Microwave assisted catalytic wet air oxidation of H-acid in aqueous solution under the atmospheric pressure using activated carbon as catalyst.
Catalytic wet air oxidation (CWAO) is a promising method for the treatment of heavily contaminated wastewater. However, its application is restricted due to severe operation conditions (high pressure and high temperature). A microwave (MW) assisted oxidation method was investigated aiming to treat heavily contaminated wastewater under milder conditions. H-acid (1-amino-8-naphthol-3, 6-disulfonic acid) was selected as target compound to evaluate the performance of this novel process. The removal of H-acid and TOC (total organic carbon) for H-acid solution of 3000 mg/L reached as high as 92.6% in 20 min and 84.2% in 60 min, respectively under optimal conditions. The existence of activated carbon and oxygen proved to be critical for effective treatment. The activated carbon acted not only as a catalyst for H-acid decomposition, but also as a special material for the absorption of MW energy. Air was supplied to the reactor as an oxygen source at constant flows. The amino group in H-acid was converted ultimately into nitrate, and sulfonic group into sulfate. This observation gave an evidence of H-acid mineralization although other organic intermediates were unable to be determined. The value of BOD(5)/COD (ratio of 5d biochemical oxygen demand to chemical oxygen demand) increased from 0.008 to 0.467 indicating a significant improvement of biodegradability for the solution, which is beneficial for the further biological treatment of the wastewater.
Zhang
Yaobin
Y
School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, China.
Quan
Xie
X
Chen
Shuo
S
Zhao
Yazhi
Y
Yang
Fenglin
F
D000143:Acids; D001274:Atmospheric Pressure; D001673:Biodegradation, Environmental; D019149:Bioreactors; D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D008872:Microwaves; D009282:Naphthalenesulfonates / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D018508:Water Purification / Q000379:methods*
D000143:Acids; D007220:Industrial Waste; D009282:Naphthalenesulfonates; C450879:1-naphthol-8-amino-3,6-disulfonic acid; D002244:Carbon; D010100:Oxygen