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Herein, poly(aniline‐co‐pyrrole) has been synthetized and investigated to adsorb phenylbutazone (PBZ), ceftiofur (CEF) and prednisolone (PRD) in aqueous medium as proof of concept. After proper adsorbent characterization, some studies were carried out in batch process, i. e., contact time, pH, and concentration. The adsorption mechanism has been conducted using kinetic and isothermal models. It was found that the reaction equilibrium was reached in 20 min for all analytes. The best fit for the experimental data were obtained employing the models of dual‐site Langmuir–Freundlich, Fritz–Schlunder and Langmuir, with R2=0.999, 0.952 and 0.974, for PBZ, CEF and PRD, respectively. For PBZ, CEF and PRD, poly(aniline‐co‐pyrrole) provided a Qmax=238.8 mg g−1 and Kmax=0.086 L g−1, Q=0.028 mg g−1 and Kmax=3.258 L g−1, Q=13.66 mg g−1 and KL=0.005 L g−1, respectively. Finally, the copolymer was evaluated in solid phase extraction, which showed recovery around 70 % for PBZ, offering also exciting opportunities for further application in the separation process. [ABSTRACT FROM AUTHOR]

SBA‐15/polypyrrole composite was synthesized by polymerizing pyrrole in the presence of SBA‐15. The samples were characterized using the following techniques: low‐angle XRD, wide‐angle XRD, FTIR, FESEM, TGA, HRTEM, and BET. From the low‐angle XRD analysis, it confirms the formation of a mesoporous hexagonal structure (p6 mm). From the HRTEM image, an orderly arrangement of mesopores is evident. Using adsorption techniques, our objective is to remove sunset yellow, indigo carmine, titan yellow, and orange G dye from aqueous solutions with SBA‐15/polypyrrole composite. The removal efficiency for all the dyes was greater than 90 %. The isotherm was verified to follow the Langmuir isotherm model. The maximum adsorption capacities for sunset yellow, indigo carmine, titan yellow, and Orange G were found to be 78.74 mg/g, 83.33 mg/g, 78.74 mg/g, and 106.38 mg/g, respectively. The adsorption kinetics followed a pseudo‐second‐order model, and the R2 value was greater than 0.99 for all the dyes. The thermodynamic parameters of ΔG°, ΔS°, and ΔH° showed negative values, indicating that the adsorption was spontaneous, decreased entropy, and was exothermic. The recycling of the SBA‐15/polypyrrole composite resulted in a 90 % removal efficiency for three cycles. Therefore, the present adsorbent could be applied to treat industrial effluents that contain these dyes. [ABSTRACT FROM AUTHOR]

Motivated by recents results for the double‐layer on Pt(111), I reexamine the theory of weak adsorption on double‐layer properties, and use it to explore the capacitance at low electrolyte concentrations. Even a very weak adsorption enhances the double layer capacitance, so that it may exceed the value CGC predicted by Gouy‐Chapman theory. A Parsons‐Zobel plot of 1/C vs. 1/CGC for the experimental capacity C does not result in a straight line of unit slope, but roughly follows a linear relation with smaller slope. These results are in line with older data on Ag(111), and with the new data on Pt(111). [ABSTRACT FROM AUTHOR]

The present article addresses the effect of various parameters on batch biosorption of nickel using an inexpensive Liagora viscida algae as a biosorbent. The experimental studies revealed that for an initial metal solution concentration of 20–200 ppm, the equilibrium is achieved after 50 min and the maximum sorption at a pH of 5. Isotherms such as Temkin, Freundlich, and Langmuir were examined. The data are well suitable by using the Langmuir isotherm with a sorption uptake of 22.77 mg/g, confirming that L. viscida can be considered as a low‐cost biosorbent. The dynamic experimental data were represented well by pseudo‐first‐order kinetics. The thermodynamic study revealed that the biosorption of nickel on to L. viscida was endothermic and spontaneous. [ABSTRACT FROM AUTHOR]

The objective of this study was the synthesis of a novel nanocomposite (CoZnAl‐layered double hydroxide [LDH]/graphene oxide [GO]) to solve the adsorption problem of positively charged pollutants by LDHs. To prepare this nanocomposite, CoZnAl‐LDH and GO were synthesized by coprecipitation and modified Hummers methods, respectively. After ultrasonic pretreatment, they were combined to produce CoZnAl‐LDH/GO nanocomposite with a smooth and uniform texture which used to remove methylene blue as a cationic model pollutant. The synthesized nanocomposite showed a good adsorption capacity with the maximum adsorption capacity of 169.49 mg/g according to the Langmuir model. The effect of temperature on the adsorption process was surveyed by thermodynamic studies confirming the desirability and the spontaneity of the adsorption process. According to kinetic results, the pseudo‐second‐order model fitted the adsorption process, well. Meanwhile, it was determined that the adsorption process, especially in the beginning, had a high rate and 70% of the pollutant was removed within the first 5 min. Also, the effect of pH on the pollutant removal efficiency was investigated. Finally, the reusability of the nanocomposite was tested. High adsorption capacity and rate, the wide range of operational pH (4–10), and good reusability all suggest that CoZnAl‐LDH/GO is a promising adsorbent for industrial and practical uses. [ABSTRACT FROM AUTHOR]

In this study, the capacity of Aspergillus terreus fungus biomass to remove Cr (VI) and Cd from aqueous solution was investigated. The present experimental study employed the shake flask method to cultivate fungal biomass. For the preparation of adsorbent, after inoculation of Aspergillus terreus in PDA medium, it was placed on a shaker at 150 rpm, at 25°C for 4 days. After separation of living biomass, it was boiled in a 0.5% NaOH solution. The ability of the biomass to remove of Cr (VI) and Cd from aqueous solution was examined under conditions including initial concentrations of (20–120 mg/L); pH of 3, 5, 7, and 9; contact times of 15–120 min; and the adsorbent doses of 0.1, 0.2, 0.5, 1, and 2 g. The concentration of the heavy metals was determined by an atomic absorption device. The results showed that in the optimum conditions of the input variables; contact time of 90 min, pH of 7, the initial metal concentration of 20 mg/L, and the adsorbent dose of 1 g, the removal efficiency of Cd and Cr (VI) was 94 and 89%, respectively. The processes of Cd and Cr (VI) adsorption were successfully described by Freundlich isotherm with R2 = 0.9463 and R2 = 0.9949, respectively, and well‐followed pseudo‐first‐order kinetic with R2 = 0.9935 and R2 = 0.9718, respectively. Due to the high adsorption capacity of this biomass in removing metals in comparison to other adsorbents, it can be proposed as a suitable adsorbent in treatment processes. [ABSTRACT FROM AUTHOR]

