Effect of potassium hydroxide activation in the desulfurization process of activated carbon prepared by sewage sludge and corn straw

Abstract

Series sludge straw–based activated carbons were prepared by sewage sludge and corn straw with potassium hydroxide (KOH) activation, and the desulfurization performance of activated carbons was studied. To obtain the best desulfurization performance, the optimum ratio between the raw materials and the activator was investigated. The results showed that when the mass ratio of sewage sludge, corn straw, and KOH was 3:7:2, the activated carbon obtained the best breakthrough and saturation sulfur sorption capacities, which were 12.38 and 5.74 times, respectively, those of samples prepared by the nonactivated raw materials. The appropriate KOH could improve the microporosity and alkaline groups, meanwhile reducing the lactone groups, which were all beneficial to desulfurization performance. The chemical adsorption process of desulfurization can be simplified to four main steps, and the main desulfurization products are elemental sulfur and sulfate. Implications: Sewage sludge (SS) and corn straw (CS) both have great production and wide distribution and are readily available in China. Much attention has been paid on how to deal with them effectively. Based on the environment protection idea of waste treatment with waste and resource recycling, low-cost adsorbents were prepared by these processes. The proposed method can be expanded to the municipal solid waste recycling programs and renewable energy plan. Thus, proceeding with the study of preparing activated carbon by SS and straw as a carbon-based dry desulfurization agent could obtain huge social, economic, and environmental benefits.