One-step synthesis of 1,6-hexanediamine modified magnetic chitosan microspheres for fast and efficient removal of toxic hexavalent chromium

Abstract

Here, we reported a novel one-step hydrothermal route for the facile synthesis of 1,6-hexanediamine functionalized magnetic chitosan microspheres (AF-MCTS), which were characterized by TEM, FT-IR and XPS to look into its morphology, surface functional groups, and adsorption mechanism of Cr(VI) from the aqueous solution. Cr(VI) adsorption on AF-MCTS as a function of contact time, Cr(VI) concentration, pH, and ionic strength was investigated. The adsorption process follows the Langmuir isotherm model and pseudo-second-order kinetic model. The AF-MCTS exhibited high performance for Cr(VI) removal with very fast adsorption rate (reaching equilibrium within 5 min) and high adsorption capacity (208.33 mg/g), which was 1.1 to 12 times that of other chitosan-based adsorbents. Cr(VI) adsorption onto AF-MCTS was an endothermic and spontaneous process. The recovery and reuse of AF-MCTS was demonstrated 11 times without obvious decrease in adsorption capacity. Mechanism study suggested that –OH rather than –NH2 groups in AF-MCTS were the electron donors for reducing Cr(VI) to Cr3+. Consumption or addition of H+ could trigger the reversible supramolecular coordination between Cr3+ and chitosan. Given the easy preparation, low cost, and remarkable performance, AF-MCTS composite is expected to show promising potential for the practical application in removing toxic Cr(VI) from aqueous media.

Synthesis of Polypyrrole-Modified Layered Double Hydroxides for Efficient Removal of Cr(VI)

“…In recent studies, removal of Cr­(VI) from wastewater has been studied through various methods such as coprecipitation, reduction, solvent extraction, adsorption, ,, ion exchange, electrocoagulation, and membrane filtration . But adsorption is prefered due to its effectiveness, environmental friendliness, efficiency, sludge-free properties, and reversibility. , Substrates like activated carbon, clay materials, polymers, natural products, and metal/mixed oxide nanoparticles have also been used as adsorbents for removal of Cr­(VI) from wastewater. − Among these, metal/mixed oxide nanoparticles have acquired greater interests due to their high surface area and unique chemical and physical properties. , These metal/mixed oxides are appropriate as a substrate for synthesis of organic–inorganic hybrid materials, which show distinct properties unlike their constituents. The inorganic part of the composite provides mechanical support and thermal stability, while the organic part provides selective chemical (bonding sites) and electric (dielectric) properties …”

Comparative removal of As(V) and Sb(V) from aqueous solution by sulfide-modified α-FeOOH

“…Kinetic investigation is crucial for understanding the adsorption mechanism as well as the equilibrium time. The pseudo-first order and pseudo-second order (Ho, 2006;Yue et al, 2018) models were adopted to probe the kinetic results. The linear equations were expressed as:…”