Retention of toxic chromium from aqueous phase by H3PO4-activated lignin: Effect of salts and desorption studies

► Removal Cr(VI) onto activated lignin from aqueous solutions has been investigated. ► Experimental equilibrium data were fitted to seven different isotherms models. ► The NaOH desorbing agent was able to release about 84% of metal ions. ► Cr(VI) removal percentage decreased in the presence of NaHCO3 and K2P2O7 salts.