THE RATE CONSTANTS KOH+S WITH SOME ANTIBIOTICS DETERMINATION BY THE COMPETETIVE INHIBITORS METHOD
Tatiana ISAC-GUŢUL, Elena TUTOVAN, Denis NICA Universitatea de Stat din Moldova
Abstract
Advanced oxidation processes (AOP) are widely used for the degradation of antibiotics and other micropollutants
in surface and waste waters. The degree of degradation of a drug by an AOP can be predicted from the rate constant of the interaction of hydroxyl radicals with the substrate - kOH+S value, as well as from other physicochemical properties accompanying the degradation processes, and therefore these factors are important for the design of technological schemes of treatment of polluted water. Moreover, a substrate with kOH+S value known can be used to evaluate the applicability and efficiency of AOP and elucidate the kinetics and degradation mechanism of the given pollutant.
In this work, the rate of the oxidation of N,N-Dimethyl-p-nitrosoaniline (PNDMA) during the photolysis of hydrogen peroxide in distilled water and in the presence of different amounts of polluted water (aqueous solutions containing sulfonamides – acetazolamide (AC) and phthalylsulfathiazole (FL), fluoroquinilones - moxifloxacin (MOX) and ciprofloxacin (CPF) as pollutants) in the UV - H2O2 systems was studied. The concentration of the drugs varied between 2.5 mg/L and 25 mg/L. The ,,ДРТ-1000” high-pressure mercury vapor lamp as the irradiation source was used. Using competitive acceptors method and based on the kinetic curves, the interaction constants of •OH radicals with the mentioned drugs were determined: kOH+AC = 8.5 ×109 L/mol×s; kOH+FL = 8.5×109 L/mol×s; kOH+MOX = 1.42×109 L/mol×s; kOH+CPF = 6.3×109 L/mol×s and the inhibiting capacity of natural waters Σ ki[Si] in the self- purification process in the model systems used. The calculated values of the respective constants are varies between (5.4-17.7)×106 s-1.
Keywords: AOP, photolysis, UV/H2O2 process, •OH radicals rate constants, specific inhibitors.
