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The adsorption property of the costless green cellulose acetate (CA) was boosted by the dual modifications: inner modification by incorporating carboxylated graphene oxide (COOH-GO) into the CA spheres and outer modification by the surface modification of the COOH-GO@CA spheres by iminodiacetic acid (IDA) for removing Pb(II). The adsorption experiments of the Pb(II) proceeded in a batch mode to evaluate the adsorption property of the COOH-GO@CA@IDA spheres. The maximal Pb(II) adsorption capacity attained 613.30 mg/g within 90 min at pH = 5. The removal of Pb(II) reached its equilibrium within 20 min, and the removal % was almost 100% after 30 min at the low Pb(II) concentration. The Pb(II) adsorption mechanism was proposed according to the kinetics and isotherms studies; in addition, the zeta potential (ZP) measurements and X-ray Photoelectron Spectroscopy (XPS) analysis defined the adsorption pathways. By comparing the XPS spectra of the authentic and used COOH-GO@CA@IDA, it was deduced that the contributed chemical adsorption pathways are Lewis acid–base, precipitation, and complexation. The zeta potential (ZP) measurements demonstrated the electrostatic interaction participation in adsorbing the cationic Pb(II) species onto the negatively charged spheres (ZP = 14.2 mV at pH = 5). The unique channel-like pores of the COOH-GO@CA@IDA spheres suggested the pore-filling mechanism of Pb(II). The promising adsorption results and the superb recyclability character of COOH-GO@CA@IDA enable it to extend of the bench scale to the industrial scale. [ABSTRACT FROM AUTHOR]

Methylene blue (MB) is a model dye used in many adsorption studies, and it is chemisorbed on activated carbon (AC) adsorbent. The adsorption of an adsorbate by a natural adsorbent is a phenomenon where kinetics is often complex despite the necessity of having reliable information on such reactions which is much needed to predict the efficiency of industrial processes of which rate of adsorption plays an integral part. Such information is, at times, not available under different experimental conditions, limiting desired applications. The research reported herein was thus performed to investigate rate of adsorption of MB onto coconut shell activated carbon by fitting experimental data to kinetics and diffusion models. According to the regression analysis of linearized pseudo-order models applied for various experimental conditions, the pseudo first order (PFO) model is found to be best suited to describe the kinetics of the MB-AC system having rate constants in the range 0.0799 – 0.2437 min−1 under different experimental conditions at the ambient temperature. The rate constants determined through the PFO model at different solution temperatures are indicative of chemisorption of MB on AC surface. Application of the Webber and Morris intra-particle diffusion (IPD) model, which accounts for the boundary layer effect on mass transfer, indicates that adsorption kinetics may be controlled by both film diffusion and intra-particle diffusion sequentially, and that the thickness of the boundary layer on the AC surface, which is a measure of the intercept of the linearized Webber and Morris IPD model, is sensitive to experimental conditions. Consequently, experimental parameters would be able to control the adsorption behaviour of the MB-AC system, which can be investigated by monitoring the magnitude of the initial adsorption factor.

In this study, a comparison was conducted involving novel chitosan/polyvinyl alcohol-based membranes comprising carbon nanotubes and molybdenum trioxide nanoparticles. This comparison's primary focus was to assess synthesized membranes' effectiveness in removing methyl red from aqueous solutions. The Fourier transform infrared spectroscopy and scanning electron microscopy confirmed the presence of specific functional groups and homogeneous dispersion of carbon nanotubes and molybdenum trioxide nanoparticles within the membranes, respectively. The membranes underwent additional characterization using various swelling parameters to assess mechanical strength and cross-linking. These parameters included swelling over time in water, swelling in electrolyte solutions, and different pH solutions and gel fraction analysis. Furthermore, the diffusion of water adhered Fickian diffusion principle. Various adsorption parameters were employed, including batch studies, isotherm studies at different pH levels, and temperature studies. The results of the batch study highlighted that chitosan/polyvinyl alcohol/carbon nanotubes membrane exhibited the highest adsorption, reaching approximately 9.7 mM/g (98%) and achieving equilibrium within 60 min. The maximum adsorption of methyl red was observed at pH 7 and decreased with increasing temperature. Moreover, the experimental data were simulated using kinetic models (pseudo-first-order, pseudo-second-order, Elovich model, and diffusion model) and isothermal models (Freundlich, Langmuir, and Langmuir Freundlich). Data indicated that pseudo-first order was the best-fitted model, which confirms physisorption. Among the isothermal models, Langmuir exhibited the most suitable fit, confirming that single-layer adsorption had taken place on the adsorbent surface. Thermodynamic parameters were studied, ensuring the adsorption process was exothermic and spontaneous. [ABSTRACT FROM AUTHOR]

A laboratory study was conducted to understand the kinetics and mechanism of adsorption of micronutrients and S onto Lantana sp., Pinus sp. and wheat straw biochars pyrolyzed at 300 °C and 450 °C. Adsorption kinetics of these nutrients onto phyto-biochars conformed well to pseudo-first-order kinetics and intra-particle diffusion model. Boyd's plots revealed the involvement of other adsorption mechanisms besides intra-particle diffusion. Simple correlation analysis revealed that higher contents of N and humin-like C fraction but lower content of alcoholic-OH groups in phyto-biochars increased the equilibrium adsorption coefficient (qe) and intra-particle diffusion rate coefficient (kid) of Fe while higher contents of total acidity and phenolic-OH groups decreased qe and kid of Zn, Cu and Mn. Higher S content in phyto-biochars increased the initial adsorption (c) for Zn and Mn adsorption. Higher cation exchange capacity of phyto-biochars increased qe and kid of B which indicated the cation bridging of B onto phyto-biochars. A significant positive correlation between the pseudo-first-order rate constant (k01) of B and the contents of H, total acidity and phenolic-OH group but a negative correlation with pH, P and water-soluble C content in biochars showed the involvement of ligand exchange mechanism for B adsorption. Higher contents of total acidity and phenolic-OH groups in phyto-biochars increased c for S adsorption. Thus, the adsorption kinetics of micronutrients and S onto phyto-biochars followed the pseudo-first-order kinetics and intra-particle diffusion process and the properties of phyto-biochars have an important bearing on the progress of the adsorption reaction of these nutrients. [ABSTRACT FROM AUTHOR]

