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The present work reports the first demonstration of zirconium oxide (ZrO) as a photoanode and rose bengal (RB) as a sensitizer. ZrO photoanode films were deposited on indium-doped tin oxide (ITO)-coated glass substrate by doctor blade technique. ZrO photoanodes were sensitized by rose bengal dye. Scanning electron microscopy (SEM) was applied to reveal the surface morphological changes for the RB-sensitized and unsensitized ZrO photoanodes. Using UV-vis spectrophotometer, optical absorption analyses were carried out for the RB-sensitized photoanodes. Platinum-coated ITO electrode was used as a counter electrode for electrons collection. The electron transfer at the interfaces was studied by electrochemical impedance spectroscopy. The device fabricated using the photoanode with dye loading time of 24 h performed better, it showed the photocurrent density ( J ), open-circuit voltage ( V ), and fill factor ( FF) of about 0.01 mA/cm, 258 mV, and 34%, respectively. [ABSTRACT FROM AUTHOR]

Zirconium oxide (ZrO) is acquiring considerable attention of most of the research groups and leading to a large number of publications due to its unique properties, especially in the context of emerging trends in the third generation of solar cell research. ZrO films offer magnificent aspects related to physicochemical properties, and the properties are found to be dependent on synthesis methods. In the present review, various deposition techniques used to grow zirconium oxide thin films and their application to enhance the quantum efficiency of titanium oxide (TiO) based dye-sensitized solar cells (DSSCs) are discussed. Also, the modulated performances of DSSCs fabricated by growing the conformal ZrO insulating films to retard interfacial recombination dynamics on preformed TiO films are discussed. [ABSTRACT FROM AUTHOR]

A new surfactant-based nanocomposite cation exchanger, sodium dodecyl sulfate-Th(IV) tungstate (SDS-TT) was prepared by the sol-gel method. The SDS-TT was characterized by FTIR, XRD, TGA, SEM, EDS and TEM. The distribution studies for various metal ions on SDS-TT were performed in different acidic mediums. On the basis of distribution coefficient values, SDS-TT was found to be selective for Cu metal ion. SDS-TT was successfully used for the quantitative separation of Cu from the synthetic mixture, pharmaceutical formulation and brass sample. The regeneration studies were performed which showed a decrease in the recovery of Cu from 88 to 70 % after seven consecutive cycles. [ABSTRACT FROM AUTHOR]

To study the ion exchange kinetics of heavy metal ions on the organic-inorganic composite cation exchanger poly- o-toluidine Zr(IV) tungstate, Nernst-Planck was computer simulated. Simulated numerical results for counter ions (Cu, Zn, Cd and Pb) of equal valence and four different ionic mobilities are presented to understand the ionic diffusion process. These results are based on the fractional attainment of equilibrium U(τ), of the counter ions under study. The forward (M-H) and reverse (H-M) ion exchange processes are justified as the particle diffusion phenomenon. The self-diffusion coefficient ( D), energy of activation ( E), and entropy of activation (∆ S*) have also been estimated to understand the ion exchange process occurring over the surface of this cation exchanger and indicated that the ion exchange process is feasible and spontaneous. It is concluded that the difference in activation energies and entropy of activation may facilitate the separation of metal ions. The regeneration capability of this cation exchanger was also explained. [ABSTRACT FROM AUTHOR]

Two cation-exchange materials, aluminium tungstate (AT) and sodium dodecyl sulphate-aluminium tungstate (SDS-AT), were synthesized. Both samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis and scanning electron microscopy. The distribution coefficients for various metal ions on SDS-AT cation-exchange material were performed in different solvent systems. On the basis of distribution coefficient values, the SDS-AT cation-exchange material was found to be selective for the very toxic metal ion, Cr. The hybrid cation-exchange material offered a variety of technological opportunities for quantitative determination and separation of Cr from synthetic mixtures of metal ions. Some binary and ternary separations of metal ions; viz., Cd-Cr, Zn-Cr, Cu-Cr, Pb-Cr, Mg-Pb-Cr and Mg-Cd-Cr, were performed using a packed column of this material. [ABSTRACT FROM AUTHOR]

There is an ever-increasing demand for rapid, sensitive, cost effective and selective detection methods for the analysis of many essential compounds. When chemiluminescence has been introduced to analytical chemistry as a detection technique, it has been shown to meet many of these requirements. This method has become a powerful tool for the determination of many compounds. Using this method, low detection limits can be obtained with simple and inexpensive instrumentation. Coupled with flow injection technique the method has become more popular for wider applications. Since many excellent reviews on the chemiluminogenic techniques have appeared in the literature in recent years, the present paper does not intend to cover the exhaustive studies in this area, but will selectively describe the analytical applications of nanoparticle sensitized lucigenin and luminol chemiluminescent reactions and evaluate their recent progress together with our present work. [ABSTRACT FROM AUTHOR]

