Chitosan-zirconia microballs for proficient removal of chromate and phosphate ions from water bodies

Zirconia-chitosan beads (Zr-CTB) were synthesized for detoxification of Chromate and Phosphate ions from water bodies. Zr-CTB was thoroughly characterized using FT-IR, SEM, EDX, TGA and BET studies. The beads were found to have a near-spherical shape with diameter of the order of 1 mm and the batch adsorption parameters such as pH, contact time, initial concentrations, amount of adsorbent, temperature, were optimized. The pH point of zero charge for the adsorbent was found to be 5.97. Maximum removal capacities towards chromate and phosphate ions were found to be 73.81 mg g(-1) and 65.51 mg g(-1), respectively at pH 5.0. The experimental data fitted well with Langmuir adsorption isotherm model and followed pseudo-second-order kinetics. Thermodynamics parameters confirmed that the process of adsorption was spontaneous, exothermic and leading to a decrease in entropy. The exposed material was regenerated using 5% NaCl solution with negligible change in adsorption efficiency up to 5 cycles. The effect of coexisting ions on adsorption efficiency was determined and the material was also tested by tea-bag model studies for convenient usage.