Chitosan (CTS) and polyvinyl alcohol (PVA) are two environmentally friend polymers. In this research, methacrylate‐modified FDU‐12 (FDU‐12‐NH2) nanoparticle was synthesized. It was used in the preparation of CTS/PVA/FDU‐12‐NH2 (2%, 5% w) composites. Fourier transfer infrared spectroscopy, nitrogen adsorption/desorption, and transmission electron microscopy techniques were applied for the characteristics of the composites. Then, the produced composites were used as the adsorbents to remove cadmium (II) from the aqueous solutions. The optimal conditions of the Cd (II) adsorption factors were achieved. The different isotherms and kinetic models were applied to obtain the equilibrium adsorption information. The results indicated that Freundlich isotherm was the best isotherm model. Also, the kinetic model followed the pseudo‐second‐order. The maximum adsorption capacities were found 125 and 200 mgg−1 of the adsorbents by the Langmuir model. The results showed that the synthesized nanocomposite exhibited a good adsorbent for cadmium metal in the aqueous solution. [ABSTRACT FROM AUTHOR]

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Two approximate analytical expressions based on third degree polynomial and Akbari–Ganji's method (AGM) were derived for the reaction/diffusion controlled kinetics of an immobilized enzyme ( IE ) systems. The approximation methods predict substrate concentration profile and effectiveness factor (η ) in a porous spherical particle. The reaction is assumed to follow reverse Michaelis–Menten ( rMM ) kinetics. The approximate methods predictions were comparable to that of numerical solution (using the Matlab finite difference function, b v p 4 c ) at wide range of ϕ 2 and y o especially at low ϕ 2 and high y o (polynomial equation) and low ϕ 2 and low y o (AGM equation). Although the approximate solution was derived for rMM kinetics, the results can be used to describe other important enzymatic reaction kinetics such as simple Michaelis–Menten ( M M) kinetics and MM with competitive product inhibition kinetics. A necessary design equation should be satisfied when using polynomial or AGM approximation for different enzyme kinetic equations. In this work, two examples of enzymatic reactions of industrial interest were studied, namely glucose-fructose isomerization follows rMM kinetics and hydrolysis of lactose follows Michaelis–Menten ( MM ) equation with competitive product (galactose) inhibition. Predictions of the developed third degree polynomial and AGM approximation equations agree with that of numerical solution, the percentage relative error for the effectiveness factor was less than 11 in comparison with the numerical solution. Good agreement between approximate and numerical estimations demonstrates the validity of these approximation methods. [ABSTRACT FROM AUTHOR]

A Monte Carlo approach is used to generate 2D and 3D networks of randomly connected cylindrical pores with a variety of configurations. These networks are created to represent the gamma‐alumina supports of hydrotreating catalysts. Textural properties from generated pore networks are compared with experimental values of porosity, specific surface area, and specific pore volume. The experimental properties were estimated using a helium pycnometer and nitrogen sorption isotherms for five gamma‐alumina samples. Simulated and experimental textural properties concur. Internal diffusion is simulated by 1D Fick diffusion within each pore of the network. A macroscopic diffusion parameter for vacuum distillate type molecules, previously obtained by inverse liquid chromatography and by pulsed‐field gradient nuclear magnetic resonance experiments on alumina samples, is predicted and confronted with experimental values. Diffusional properties are in good agreement when considering two hierarchically organized porous domains. [ABSTRACT FROM AUTHOR]

Abstract Among various environmental pollutants, dyes have been reported to contaminate a large quantity of surface water. Rhodamine B, a widely applicable basic dye, is known for its hazardous impact on environment. The present study proposes the application of readily available waste banana peels for the remediation of water contaminated with Rhodamine B. The potential of prepared material to decontaminate Rhodamine B was examined as the function of various parameters. Variation in adsorption time, dose of adsorbent, pH value, and initial concentration has been observed under the influence of diverse condition. Quantitative adsorption was observed at a contact time of 60 min with an adsorbent dose of 12 mg. An increase in the initial dye concentration resulted in the enhancement of adsorption capacity of adsorbent. The value of enthalpy change was observed to be − 8.95 kJ mol−1. The negative value indicates the exothermic removal of Rhodamine B from water. Various models were applied to explain thermodynamics and kinetics of the process. Adsorption kinetics was better explained with pseudo-second-order model, whereas adsorption mechanism by intra-particle diffusion model reveals that pore diffusion was not only the rate-controlling step.

Adsorption processes are widely used in different technological areas and industry sectors, thus continuously attracting attention in the scientific research and publications. Design and scale-up of these processes are essentially based on the knowledge and understanding of the adsorption kinetics and mechanism. Adsorption kinetics is usually modeled by using several well-known models including the pseudo-first and pseudo-second order models, the Elovich equation, and the intra-particle diffusion based models. However, in the scientific literature there are a significant number of cases with the inappropriate use of these models, utilization of erroneous expressions, and incorrect interpretation of the obtained results. This paper is especially focused on applications of the pseudo-second order, intra-particle diffusion and the Weber-Morris models, which are illustrated with typical examples. Finally, general recommendations for selection of the appropriate kinetic model and model assumptions, data regression analysis, and evaluation and presentation of the obtained results are outlined. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45019]

This study investigates the kinetic model of chemical oxygen demand (COD) removal from olive oil mill synthetic wastewater through electrocoagulation using stainless steel and aluminum as a cathode and anode electrodes, respectively. The one-factor method was used to evaluate interactions between the operational parameters that affect COD removal. A reactor with a volume of 250 mL was utilized to perform the process. The optimal conditions with 99% COD were found to be the current density of 12.5 mA cm-2, 400 mg L-1 NaCl as supporting electrolyte, initial COD concentration of 17,500 mg L-1, and operation time of 60 min. The highest efficiencies of COD removal were achieved at pH values of 5 and 9 using stainless steel and aluminum electrodes as cathode and anode, respectively. The results demonstrated a direct relation between the coagulant adsorption rate and efficiency of COD removal by olive oil. According to the obtained results, the process follows an intra-particle diffusion kinetic model, in which absorption capacity is high at the beginning, and removal efficiency increases over time. [ABSTRACT FROM AUTHOR]