Excessive phosphate effluent discharged in the surface water source rush to eutrophication. Consecutively this disturbs the water quality and aquatic ecosystem, due to the depletion of dissolved oxygen. Reduced oxygen level in water bodies affects aquatic life and decreases biodiversity. The present investigation emphasized the phosphate adsorption over nano‐alumina. Surface characteristics of the adsorbents, BET, FTIR, XRD, TEM, and SEM were analyzed to reveal the phosphate adsorption mechanisms. The adsorption isotherms, kinetics, pH effect were observed in batch experiments. The pHpzc value of nano‐alumina adsorbent was found as 8.1. The maximum phosphate adsorption was found to be 98.75% at contact time of 90 min and pH 6. Different models, e.g., Langmuir, Freundlich, Temkin, and Dubinin‐Radushkevich were used for isotherm study. The kinetic data were tested by pseudo‐first order and second order models. An attempt was made to regenerate the spent adsorbent for reuse in the adsorption process. Low cost and high capability of nano‐alumina make it feasible to utilize as cost‐effective phosphate remediation from wastewater. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S77–S85, 2019 [ABSTRACT FROM AUTHOR]

The current study discusses application of the lanthanum ions (La3+) as an activating agent incorporated /immobilized into coconut shell–based granular activated carbon (GAC) for porosity development; subsequently, the carbon material is used for the adsorption of phenol from aqueous solutions. The new carbons were characterized using FTIR, XRD, CHNO, burn off, and carbon yield. The surface functional groups were determined by Boehm titration. The Brunauer–Emmett–Teller (BET) surface area of the carbons is 953 m2 g−1 (GACLa1073), 997 m2 g−1 (GAC383), and 973 m2 g−1 (GACO383). Langmuir, Freundlich, Dubinin–Radushkevich, and John–Sivanandan Achari (J‐SA) isotherm models on the equilibrium isotherm data were examined for the new carbon‐phenol system. It is found that the Langmuir isotherm fits better with a monolayer adsorption capacity, highest for GACLa1073 (387.59 mg g−1) followed by GAC383 (303.03 mg g−1) and GACO383 (197.62 mg g−1). Kinetic studies reveal that the adsorption system follows the pseudo–second‐order kinetic model. Isotherm analysis by the phase change method of John‐Sivanandan Achari (J‐SA) isotherm gives a better insight into adsorption phenomena, which is accompanied by regeneration studies of carbon with >75% for GACLa1073 after three cycles. [ABSTRACT FROM AUTHOR]

Adsorption and photocatalytic decomposition of anionic and cationic surfactants are presented. Two different types of photocatalysts were studied, commercial TiO2‐P25 (Evonik) with pHpzc = 5.65 and nitrogen‐modified TiO2/N pHpzc = 6.7 (point of zero charge). Two different types of surfactants were used: anionic surfactant NaDBS (sodium dodecylbenzene sulfonate) and cationic surfactant BtCl (benzethonium chloride). Obtained adsorption isotherms of NaDBS and BtCl comply with the conditions of monolayer Langmuir model isotherms. The maximal anionic surfactant adsorption took place at acidic pH and it was higher for TiO2/N (196 mg g−1) than for commercial TiO2‐P25 (140 mg g−1). There was the opposite situation in the case of cationic surfactants, higher adsorption took place at alkaline condition and it was higher for TiO2/N (100 mg g−1) than for commercial TiO2‐P25 (85 mg g−1). Photocatalytic degradation has been found to be more effective in neutral and high than in low pH solutions for both surfactants. It is mainly the difference between charges of the surface of photocatalysts and ionic parts of individual surfactants that determined the effectiveness for each of them. [ABSTRACT FROM AUTHOR]

Adsorption and photocatalytic decomposition of anionic and cationic surfactants are presented. Two different types of photocatalysts were studied, commercial TiO2‐P25 (Evonik) with pHpzc = 5.65 and nitrogen‐modified TiO2/N pHpzc = 6.7 (point of zero charge). Two different types of surfactants were used: anionic surfactant NaDBS (sodium dodecylbenzene sulfonate) and cationic surfactant BtCl (benzethonium chloride). Obtained adsorption isotherms of NaDBS and BtCl comply with the conditions of monolayer Langmuir model isotherms. The maximal anionic surfactant adsorption took place at acidic pH and it was higher for TiO2/N (196 mg g−1) than for commercial TiO2‐P25 (140 mg g−1). There was the opposite situation in the case of cationic surfactants, higher adsorption took place at alkaline condition and it was higher for TiO2/N (100 mg g−1) than for commercial TiO2‐P25 (85 mg g−1). Photocatalytic degradation has been found to be more effective in neutral and high than in low pH solutions for both surfactants. It is mainly the difference between charges of the surface of photocatalysts and ionic parts of individual surfactants that determined the effectiveness for each of them. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Pomelo (Citrus grandis) is the largest citrus fruit, the peel of which is a well‐known agricultural wastes. Disposal of pomelo peel after consumption is a serious environment problem. As a natural, versatile bio‐absorbent, pomelo peel has shown excellent adsorption capacity for several pollutants, attributed to its micro‐pores; however, there is no relevant report on its adsorption capacity for natural products or food ingredients. The ability of pomelo peel to adsorb epigallocatechin‐3‐gallate (EGCG) was examined in this study. The physicochemical characterizations of pomelo peel were determined by Fourier transform infrared spectroscopy, scanning electron microscopy and high‐performance liquid chromatography. The adsorption process of EGCG onto pomelo peel from aqueous solution was carried out at a range of concentrations (50–800 mg L−1) and temperatures (25, 40 and 55 °C). RESULTS: The main components of pomelo peel are composed of dietary fiber, which provide sufficient adsorption sites during the adsorption process. The adsorption of EGCG onto pomelo peel showed excellent fitness with a pseudo‐second‐order model. Both Langmuir and Freundlich models were able to describe the isothermal adsorption of EGCG onto pomelo peel. The results of thermodynamic analysis suggested that adsorption is spontaneous and endothermic in nature, and that the process is likely to be dominated by a physisorption mechanism. CONCLUSION: The results of this study indicate that pomelo peel has potential adsorption capacity for EGCG, which can be used as an effective, low‐cost carrier for delivery of natural products in functional food and dietary supplement applications. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Silicate‐bearing hectorites (laponite) were synthesized by hydrothermal method, and the laponite sample was characterized by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), zeta potential, Brunauer‐Emmett‐Teller (BET) surface area, and pore size analyses. The adsorption of Ni(II) from aqueous solution on laponite as a function of contact time, pH, ionic strength, laponite dosage, and temperature was studied via batch technique. The maximum removal of 99% (approx) could be achieved at the optimum adsorbent dosage of 2.5 g L−1 and near‐neutral pH. Adsorption of Ni(II) on laponite is strongly dependent on pH but independent on ionic strength. At low pH, the adsorption of Ni(II) was dominated by ion exchange with Li+ on laponite surfaces, whereas inner‐sphere surface complexation and surface precipitation were the main adsorption mechanisms at near‐neutral pH and alkaline environment, respectively. The adsorption kinetic data of Ni(II) on laponite were well described by the pseudo‐second‐order kinetics model. The intraparticle diffusion was involved in the adsorption process but was not the only rate‐controlling step. The adsorption isotherms of Ni(II) on laponite can be described well by the Langmuir model and the maximum Ni(II) adsorption capacity of laponite obtained from Langmuir model was 65.79 mg g−1. The thermodynamic studies indicated that the adsorption of Ni(II) on laponite was endothermic and spontaneous. The laponite exhibited excellent adsorption properties for Ni(II) uptake compared with various adsorbents, indicating that it is a suitable material as an adsorbent for preconcentration and immobilization of Ni(II) from aqueous solution. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 942–950, 2018 [ABSTRACT FROM AUTHOR]

