Environmentally friendly processes that aid human and environmental health include recovering, recycling, and reusing limited natural resources and waste materials. In this study, we reused iron-rich solid waste materials from a water treatment plant to synthesize magnetic iron-oxide adsorbents through an innovative combustion method for the removal of phosphates and arsenic from wastewater. In order to synthesize the magnetic adsorbents, the iron-rich solid waste residuals were mixed with poly-vinyl alcohol (PVA) in different ratios (1:1; 1:2, 1:3, and 1:5). Then, the mixtures were calcined with a conventional furnace to induce magnetization, followed by their conversion to powder and pellet forms. The physicochemical properties of the synthesized adsorbents were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution-TEM (HR-TEM), and a porosimetry analyzer. SEM images showed aggregation of small particles at lower ratios of PVA, but at a high ratio (i.e., 1:5), small particles did not aggregated due to the capping effect of PVA. TEM and HR-TEM images showed that the small nanoparticles (&lt; 20 nm) were aggregated in control while large particles (&gt; 50 nm) were observed in magnetic samples. The results of XRD showed that magnetite (Fe<sub>3</sub>O<sub>4</sub>) was synthesized by the combustion method using PVA, indicating non-magnetic iron in the wastes was converted into magnetic iron. The adsorption properties of the synthesized adsorbents for the removal of arsenic and phosphate was evaluated in both batch and equilibrium experiments under different experimental conditions. Under neutral pH (pH=7), the 1:3 ratio adsorbent demonstrated the highest phosphate adsorption (&gt; 10 mg/L of phosphate in one hour). For the sample synthesized with a 1:1 ratio, the highest phosphate removal was observed at alkaline pH (pH=9) in 1.5 hr.

Resource recovery and reuse: Recycled magnetically separable iron-based catalysts for phosphate recovery and arsenic removal

251st National Meeting (2016)

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