Hydrophilic organic micropollutants are commonly detected in source water used for drinking water production. Effective technologies to remove these micropollutants from water include adsorption onto granular activated carbon in fixed-bed filters. The rate-determining step in adsorption using activated carbon is usually the adsorbate diffusion inside the porous adsorbent. The presence of mesopores can facilitate diffusion, resulting in higher adsorption rates. We used two different types of granular activated carbon, with and without mesopores, to study the adsorption rate of hydrophilic micropollutants. Furthermore, equilibrium studies were performed to determine the affinity of the selected micropollutants for the activated carbons. A pore diffusion model was applied to the kinetic data to obtain pore diffusion coefficients. We observed that the adsorption rate is influenced by the molecular size of the micropollutant as well as the granular activated carbon pore size. Image 1 • Pore diffusion coefficients correlate negatively to micropollutant size. • Diffusion of large molecules is hindered in activated carbon micropores. • Diffusion rate does not correlate to adsorption affinity. • Affinity between micropollutant and AC correlates to micropore surface area. • Adsorption affinity of hydrophilic micropollutants does not correlate to Log Dow. [ABSTRACT FROM AUTHOR]

Due to the high specific surface area and unique pore properties, two-dimensional materials (2D) are promising candidates in adsorption. In this work, 2D δ-MnO 2 is synthesized through one-step self-assembly and its adsorption properties to methylene blue (MB) are examined. The maximum adsorption amount achieved 267.6 mg/g, it is far high beyond adsorbents reported previously which have similar structures. Considering the unique properties of GO, the prepared 2D MnO 2 is combined with GO to enhance the adsorption capacities further. The combined compounds exhibit super high adsorption capabilities and the adsorption amount of 2D δ-MnO 2 /GO to MB increased to 1432.0 mg/g, which is more than 5 times higher than that of 2D δ-MnO 2 , the significant increase of adsorption amount is owing to the increase of pore size, which initiates the intra-particle diffusion channel. The adsorption kinetics and adsorption isotherms of 2D MnO 2 and 2D δ-MnO 2 /GO are also analyzed with pseudo-second-order model and Langmuir isotherm model at different equilibrium concentration respectively. Image 1 •2 D δ-MnO 2 nanosheets and 2D δ-MnO 2 /GO nanosheets compounds are synthesized through simple self-assembly method. • Structure, morphology, element state and adsorption capability of 2D δ-MnO 2 and 2D δ-MnO 2 /GO compounds were characterized, the adsorption kinetics of two samples were also calculated. •2 D δ-MnO 2 and 2D δ-MnO 2 /GO compounds all exhibited good adsorption properties, and 2D δ-MnO 2 /GO compounds has more excellent adsorption properties. [ABSTRACT FROM AUTHOR]

In this study, jute stick powder (JSP) was used as a potential low-cost adsorbent for the removal of organic dye, methylene blue (MB), from aqueous solution by batch adsorption technique. The adsorbent was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The batch adsorption experiments were carried out at room temperature and atmospheric pressure. Various operational parameters such as solution pH, initial dye concentration, adsorbent dosages and contact time were optimized. The kinetics data were analyzed using pseudo- first order and pseudo-second order models and the second order model fits the kinetic data quite better. The adsorption equilibrium was studied using the Langmuir, Freundlich and Sips isotherm models. The coefficient of correlation indicating the well acceptance of Langmuir model to predict the adsorption equilibrium and the maximum adsorption capacity was obtained as 37.89 mg/g. This result indicates that the natural material, JSP can be employed as a low-cost and efficient adsorbent for the removal of methylene blue from colored wastewater. [ABSTRACT FROM AUTHOR]

The aim of the present work was to study the application of natural clays to remove a cationic dye (methylene blue (MB) chosen as a pollutant model) from wastewater. Rhassoul-clay and Red clay investigated in this study were extracted from two different sites in Morocco. These clays have different swelling properties. A comparison of their affinity towards cationic dye help to understand the limiting factors controlling the adsorption process. Rhassoul clay and Red clay were characterized using powder X-ray diffraction, Scanning Electron Microscopy, X-ray Fluorescence spectroscopy and surface area measurement (BET). The adsorption capacities of the solids were measured using batch sorption studies as a function of contact time, pH, temperature and initial concentration. Pseudo-second-order model and intraparticle diffusion model were applicables to describe the MB adsorption on both adsorbents. Langmuir and Freundlich isotherms were employed to determine adsorption mechanism. According to the results, the Langmuir model was more suitable to describe MB adsorption on both adsorbents. The maximum monolayer adsorption evaluated with this model is 166.7 mg g−1 and 18.7 mg g−1 for Rhassoul-clay and Red clay, respectively. The temperature exhibited a positive effect on MB adsorption. According to Gibbs energy and enthalpy, the adsorption process was spontaneous and endothermic for both clays, but was more favorable for Rhassoul clay. Hence, Rhassoul clay exhibits much higher adsorption capacity than Red clay. The both clays studied could be potentially used for the removal of cationic dye from wastewater. • Rhassoul-clay is more effective than Red clay for removing methylene blue from aqueous medium. • Adsorption of methylene blue onto clays is fitted well to Pseudo-second-order and intraparticle diffusion models. • The increase of temperature enhance the adsorption process. • Adsorption process is spontaneous and endothermic for the clays studied. • Langmuir isotherm is suitable to describe methylene blue adsorption on the clays studied. [ABSTRACT FROM AUTHOR]

• Charged micropollutants GLY and AMPA can be removed by adsorption with UF–PBSAC. • UF–PBSAC achieved 98 % GLY and 95 % AMPA removal at optimized conditions. • GLY and AMPA adsorb on UF–PBSAC via mass transfer on external surface and diffusion into internal surface of PBSAC. • External surface area and hydraulic residence time limit GLY and AMPA at concentrations of 1000 ng/L. • Adsorption is favoured at pH < 10 and dominated by hydrogen bonding and van der Waals interactions. Glyphosate (GLY) is the most commonly used herbicide worldwide, and aminomethylphosphonic acid (AMPA) is one of its main metabolites. GLY and AMPA are toxic to humans, and their complex physicochemical properties present challenges in their removal from water. Several technologies have been applied to remove GLY and AMPA such as adsorption, filtration, and degradation with varied efficiencies. In previous works, an ultrafiltration membrane with permeate-side polymer-based spherical activated carbon (UF–PBSAC) showed the feasibility of removing uncharged micropollutants via adsorption in a flow-through configuration. The same UF–PBSAC was investigated for GLY and AMPA adsorption to assess the removal of charged and lower molecular weight micropollutants. The results indicated that both surface area and hydraulic residence time were limiting factors in GLY/AMPA adsorption by UF–PBSAC. The higher external surface of PBSAC with strong affinity for GLY and AMPA showed higher removal in a dynamic process where the hydraulic residence time was short (tens of seconds). Extending hydraulic residence times (hundreds of seconds) resulted in higher GLY/AMPA removal by allowing GLY/AMPA to diffuse into the PBSAC pores and reach more surfaces. Enhancement was achieved by minimising both limiting factors (external surface and hydraulic residence time) with a low flux of 25 L/m2.h, increased PBSAC layer of 6 mm, and small PBSAC particle size of 78 µm. With this configuration, UF–PBSAC could remove 98 % of GLY and 95 % of AMPA from an initial concentration of 1000 ng/L at pH 8.2 ± 0.2 and meet European Union (EU) regulation for herbicides (100 ng/L for individuals and 500 ng/L for total herbicides). The results implied that UF−PBSAC was able to remove charged micropollutants to the required levels and had potential for application in wastewater treatment and water reuse. [Display omitted] [ABSTRACT FROM AUTHOR]