Abstract: Molecular simulation, through the computation of adsorption isotherms, is a useful predictive tool for the selective capacity of nanoporous materials. Generally, adsorbents are modelled as rigid frameworks, as opposed to allowing for vibrations of the lattice, and this approximation is assumed to have negligible impact on adsorption. In this work, this approach was tested in an especially challenging system by computing the adsorption of the chiral molecules 2‐pentanol, 2‐methylbutanol and 3‐methyl‐2‐butanol in the all‐silica and germanosilicate chiral zeolites STW and studying their lattice vibrations upon adsorption. The analysis of single‐ and multicomponent adsorption isotherms showed the suitability of STW‐type zeolites as molecular sieves for chiral separation processes, which pose a challenging task in the chemical and pharmaceutical industries. Moreover, new experimental adsorption data validate the force field employed. The results reveal that the lattice vibrations of the all‐silica framework are sorbate‐independent, while those of germanosilicate STW show host–guest coupling modulated by uptake and sorbate type that disrupts the chiral recognition sites. This study indicates that the effects of intrinsic flexibility on the selective capacity of nanoporous materials may range from low to high impact, and some of them could not have been foreseen even after examination of the structural dynamics of an empty framework. [ABSTRACT FROM AUTHOR]

Zr(IV)‐crosslinked HACC/BT composite was prepared and characterized by FTIR, XRD, and SEM techniques. This composite was applied for the adsorption of phosphate ions from aqueous solutions. The factors of various parameters including adsorbent dosage, pH, competing anions, and contact time affecting phosphate adsorption were studied. The adsorption isotherm data were well described by both Langmuir and Freundlich models, and the maximum monolayer adsorption capacity for phosphate was estimated to be 65.35 mg/g at 293 K and natural pH. Kinetic experiments demonstrated that phosphate adsorption fitted better with a pseudo‐second‐order model. The adsorption mechanisms included the electrostatic interaction, ligand exchange, and hydrogen bond formation between phosphate and this composite. Thermodynamic parameters confirmed the exothermic and spontaneous nature of the phosphate adsorption. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 267–275, 2018 [ABSTRACT FROM AUTHOR]

Cerium oxide (CeO2) nanoparticles of size 3–5 nm and surface area 257 m2 g−1 were synthesized using simple, single‐pot, and surfactant‐free aerogel process. Efforts were made to tune the surface area and porosity of CeO2 nanoparticles by changing the concentration of precursors. CeO2 nanoparticles were characterized by TEM, SEM, XRD, N2‐BET, and FTIR. Prepared CeO2 was used to remove As(III) and As(V) from water at variable contaminant concentrations (25–100 ppm) and pH (3–10). The adsorption process found extremely fast for the first few minutes of exposure. CeO2 nanoparticles indicated adsorption capacities of 71.9 and 36.8 mg g−1 against As(III) and As(V), respectively. The adsorption data best fitted with Redlich–Peterson model, depicting monolayer adsorption. The adsorption followed pseudo‐second‐order kinetics and intraparticle diffusion with three‐step diffusion process. The effect of co‐existing anions (H2 PO 4 −, SO 4 2 −, and HCO 3 −) indicated 80–96% reduction in adsorption capacity. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 221–231, 2018 [ABSTRACT FROM AUTHOR]

In this study, a natural loess soil was evaluated as an adsorbent of Li+ in seawater. Only Li+ was adsorbed preferentially by loess over other cations in seawater despite having the lowest concentration. The adsorption studies of Li+ with loess were assessed using the batch equilibration method. In batch adsorption experiment, the various factors such as agitation time, initial concentration, and amount of dose were investigated. Adsorption isotherm and kinetic studies were performed to quantify the adsorption capacity and adsorption rate of Li+ by loess from seawater. The equilibrium data of adsorption were fitted by using the Freundlich and Langmuir isotherm models. It was seen that the Langmuir isotherm is better in describing the adsorption process of Li+ by loess due to its higher correlation coefficient R2 value. The maximum adsorption capacity of loess for Li+ obtained by Langmuir isotherm was 0.193 mg/g. The pseudo-first-order, the pseudo-second-order, and the intra-particle diffusion kinetic models were employed to analyze the time-dependent adsorption rate of Li+. It was found that the adsorption of Li+ closely follows the pseudo-second-order kinetic model, from which a very accurate estimation of the equilibrium adsorption capacity ( qe,cal) was achieved, as well as the higher R2. Because of its low-cost and high selectivity towards Li+, loess could be probably an applicable adsorbent for the recovery of Li+ from seawater. [ABSTRACT FROM AUTHOR]

A simplified thermodynamic analysis of adsorption processes in temperature swing adsorption (TSA) and pressure swing adsorption (PSA) modes as a function of adsorbate concentration and the adsorbent-adsorbate interaction strength is presented in this article. The thermodynamic separation efficiency of a TSA process is optimal at dilute feed conditions, and becomes more thermodynamically efficient with increasing adsorbate affinity even though the energy of separation increases. The adsorption process is spontaneous, and for a strong isotherm, the energy required to reverse the adsorption is nearly independent of the adsorbate concentration as adsorbate loading in nearly-saturated materials is essentially constant with feed concentration. PSA units are efficient thermodynamically and the efficiency increases with the concentration of the desired adsorbate. This thermodynamic treatment has implications for separation processes that address carbon emissions. TSA systems operate more efficiently (thermodynamically) in the 'air capture' case because they apply work to the concentrated product rather than the dilute feed. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3699-3705, 2016 [ABSTRACT FROM AUTHOR]

