 2s and 2p3 orbitals. Although no copper peaks were observed for Cu/Al-PB, the 2p3 and 2p1 orbitals of copper as well as the 3d3 and 3d5 orbitals of silver were observed in the copper or silver impregnated samples, respectively. Metal incorporation resulted in an increase especially in the strength of the Brønsted acid peaks in the FTIR, Fourier transform infrared spectra. The intensity of the peaks corresponding to the Brønsted sites did not change substantially as pyridine desorption temperature increased. The impregnated samples created a decrease in the 50% conversion temperature for carbon monoxide oxidation. Cu@Al-PB, which was calcined at 500 °C, gave a carbon monoxide conversion that was as high as 100% at approximately 200 °C and maintained its activity to 500 °C. In the impregnated samples, the reaction may use the surface oxygen provided by the metal oxide.

Acid activation effect on the catalytic performance of Al-pillared bentonite in alkylation of benzene with olefins

In this research pillared catalysts were prepared by pillaring of bentonite and acid-treated bentonite with aluminum. The synthesized samples were characterized by X-ray diffraction, FT-IR spectroscopy, N2 adsorption isotherms, NH3 temperature programmed desorption, scanning electron microscopy (SEM) and elemental and thermal analysis techniques. Acid-treated sample contained lower Al content compared to the untreated sample, but its total pore volumes (TPV) and BET surface area was higher. Alkylation of benzene with linear olefins (1-decene and 1-dodecene) was studied with the prepared catalysts. Acid-activated pillared catalyst, due to its higher surface acidity showed enhanced catalytic activity compared to the untreated sample. The catalysts activity was also enhanced by increasing benzene to olefin molar ratios and reaction temperature. The catalysts showed higher activity when shorter chain hydrocarbon olefin was used. In acid-activated pillared catalysts higher selectivity for 2-phenyl isomer was obtained with 1-dodecene.

Study on the Reaction Kinetics and Catalytic Stability of Pillared Bentonite in Heterogeneous UV-Fenton Process

An investigate was carried out to evaluate the catalytic performance of Fe, Al-pillared bentonite in heterogeneous UV-Fenton process. The catalysts were prepared by a cation doping technique. X-ray diffiraction and infraed spectroscopy were used to characterize their properties. Results showed that intercalated process could obtained larger interlayer spacing. Some bands of infrared spectroscopy shifted to lower wave length, indicating that FexAly has intercalated into the layers of the bentonite. The higher ratio of Fe to Al was in the pillaring solution, the higher discolouration rate could be obtained. The discoloration rate reached 79.9% at 20 min and 283K when the ratio of Fe to Al in pillaring solution was 9:1. The reaction constants of the heterogeneous UV-Fenton process increased from 0.074 min-1 at 283K to 0.094min-1 at 323K. Its activation energy was 36.7kJ.mol-1, indicating that temperature had little effect on this process. Little Fe-leaching made it possible for Fe, Al-pillared bentonite to remain a high stability during recycling uses.

Synthesis and Catalytic Performance of Al-Pillared Clays Supported Fe<sub>3</sub>O<sub>4</sub> Nanoparticles

Al-pillared bentonite supported Fe3O4 nanoparticles were prepared by co-precipitation and characterized with X-ray diffraction (XRD), specific surface area (BET) and scanning electron microscopy (SEM). The supported Fe3O4 nanoparticles exist on the surface of clays, with better dispersing and no obvious aggregation than the ones without bentonite support. Batch tests were carried out to investigate the catalytic oxidation Orange II by the obtained heterogeneous catalysts. The effect of pH, temperature and initial H2O2 concentration on degradation was discussed, and the regeneration ability of catalyst was also studied.

Heterogeneous Catalysts in Pictet‐Spengler‐Type Reactions

Several solid catalysts were evaluated as an alternative for 1,2,3,4‐tetrahydroisoquinoline synthesis by means of the Pictet‐Spengler reaction. The reaction catalysed by a mixed oxide (Mg and Al) led to the best yield and good regioselectivity; using an Al‐pillared bentonite led to good yields and total regioselectivity. The results revealed no direct relationship between catalyst acidity and yield.