• Determined experimental effective diffusion coefficients (D eff) under HILIC conditions. • Applied Effective Medium Theory to derive intra-particle diffusion (D part) from D eff. • Analyzed mesopore composition as a function of mobile phase composition. • D part / D m reaches minimum when stationary phase layer thickness is largest. • Proposed model linking mesopore composition, analyte retention and size to D part. A detailed analysis of intra-particle volumes and layer thicknesses and their effect on the diffusion of solutes in hydrophilic interaction liquid chromatography (HILIC) was made. Pycnometric measurements and the retention volume of deuterated mobile phase constituents (water and acetonitrile) were used to estimate the void volume inside the column, including not only the volume of the mobile phase but also part of the enriched water solvent acting as the stationary phase in HILIC. The mobile phase (hold-up) volume accessible to non-retained components was estimated using a homologous series approach. The joint analysis of the different approaches indicated the formation of enriched water layers on the hydrophobic silica mesopore walls with a thickness varying significantly with mobile phase composition. The maximal thickness of the enriched water layers, which corresponded to the minimum void volume accessible to unretained solutes, marked a transition in the retention behavior of the studied analytes. Discrepancies between deuterated solvent measurements and pycnometry were explained by the existence of an irreplaceable water layer adsorbed on the silica surface. Regarding the diffusion behavior in HILIC, peak parking experiments were used to interpret the influence of the acetonitrile content on the effective diffusion coefficient D eff. A systematic decrease in D eff and molecular diffusion D m was observed with decreasing acetonitrile concentration, primarily attributed to variations in mobile phase viscosity. Notably, D eff / D m remained nearly unaffected by variations in mobile phase composition. Finally, the effective medium theory was used to make a comprehensive analysis of D part / D m to study the contribution to band broadening when the solute resides in the mesopores. The obtained data unveiled a curvature with a minimum corresponding to conditions of maximum water-layer thickness and retention. For the weakly retained compounds (k ' < 0.5) the D part / D m -values were found to be relatively high (order of 0.35-0.5), which directly reflects the high γ s D s / D m -values that were observed (order 0.35-7). [ABSTRACT FROM AUTHOR]

The presence of arsenic (As) in drinking water is of serious concern due to its negative impact on human health. This work reports on the kinetics of nanoscale zero-valent iron (Fe0) supported by activated carbon (NZVI/AC) for the removal of As (V) species from aqueous solutions. To better understand the factors affecting this process, we investigated the effects of various experimental parameters including initial As (V) concentration, adsorbent dosage, pH, temperature, and coexisting ions on the adsorption kinetics using a batch-adsorption method. The optimum conditions for As (V) removal by NZVI/AC were found to be: 318 K, pH 3.5, an adsorbent dosage of 1.5 g/L, and an equilibrium time of 72 h. A greater mass of NZVI/AC, lower concentration of As (V) and lower pH positively promoted adsorption kinetics. The presence of phosphate (PO43−) and silicate (SiO42−) markedly inhibited As (V) removal kinetics. However, in the presence of 4.5 g/L NZVI/AC, ≥99.9% of As (V) was removed from raw groundwater.

The present work was carried out to evaluate the removal of p-nitrophenol by adsorption onto olive cake based activated carbon having a BET surface area of 672 m²/g. The batch adsorption experimental results indicated that the equilibrium time for nitrophenol adsorption by olive cake-based activated carbon was 120min. The adsorption data was modeled by equilibrium and kinetic models. The pseudo- first and second order as well as the Elovichkinetic models were applied to fit the experimental data and the intraparticle diffusion model was assessed for describing the mechanism of adsorption. The data were found to be best fitted to the pseudo-second order model with a correlation coefficient (R2=0.986). The intraparticle diffusion mechanism also showed a good fit to the experimental data, showing two distinct linear parts assuming that more than one step could be involved in the adsorption of nitrophenol by the activated carbon. The equilibrium study was performed using three models including Langmuir, Freundlich and Temkin. The results revealed that the Temkin equilibrium model is the best model fitting the experimental data (R2=0.944). The results of the present study proved the efficiency of using olive cake based activated carbon as a novel adsorbent for the removal of nitrophenol from aqueous solution.

Abstract Hazardous materials are very harmful to the environment and their removal is quite challenging, and methylene blue is one of them. In the present study, we have successfully designed a bentonite encapsulated alginate bead system for the effective removal of methylene blue, extensively used in chemical industries. Synthesized beads were characterized using Field Emission Scanning Electron Microscope, Energy Dispersive X-Ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer Emmett Teller Surface Analyser, and Dynamic Light Scattering. Bentonite/alginate beads system was optimized at physiological pH 7, and 25 °C and fitted well to pseudo-second-order kinetic model. The maximum adsorption capacity of system as calculated by Langmuir isotherm was found to be 2024 mg g−1 or 6.33 mmol g−1, which is many folds higher as compared to the reported clay-related and other adsorbents. Adsorption process was found be combination of surface adsorption and intra-particle diffusion (IPD) with dominancy during initial phase (30 min) and later phase, respectively. The designed beads enhanced the rates of both surface adsorption and IPD as compared to only bentonite powder as adsorbent. The thermodynamic studies confirmed the spontaneous and exothermic nature of adsorption process. FTIR, and EDX analyses of the removal data confirmed the possibility of both chemisorption and physiosorption. The designed beads imparted recyclability to bentonite powder and exhibited excellent removal efficiency (85%) after four consecutive adsorption-desorption cycles. Graphical abstract Unlabelled Image Highlights • Bentonite encapsulated alginate beads were designed by crosslinking with calcium. • Optimized adsorption conditions for removal of MB were physiological pH 7 and 25 °C. • Designed beads enhanced rates of surface adsorption and IPD as compared to bentonite. • q m was found to be 2041 mg g−1 many folds higher as compared to related adsorbents. • The designed system was found to be highly effective and reusable for MB removal. [ABSTRACT FROM AUTHOR]

