Thorium(IV) Removal and Recovery from Aqueous Solutions using Tannin-Modified Poly(glycidylmethacrylate)-Grafted Zirconium oxide Densified Cellulose

A novel adsorbent, tannin-modified poly(glycidylmethacrylate)-grafted zirconium oxide-densified cellulose (TMPGZDC) was synthesized by graft copolymerization reaction of glycidylmethacrylate onto zirconium oxide densified cellulose (ZDC) in the presence of N,N'-methylenebisacrylamide as cross-linker followed by tannin immobilization, and well characterized. The adsorption efficiency of TMPGZDC toward thorium(IV) from aqueous solutions was studied at different optimized conditions. The optimum pH for maximum adsorption was found to be 5.5 with the adsorption percentage of 99.2% for an initial concentration of 10 mg/L. Equilibrium was achieved within 2 h. The kinetic data were found to follow pseudo-second-order model, which assumes the presence of chemisorption. The temperature dependence indicates an exothermic process. The well agreement of equilibrium data with Langmuir isotherm and Redlich-Peterson isotherm models confirms the monolayer coverage of Th(IV) onto TMPGZDC surface and the maximum adsorption capacity was found to be 96.7 mg/g. Complete removal of Th(IV) from simulated seawater was possible with an adsorbent dosage of 3.0 g/L. Spent adsorbent was effectively degenerated with 0.1 M HNO3. The present investigation shows that TMPGZDC is a promising adsorbent for the removal and recovery of Th(IV) from aqueous solutions.