COMPARATIVE STUDY OF OXIDATIVE DEGRADATION OF TETRACYCLINE IN AQUEOUS SOLUTION BY Fe2+/Na2S2O8 AND Fe0/Na2S2O8 PROCESS

Comparative experimental studies were conducted to investigate the oxidative degradation of tetracycline (TC), one of the most frequently detected pharmaceuticals in waters, by Fe2+Na2S2O8 andFe0/Na2S2O8 process. Results showed that theremoval efficiencies of TC in Fe0/Na2S2O8 system were higher than those in Fe2+/Na2S2O8 system in certain adding dosage of activator, concentration of persulfate (PS), temperature, pH and initial concentration of TC. The TC removal increased with the increments of PS concentration, temperature and the initial concentration of TC in the two systems. However, the rise of pH caused a negative effect on the performance of TC degradation. In addition, TC removal increased and then decreased with the increment of initial activator (Fe2+ and Fe0) dosages. Results showed that 0.1 mmol·L-1 was the best amount of Fe2+ and Fe0, where the removals of TC could reach to 87.6% and 91.8% respectively. When the concentration of PS was 2.0 mmol·L-1 , the removals of TC in Fe2+/Na2S2O8 and Fe0/Na2S2O8 system could reach 59.0% and 77. 7%, respectively. The TC degradation followed a first-order kinetics pattern and acidic circumstance favored the degradation of TC in the two systems. For Fe0/Na2S2O8 system, the removals of TC were high, increased from 75.3% to 79.9% corresponding of TC initial concentrations from 30 to 100 mg ·L-1 However, for Fe2+/Na2S2O8 system, the removals of TC increased from 25.7% to 52.7% under same reaction conditions.