A new crystalline organic-inorganic composite cation exchanger polyaniline Sn(IV) molybdate was developed by mixing polyaniline into the inorganic precipitate of Sn(IV) molybdate. This material was characterized using Fourier transform infrared spectroscopy (FTIR), simultaneous thermogravimetry-differential thermogravimetry (TGA-DTA), X-ray, scanning electron microscopy (SEM) and elemental analysis studies. Ion-exchange capacity, effect of calcinations (100-500 °C) on ion exchange capacity, pH-titrations, chemical stability, elution and distribution behavior were also carried on this material. On the basis of distribution studies, the material was found to be highly selective for Pb ion and its selectivity was tested by achieving some important binary and ternary separations. In order to demonstrate the practical utility of the material, quantitative separations of Pb from a standard reference material (Rompin Hematite) of lead have been achieved. Thermodynamic parameters viz- entropy change (ΔS), enthalpy change (ΔH) and Gibb's free energy change (ΔG) were also calculated. [ABSTRACT FROM AUTHOR]

An inorganic cation exchanger, aluminum tungstate (AT), has been synthesized by adding 0·1 M sodium tungstate gradually into 0·1 M aluminium nitrate at pH 1·2 with continuous stirring. The ion exchange capacity for Na+ ion and distribution coefficients of various metal ions was determined on the column of aluminium tungstate. The distribution studies of various metal ions showed the selectivity of Fe(III) ions by this cation exchange material. So, a Fe(III) ion-selective membrane electrode was prepared by using this cation exchange material as an electroactive material. The effect of plasticizers viz. dibutyl phthalate (DBP), dioctylphthalate (DOP), di-(butyl) butyl phosphate (DBBP) and tris-(2-ethylhexylphosphate) (TEHP), has also been studied on the performance of membrane sensor. It was observed that the membrane containing the composition AT: PVC: DBP in the ratio 2 : 20 : 15 displayed a useful analytical response with excellent reproducibility, low detection limit, wide working pH range (1-3·5), quick response time (15 s) and applicability over a wide concentration range of Fe(III) ions from 1 × 10-7 M to 1 × 10-1 M with a slope of 20 ± 1 mV per decade. The selectivity coefficients were determined by the mixed solution method and revealed that the electrode was selective for Fe(III) ions in the presence of interfering ions. The electrode was used for atleast 5 months without any considerable divergence in response characteristics. The constructed sensor was used as indicator electrode in the potentiometric titration of Fe(III) ions against EDTA and Fe(III) determination in rock sample, pharmaceutical sample and water sample. The results are found to be in good agreement with those obtained by using conventional methods. [ABSTRACT FROM AUTHOR]

In this current study, aminated graphene oxide (AGO) doped on alginate (Alg) matrix offers AGO@Alg hybrid spheres was developed to investigate its potential for retention of fluoride from water. The sophisticated characterization methods likely TGA, SEM, XPS and FTIR studies of AGO@Alg hybrid spheres were attained to recognize its physicochemical properties like thermal stability, morphology, elemental binding energy and functional groups determination. The responsible parameters for fluoride adsorption on AGO@Alg hybrid spheres were optimized under a batch mode to achieve improve defluoridation capacity (DC). The developed AGO@Alg hybrid spheres follow the electrostatic interaction mechanism on fluoride removal. The adsorption isotherms (Langmuir, Temkin, Dubinin–Radushkevich (D–R) and Fruendlich models), kinetics (reaction and diffusion based models) and thermodynamic parameters (ΔS°, ΔG° and ΔH°) were investigated at 303, 313 and 323 K. To minimize the cost-effectiveness of AGO@Alg hybrid spheres the reusability test was carried out. The suitability of AGO@Alg hybrid spheres was also analyzed for the fluoride contaminated field sample taken from fluoride prevalent village. [ABSTRACT FROM AUTHOR]