A series of four micro- or mesoporous metal-organic frameworks [UiO-66(Zr), UiO-66(Zr)_NH2, MIL-100(Fe), MIL-127(Fe)] were synthesized in powder form and pelletized in the form of spheres by using a polyvinyl-based binder. The effect of pelletization on the adsorption of a series of gasses (N2, CO, CO2, CH4, C2H6, C3H8, C3H6, C4H10) at 303 K was evidenced in the adsorption isotherms and the enthalpies of adsorption measured by using microcalorimetric analysis. As expected, uptakes of gas per gram of material were lower for the spheres than for the powder. However, taking into account the bulk density, this tendency was inverted, suggesting that the spherical materials are of distinct interest for gas-based applications. Nevertheless, other effects including partial pore restriction and active site 'protection' may equally be evidenced for some pelletized materials, suggesting that the polyvinyl binder may play a more complex role. [ABSTRACT FROM AUTHOR]

Two zeolitic imidazolate frameworks, ZIF-9 and ZIF-71, are evaluated by adsorption experiments and molecular simulations with respect to their potential towards olefin/paraffin separation. Pure component adsorption isotherms are measured and compared to grand-canonical Monte-Carlo (GCMC) simulations. The experiments show that the adsorption of the paraffin is favorable over the olefin in both structures. Whereas the isotherms are predicted well by simulations for ZIF-71, in case of ZIF-9 only the saturation loading could be computed accurately because the latter material seems to undergo a so-called gate-opening effect upon adsorption of guest molecules; ZIF-71 does not show this effect. Both structures show promising results with respect to olefin/paraffin separation. [ABSTRACT FROM AUTHOR]

Preparation of polyethyleneimine functionalized magnetic Fe3O4 by using a one-step solvothermal method is reported in this paper. The effect of the amount of polyethyleneimine on the properties of the prepared materials including the shape, size, and adsorption performance was investigated in detail. The magnetic adsorbent with the best adsorption capacity was prepared and used for the removal of Pb(II) in an aqueous medium. Adsorption experiments were performed to evaluate the effect of different sorption parameters, such as pH, initial concentration of Pb2+, and contact time. Langmuir and pseudo-second-order models were used for isotherm and kinetic studies, through which a maximum adsorption capacity of 143 mg g−1 could be calculated. Pb(II) could be desorbed from magnetic Fe3O4 nanoparticles modified with polyethyleneimine by 0.5 mol L−1 HCl and used for five cycles without any adsorption performance loss, indicating that the polymeric magnetic adsorbent used in this work had good reusability and great potential for practical application. [ABSTRACT FROM AUTHOR]

The usage of agricultural waste-based bio-adsorbents for the removal of environmental pollutants from water is gaining extensive attention. In this paper, carrot residue (CR) ( Daucus carota L.) was used for the production of activated carbon (AC) via chemical activation with HNO3. CR derived activated carbon (CAC) was characterized by various analytical techniques. The Brunauer-Emmett-Teller surface area was found to be 17.76 m2 g−1. The efficacy of this AC in adsorbing BrO3− from water samples was studied at time, pH, temperature, and initial BrO3− concentrations by batch studies. The concentration of BrO3− was assessed by ultra-performance liquid chromatography-mass tandem spectrometry. A maximum adsorption capacity of 16.66 mg g−1 at 298 K was obtained from the Langmuir isotherms fit. The kinetic data followed closely the pseudo-first-order rate kinetic model. The thermodynamic study of BrO3− adsorption data showed that the adsorption was feasible, spontaneous, and endothermic in nature. The practical efficacy of CAC was performed for BrO3− removal from tap water as well as bottled water samples. [ABSTRACT FROM AUTHOR]

Activated carbons are one of the most common industrial adsorbents in liquid-phase applications. It is known that the surface groups of the activated carbon can have a significant influence on the adsorption process from the liquid phase. Therefore, it is desirable to measure surface groups on activated carbons. This opens up the possibility to use group-contribution methods to model and predict adsorption isotherms. An idea is presented to characterize the inner surface of activated carbons by three types of surface groups: aromatic, polar, and nonpolar surface groups. The amounts of these surface groups were calculated from excess adsorption isotherms of probe molecules on ten activated carbons. This lays the groundwork for further simulation studies of liquid-phase adsorption using group-contribution methods. [ABSTRACT FROM AUTHOR]

ABSTRACT To enhance the affinity of 4-vinyl pyridine to l-phenylalanine ( l-Phe) and convert the imprinting process from the aqueous phase to the organic phase, an oil-soluble amino acid ionic liquid was introduced as a template. In this study, 1-butyl-3-methylimidazolium α-aminohydrocinnamic acid salt was first applied to prepared surface molecularly imprinted polymers (MIPs) in acetonitrile for the selective recognition of l-Phe. Fluorescence quenching analysis of the functional monomer on the template was investigated under different conditions to study the imprinting mechanism. Several binding studies, such as the sorption kinetics, sorption thermodynamics, and solid-phase extraction application, and the chiral resolution of racemic phenylalanine were investigated. The binding isotherms were fitted by nonlinear regression to the Freundlich model to investigate the recognition mechanism. The affinity distribution analysis revealed that polymers imprinted by ionic liquid showed higher homogeneous binding sites than those imprinted by l-Phe. The competition tests were conducted by a molecularly imprinting solid-phase extraction procedure to estimate the selective separation properties of the MIPs for l-Phe. The target MIP was shown to be successfully for the separation of l-Phe from an amino acid mixture. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42485. [ABSTRACT FROM AUTHOR]

This article presents the immobilization of nanostructured biosilica within calcium alginate biopolymer and its potential for the adsorption of Direct Red 12B (DR12B) as an azo dye in batch flow mode reactors. The immobilization of biosilica was performed well according to the images of scanning electron microscopy. Moreover, the results of Fourier transform infra-red analysis confirmed strong binding of dye molecules by surficial functional groups. The adsorption process was pH-dependent and increasing initial pH from 3 to 11 led to the decrease in adsorbed dye from 16.02 to 11.88 mg/g, respectively. Increasing adsorbent dosage from 0.5 to 4 g/L led to decreasing the adsorption of DR12B from 75.13 to 12.10 mg/g, respectively. Among various isotherm models, Langmuir isotherm had the highest correlation coefficient (R2 = 0.9924) with a maximum adsorption capacity of 33.78 mg/g. The value of mean free energy (E = 15.81 KJ/mol) related to Dubinin-Radukevisch (D-R) model demonstrated chemical nature of the adsorption process. The results of kinetic study revealed the fitness of experimental data to pseudo-second order model. The negative values of Gibbs free energy (ΔG°) and enthalpy change (ΔH°) suggested a simultaneous and exothermic adsorption process, respectively. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1435-1443, 2015 [ABSTRACT FROM AUTHOR]