Comparison between granular pillared, organo- and inorgano–organo-bentonites for hydrocarbon and metal ion adsorption

Granular reactive materials have higher permeability and are therefore desirable for in situ groundwater pollution control. Three granular bentonites were prepared: an Al-pillared bentonite (PBg), an organo-bentonite (OBg) using a quaternary ammonium cation (QAC), and an inorgano–organo-bentonite (IOBg), using both the pillaring agent and the QAC. Powdered IOB (IOBp) was also prepared to test the effect of particle size. The modified bentonites were characterised with X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA) and uniaxial compression tests. The d-spacing increased only with QAC intercalation. The Young's modulus of IOBg was twice as high as OBg. Batch adsorption tests were performed with aqueous multimetal solutions of Pb2+, Cu2+, Cd2+, Zn2+ and Ni2+ ions, with liquid dodecane and with aqueous dodecane solutions. Metal adsorption fit the Langmuir isotherm. Adsorption occurred within 30min for PBg, while the granular organo-bentonite needed at least 12h to reach equilibrium. IOBp had the maximum adsorption capacity at higher metal concentration and lower adsorbent content (Cu2+: 2.2, Ni2+: 1.7, Zn2+: 1.4, Cd2+: 0.9 and Pb2+: 0.7 all in mmolg−1). The dual pillaring of the QAC and Al hydroxide increased the adsorption. The adsorption of liquid dodecane was in the order IOBg>OBg>PBg (3.2>2.7>1.7mmolg−1). Therefore IOBg has potential for the removal of toxic compounds found in soil, groundwater, storm water and wastewater.

Synthesis and Characterization of Al-Pillared Bentonite Clay Minerals

Synthesis and Characterization of Al-Pillared Bentonite Clay Minerals

Dissolved organic nitrogen (DON) adsorption by using Al-pillared bentonite

Dissolved organic nitrogen (DON) is now considered as one of the most important issues in drinking water field. In this study, DON removal by using Al-pillared bentonite adsorption is studied. Adsorption kinetics, equilibrium isotherms and the effect of pH are investigated. The method based on pillared bentonite adsorption is proved to be effective in removing DON and related substances. The maximum adsorption capacities of the bentonites vary from 7.11 to 7.61mg/g. Kinetic studies show that the adsorption of DON on the bentonites can be described by the pseudo-second-order kinetic model, and the intra-particle diffusion controls the limiting rate. pH is found to be the key parameter affecting DON removal. Acidic conditions are favored while alkaline conditions are impeded. Furthermore, it is found that the adsorption capacity of the pillared bentonites depends on the ratio of OH−/Al3+ during the pillaring process. Three-dimensional excitation–emission matrix (EEM) is also applied to assess the effect of adsorption on the removal of different DON fractions, and the results show that the tyrosine-like fractions are easier to be adsorbed.

Micro-mesopore analysis of Cu 2+ and Ag + containing Al-pillared bentonite

Copper impregnated Cu@Al-PILCs, silver impregnated Ag@Al-PILCs and copper aluminum mixed Cu/Al-PILCs were prepared using a bentonite sample from the Hançılı region, Turkey. Incorporation of the Cu 2+ or Ag + ions forming CuO and Ag 2O after calcination at 573 K decreased the basal spacing of 1.85 nm for Al-PILC by approximately 0.35 nm. The specific BET surface area and mesopore + micropore volumes measured by 77 K nitrogen adsorption after calcination at 573 K decreased from 236 m 2 g − 1 and 0.174 cm 3 g − 1 to 174 m 2 g − 1 and 0.172 cm 3 g − 1 by Cu 2+ impregnation and 171 m 2 g − 1 and 0.168 cm 3 g − 1 by Ag + impregnation, while the values for Cu/Al-PILC were 209 m 2 g − 1 and 0.184 cm 3 g − 1 . The micropore volume of all samples was about 20% of the total pore volume. The average Barrett–Joyner–Halenda (BJH) mesopore and Horvath–Kawazoe (HK) micropore dimensions were within 3.5–3.9 nm and 0.44–0.48 nm, respectively. Structural properties estimated from the Dubinin–Radushkevich (DR) method by using the nitrogen adsorption data were higher than those derived from the carbon dioxide adsorption data. SEM images indicated that Cu 2+ incorporation increased the mesopore volume of the Al-PILC.