TiO2-grafted cellulose via click reaction: an efficient heavy metal ions bioadsorbent from aqueous solutions

Abstract

In this paper, preparation, characterization and adsorption properties of a new biocompatible cellulose-titania based nanocomposite (Cell-Com) made by the click reaction were investigated. FTIR, XRD, FESEM, BET, EDX and ICP-OES analyses were used to characterize the structure of Cell-Com. The adsorption behavior of the Cell-Com for the removal of Pb2+, Cd2+ and Zn2+ ions from aqueous solutions was performed by batch experiments. The effects of pH, contact time, adsorbent dose, initial metal ion concentration, temperature, coexisting ions and the regeneration performance of synthesized nanocomposite were evaluated. The optimal adsorption conditions was determined to be at pH 7.0, 60 min contact time, 10 mg adsorbent dose and 20 ppm initial metal ion concentration at 298 K. The equilibrium data was fitted well with the Langmuir isotherm among the examined isotherms and the maximum adsorption capacity of the bioadsorbent for Zn2+, Cd2+ and Pb2+ ions found to be 102.04, 102.05 and 120.48 mg g−1, respectively. The pseudo-second order model was the best kinetic model to explain the adsorption kinetic data, suggesting chemical sorption as the rate-determining step of sorption mechanism. The ΔG°, ΔH° and ΔS° values were estimated from Van’t Hoff plot together with activation energy (Ea) determined using Arrhenius equation, displayed that the adsorption process is spontaneous and endothermic in nature. The synthesized nanocomposite showed high selectivity and interference resistance from coexisting ions for the adsorption of Pb2+ ion. The Cell-Com can be easily regenerated and reused without significant loss of adsorption capacity. Recovery and reusability of Cell-Com were performed after 4–5 repeated adsorption/desorption cycles in HCl or in EDTA solutions.