Activated carbon was prepared from Citrus limettioides seed (CLSC), a novel waste material by chemical modification with sulfuric acid was applied for the adsorption Ni(II) from aqueous solutions. The effect of contact time, pH, adsorbent dose, initial metal ion concentration, and temperature were studied in batch experiments. According to the experimental results, the equilibrium time, optimum pH range, and adsorbent dosage were found to be 3 h, pH = 4.0-8.0 and 1 g L−1, respectively. In addition, raw Citrus limettioides seeds (CLS) were used as adsorbents at the same parameters. Ni(II) removal for CLSC and CLS were obtained 99.00% and 37.00% in turn. The equilibrium data agreed well with Langmuir model, which confirmed the monolayer coverage of Ni(II) ions onto CLS and CLSC. The Langmuir monolayer adsorption capacity of the CLSC was found to be 36.06 mg g−1 which was significantly about 3.5 times greater than that of CLS (10.23 mg g−1) at 300 K. The kinetic data followed pseudo-second order model and intra-particle diffusion was not the sole rate-controlling factor. Surface morphology and structural analysis of CLSC prior to and after adsorption were characterized by SEM and EDX. The presence of hydroxyl, carboxylic, and sulfonic acid groups are confirmed by FTIR spectra. The adsorbents were also tested for the removal of Ni(II) from electroplating wastewater in connection with the reuse and selectivity of the adsorbents. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1384-1395, 2015 [ABSTRACT FROM AUTHOR]

Prediction of multicomponent adsorption equilibria has been investigated for several decades. While there are theories available to predict the adsorption behavior of ideal mixtures, there are few purely predictive theories to account for nonidealities in real systems. Most models available for dealing with nonidealities contain interaction parameters that must be obtained through correlation with binary-mixture data. However, as the number of components in a system grows, the number of parameters needed to be obtained increases exponentially. Here, a generalized procedure is proposed, as an extension of the predictive real adsorbed solution theory, for determining the parameters of any activity model, for any number of components, without correlation. This procedure is then combined with the adsorbed solution theory to predict the adsorption behavior of mixtures. As this method can be applied to any isotherm model and any activity model, it is referred to as the generalized predictive adsorbed solution theory. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2600-2610, 2015 [ABSTRACT FROM AUTHOR]

The aim of the present study is to explore the possibility of utilizing fly ash, loess and activated charcoal for the adsorption of Li in aqueous solution. Batch adsorption experiments were performed to evaluate the influences of various factors like initial concentration, contact time, and temperature. The adsorption data showed that fly ash and activated charcoal are not effective for the adsorption of Li. On the contrary, loess showed much higher adsorption capacity for Li. The adsorption of Li on loess was highly concentration dependent. It was found that the adsorption capacity of loess is favored at a lower Li concentration. At equilibrium, approximately 95% of adsorption was achieved by loess. The equilibrium data were fitted well to the Freundlich isotherm model. The pseudo-second-order kinetic model appeared to be the better-fitting model because it has higher R2 compared to the pseudo-first-order kinetic models. The thermodynamic parameters such as free energy Δ G, the enthalpy Δ H, and the entropy Δ S were calculated. [ABSTRACT FROM AUTHOR]

There is a significant interest in synthesizing inexpensive adsorbents for mitigating pollutants emitted from animal agriculture industry such as p-cresol. Biochar, a byproduct obtained from thermochemical biomass processing is one such source of adsorbent materials. However, presently there is not enough quantitative information on adsorption of p-cresol on biochar. Hence, the goal of this research is to investigate swine manure char as an inexpensive adsorbent for removal of p-cresol from an aqueous system. Swine manure was gasified for 15 min at 704°C to obtain gasified manure char. The char was characterized using physical and chemical techniques. Batch experiments were performed in duplicates at 25°C, 35°C, and 45°C to determine the adsorption isotherms and kinetics. Results indicated that gasification enhanced surface area and acid value of manure from 11.42 ± 0.20 to 49.12 ± 0.79 m2 g−1 and 7.81 ± 0.05 to 8.57 ± 0.01, respectively. The enhanced basicity of the resultant char promoted chemisorption of p-cresol on char surface with maximum adsorption capacities of 7.63 mg g−1 (25°C), 14.99 mg g−1 (35°C), and 14.84 mg g−1 (45°C). Langmuir and Freundlich models suggested that adsorption of p-cresol on char was favorable. Kinetic analysis of the data also confirmed chemisorption of p-cresol while the analysis of transport processes suggested that internal diffusion of p-cresol within the pores was the rate-limiting step. Use of biochar as an adsorbent for p-cresol will add value to gasification byproducts and simultaneously reduce water and air pollution associated with swine farming operations. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 125-131, 2015 [ABSTRACT FROM AUTHOR]

We present a systematic study of metal-organic frameworks (MOFs) for the storage of oxygen. The study starts with grand canonical Monte Carlo simulations on a suite of 10 000 MOFs for the adsorption of oxygen. From these data, the MOFs were down selected to the prime candidates of HKUST-1 (Cu-BTC) and NU-125, both with coordinatively unsaturated Cu sites. Oxygen isotherms up to 30 bar were measured at multiple temperatures to determine the isosteric heat of adsorption for oxygen on each MOF by fitting to a Toth isotherm model. High pressure (up to 140 bar) oxygen isotherms were measured for HKUST-1 and NU-125 to determine the working capacity of each MOF. Compared to the zeolite NaX and Norit activated carbon, NU-125 has an increased excess capacity for oxygen of 237 % and 98 %, respectively. These materials could ultimately prove useful for oxygen storage in medical, military, and aerospace applications. [ABSTRACT FROM AUTHOR]

ABSTRACT Extractant impregnated resins (EIRs) were prepared by impregnation of Amberlite XAD-7 with tetraalkylphosphonium chloride ionic liquid (IL). The EIRs were tested for the sorption of Hg(II) in HCl solutions. Mercury is bound on the EIR through an ion exchange mechanism involving chloroanionic species and the IL. The effect of HCl concentration and IL content is studied and the sorption isotherms are obtained in 1 M HCl solutions: the sorption capacity linearly increases with IL loading up to 100 mg Hg L−1. A little fraction of the IL immobilized on the resin (about 40 mg IL g−1) is tightly bound to the polymer limiting its reactivity with metal ions. The uptake kinetics are mainly controlled by intraparticle diffusion. At high IL loading the kinetics are slowed down, while the temperature has a limited impact. Nitric acid can be used for desorbing mercury and recycling the EIR for at least five cycles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41086. [ABSTRACT FROM AUTHOR]

The structural and chromatographic characterization of two novel fluorinated mesoporous materials prepared by covalent reaction of 3-(pentafluorophenyl)propyldimethylchlorosilane and perfluorohexylethyltrichlorosilane with 2.5 μm fully porous silica particles is reported. The adsorbents were characterized by solid state 29Si, 13C, and 19F NMR spectroscopy, low-temperature nitrogen adsorption, elemental analysis (C and F), and various chromatographic measurements, including the determination of adsorption isotherms. The structure and abundance of the different organic surface species, as well as the different silanol types, were determined. In particular, the degree of so-called horizontal polymerization, that is, Si-O-Si bridging parallel to the silica surface due to the reaction, under 'quasi-dry' conditions, of trifunctional silanizing agents with the silica surface was quantified. Significant agreement was found between the information provided by solid-state NMR, elemental analysis, and excess isotherms regarding the amount of surface residual silanol groups, on the one hand, and the degree of surface functionalization, on the other. Finally, the kinetic performance of the fluorinated materials as separation media for applications in near-ultrahigh-performance liquid chromatography was evaluated. At reduced velocities of about 5.5 (ca. 600 bar backpressure at room temperature) with 3 mm diameter columns and toluene as test compound, reduced plate heights on the order of 2 were obtained on columns of both adsorbents. [ABSTRACT FROM AUTHOR]