Nanocomposite hydrogels are polymeric networks that possess a unique property of hydration. The presence of alcohols, carboxylic acids and amides as hydrophilic moieties in structure of nanocomposite hydrogels enhances their stiffness and water-absorbing capacity. Addition of cross-linker in the synthesis of hydrogels increases their stability under extreme conditions of temperature, pH and pressure. Natural polymer-based nanocomposite hydrogels are biodegradable, highly hydrophilic and possess good mechanical strength. Gelatin, chitin, cellulose, pectin, carrageenan, starch and alginate are natural polymers commonly used to fabricate nanocomposite hydrogels. Nanocomposite hydrogels have special characteristics such as high swelling rate, selectivity and stimuli-sensitive nature. Here we review nanocomposite hydrogels for environmental protection and biomedical engineering. Applications in biomedical engineering include drug delivery agents, wound dressing, tissue engineering and antibacterials. Applications in environmental protection include ion exchangers, adsorption, photocatalysis and soil conditioning. Many nanocomposite hydrogels show excellent adsorption selectivity for heavy metal ions: Cu2+ up to 30.35 mg/g, Pb2+ up to 35.94 mg/g, and Zn2+ and Fe3+ up to 94.34 mg/g. Xanthan gum-based nanocomposite hydrogel has removed 96% dye from industrial effluent as reported. In addition, most of the nanocomposite hydrogels showed better adsorption capacity for pollutants in the pH range from 5 to 7. The nanocomposite hydrogels could also be regenerated and successfully utilized for several times. Nanocomposite hydrogels are therefore good bio-absorbent materials for environmental detoxification. [ABSTRACT FROM AUTHOR]

The copper-doped lithium borate glass as a thermoluminescent (TL) material (100− x) BO- xLiO : Cu ( x= 20, 50 and 80 mol%) was prepared by the combustion method. The formation of (100 − x)BO- xLiO : Cu after doping 2, 3 and 5 ppm Cu, was characterized by Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The TL characteristics of the synthesized material were studied at different parameters. The synthesized glass 50BO-50iO : Cu with 3 ppm of doped Cu, exhibited the superior TL properties than other glasses prepared in the current study. The spin-Hamiltonian parameters were assessed using the electron spin resonance spectra of 50BO-50LiO : Cu doped with 3 ppm Cu. The spin-Hamiltonian parameter values in the case of Cu revealed that the ground state of Cu was d x- y orbital ( $^{\mathbf {2}}\text {B}_{\mathbf {1g}}$) and the site symmetry around Cu ion was distorted octahedral. TL glow curves were recorded with different heating rates (1, 2, 5, 10, 15, and 20C s) at the fixed dose 10 × 10 Gy. The results revealed that the glow peak position shifted to higher temperature with heating rate and the heating rate of 10C s showed the superior TL response with highest glow peak which is very good for dosimetry purposes. [ABSTRACT FROM AUTHOR]

Energy shortage and escalating pollution are major challenges globally. Heterogeneous photocatalysis is one of the most cost-effective methods for producing renewable energy and removing pollutants. In particular, ZnO nanostructures are promising photocatalysts that are economic, stable, and biologically safe. ZnO-based nanoheterostructures have been used for heavy metal reduction, organic pollutants degradation, photocatalytic hydrogen production, and drug mineralization. Here, we review ZnO-based nanoheterojunctions as photocatalysts for hydrogen production and pollutant degradation. Hydrogen production has reached 1200 mol g−1 h−1 using Ce-doped ZnO/ZnS heterojunction, with a 8.5-fold higher efficiency than bare ZnO. Nearly complete removal of a dye pollutant was achieved in 15 min using hybrid ethyl cellulose-modified g-C3N4/ZnO. Moreover, ZnO/Ag2WO4/Fe3O4 showed a 152% and 143% higher antibiotic degradation rate than bare Ag2WO4 and ZnO, respectively. We present methods to modify ZnO, including coupling with other semiconductors, metal/non-metal doping, and carbon-based materials coupling; and methods for charge divergence in binary and ternary ZnO-based nanocomposites. [ABSTRACT FROM AUTHOR]

Providing sustainable energy and cleaning water pollution are actually major societal issues requiring new catalysts. In particular, transition metal phosphides are emerging as effective photocatalytic materials. Here we review synthetic strategies for metal phosphides by various methods. We discuss passivation strategies for engineering electronic and structural properties of metal phosphide nanocomposites. Electronic properties, stability and activity depend upon the type of metal phosphides, either phosphorus-rich or metal-rich. Typically, a high content of phosphorous in metal phosphides improves the catalysis. The crystalline structure of metal phosphides also varies and depends upon their chemical composition. We present the latest developments in H2 production and photodegradation of aqueous pollutants using metal phosphide-based heterojunctions, with focus on type-II-, Z-scheme- and S-scheme-based heterojunctions. [ABSTRACT FROM AUTHOR]

