COMPARATIVE STUDY OF OXIDATIVE DEGRADATION OF TETRACYCLINE IN AQUEOUS SOLUTION BY Fe~(2+)/Na_2S_2O_8 AND Fe~0/Na_2S_2O_8 PROCESS

摘要

Comparative experimental studies were conducted to investigate the oxidative degradation of tetracycline (TC), one of the most frequently detected pharmaceuticals in waters, by Fe~(2+)/Na_2S_2O_8 and Fe~0/Na_2S_2O_8 process. Results showed that the removal efficiencies of TC in Fe~0/Na_2S_2O_8 system were higher than those in Fe~(2+)/Na_2S_2O_8 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 (Fe~(2+) and Fe~0) dosages. Results showed that 0.1 mmol ?L~(-1) was the best amount of Fe~(2+) and Fe~0, 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 Fe~(2+)/Na_2S_2O_8 and Fe~0/Na_2S_2O_8 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 Fe~0/Na_2S_2O_8 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 Fe~(2+)/Na_2S_2O_8 system, the removals of TC increased from 25.7% to 52.7% under same reaction conditions.