OZONOLYTIC DEGRADATION OF TETRACYCLINE ANTIBIOTIC: EFFECT OF PH

Abstract

In this study, ozonolytic degradation of protein synthesis inhibitor antibiotic tetracycline was evaluated. Effect of pH on ozonolytic degradation was studied at pH 3, 7, and 11, and the most efficient pH was determined to be 3. The results showed that more than 50% of the tetracycline was degraded within 10 min and it was completely removed after 40 min in all initial antibiotic concentrations. The degradation kinetic was well described by a pseudo first-order kinetic model. The first-order rate constant decreases with increasing of the initial antibiotic concentrations. The kinetic rate constants were determined between 0.128 and 0.091 min(-1). The total organic carbon (TOC) removal was monitored during ozonolytic antibiotic degradation (120 min). The percentage TOC removal after 120 min ozone treatment of tetracycline was determined to be 33, 28 and 28% at pH 3, 7 and 11, respectively. Disc diffusion technique was performed for antibacterial susceptibility testing. Inhibition zone diameter was decreased with ozone treatment. Inhibition zone was not determined for Escherichia coli K-12 (ATCC) after 10 min and for Bacillus subtilis (NRRL B-354) after 15 min ozone treatment at pH 3, 7 and 11. The inhibition zone of tetracycline on the Staphylococcus epidermidis (NRRL B-4268) was removed after 15 min ozone treatment at pH 7 and 11, however, after 20 min ozone treatment it was removed at pH 3.