This article provides a review in the area of zirconium(IV) based organic-inorganic composite ion exchange materials used in analytical, pharmaceutical and environmental protection processes. It focuses on the synthesis, characterization and electroanalytical applications of various Zr(IV)-based composite ion exchangers in detail. The results obtained in different studies have also been critically reviewed. Also reviewed are the various composite cation exchange materials used as electroactive materials for the fabrication of ion-selective membrane electrodes. The ion exchange kinetic parameters of Zr(IV) based composite ion exchangers have been discussed, which provide the preliminary idea before the selection of the material for a particular application. [ABSTRACT FROM AUTHOR]

An electrically conducting 'organic-inorganic' composite material polyaniline Ce(IV) molybdate was prepared by incorporating electrically conducting polymer, i.e., polyaniline into inorganic precipitate of polyvalent metal acid salts i.e., Ce(IV) molybdate. The temperature dependence of electrical conductivity of this composite system with increasing temperatures was measured on compressed pellets by using a 4-in-line-probe dc electrical conductivity-measuring instrument. The values of conductivity lies in the semiconductor region, i.e., they are of the order of 10-10 S cm and obey the Arrhenius equation. The thermal stability of this composite material in terms of dc electrical conductivity retention was studied under isothermal and cyclic techniques and electrical conductivity of composite was found to be sufficiently stable under ambient temperature conditions. The dependence of the electrical conductivity prepared with different concentrations of aniline monomers, on the concentration of conducting phases i.e., polyaniline was showed that electrical conductivity increase followed the percolation threshold. [ABSTRACT FROM AUTHOR]

In the present study, Ag2O–Al2O3–ZrO2 based trimetallic oxide nanocatalyst was designed using simple microwave assisted reduction method. It was characterized using various techniques such as Fourier transform-infrared (FT-IR), X-ray diffractometer (XRD), electron microscopy [scanning electron microscope (SEM), transmission electron microscope (TEM)] and X-ray photoelectron spectroscope (XPS). It was utilized for the degradation of nicosulfuron herbicide and the influence of microwave (MW) and UV radiations on the degradation rate was also studied. Maximum of 78% degradation was obtained within 50 min. Scavenging studies showed the major involvement of ·OH and ·O2− radicals in the degradation process. Possible heterostructures (traditional and Z-scheme) with their possible charge transfer were also studied. Nyquist plots and photoluminescence (PL) analysis showed the high charge transfer and lowered recombination in Ag2O–Al2O3–ZrO2. Possible degradation mechanism was also developed using LC–MS. Reusability studies were carried out for consecutive 5 cycles and results indicated the appreciable photocatalytic ability after every repeated cycles. [ABSTRACT FROM AUTHOR]

The water management sector is becoming extremely challenging these days because of poor water quality which is due to the presence of noxious pollutants at an alarming level. Herein, we report the synthesis of FeO/ZnO magnetic metal oxide (FZ MMO) and its nanocomposite with polyaniline (FZP). Designed photocatalyst has been characterized by various techniques such as X-Ray diffractometer (XRD), Scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Transmission electron microscopy (TEM) and Fourier transform infrared spectrophotometer (FTIR). Bandgap values as determined using Tauc plots has been found to be 2.46 and 1.80 eV for FZ MMO and FZP, respectively. Photocatalytic activity of FZ MMO and FZP under visible light irradiations has been studied for degradation of 3-aminophenol. The influence of adsorption on the degradation rate has also been studied. 92% of 3-aminophenol present in the solution was removed in 120 min using FZP under visible light. Thus present study gives a deep insight for the designing of highly photocatalytic and reusable photocatalyst that can be utilized for the removal of various pollutants from the water system. [ABSTRACT FROM AUTHOR]

Pollution is a major issue impacting the health of life and ecosystems. In particular, some pollutants may alter gene expression by epigenetic mechanisms such as deoxyribonucleic acid (DNA) methylation, histone modifications, and microRNA (miRNA) expression. Epigenetics is the study of heritable changes without alteration in the DNA sequence. In the healthy state, the coordinated actions of interconnected epigenetic factors are responsible for proper cell development and cell regulation. Epigenetic mechanisms are tissue-specific; hence, a pollutant may or may not cause an alteration depending on the type of tissue. Here we review mechanisms by which pollutants disrupt epigenetic factors. We focus on the impact of arsenic, cadmium, nickel, mercury, benzene, bisphenol A, dioxin, hexahydro-1,3,5-trinitro-1,3,5-triazine and diethylstilbestrol. A list of diseases related to epigenetic factors and heavy metals exposure is provided. [ABSTRACT FROM AUTHOR]

