Modification of activated carbon by 4‐(8‐hydroxyquinoline‐Azo)benzamidine for removal of Hg 2+ from aqueous solutions

In this research, the activated carbon prepared from walnut shells was chemically activated by ZnCl 2 and modified by 4‐(8‐hydroxyquinoline‐azo)benzamidine. The synthesized adsorbent was used for the removal of Hg 2+ from aqueous solutions. The effect of different parameters including pH, initial concentration, adsorbent dose, contact time, and temperature was studied and optimized. At optimized conditions, pH = 2, contact time of 20 min, initial concentration of 600 mg/L, and 0.01 g sorbent, the adsorption capacity of 118 mg/g was obtained which was higher than the reported values. The adsorbent was highly selective for Hg 2+ . The results showed that the adsorption process was spontaneous and exothermic. Regeneration of the modified activated carbon by acid treatment showed that the adsorbent retained more than 84% of its initial adsorption capacity after four consecutive regeneration cycles. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1562–1567, 2015