Here, we demonstrate a pyrolysis route for the synthesis of flower buds like magnesium oxide nanoparticles using a magnesium carbonate precursor without additional chemicals. The effect of heating at different time intervals upon the structure and morphology of the acquired nanostructures were investigated via X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and Fourier transformation infrared spectroscopy. Nitrogen adsorption was employed to study its porosity. The obtained data confirmed the formation of target nanoparticles that exhibited increasing sizes as pyrolysis time was lengthened. As a consequence a high surface area up to 27 m2 g−1 was recorded for the sample heated for 1 h duration. Furthermore, Indigo Carmine dye adsorption was carried out using the largest surface area species which showed an adsorption capacity of 158 mg g−1. The adsorption was found to comply with the Langmuir isotherm and it follows the pseudo-second-order kinetics. The diffusion process showed intra-particle along with film diffusion mode. [ABSTRACT FROM AUTHOR]

In this study, batch experiments were carried out to evaluate the biodegradation of phenol by Sphingomonas sp. GY2B, which were immobilized in polyvinyl alcohol (PVA) – sodium alginate – kaolin beads under different conditions. The optimal degradation performance was achieved by GY2B immobilized in beads containing 1.0% (w/v) of kaolin, 10% (w/v) of PVA, 0.3% (w/v) of sodium alginate, 10% (v/v) of biomass dosage, and exposed to an initial phenol concentration of 100 mg/L. The experimental results indicated that PVA-sodium alginate-kaolin beads can accelerate the degradation rate of phenol by reducing the degradation time and also improve degradation rate. The biodegradation rate of phenol by immobilized cells (16.79 ± 0.81 mg/(L·h)) was significantly higher than that of free cells (11.49 ± 1.29 mg/(L·h)) under the above optimal conditions. GY2B immobilized on beads was more competent than free GY2B in degradation under conditions with high phenol concentrations (up to 300 mg/L) and in strong acidic (pH = 1) and alkaline (pH = 12) environments. Higher phenol concentrations inhibit the biomass and reduce the biodegradation rate, while the lower biodegradation rate at low initial phenol concentrations is attributed to mass transfer limitations. The Haldane inhibitory model was in agreement with the experimental data well, revealing that phenol showed a considerable inhibitory effect on the biodegradation by Sphingomonas sp. GY2B, especially at concentrations higher than 90 mg/L. Intra-particle diffusion model analysis suggests that adsorption of phenol by immobilized beads was controlled by both rapid surface adsorption as well as pore diffusion mechanism. It's worth noting that the presence of 1 mg/L Cr(VI) enhanced the biodegradation of phenol by free cells, while Cr(VI) showed no obvious impact on the removal of phenol by immobilized cells. In addition, immobilized cells were reused 16 times and removed 99.5% phenol, and when stored at 4 °C for 90 days, more than 99% phenol was removed. These results showed that immobilized cells can significantly improve the microbial degradation performance, and protect microorganisms against unfavorable environment. It is implied that PVA -sodium alginate-kaolin beads have great potential to be applied in a practical and economical phenolic wastewater treatment system. [ABSTRACT FROM AUTHOR]

The present communication addresses the removal of toxic lead, cadmium, and arsenic using iron oxide modified clay-activated carbon composite beads from aqueous solutions. The SEM-EDX analysis was conducted to study the heterogeneity of the surface and the elemental composition of the composite beads. The specific surface area of the composite beads was found to be 433 m 2 /g. Furthermore, the XRD pattern indicates the intercalation of iron particles between the layers of bentonite clay. The FT-IR analysis suggests that the hydroxyl, carboxyl, and Fe-O were the major functional groups responsible for the removal of lead, cadmium, and arsenic. The Langmuir monolayer sorption capacity of Pb(II), Cd(II) and As(V) were observed to be 74.2, 41.3 and 5.0  mg/g respectively. Kinetic studies indicate that intra-particle diffusion plays a significant role in the removal of these three toxic pollutants. In addition, the composite beads were applied for the adsorption of a ternary mixture of subjected pollutants at low concentrations and found efficient to remove these pollutants up to an acceptable permissible limit of drinking water. The significances of this study propose the potential of composite beads for purifying the water containing toxic pollutants, viz., lead, cadmium, and arsenic. [ABSTRACT FROM AUTHOR]

Drinking water contamination by fluoride component (F-) is considered as a main public problem in Basra city. The current study highlights on the removal of (F-) from drinking water using effective and low cost materials namely, banana shell and new technical that prepared from orange shell loaded with Zirconyl chloride solutions (Z-r4 (O-H)8 (H2-O)16] C18 (H2- O)12) to develop active adsorption sites for fluoride . High removal efficiency of 94.4 was achieved using fixed bed column loaded (Zc-dejr) under optimum operating conditions, 15.1 ppm of feed concentration, 4.5 pH of feed solution and 4 cm of bed depth. Result of breakthrough profile showed that Thomas was coincided well with the experimental data. Two model, Pseude first order and Pseudo second order where used for finding the mechanism of adsorption kinetics for fluoride (F-) removal by two-bio adsorbents. The result showed that the external adsorption besides to the intra-particle diffusion contributes to the rate influential step. Lagmaier model gives the better result model for the two adsorbents then Temkin isotherm model (TIM). The final concentration of fluoride in treated water with the banana shell adsorbent was 1 mg/l, and with the new solution (Z-r4 (O-H)8(H2-O)16] C18 (H2-O)12 ) was 0.5 mg /l which is acceptable with the standard World Health Organization (WHO). [ABSTRACT FROM AUTHOR]

Adsorptive separation of Sodium dodecyl benzene sulfonate (SDBS) using thermo-chemically and chemically activated coconut shell based adsorbent as well as using waste graphite powder has been investigated. The dependency of the extent of SDBS removal on pH, concentration, adsorbent dose and temperature has been demonstrated. Under optimized conditions, 92.84%, 39.41% and 34.23% SDBS could be removed in 3 h using Phosphoric Acid Activated Coconut Shell-I (PAACS-I), Phosphoric Acid Activated Coconut Shell-II (PAACS-II) and graphite powder respectively. Adsorption kinetics was established to follow pseudo-second order mechanism and isotherm data fitted well with the Langmuir isotherm. Maximum adsorption capacity was estimated to be 28.57 mg/g under optimized conditions of pH as 2, adsorbent dose of 3 g/L and temperature of 293 K. It was also established that adsorption was spontaneous and exothermic. Appreciable activity till 5 th reuse cycle confirmed promising nature of the adsorbent. [ABSTRACT FROM AUTHOR]

