Heavy metals removal from drinking water by nanocomposite tannin resin- TiO2

Abstract

The aim of study was to determination the kinetics adsorption of heavy metals  from water samples obtained after sand filtration stage in AL-Wihda station of drinking water production in Baghdad by using three types of synthesized nanocomposite resins of tannin loaded with TiO₂NPs in order to select the best formula. The photocatalytic degradation and photochemical characteristics of TiO₂NPs on different organic and inorganic pollutants in water types were exploited. form Acacia nilotica leaves powder and synthesized  the tannin resin (TR). Three types of  nancomposites of tannin resin (TR) loaded with TiO₂NPs (TR-TiO₂-1, TR-TiO₂-2, and TR-TiO₂-3) synthesized  by adding the TiO₂NPs before the formalin (TR-TiO₂-1) and after formalin addition (TR-TiO₂-2) and chemical green synthesis of TiO₂NPs from TiCl₄ by TR solution (TR-TiO₂-3). The results showed that the nanocomposite TR-TiO₂ -2 was the most efficient in removing the heavy metals pollutants from water samples compared to the Iraqi and Word Health Organization (WHO) standareds. Four metals ( Mn, Cr, Cd and Hg) were selected for monitoring their removal from water samples after treating with TR-TiO₂ -2 composite. The remaining concemtration of Mn was 0.03 mg/L after 10 min of treatment; Cr, 0.006 mg/L after 50 min; Cd and Hg were not detected in water samples before and after treatments. Study of the adsorption kinetics of heavy metals for both equilibrium and the relationship of mass adsorption with time was showed that the maximum adsorption at the fixed times for each mineral especially the Mn and Cr, where the equilibrium state of the maximum concentrations of the adsorbed material was obtained on the nanocomposite            

TR-TiO₂-2. The results showed that the Cr and Mn adsorption equilibrium were subjected to the pseudo- second order equation.