Treatment Of Waste Sulfuric Acid By H₂O₂ Catalytic Oxidation With Activated Carbon

Numerous waste sulfuric acids are produced during the use of sulfuric acid.These waste acids need to be treated.There are lots of methods to treat waste sulfuric acids such as thermal decomposition,distillation,solvent extraction,adsorption,oxidative degradation and membrane separation.In this paper,waste sulfuric acids containing organic impurities were studied which were generated from the purification of acetylene gas.Researches on H₂O₂ catalytic oxidation of waste sulfuric acids by using activated carbon as catalyst were carried out.Operating parameters such as catalyst dosage,rate of addition of H₂O₂,and reaction temperature were discussed to optimize operating process,and the reaction kinetics of H₂O₂ catalytic oxidation of waste sulfuric acids with activated carbon were also discussed.The experiments results showed that the organic impurities in the waste sulfuric acids were removed effectively using H₂O₂ catalytic oxidation with activated carbon.The recovered sulfuric acid can be reused to the original process directly or after distillation.Under the experimental conditions,at a temperature of 90 ?,H₂O₂ addition rate of 50 g·?kg waste acid?-1 per hour,and catalyst dosage of 0.2 wt%?waste acid weight?,COD was decreased from 220000 mg/L to 1000 mg/L and its removal efficiency was99.55%,the chrominance was decreased from 80000 times to 4 times and its removal efficiency was 99.99%,after reaction of 21 h.The dosage of H₂O₂ was 1.05 g/?g waste sulfuric acid?and its utilization ratio was 88.57%.The concentration of sulfuric acid after reaction was 70%,and the recovery ratio of sulfuric acid was over 95%.The operation costs was about 1123.57 yuan/?ton wastesulfuric acid?which was 50% lower than the market prices of treating waste acids as hazardous waste,and was 43.50% lower than thermal decomposition.And its investment cost was only 15% of thermal decomposition.This method is suitable for most small and medium-sized businesses whose productions of waste sulfuric acid are about hundreds to thousands tons because of its simple device and low cost.The research on reaction kinetics showed that the reaction kinetics of H₂O₂ catalytic oxidation with activated carbon confirmed to the first-order reaction.The first-order kinetics equation was described as follows when catalyst dosage was equal or great than 1:500:-dC/dt=8.28×10^-5exp?-2502/T?C?H₂O₂?₀¹.99...