Preparation and characterization of cauliflower-like γ-Fe2O3/H-γ-AlOOH magnetic composites with high adsorption performance towards As(V)

That long-term consumption of water with arsenic concentrations greater than 10 mu g L-1 induces renal, hepatic, and cardiovascular diseases, in addition, the effective adsorbents for removing arsenic are limited by their harsh synthesis conditions, slow adsorption kinetics, low adsorption capacities and hard solid-liquid separation. Herein, a hierarchical cauliflower-like gamma-Fe2O3/H-gamma-AlOOH magnetic composites for the treatment of As(V)-contaminated wastewater is firstly proposed to avoid the complex centrifugation and filtration process, and achieve the purpose of simplifying operation. A series of physicochemical characterization tools reveal the successful synthesis of hierarchical cauliflower-like gamma-Fe2O3/H-gamma-AlOOH magnetic composite adsorbent with a large specific surface area (S-BET) of 131.82 m(2) g (1), high Zeta potential of +17.22 mV, and magnetic saturation (Ms) of 26.1 emu g(-1), which synergistically improves the adsorption performance and achieve the purpose of simplifying operation. The related adsorption experimental data demonstrates that the saturated adsorption capacity for As(V) reaches 130.17 mg g(-1) and decreases by only 17.6 % after six adsorption-desorption experiments, and the whole adsorption process conforms to Pseudo-second order model and the Langmuir model, which proves it is more inclined to be monolayer adsorption and there is no chemical reaction between As(V) and adsorbent. In addition, the adsorption of As(V) onto the cauliflower-like gamma-Fe2O3/H-gamma-AlOOH magnetic composites is assigned to a spontaneous, endothermic and entropy increased process. The main adsorption mechanism is that, combined with X-ray photoelectron spectroscopy (XPS) analysis, all components of the composite are involved in the adsorption of As(V), with the predominance of metal hydroxyl groups. The synthetic route of a novel and highly effective adsorbent, the hierarchical cauliflower-like gamma-Fe2O3/H-gamma-AlOOH magnetic composite material, provides a more promising alternative candidate for the As(V) treatment, from the perspective of aquatic ecosystem protection and solid-liquid separation.