Alow-cost adsorbent produced fromMn2+-modified bentonite clay was evaluated for groundwater defluoridation. Batch experiments were used to evaluate the effect of contact time at various adsorbent dosages, adsorption isotherms and the effect of pH on fluoride removal. The results showed that the optimum F- uptake occurred within the first 30 min contact time and the percentage removal increased with increasing adsorbent dosage. The data fitted better to pseudo-second-order reaction indicating that F- adsorption occurred via chemisorption. The Weber-Morris model of intra-particle diffusion revealed that both surface and intra-particle diffusion processes were involved during the F- adsorption process. Furthermore, the batch results showed that pH of the solution governed the percentage of fluoride removal with the optimum of 75.2 % fluoride removal achieved at pH 4. The adsorbent chemical stability assessment showed that chemical species were leached at trace concentrations which are within the South African National Standards (SANS) limits. Electrostatic attraction and ion-exchange were established as the major mechanisms responsible for fluoride adsorption at acidicpHand at moderate to alkalinepHlevels, respectively. The study demonstrated that Mn2+ intercalated bentonite clay has potential for application in defluoridation of groundwater. [ABSTRACT FROM AUTHOR]

NaP zeolite crystals were synthesized and used as templating support species for the purpose of hosting and the confinement of silver nanoparticles. This was being adapted primarily by introducing trace amounts of alkyl dimethyl hydroxyethyl ammonium chloride (ADHA) ranging from 50 to 200 ppm into the zeolite (Ag/ADH-NaP). For comparison purposes, ADHA/NaP and Ag/NaP were also prepared under the same conditions. These solids have been examined by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy (LRS), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-Vis spectroscopy as well as surface texture measurements. By increasing the concentration of ADHA and under the effect of UV radiation, the XRD analysis of Ag/ADHA-NaP has shown increase in unit cell parameters of the zeolite along with new peaks attributed to silver nanoparticles (AgNPs) were observed at d values of 2.370 and 2.047 Å. This was confirmed by XPS peaks corresponding to Ag 3d at 368.7 and 374.7 eV. Upon addition of aqueous Cr(VI) to the Ag/ADHA-NaP sample, adsorbed species on the silver surface such as CrO and Cr(OH) produced Raman scattering at 853 and 664 cm, respectively. The latter sample was able to adsorb the Cr(VI) completely, but unlike the other samples, at an initial concentration of 20 ppm. The high effective surface area of AgNPs shows enhanced adsorption and photreduction of Cr(VI) to Cr(III), in compatible with the evaluation of optical band gaps. The adsorption process of Cr(VI) was thought to result from a surface uptake and intra-particle diffusion which operate simultaneously through the interaction between Cr(VI)ions and Ag/ADHA-NaP. [ABSTRACT FROM AUTHOR]

Co-gasification of biomass/coal blends is very promising due to many advantages. Kinetic modeling of the co-gasification process is, however, lagged behind, which is adverse to the development of the co-gasification technology. In this work, a scheme to set up kinetic models for the co-gasification of biomass/coal char blends is proposed. Based on the scheme, a kinetic model for the steam co-gasification of the blended biomass/coal char is built. The intra-particle diffusion, particle structure evolution and peripheral fragmentation are allowed for, and the effects of biomass blending ratio (BBR), gasification temperature, and steam partial pressure on the apparent co-gasfication kinetics are considered. The model prediction is compared against a series of experimental data in literature, and good agreement is achieved. It is concluded that the effects of BBR on the co-gasfication kinetics can be treated as a net increment of the coal char conversion rate, and the net increment can be well predicted by the random pore model. BBR has great impact on the particle structure and composition which greatly affect both the intrinsic kinetics and the intra-particle diffusion. [ABSTRACT FROM AUTHOR]

In the present study, a series of hypercrosslinked resins (CH series) was prepared in systematically designed conditions for the adsorption of nitroaromatics from aqueous solution. The newly synthesized CH-10 possesses a Brunauer-Emmett-Teller (BET) surface area up to 1,329.3 m²/g which is larger than that of the widely used hypercrosslinked resin H-103 and it exhibits great advantage over H-103 when subjected to nitrobenzene at low concentrations. The adsorption capacity of CH-10 for nitrobenzene is 1.4 times as much as that of H-103 at the concentration of 100 mg/L. Kinetic study by film diffusion model and intra-particle diffusion model revealed that its distinctive mesoporous structure within pore diameters between 2 and 6 nm played significant role in the mass transfer at low concentrations, and these unique mesopores also resulted in better adsorption capacity, which was confirmed by adsorption thermodynamics study. Moreover, the CH series displayed a good affinity to a wide scope of nitroaromatics and exhibited excellent dynamic adsorption and desorption properties in fixed bed. [ABSTRACT FROM AUTHOR]

In this study chelating resins have been considered to be suitable materials for the recovery of Copper (II) ions in water treatments. Furthermore, these modified resins were reacted with 1,2-diaminoethane in the presence of ultrasonic irradiation for the preparation of a tridimensional chelating resin on the Nano scale for the recovery of Copper (II) ions from aqueous solutions. This method which is used for removing and determining Copper (II) ions using copolymers derived resins of poly (styrene-alternative-maleic anhydride) (SMA) and atomic absorption spectroscopy. The method is simple, sensitive, inexpensive and fast. The various parameters such as pH, contact time, concentrations of metal ions, mass of resin, and agitation speed were investigated on adsorption effect. The adsorption behavior of Copper (II) ions were investigated by the synthesis of chelating resins at various pHs. The prepared resins showed a good tendency for removing the selected metal ions from aqueous solution, even at an acidic pH. Also, the prepared resins were examined for the removal of Copper (II) ions from real samples such as industrial wastewater and were shown to be very efficient at adsorption in the cases of Copper (II) ions. The pseudo-first-order, pseudo-second-order, and intra-particle diffusion kinetics equations were used for modeling of adsorption data and it was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. The intra-particle diffusion study revealed that external diffusion might be involved in this case. The resins were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

"n "n "nBackgrounds and Objectives: Treatment of colored wastewater is one of the important challenges of environmental engineers. Adsorption process is a key option for removal of organic matter from wastewater. The aim of present work was to investigate pumice stone as an adsorbent for removal of Acid Black 1 from aqueous solution."nMaterials and Methods: Removal of Acid Black 1 by pumice stone was investigated. Acid Hyrdo Chloric(HCL) 1 N was used to increse adsorbent porosity. Various parameters such as pH, initial dye concentration and contact time were studied."nResults: Results showed that removal of Acid Black 1 was increased by increasing of contact time and initial dyeconcentration although it was decreased by increasing of pH. Experimental data was best fitted to Longmuir isotherm model (r2>0.98). Study of diffusion model revealed that intraparticle diffusion is rate-controlling step in removal of Acid Black 1 by pumice stone."nConclusion : The results indicated that pumice stone was a dominant adsorbent for Acid Black 1 removal.

