Removal of the As(V) from the water using magnetite/3D-printed wollastonite hybrid sorbent

Abstract

The very serious problem in developing countries has become the presence of the arsenic contamination in the water for the public health. Still, millions of people in their daily lives are highly dependent on groundwater containing high levels of arsenic, as well as, in drinking water, which causes excessive exposure to this toxic element, due to the high cost and lack of watertreatment infrastructures. The maximal allowed concentration (MAC) for As(V) in water decreased from 50 to 10 μg/l, by considering the harmful effects of arsenic on the environment and human health. In order to achieve the established rigorous requirements, it is necessary to develop new materials and design new forms of adsorbents that can reduce the concentration of arsenic in drinking water. Therefore, in this study, the target was to synthesize magnetite/3Dprinted wollastonite hybrid sorbent that was used to remove As(V) from aqueous solutions. 3Dprinted wollastonite was obtained using the 3D-printing technique from methylhydrocyclosiloxane and calcium carbonate as precursors. Synthesis of adsorption material was carried out by depositing magnetite from an iron(II)-sulfate solution by potassium hydroxide on 3D-printed wollastonite. Characterization of the obtained material was performed using FTIR and SEM. An investigation of the sorption properties of hybrid adsorbents was carried out for As(V) removal - one relative to the starting pH value of the solution, the adsorbent mass and the temperature and the adsorption time. Determination of adsorption parameters was performed by applying Langmuir, Freundlich and Dubinin-Radushkevich equations. Determination of kinetics and adhesion parameters at three different temperatures enabled the calculation of thermodynamic and activation parameters of the adsorption process, which contributed to a better understanding of the adsorption mechanism. Also, based on the results, it was noticed that the highest adsorption capacity of the mentioned material for arsenic ions at a temperature of 45 °C. The compact filter presented in this report should serve well as a small-scale water-purification unit that can be easily carried to any site having water contaminated with arsenic