An investigation on the removal of tramadol analgesic in deionized water and final wastewater effluent using a novel continuous flow dielectric barrier discharge reactor

Abstract

In this study, the degradation of tramadol (TRA) was studied for the first time in deionized water (D⋅I) and final wastewater effluent (FWWE) using a dielectric barrier discharge reactor operated in a continuous flow mode. Initially, the reactor was optimized for voltage and initial concentration conditions. After 60 min treatment, the degradation efficiency of TRA was 93 % in D⋅I and only 27 % in FWWE. Also, the pseudo-first-order rate constant in D⋅I (0.056 min 1) was an order of magnitude higher than the FWWE (0.0056 min 1). To understand the reasons for this disparity, experiments were conducted to investigate the impact of conductivity, pH, and certain natural radical scavengers present in the wastewater. The results revealed that the rate of degradation and kinetics of TRA in the presence of HCO3 was comparable to those observed in FWWE due to the scavenging of the ●OH radicals. Meanwhile, Fenton reaction with TRA was confirmed with the synthetic solution based on the increased production of H2O2. Toxicity tests showed that the treated TRA solution did not inhibit the growth of Escherichia coli as opposed to the untreated solution.