In the present research work Saw palmetto spent (SPS) was used to remove Methylene blue (MB) from aqueous solution economically. SEM and FTIR Studies were made to understand the Morphological properties of the adsorbent. Various parameters of adsorption such as, initial dye concentration, contact time, pH and temperature were studied. Langmuir, Freundlich and Temkin isotherm models were used to explain the adsorption behaviour. Pseudo-first order, pseudo-second order kinetic models and Intra-particle diffusion model were used to study adsorption kinetics. The maximum adsorption capacity value ( q = 90.9 mg g) for Langmuir isotherm was near to the experimental value ( q = 71.00 mg g). Thermodynamics of adsorption was studied and the values obtained indicate that the process is endothermic and spontaneous. It is confirmed that, SPS is an efficient adsorbent for removal of MB from aqueous solution. [ABSTRACT FROM AUTHOR]

This paper deals with the kinetic and isotherm studies of manganese ion removal by zeolite X and its hierarchically porous composites as ion-exchange materials. A hydrothermal treatment was applied to grow a layer of zeolite X over diatomite and carbon surfaces. The hierarchically porous composites used for Mn 2+ ion removal showed higher ion-exchange capacity when compared to pure zeolite X under same conditions. A thermodynamic study of the rate of ion-exchange revealed that the intra-particle diffusion rate constant of zeolite X/carbon and zeolite X/diatomite was higher than that of pure zeolite X indicating that the intra-particle diffusion was enhanced when zeolite was prepared in form of hierarchically porous composites. The study showed that the thickness of boundary film of zeolite X/carbon and zeolite X/diatomite was less than that of pure zeolite X indicating ion diffusion resistance to the active sites was reduced when the composites were utilised. The experimental data showed good agreement with Freundlich model. The calculated thermodynamic parameters such as ΔG°, ΔH° and ΔS° indicated the ion-exchange process of Mn 2+ ion by zeolite X and its composites was spontaneous, endothermic and the randomness increased at the liquid/solid interface under the conditions studied. The results of kinetic study showed that the ion-exchange of Mn 2+ ion by zeolite X and its composites followed a pseudo second order kinetic model indicating Mn 2+ ion removal is a chemical reaction related to valence forces. The encapsulation of Mn 2+ ion was successfully achieved by vitrification and geopolymerization processes demonstrating the efficacy of both processes for environmental management. [ABSTRACT FROM AUTHOR]

This study demonstrated that soil washing using ethylenediaminedisuccinic acid (EDDS) as a chelating agent was efficient at removing copper and zinc from real polluted soils. Only the exchangeable and reducible fractions of Cu and Zn were extracted by EDDS. Intra-particle diffusion was the main rate controlling step in this extraction of heavy metals from the solid matrix. Different contributions were found by applying the Weber and Morris intraparticle diffusion model resulting from the different roles of superficial and intra-particle diffusive processes.The diffusion coefficients of the Cu/EDDS and Zn/EDDS complexes in real contaminated soils were estimated using simplified diffusive models (based on Crank’s and Vermeulen's approximations). The relationship between the grain size and diffusion coefficient was also evaluated. In particular, the intraparticle diffusion coefficients increased with increasing the particle size, thus indicating that the smallest granulometric fractions are characterized by a higher percentage of micropores than the largest fractions. [ABSTRACT FROM AUTHOR]

Two categories of pesticide soil models now exist. Government regulatory agencies use pesticide fate and transport hydrology models, including versions of PRZM.gw. They have good descriptions of pesticide transport by water flow. Their descriptions of chemical mechanisms are unrealistic, having been postulated using the universally accepted but incorrect pesticide soil science. The objective of this work is to report experimental tests of a pesticide soil model in use by regulatory agencies and to suggest possible improvements. Tests with experimentally based data explain why PRZM.gw predictions can be wrong by orders of magnitude. Predictive spreadsheet models are the other category. They are experimentally based, with chemical stoichiometry applied to integral kinetic rate laws for sorption, desorption, intra-particle diffusion, and chemical reactions. They do not account for pesticide transport through soils. Each category of models therefore lacks what the other could provide. They need to be either harmonized or replaced. Some preliminary tests indicate that an experimental mismatch between the categories of models will have to be resolved. Reports of pesticides in the environment and the medical problems that overlap geographically indicate that government regulatory practice needs to account for chemical kinetics and mechanisms. Questions about possible cause and effect links could then be investigated. [ABSTRACT FROM PUBLISHER]

The present communication addresses the development of a novel hybrid material precursor to natural sericite. The hybrid material is then successfully utilized for efficient removal of cadmium and phenol from aqueous solutions. Initially, sericite was annealed and activated with hydrochloric acid. The activation caused a significant increase in specific surface area of sericite, thereby provided a suitable surface structure for grafting of organosilanes. The activated sericite (AS) was functionalized with 3-aminopropyltriethoxysilane (APTES), and the resultant AS-APTES along with pristine sericite and AS were characterized using SEM–EDX, BET, XRD and FT-IR analyses. Batch reactor studies showed that increase in sorptive pH, contact time, initial concentration and temperature significantly favored the sorption of Cd(II), and a 100-fold increase in background electrolyte concentration did not significantly affect the uptake of Cd(II) or phenol from aqueous solutions. Cd(II) removal was found to be spontaneous and the uptake process was endothermic in nature. Further, the intra-particle diffusion was found to be the rate-limiting step in the sorption of Cd(II). Various physico-chemical parametric studies enabled to discuss the sorption mechanism of these contaminants at the solid/solution interface. In a single pollutant sorption studies, it was deduced that the Cd(II) was forming an inner-sphere complexes, whereas phenol was sorbed through the hydrogen bonding with the amino groups or partitioned within the interspace region. Simultaneous sorption studies suggested that these two pollutants were possibly removed simultaneously by the prevailing hydrophilic and hydrophobic groups. Furthermore, desorption and reusability studies as well as the applicability of the material for real wastewater treatment demonstrated that AS-APTES is a promising solid material for the efficient removal of two important water pollutants i.e., Cd(II) and phenol from aqueous waste. [ABSTRACT FROM AUTHOR]

