Materials, Methods & Technologies, Volume 12, 2018

Abstract: The sorption properties of amorphous titanium hydroxide ion-exchanger (ATH) toward non-ferrous metal cations are investigated. The sol-gel synthesis of ATH is based on the method of limited hydrolysis of ammonium titanyl sulfate (NH4)2TiO(SO4)2·H2O (ATS) without the usage of organometalic compounds. The presence of ammonium ion in sol prevents the polymerization of gels, which has a positive impact on porosity of the obtained compounds and, consequently, on ion-exchanging characteristics. The sorption isotherms for five divalent metal ions including Pb2+, Cd2+, Cu2+, Zn2+, and Ni2+ are built. The isotherms are best described with the Freundlich model in the case of sorption of cadmium and lead cations, and with the Langmuir and Freundlich models in the case of sorption of zinc, copper and nickel cations. The sorption kinetics of these metal ions on the ATH is limited by internal diffusion. The selectivity order of the metal ions on TiP1 is determined as follows: Pb2+ > Co2+ > Cu2+ > Ni2+ > Cd2+ > Zn2+. Additional sorption studies are carried on industrial water containing a mixture of divalent and hardness cations. The quality of water after the sorption on the ATH sorbent reaches the EU recommendations for drinking waters for most of the metal ions concentrations. In the case of wastewater treatment in tannery industry, the sorption of chrome cations on the ATH exceeds 99% for all types of wastewater and the remaining concentration of chrome ions (III, VI) in the solution is lower than maximum concentration limit.