Efficient Removal of Organic Pollutants in Waste Sulfuric Acid by Advanced Oxidation Process Using Coconut Shell-Derived Biochar to Produce Qualified Poly Aluminum Sulfate

Abstract

The hazardous waste sulfuric acid from alkylation process contains numerous organic pollutants and seriously threatens the ecological environment. Conventional pyrolysis process inevitably demands high investment and energy-extensive input, which constrains further large-scale applications. Herein an alternative utilization strategy of waste sulfuric acid to produce poly aluminum sulfate has been proposed using coconut shell-derived biochar (CBC) as a catalyst to enhance the removal of organic pollutants through the advanced oxidation process. The advanced oxidation process, stimulated by the surface oxygen groups and the absorbed metal ions from the CBC, was demonstrated to promote the production of reactive radicals, boosting the oxidative degradation of organic pollutants in crude Al2(SO4)3 solution. Under the optimal operating conditions, the removals of color and total organic carbon of the Al2(SO4)3 solution were 96.2 % and 93.8 %, respectively. The qualified poly aluminum sulfate product was obtained by the subsequent hydrolytic polymerization and concentrated crystallization of the treated Al2(SO4)3 solution. This technique is of great significance in valorization of waste sulfuric acid and application of recycled agricultural residues in advanced process.

Keywords: Advanced oxidation process, waste sulfuric acid, organic pollutants, coconut shell-derived biochar, poly aluminum sulfate