Effect of activator on the structure and desulphurization efficiency of sludge-activated carbon

Abstract

Sludge-activated carbons (SACs) prepared with excess of activated sludge are used to solve the problems of sludge disposal and odour pollution in a sewage treatment plant. For the preparation, ZnCl ₂, KOH and H ₂SO ₄ are used as activators, respectively. The structure of the SACs are characterized by scanning electron microscope, X-ray photoelectron spectrometer, specific surface area and pore structure technologies, and the adsorption performance of H ₂S is investigated. Results indicate that the desulphurization activity of SACs, whose activators are ZnCl ₂ and KOH (SACZ and SACK), is better than that of carbon with H ₂SO ₄ as the activator (SACH). The breakthrough time of SACZ and SACK is up to 86 min, the sulphur capacity is 7.7 mg/cm³, and the maximal iodine value is 409.95 mg/g. While the breakthrough time of SACH is only 26 min with the sulphur capacity of 2.3 mg/cm³. A large percentage of pore volume with a diameter of 2–5 nm in the total pore volume is conductive to the desulphurization reaction. The large amount of surface acid functional groups is also helpful to the adsorption of H ₂S. The desulphurization activity of SACZ and SACK is superior over that of commercial-activated carbon.

Keywords:

• sludge-activated carbon
• activator
• desulphurization
• excess sludge
• hydrogen sulphide