Delivering the right amount of fluoride to drinking water protects the teeth from decay and reduces the risk of cavities. Nonetheless, fluorosis has been diagnosed as the result of excessive exposure of fluoride, which induces brain impairment, muscle disorders and hyperactivity. Fluoride ingestion during the formation of the tooth enamel is the main reason for fluorosis, which is characterized by hypomineralization. Dissolution of fluoride-containing rock minerals contributes to naturally occurring fluoride contamination in water. The intentional addition of fluoride to water in dental care is alarming in growing countries such as India. This article reviews the origin of fluoride, the analysis of fluoride derivatives and the technologies to remove fluoride from water. The manuscript presents adsorption techniques for fluoride removal, using different types of adsorbents. The adsorption capacities of adsorbents under various conditions, such as contaminant concentration, adsorbent dosage, time, pH and temperature, are presented. Adsorbent types include alumina, zeolites, organic waste, shell-based and carbon-based including graphite and carbon nanotubes. Defluoridation of water using clays and muds, modified activated alumina, chitosan derivatives and composites are also discussed. [ABSTRACT FROM AUTHOR]

Effective technologies and materials are needed for environmental detoxification and clean energy production. The actual photocatalytic technology is largely dependent on metal oxide-based semiconductors, which have issues such as cost, limited spectral response and recombination problems. Alternatively, non-metal photocatalysts have recently emerged. This article reviews non-metal oxide photocatalytic materials such as carbon nitride, metal nitrides, phosphides, chalcogenides, perovskites and carbides for environmental clean-up and energy production. [ABSTRACT FROM AUTHOR]

Polluted soil and water impact the quality of food and nutrients of human and animal biota. Soil and water are mainly polluted by effluent discharges from industries, which are broadly classified into metallic and nonmetallic pollutant-bearing effluents. In order to tackle this problem, a plant-based technology called phytoremediation is used to clean contaminated lands. Phytoremediation is based upon several processes such as phytodegradation, phytovolatilization, phytoaccumulation and phytoextraction. These methods are efficient, eco-friendly and economic. This paper reviews the methods and mechanisms involved in phytoremediation of heavy metals, and enhancement processes. [ABSTRACT FROM AUTHOR]

Environmental pollution and climate change are requiring new methods to clean pollutants and produce sustainable energy. Aerogels and metal organic frameworks are emerging as advanced porous materials with higher functionality, high surface area, high porosity and flexible chemistry. Aerogels are dried gels prepared using the sol-gel procedure, whereas metal organic frameworks are networks of organic ligands and metal ions connected by coordination bonds. Applications of aerogels include the removal of heavy metals, CO2 capture and reduction, photodegradation of pollutants, air cleanup and water splitting. This article reviews the synthesis and types of aerogels and metal organic frameworks, and the application to pollutant removal, energy production including hydrogen, methane reforming, CO2 conversion and NOx removal. [ABSTRACT FROM AUTHOR]

Present work deals with a two-step synthesis and electrochemical properties of nickel oxide @copper oxide@copper (NiO@CuO@Cu) bilayered electrode. In the first step, anodization (40 V for 25 min) of Cu foil has been carried out for forming Cu-hydroxide@Cu which when annealed at 300 °C for 1 h produces CuO@Cu. In the second step, Ni-hydroxide is deposited onto CuO@Cu by applying current density of 0.03 A/cm for 3 min which when re-annealed at 300 °C for 1 h gives out NiO@CuO@Cu bilayered electrode. Obtained NiO@CuO@Cu bilayered electrode demonstrates separate CuO and NiO phases. The electrochemical properties have obtained using cyclic voltammetry, galvonostatic charge-discharge, and Nyquist plot measurements that reveal an importance of NiO@CuO@Cu as a potential electrode material in the electrochemical supercapacitor application with 58.14, 51.25, and 4.73 F g values in 0.5 M, NaOH, KOH, and NaSO electrolytes, respectively, measured at 2 mVs scan rate. [ABSTRACT FROM AUTHOR]