The application of raw Bangalora (Totapuri) mango seed kernel powder (RMS) and surface-modified Bangalora (Totapuri) mango seed kernel powder (SMMS) for the removal of methylene blue (MB) dye from aqueous solution was investigated under ambient conditions. The adsorbent was characterized by the FTIR and SEM analyses. Batch adsorption studies were conducted by varying the solution pH, adsorbent dose, initial MB dye concentration, and contact time. The optimum conditions for the adsorption of MB dye onto the adsorbent was found to be: pH (8.0), adsorbent dose (1.0 g: RMS and 0.4 g: SMMS), contact time (60 min: RMS and 30 min: SMMS), temperature of 30°C for an initial MB dye concentration of 100 mg/L. Adsorption isotherm data were analyzed by the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models. Experimental data was successfully applied to the Freundlich model than the Langmuir model, and the maximum monolayer adsorption capacity was found to be greater for SMMS than the RMS. Adsorption kinetics was tested with the pseudo-first-order and pseudo-second-order kinetic models. The kinetic results show that the adsorption process followed the pseudo-second-order kinetic model. Adsorption kinetic data were further applied to the intraparticle diffusion, Boyd kinetic and shrinking core models to explain the adsorption mechanism. Adsorption mechanism results shows that the adsorption process was controlled by both internal and external diffusion. The results of this study show that the SMMS could be used as an effective and low-cost adsorbent for the removal of dyes from aqueous solution. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 87-98, 2014 [ABSTRACT FROM AUTHOR]

Porous carbon fiber with hollow structure and hydrophilic groups was successfully prepared from cotton. The structures and surface chemical properties of the porous carbon fiber were characterized by nitrogen adsorption isotherms, thermogravimetry, FTIR spectroscopy, and scanning electron microscopy. The morphologies of porous carbons prepared under different conditions were observed and compared. The resulting porous carbons had a microporous structure with a pore size distribution around 0.7-2.0 nm. The pyrolysis and decomposition of cotton to form a condensation cross-linked ring structure took place from 230 to 350 °C. Nitrogen-containing groups could be incorporated into the carbon matrix by urea decomposition during the carbonization process. The porous carbon contained more hydrophilic groups and its fiber structure was kept; the carbon yield was improved in the presence of KOH/urea. The porous carbon fiber showed high adsorption capacities of CO2 as a result of its surface hydrophilic groups and developed pore structure. [ABSTRACT FROM AUTHOR]

The adsorption of 5-hydroxymethylfurfural (HMF), DMSO, and water from binary and ternary mixtures in hydrophobic silicalite-1 and dealuminated Y (DAY) zeolites at ambient conditions was studied by experiments and molecular modeling. HMF and DMSO adsorption isotherms were measured and compared to those calculated using a combination of grand canonical Monte Carlo and expanded ensemble (GCMC-EE) simulations. A method based on GCMC-EE simulations for dilute solutions combined with the Redlich-Kister (RK) expansion (GCMC-EE-RK) is introduced to calculate the isotherms over a wide range of concentrations. The simulations, using literature force fields, are in reasonable agreement with experimental data. In HMF/water binary mixtures, large-pore hydrophobic zeolites are much more effective for HMF adsorption but less selective because large pores allow water adsorption because of H2O-HMF attraction. In ternary HMF/DMSO/water mixtures, HMF loading decreases with increasing DMSO fraction, rendering the separation of HMF from water/DMSO mixtures by adsorption difficult. The ratio of the energetic interaction in the zeolite to the solvation free energy is a key factor in controlling separation from liquid mixtures. Overall, our findings could have an impact on the separation and catalytic conversion of HMF and the rational design of nanoporous adsorbents for liquid-phase separations in biomass processing. [ABSTRACT FROM AUTHOR]

The adsorption isotherms of hydrogen on microporous zeolite ZSM-5, at supercritical conditions, have been modeled using the monolayer lattice density functional theory (LDFT) models, where the simple cubic lattice, face-centered cubic lattice, body-centered cubic lattice and tetragonal lattice structures are assumed for the arrangements of the adsorption sites inside pores based on the size and shape of the zeolite. The results indicate that the monolayer LDFT models appear to be effective in describing hydrogen adsorption on zeolite ZSM-5 at supercritical conditions, and the calculated adsorption isotherms agree well with the experimental isotherms measured previously. The layer density of adsorbed phase is presented versus the bulk density and temperature. It is found that the densities of adsorbed phase on adsorbent surface are much higher than the bulk density for temperature range under study. However, in the core region, the layer densities are close to the bulk density. The monolayer adsorption is suitable for hydrogen on ZSM-5 zeolite. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A novel synthetic method for the preparation of different sorbent-polymer composite beads has been developed under simple laboratory conditions. Copper hexacyanoferrate was synthesized, and its composite beads of required size were synthesized by phase-inversion technique, using polyethersulfone as the polymer matrix. Suitable size and mechanical stability, along with their spherical shape, make these composite beads most appropriate for column operation. The efficiency of these composite beads was tested for the removal of cesium, using radioanalytical techniques, in batch conditions. The effect of pH, the initial metal ion concentration, and contact time was also investigated. The synthesized beads perform best in the pH range 5-9. Different sorption isotherm models were applied to the experimental data. Equilibrium data are represented well by the Langmuir isotherm equation, with a monolayer sorption capacity of 1.56 mg g−1 for the swollen beads. Kinetic modeling analysis, by fitting the data in the pseudo first-order, pseudo second-order, and intraparticle diffusion equations, shows that the pseudo second-order equation is the most appropriate model for the description of sorption of cesium ions onto the composite beads. The process mechanism is found to be complex, consisting of both intraparticle diffusion and film diffusion. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

