Efficient treatment of coking wastewater by coal-based activated carbon prepared through coal blending method

Abstract

In this study, the adsorption performance of coal-based activated carbon produced from Shandong gas-fertilized coal, Taixi anthracite coal, and Datong weakly viscous coal, was investigated for coking wastewater treatment. All prepared activated carbons demonstrated excellent adsorption performance, boasting an iodine number surpassing 1000 mg/g and achieving a chemical oxygen demand determined by the dichromate method (COD_cr) removal rate of over 85 % under static coking wastewater adsorption. A positive correlation exists between the total pore volume of activated carbon and its iodine number, methylene blue value, and caramel decolorization rate. Furthermore, dynamic adsorption experiments were conducted and there was an evident increase in the COD_cr removal rate as the flow rate decreased. However, increasing the bed height beyond 400 mm only marginally enhanced the COD_cr removal rate. The burn-off rate of activated carbon and the ratio of raw materials significantly influenced the pore structure. Notably, with a high anthracite ratio (40 %), elevating the burn-off rate (up to 70 %) did not enhance the effective porosity of activated carbon. The mesopore volume, particularly within 1.2–2.8 nm range, exerted a substantial influence on the coking wastewater adsorption efficiency. Overall, coal-based activated carbon demonstrated significant promise as a cost-effective adsorbent for coking wastewater treatment.