Nanorods (NRs) of TiO have biogenically been prepared, i.e., from the extract of Phellinus linteus mushroom. The presence of mixed anatase and rutile TiO phases, rod-type crystallites, and 114.16 g/cm and 3.7-nm surface area and pore-diameter is evidenced by various measurements. The dye-sensitized solar cell (DSSC) is fabricated using as-prepared TiO NR-based photoanode in the presence of N719 sensitizing dye prepared in 0.5 M lithium iodide and 0.05 M iodine with acetonitrile as redox electrolyte. Solar-to-electrical energy conversion efficiency ( η%) of 3.8 % is recorded and electrochemical impedance spectroscopy (EIS) curve obtained for TiO-based DSSCs is fitted using an equivalent circuit for explaining various electrical parameters involved in developed DSSC. [ABSTRACT FROM AUTHOR]

The present work describes the outcomes of the assessment on acrylamide contents in a number of thermally treated foods (Arabic coffee Qahwa, coffee and tea) obtained from the Saudi Arabian markets. A total of 56 food samples of different brands and origin were studied, the amounts of acrylamide in Arabic coffee Qahwa, coffee and tea were obtained in the range of 10 to 682 μg kg−1. In comparison to coffee (152-682 μg kg−1), the Arabic coffee Qahwa (73-108 μg kg−1) and tea (10-97 μg kg−1) contain lower amounts of acrylamide. Among the analyzed samples, the green tea contained low amounts of acrylamide ranged from 10 to 18 μg kg−1, and thus the green tea could be considered as a healthier hot drink. A great variation of acrylamide formation has been observed in these food products. This divergence may be due to the initial concentration of amino acids especially asparagines and reducing sugars in food products, in addition to roasting temperature and time, pH and water activity. The obtained data can also be used in epidemiological investigation to estimate the acrylamide exposure from nutritional survey. [ABSTRACT FROM AUTHOR]

A single wall carbon nanotubes (SWNTs)/graphene/ferritin/GOx layer on a glassy carbon electrode (GCE) acting as a biofuel cell anode was fabricated using a SWNTs/graphene/ferritin composite as an electron transfer mediator from the enzyme to the electrode. In the presence of glucose, the SWNTs/graphene/ferritin/GOx composite showed a higher current response than SWNTs/graphene/GOx composite and the electrocatalytic oxidation of glucose on the anode increased linearly with increasing concentration of glucose. The highly distributed SWNTs/graphene/ferritin composite acts as a platform for enzyme immobilization resulted in an enhanced electrocatalytic activity towards glucose. The SWNTs/graphene/ferritin composite showed an enhanced electron transfer from enzyme to the electrode; therefore, SWNTs/graphene/ferritin/GOx composite can be used as an anode in biofuel cells. [ABSTRACT FROM AUTHOR]

The thermodynamics of nicotinic acid adsorption from aqueous solution on carboxymethyl cellulose Ce(IV) molybdophosphate composite cation exchanger were studied. The composite cation exchanger was synthesized by sol-gel method and thereby characterized using scanning electron microscopy, thermogravimetric analysis, X-ray powder diffraction and fourier transform infra red spectroscopy. The analytical applicability and thermodynamic parameters, such as Freundlich constant, thermodynamic equilibrium constant ( K), standard free energy changes (Δ G°), standard enthalpy changes (Δ H°) and standard entropy changes (Δ S°) of this composite cation exchanger have been evaluated. The thermodynamic parameters showed that the adsorption of nicotinic acid onto composite cation exchanger is feasible, spontaneous and exothermic, suggesting their suitability for the potential application of nicotinic acid removal from waste water. [ABSTRACT FROM AUTHOR]

The Nernst-Planck equations with some additional assumptions was used in this study to investigate the forward kinetics and ion-exchange mechanism of heavy metal ions viz. Ni-H, Cu-H, Mn-H and Zn-H on the surface of carboxymethyl cellulose Sn(IV) phosphate composite nano-rod-like cation-exchanger. It was observed that heavy metals' exchange processes were imparted by the particle diffusion-controlled phenomenon. Some physical parameters i.e., fractional attainment of equilibrium U( τ), self-diffusion coefficients ( D), energy of activation ( E), and entropy of activation (Δ S*) were estimated. These investigations revealed that the equilibrium is attained faster at higher temperature probably because of availability of thermally enlarged matrix of carboxymethyl cellulose Sn(IV) phosphate composite nano-rod-like cation-exchange material. The physical parameters observed for this composite cation exchanger were also compared with other composite ion exchangers. The results showed that the ion-exchange phenomenon is more feasible on the surface of this composite cation exchanger as compared with the other ion exchangers which indicated the usefulness of this composite ion exchanger in various applications. [ABSTRACT FROM AUTHOR]