The feasibility of the use of jute fiber for the adsorption of azo dye from an aqueous solution was evaluated with batch and fixed-bed column studies. The batch studies illustrated that dye uptake was highly dependent on different process variables, namely, the pH, initial dye concentration of the solution, adsorbent dosage, contact time, ionic strength, and temperature. The exothermic and spontaneous nature of adsorption was revealed from thermodynamic study. The equilibrium adsorption data were highly consistent with the Langmuir isotherm and yielded an R2 value of 0.999. Kinetic studies divulged that the adsorption followed a pseudo-second-order model with regard to the intraparticle diffusion. In the column studies, the total amount of adsorbed dye and the adsorption capacity decreased with increasing flow rate and increased with increasing bed height and initial dye concentration. Also, the breakthrough time and exhaustion time increased with increasing bed depth but decreased with increasing flow rate and influent dye concentration. The column performances were predicted by the application of the bed-depth service time model and Thomas model to the experimental data. The virgin and dye-adsorbed jute fiber was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy analyses. The investigation suggested that jute fiber could be applied as a promising low-cost adsorbent for dye removal. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Ad- and desorption are common techniques for the purification of natural substances. The main drawback is the tedious experimental procedure for resin and solvent screening. An approach of fully automated batch experiments is presented. In order to fulfill all requirements like automation of flexible dosing of loose resins, handling organic solvents, and providing reproducible conditions, these experiments are performed on a custom-built modular robotic platform. The batch ad- and desorption experiments were fully automated for the determination of essential process parameters like kinetics, isotherms, and thermodynamic parameters without the need of manual intervention. Thus, the hands-on time could be significantly reduced by more than 90 % which contributes to improved health and safety outcome by preventing the contact of operators to potentially hazardous materials. [ABSTRACT FROM AUTHOR]

Three Schiff bases, 2-acetylpyridine thiosemicarbazone ( I), 2-acetylpyridine-(4-methylthiosemicarbazone) ( I), and 2-acetylpyridine-(4-phenylthiosemicarbazone) ( I) were tested against corrosion of cast iron in aqueous solutions of HCl, NaOH, NHCl, and NaCl by means of a mass loss method and electrochemical measurements. The inhibition efficiency is directly proportional to inhibitor concentration, while it decreases with prolonged immersion time and at low temperatures. In order to study the effect of an additive, synergism of KI was also studied. The adsorption of Schiff bases in corrosive media obeys Langmuir's isotherm, both in the presence and absence of KI. The UV-Vis, FT-IR, WAXD and SEM analyses were carried out to support the mechanism of corrosion inhibition. The ΔG values reveal that the inhibition was mainly due to physisorption of the inhibitor molecules on the surface of cast iron. The electrochemical polarization results showed the predominantly cathodic nature of the inhibitors. [ABSTRACT FROM AUTHOR]

The surface properties of a series of imidazoline-based dissymmetric bis-quaternary ammonium (DBA) salts with different hydrophobic chain lengths DBA-12, DBA-14 and DBA-16 were determined. The adsorption behaviors of these compounds in 1 M HCl solution and their inhibitive effect on Q235 steel (U12350) were investigated using the weight-loss method, polarization, and electrochemical impedance spectroscopy. Results indicate that the three inhibitors all showed good inhibition performance for Q235 Steel in 1 M HCl solution and were found to be mixed-type inhibitors. The adsorption behavior of the three inhibitors can fit the Langmuir isotherm equation and the values of $$ \Updelta G_{\text{ads}}^{0} $$ are around or lower than 40 kJ mol, indicating that there is a stronger chemical adsorption. [ABSTRACT FROM AUTHOR]

In this study, hexamethylenediamine (HMD) and hexamethyleneimine (HMI) were removed from a real wastewater by carboxyl group-modified polyacrylonitrile (RPFC-I) fibers. Adsorption of organic amines by fibrous absorbents is a new technique. Adsorption by fibers has advantages of fast kinetic, high adsorption capacity, and efficiency. Moreover, the fibers could be repeatedly used after regeneration. Batch adsorption tests were conducted to investigate adsorption comparison of the three fibers, adsorption kinetic, adsorption isotherms, regeneration, and readsorption stability. The experiments showed that RPFC-I fibers had excellent adsorption capacity for HMI and HMD. The adsorption equilibrium was achieved very fast within about 5 min, and the removal rate of total nitrogen (TN) was above 99%. The adsorption kinetic could be well fitted by the pseudo-second-order equation. And the adsorption isotherm could be well fitted by the Langmuir model. The estimated maximum adsorption capacity was 105.2 mg g−1, nearly similar with cation exchange capacity (CEC) of RPFC-I fibers. Results from adsorption stability tests demonstrated that the RPFC-I fibers could be fully regenerated by HCl and the regenerated fibers could be repeatedly used even after 12 adsorption-desorption cycles. Analyses from Fourier transform infrared and the adsorption tests suggested that chemical reaction between carboxyl groups and organic amines was the main mechanism for removal of HMI and HMD from the wastewater. The RPFC-I fibers prepared in the current study have a wide application in wastewater treatment and useful substance recovery. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

The adsorption-desorption characteristics of Acid Red G (ARG) on the polypyrrole-modified TiO2 (PPy/TiO2) composite as a novel adsorbent was investigated. PPy/TiO2 was synthesized via the in-situ polymerization of pyrrole monomer in the prepared TiO2 sol solution. Results from X-ray diffraction and Fourier transform infrared spectra indicated the formation of the PPy/TiO2 composite. The adsorption experiments showed that the modification of PPy substantially improved the adsorption and regeneration abilities of PPy/TiO2. The adsorption equilibrium was achieved in a short time of 20 min, and the adsorption kinetics followed the pseudo-second-order model. The Langmuir adsorption isotherm was found for PPy/TiO2, with the maximum adsorption capacity of 179.21 mg/g. The regeneration experiments showed that PPy/TiO2 could be successfully regenerated by simple alkali-acid treatment. The adsorption efficiency of the regenerated PPy/TiO2 adsorbent for ARG was still greater than 90% after regeneration for 10 times. Additionally, the adsorption efficiency of PPy/TiO2 for the ARG effluent was still higher than 78% after adsorption-desorption for four times. It is expected that the PPy/TiO2 composite can be considered as a stable adsorbent for the removal of dye. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

A study on the removal of hexavalent chromium ions from aqueous solution by using activated carbon prepared from Ricinus communis has been done. In this process, it was carbonised and activated by treating with concentrated sulphuric acid followed by heating for 5 h at 500°C. Batch adsorption experiments are also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage and temperature. The experimental data are fitted well to the Freundlich adsorption isotherm. Thermodynamic parameters such as Δ H°, Δ S° and Δ G° are calculated, which indicated that the adsorption is spontaneous and endothermic in nature. Adsorbent used in this study is characterised by FT-IR and SEM before and after the adsorption of Cr(VI). © 2011 Canadian Society for Chemical Engineering [ABSTRACT FROM AUTHOR]

