DMol 3 is a unique quantum mechanical code for molecular DFT calculations which can rapidly perform structure optimizations of molecular systems using a numerical radial function ( Delley 1990) basis to calculate the electronic properties. MATERIALS AND METHODSĪll density functional calculations were performed with the help of the DMol 3 modeling program in which graphical displays were generated using BIOVIA Materials Studio.
The presented work aims to prepare a combined system of clay and aminated starch stabilized with oxyhydroxide and to evaluate its efficiency for successful remediation of trivalent arsenic from aqueous solution. Grafting with glycidyl methacrylate may be an efficient technique to introduce amine functionality in starch biopolymer. Amination of starch increases active binding sites on its backbone. Starch in its pristine form may not be suitable for immobilization of the nanomaterials. (2014) explained the dispersion of FeO(OH) particles in chitosan matrix for removal of As(III) and As(V) simultaneously where the former themselves can act as crosslinking agent for the matrix. The stabilization of mixed metal oxyhydroxide in chitosan biopolymer matrix has been reported in many studies ( Zubair et al. Many studies have demonstrated the stabilization of the nanomaterials by dispersing them on host materials such as granular activated carbon, cellulose, and biopolymers, etc.
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However, the free release of nanoparticles to the environment and tendency to agglomerate or probability of structural disintegration during cyclic run can limit their applicability ( Lenoble et al. Surfactant modification can alter the nature of clay surface charge to make it a potential binder for negatively charged arsenic species from aqueous solution ( Li & Bowman 2001). However, clay minerals are more effective towards positively charged species ( Kumar et al. The material retained its efficiency even after six cyclic runs. (2019) have synthesized a new material of bentonite clay for successful removal of certain harmful metal ions. Clay such as kaolinite, montmorillonite, etc., and their modified forms have been successfully utilized in the removal of many heavy metals, other contaminants and different forms of arsenic ( Lenoble et al. Srinivasan (2011) has demonstrated the usability of numerous clay minerals found in India in arsenic treatment. Arsenic detoxification by clay minerals and their modified forms are also well reported ( Mohapatra et al. Activated carbon with iron oxyhydroxide showed good arsenic uptake, though the sorption capacity was not so high ( Vitela-Rodriguez & Rangel-Mendez 2013). Iron oxyhydroxide is another iron(III) compound which has outstanding capability to adsorb both As(III) and As(V) species. 2017a, 2017b, 2017c) Cumbal & Sen Gupta (2005) have reported polymer supported hydrated iron(III) oxide nanoparticles with high arsenic uptake capacity. Fe(III)-based sorbents such as magnetite, siderite, hematite, ferrihydrite, etc., have strong affinity and selectivity towards arsenic species ( Catalano et al. The binding of As(III) on the material was governed by a pseudo second order kinetic model.Ĭlay minerals and iron-based nanomaterials have been gaining special attention in this concern owing to their unique arsenic sorption ability. The sorption followed a monolayer chemisorption pattern as determined by the Langmuir model (R 2 = 0.973, R L = 0.081) with a q max = 2.04 at 303 K. ΔG (>–11 kJ/mol), ΔH (42.48 kJ/mol), ΔS (177.6 JK −1 mol −1) and E a (59.16 kJ/mol) determined the feasibility of the process, its endothermic behavior and most importantly the chemical nature of the sorption accompanied by ion-exchange to some extent. Influence of material dose, treatment time, initial ion concentration, varying temperatures, etc., on extent of sorption was studied in detail. A molecular modeling on the basis of density functional theory was carried out to verify the above findings. All binding interactions during material preparation and arsenic sorption were exclusively characterized with FT-IR, XRD and other spectroscopic tools. This new material was highly efficient in arsenic water treatment which could reduce arsenic concentration far below detection limits. In this study a hybrid material (SICC) of aminated starch, oxyhydroxide of iron and OMMT clay has been demonstrated for arsenic treatment. Materials which are chemically, energetically and operationally acceptable for arsenic water treatment are highly required.
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