Effective treatment and utilization of hazardous waste sulfuric acid generated from alkylation by lignocellulose ester-catalyzed oxidative degradation of organic pollutants.

Alkylation reaction catalyzed by concentrated H2SO4 generates hazardous waste H2SO4 containing a large amount of organic pollutants. This study focused on effective utilization and treatment of the waste H2SO4 for simultaneous consumption of H2SO4 and deep oxidative degradation of the organics. The waste H2SO4 could completely react with magnesium oxide ore to prepare crude MgSO4 solution, and the organic pollutants in the solution were deeply degraded and mainly mineralized to H2O and CO2 with H2O2 as oxidant and sugarcane bagasse citrate (SBC), a kind of lignocellulose ester, as catalyst. The total amount of acidic groups of SBC significantly affected its catalytic activity, attributing to that these oxygen-containing functional groups adsorbed and immobilized metal ions on SBC to form catalytic active sites, which could activate and catalyze H2O2 to generate •OH and HO2• radicals for effective degradation of the organics. The resulting purified MgSO4 solution with color removal of 93.71% and total organic carbon removal of 85.89% under optimum catalytic reaction conditions was used to produce qualified MgSO4∙7H2O product. These results highlighted the feasibility of using lignocellulose ester as effective catalyst for deep oxidative degradation of hazardous organic pollutants.