Synthesis of Ag2O-TiO2-Kaolinite Clay Nanocomposite for Efficient Removal of Mn2+, Fe3+, Cu2+, and Pb2+ and Pathogens in Mining Wastewater

Synthesis of Ag2O-TiO2-kaolinite clay nanocomposite was undertaken to eliminate some selected heavy metals released into the environment from mining wastewater. Silver nitrate and titanium-tetra-isopropoxide were employed as the bulk reagents for the Ag2O-TiO2 nanoparticles synthesis, using an aqueous extract of Parkia biglobossa leaf (green synthesis method). The Ag2O-TiO2 nanoparticles were supported on acid-activated kaolinite clay via wet impregnation method, to develop the nanocomposite and were characterized for phase structure, morphology, and oxidation states. The functionality of the nanocomposite for the sequestration of Mn2+, Fe3+, Cu2+, and Pb2+ ions from mining wastewater was examined by adsorption studies. The XRD pattern of the Ag2O-TiO2-kaolinite clay reveals the synthesis of the rutile phase of TiO2 embedded in the kaolinite clay. While the HRSEM shows an evenly distributed arrangement of hemispherical stacks of kaolinites. The oxidation states of Ag2O and TiO2 revealed by the XPS are + 1 and + 4 respectively either as binary or ternary nanocomposite. The Ag2O-TiO2-clay nanocomposite adsorbed 99.85%, 97.85% 95.18%, and 40% of Mn2+, Fe3+, Cu2+, and Pb2+ ions at 120 min from the mining wastewater respectively. The synergetic efforts of the Ag2O-TiO2-clay were responsible for the adsorptive capability of the nanocomposite for the removal of the selected heavy metal ions.