The Vigna Subterranean (L.) Verdc hull's (VSVH) potential to remove Cr(VI) ions from aqueous solutions was investigated. The biosorbent was characterised by FTIR, SEM-EDX and XRF before and after exposure to Cr(VI). The surface comprised of phenolic, carboxylate, sulphonate, carboxyl, ammines, silica, silanol, phosphite esters, alkyl and hydroxyl functional groups responsible for Cr(VI) removal. Batch experiments were carried out in erlenmeyer flasks to optimize pH, contact time, biosorbent dosage and initial concentration of Cr(VI) ions. Reutilization of biosorbent was investigated using predetermined and optimized 0.14 M H2SO4. The initial and residual total chromium concentrations were estimated by FAAS. The optimum pH, contact time and biosorbent dosage were found to be 2, 180 minutes and 3 g/L respectively. The data generated from the effect of contact time and initial Cr(VI) concentration was subjected to kinetics and isotherm modelling respectively. The kinetic data fitted the pseudo first order model (R2 = 0.9334) and the sorption mechanism was diffusion controlled with both film and intra particle diffusion involved in the rate limiting step. The isotherm study confirmed favourable monolayer sorption best described by Langmuir model (R2 = 0.9986) with a very high monolayer sorption capacity of 232.5581 ± 0.9 mg/g. The Temkin model confirmed the endothermicity and weak ion-exchange nature of the Cr(VI)-biosorbent interactions that are important for biosorbent reuse. The biosorbent was recycled three times without significant loss of sorptiondesorption capability. VSVH powder provides a renewable and reusable alternative for simple and effective Cr(VI) removal from wastewaters worth exploring for commercial-industrial application. [ABSTRACT FROM AUTHOR]

The suitability of trimetal-oxide (a refractory waste material) as a possible adsorbent has been studied for the removal of fluoride ion from the aqueous solution. Batchwise experiments have been conducted for following the adsorption behavior. The effect of various variables such as shaking time, hydronium ion concentration, initial fluoride concentration, and adsorbent dose were studied. Freundlich, Langmuir, Dubinin–Radushkevich, and Temkin isotherms were applied to calculate the adsorption behavior of fluoride and were found to be in good agreement with the experimental data, and the mechanism was of chemisorption. The kinetics of the adsorption phenomenon was also studied using Lagergren pseudo-first-order, pseudo-second-order and intra-particle diffusion models, and the results showed that the process of the adsorption of fluoride follows pseudo-first-order as well as pseudo-second-order kinetic models. The adsorbent has shown high defluoridation efficiency of 78% between pH 6.0 and 7.0. The trimetal-oxide was characterized by WD-XRF and XRD techniques before adsorption, and the most dominant components were found to be Al2O3, CaO, and MgO with diaspore, calcite, and dolomite being the major mineral phases. [ABSTRACT FROM AUTHOR]

Due to the developing insights in the theory of chromatography, column manufacturers of any kind (industrial, academic) nowadays have a broad array of experimental column testing tools at their disposal. The present tutorial aims at helping the novice in the field getting an overview of these tools and provides a fixed procedure to carry out the subsequent steps in the column quality analysis (guided via an Excel template file). After some brief introduction about the main equations, the reader is taken step by step through the theories underlying the measurement methods for the different column and performance parameters. In the final section, the reader is taken through the different items in the Excel template. [ABSTRACT FROM AUTHOR]

This study investigated potentials of fluidized bed systems with zeolite A beads for removal of heavy metal ions from aqueous solutions. Two commercial zeolite bead fractions (0.7 and 2.2 mm in diameter) were used, while Cu(II) served as a model ion. Fluidized bed systems were characterized first regarding the hydrodynamic properties so that the operating regime was determined between the minimum fluidization velocity and the terminal velocity, corresponding to 0.2 and 5.6 cm s-1, respectively, for smaller beads, and 2.0 and 13.2 cm s-1, respectively, for larger beads. Cu(II) sorption kinetics was studied next in the fluidized system with recirculation and at the initial Cu(II) concentration of 300 mg dm-3 at selected superficial velocities of 2.6 and 3.0 cm s-1, for small and large beads, respectively. In parallel, Cu(II) sorption kinetics was studied in shaken flasks. In both systems and for both zeolite A bead fractions, intra-particle diffusion was shown to be the rate limiting step. Calculated Cu(II) diffusivities were in the range of (2-15)×10-13 m² s-1 with slightly higher values determined in fluidized bed systems and for larger beads. These slight variations were explained by minor differences in the texture of small and large beads. Still, diffusion through the zeolite lattice was indicated as the slowest step in the process. The maximal sorption capacity of zeolite A beads for Cu(II) at 20°C was predicted as 23.3 mg g-1 based on the Langmuir model applied to the sorption isotherm. Results from the present study have shown potentials for the use of zeolite A beads in fluidized bed systems for removal of heavy metals from industrial wastewaters. [ABSTRACT FROM AUTHOR]

Fourier transform infrared spectroscopy (FTIR) has been used to investigate the acetylation of corn cobs such that the effects of time were not significant, but the effects of temperature and catalyst were significant. Kinetic analyses suggest surface reaction and intra-particle diffusion mechanisms for corn cob acetylation at 30 °C and 100 °C. Thermodynamic models used enabled the evaluations of heat of acetylation (0.0291 Jmol −1 ), critical temperature (0.814 °C), heat capacity (4.157 × 10 −4 Jmol −1 K −1 ), entropy change (5.005 × 10 −4 Jmol −1 ) and values of Gibb's free energy changes at studied temperatures for corn cob acetylation respectively. The water absorption capacity studies showed that the raw corn cobs had its water absorption capacity reduced after treatment indicating a considerable increase in hydrophobicity, thereby enhancing its potentials for use in: non-aqueous absorption processes like oil sorptions and oil spill remediations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Highly dispersed CdSe nanoparticles in Montmorillonite clay. [•] Kinetics and adsorption behavior of IC on CdSe-MMT nanocomposites. [•] Spontaneous, exothermic and chemisorptive mineralization of IC. [•] Pseudo-multilayer boundary diffusion controlled adsorption process. [ABSTRACT FROM AUTHOR]