**9. Desorption and recovery of metals**

After biosorption of heavy metal from environment, its recovery is another crucial step which involves desorption of metal from biosorbent. According to previous literatures [105–107], various agents were used for this purpose which includes complexing agents (thiosulfate, EDTA), mineral acids (HNO<sup>3</sup> , H2 SO4 , HCl), organic acids (acetic acid, citric acid). Before choosing the recovery agents, it should be kept in mind that chosen recovery agent should given least harm to physical properties of a biosorbent so that its efficiency of metal binding must remain in its original state to ensure its maximum efficiency for metal binding [94, 106, 107].
