Regeneration study of adsorbents loaded with zinc metal ions from contaminated water

Abstract

Regeneration of adsorbents is very important from the environmental as well as economical point of view. It allows reuse of adsorbents multiple times and recovery of heavy metals from spent adsorbents, thus lowering the processing costs of separation and facilitating safe disposal of the adsorbents. Desorption is the simplest, cheapest and commonly used technique for regeneration and metal recovery. In the present study, zinc ions were desorbed from mango leaf powder using HCl, HNO3, NaOH and distilled water as desorbing agents. HCl showed the best elution efficiency (94.7%) followed by HNO3 (89.5%). NaOH and distilled water showed very low elution efficiency (<10%). Regeneration allowed adsorbent to be used for 3 consecutive adsorption cycles with only 11% loss in adsorption efficiency and 16.6% loss in desorption efficiency. Adsorption and desorption isotherms resulted in adsorption hysteresis.