Comparison of the efficiency of two adsorbents activated carbon and beech wood powder copper-modified in removing sulfide ions (S-2) from the black liquor of Kraft pulp and paper

Sulfide ions (S-2 ) derived from Na2S remaining in black liqueur are the source of H2S gas production along the black liquor recovery cycle in the Kraft pulp and paper industry. In this study, we tried to prevent the production of H2S by removing the mentioned ions from black liquor by using of synthesized adsorbents (Cu-PAC and Cu-BWP100). The adsorbents were produced by immersing powdered activated carbon (PAC) and beech powder with 100 mesh (BWP100) in 0.1 M solution of CuCl2. The adsorbent properties were obtained before and after copper ion loading by FTIR, BET and SEM-FEI analyses. Finally, the performance of these adsorbents in the removal of S-2 from black liquor with three levels of sulfide (22%, 20, 18) was investigated. The results of FTIR, BET and SEM-FEI analysis showed that Cu+ 2 was located on the surfaces of raw organic material without any change in the structure of them. Experimental data for the Cu-PAC adsorbent showed that it was more agreement with the Freundlich equation and more follow to the pseudo-second-order kinetic model, whereas for Cu-BWP100 adsorbent it was the more consistent with the Langmuir equation and adherence to the pseudo-first-order kinetic model. The Cu-PAC adsorbent has the ability to remove 79.93% and Cu-BWP100 60.03% of S-2 from black liquor. The Cu-PAC, with its higher specific surface area, has a higher ability to remove S-2 from the black liquor than the Cu-BWP100. In general, the mentioned adsorbents will have a high ability to reduce H2S production by eliminating S-2.