Removal of dye crystal violet from wastewater by a low-cost abundantly available adsorbent was investigated. By varying the parameters such as agitation time, dye concentration, adsorbent dose, pH and temperature, potential feasibility for the removal of crystal violet by Sagaun sawdust was explored. The adsorption efficiencies were found to be pH dependent. A greater percentage of dye was removed with a decrease in the initial concentration of dye and increase in the amount of adsorbent. Characterization of the adsorbent by infrared spectroscopy was undertaken. Kinetic study showed that the adsorption of dye on sawdust was a gradual process. The equilibrium adsorption capacity of adsorbent for dye removal was measured which followed Langmuir isotherm. The dimensionless factor, RL revealed that the adsorption process is favorable in nature. © 2011 American Institute of Chemical Engineers Environ Prog, 2011 [ABSTRACT FROM AUTHOR]

The potential of eggshell-a domestic waste to remove hazardous Malachite Green dye from aqueous solution was investigated in a batch experimental setup. Adsorption conditions were studied with respect to particle size, initial solution pH, adsorbent dose, contact time, initial dye concentration, and temperature. The optimum conditions for Malachite Green removal were found to be pH = 9.0, contact time = 90 min, adsorbent dose = 2.0 g L−1, initial dye concentration = 50 mg L−1. The temperature had a strong influence on the sorption process. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and surface area analysis were used to characterize the adsorbent material. FTIR analysis revealed that OH, CO, and PO4 functional groups were mainly responsible for the adsorption process. The rate of the adsorption reaction followed the pseudo second-order kinetics while the sorption equilibrium data well fitted to the Freundlich and the Langmuir isotherm models. The Arrhenius and Eyring equations were used to evaluate the activation parameters. A thermodynamic study showed spontaneous and endothermic nature of the adsorption process. Owing to its low cost and high dye uptake capacity, eggshells seem to be one of the most promising adsorbents for removal of Malachite Green from aqueous solutions. © 2011 American Institute of Chemical Engineers Environ Prog, 2011 [ABSTRACT FROM AUTHOR]

Industrial wastewater may contain high molybdenum concentrations, making treatment before discharge necessary. In this paper, the removal of molybdate anions from water is presented, using clinoptilolite zeolite coated with magnetite nanoparticles. In batch experiments the influence of pH, ionic strength, possible interfering (oxy)anions, temperature and contact time is investigated. Besides determination of kinetic parameters and adsorption isotherms, thermodynamic modeling is performed to get better insight into the adsorption mechanism; molybdenum is assumed to be adsorbed as a FeOMoO2(0H).2H2O inner-sphere complex. At the optimum pH of 3, the adsorption capacity is around 18 mg molybdenum per gram adsorbent. The ionic strength of the solution has no influence on the adsorption capacity. Other anions, added to the molybdenum solution in at least a tenfold excess, only have a minor influence on the adsorption of molybdenum, with the exception of phosphate. Adsorption increases when temperature is increased. It is demonstrat-ed that the adsorbent can be used to remove molybdenum from industrial wastewater streams, and that the limitations set by the World Health Organization (residual concentration of 70&mgr;g/1 Mo) can easily be met. Water Environ. Res., 84, 753 (2012). [ABSTRACT FROM AUTHOR]

The adsorption of fluoxetine onto activated carbons (ACs) prepared from almond tree pruning by steam and CO2 activation under different temperature conditions (650-950°C), was studied. In both series increasing the temperature caused an increase in the BET apparent surface area, yielding ACs with SBET up to 870 and 710 m2 g−1 after steam and CO2 activation, respectively. Also, a slight widening of the porosity was found in both cases. In order to modify the functionality of the ACs, two of them were impregnated with triethylenediamine (TEDA) prior to the adsorption process, which caused a decrease in the AC apparent surface mainly due to micropore blockage. The fluoxetine adsorption isotherms at 25°C showed maximum adsorption capacities between 110 and 224 mg g−1. The adsorption isotherms were analyzed using Langmuir and Freundlich models. Although the impregnation reduced the pore volume, it did not cause a decrease in the fluoxetine maximum adsorption capacity, but a modification in the adsorption mechanism was observed. [ABSTRACT FROM AUTHOR]

Porous a crylonitrile (AN)/methyl acrylate (MA) copolymer beads were synthesized by suspended emulsion polymerization and amidoximated for the purpose of Ag+ adsorption. Optimum amidoximation temperature and time were determined by following the adsorption capacity for Ag+. The results showed that amidoximated AN/MA (AO AN/MA) with the amidoximation temperature 70°C and amidoximation time 20 hr had a relatively higher adsorption capacity for Ag+. The effect of pH on adsorption for Ag+ was studied; the highest adsorption capacity presented at pH 5.0. Adsorption kinetics and isotherms of AO AN/MA copolymer beads for Ag+ were also investigated. The kinetics data indicated that the adsorption process was governed by the film diffusion and followed both pseudo-first-order and pseudo-second-order rate model. The isotherms indicated that adsorption capacities increased with equilibrium concentration and temperature. The Langmuir model and Sips model could describe the isothermal process. Thermodynamic analysis revealed that the adsorption behaviors of Ag+ ions on AO AN/MA could be considered as endothermic and physical sorption process. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Seeking solution to pollution problems is a prime concern of many researchers today. The waste from one industry can be judiciously used to treat another waste. This concept has been used in this study, wherein, the fleshing, a solid waste (biopolymer) emanating from leather industry has been used as an adsorbent for removal of dyes from wastewater. Fleshing has been crosslinked with glutaraldehyde to stabilize it against degradation. The various parameters like effect of pH, role of salt concentration, adsorbent dosage, and initial concentration of dye have been standardized. About 90% dye removal has been achieved by treating 100 mg/L dye solution with 12 g/L of glutaraldehyde-crosslinked fleshing. The dye removal has been found to follow Langmuir type of adsorption isotherm. The optimized parameters of batch adsorption studies have been applied to treat sectional wastewater from a commercial tannery. The study also explores the possibility of reusing the dye loaded fleshing as a reductant in the manufacture of a tanning salt, which is used in leather industry for tanning of leathers. Thus, a holistic solution to both solid and liquid waste has been presented in this work. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

This work investigated the use of ultrafiltration (UF) or microfiltration (MF) membranes combined with natural minerals for the pre-treatment of wastewater containing high amounts of lead. The effects of initial lead concentration, solution pH, membrane pore size, mineral type and concentration and mineral - metal contact time were investigated. Lead removal accomplished by the UF system was higher in wastewater compared to that obtained in aqueous solutions and this was attributed to the formation of insoluble metal precipitates/complexes, which were effectively retained by the membranes. At pH = 6 the dominant removal mechanism was precipitation/complexation, while mineral adsorption enhanced lead removal. The combined use of minerals and UF/MF membranes can effectively remove lead from wastewater resulting in a final effluent that can be further treated biologically with no biomass inhibition problems or can be safely discharged into municipal sewers. Kinetics investigation revealed a two-stage diffusion process for all minerals employed. The Langmuir isotherm exhibited the best fit to the experimental data. [ABSTRACT FROM AUTHOR]