Regeneration of hexamminecobalt(II) under the catalysis of activated carbon modified with ZnCl2 solution

The simultaneous scrubbing of NO and SO 2 can be accomplished by hexamminecobalt(II) solution. Activated carbon acts as a catalyst to regenerate hexamminecobalt(II), Co(NH 3 ) 6 2+ , to sustain the NO removal efficiency. In this paper, ZnCl 2 solution has been used to ameliorate the catalytic performance of coconut activated carbon in the regeneration of Co(NH 3 ) 6 2+ . The effects of the modification condition on the catalytic performance of activated carbon have been investigated in a batch stirred cell. The change of the surface chemical characteristics of the activated carbon caused by ZnCl 2 treatment was measured by determining the concentrations of acidic and basic groups as well as their points of zero charge (pH pzc ) with Boehm titration and mass titration. The alteration of the surface physical characteristics of the carbons was determined with an ASAP2000 Surface Analyzer using N 2 as the adsorbate. The experiments demonstrate that the catalytic performance of the coconut activated carbon may be improved when the carbon is treated by ZnCl 2 solution with concentration above 0.30 mol l −1 . The best ZnCl 2 concentration may be 0.50 mol l −1 . The optimal impregnation duration is 9 h. High activation temperature is propitious for the amelioration of the catalytic capability of carbon. 4 h may be the best time for the activation of activated carbon. In our experiment, the NO removal efficiency is maintained at a level of 73% when the regeneration of Co(NH 3 ) 6 2+ is under the catalysis of modified carbon while that is 57% with the regeneration of Co(NH 3 ) 6 2+ catalyzed by original carbon. It can be concluded that such modification can improve the catalytic performance of coconut activated carbon in the simultaneous removal of SO 2 and NO with Co(NH 3 ) 6 2+ ammonia solution.