Modification of activated carbon by 2,6-diaminopyridine for separation of Hg2+ from aqueous solutions

The activated carbon prepared by pine cone was chemically activated by H3PO4 and then modified with 2,6-diaminopyridine. The synthesized adsorbent was characterized by FTIR and SEM techniques. The modified adsorbent was used for removal of mercury from aqueous solution under different experimental conditions. At optimized conditions the adsorption capacity of 377.68 mg/g was obtained which was much higher the previous reported values. The adsorption process was fast and the equilibration was attained in 20 min. The process was exothermic and spontaneous. Regeneration studies showed that the adsorbent retained most of its initial capacity after four regeneration cycles. The Langmuir isotherm provided the best description of the equilibrium adsorption giving a maximum uptake capacity for Hg2+ as 384.62 mg/g for activated carbon modified with 2,6-diaminopyridine.