This study aims to evaluate the degradation and mineralization of Malachite Green (MG) in an electro-Fenton process (EFP). We studied the influence of several important parameters including solution pH (2-11), current density (0-20 mA/cm 2), H 2 O 2 concentration (0-200 mg/L) and MG concentrations (200, 600, 1000, 1500, 2000, 3000 mg/L) at different reaction time (2.5-30 min). The intermediates produced during the degradation were determined by GC-MS. The optimum pH, current density and H 2 O 2 concentration were found to be approximately 3, 10 mA/cm 2 and 50 mg/L, respectively. It was concluded that acidic pH was required to increase the efficiency of the EFP. At optimum conditions and a reaction time of 15 min, MG was completely removed without any significant variation in the corresponding maximum wavelengths or new absorption bands. Due to formation of intermediates, almost all the organic compounds were completely mineralized (95.3%) to CO 2 and water at reaction time of 30 min. Results indicated the effect of hydroxyl radical (• OH) on MG degradation is greater than that of superoxide radical scavenger (O ⋅− 2). The results showed that the degradation process of MG followed pseudo-firstorder kinetic model and the treatment time required in EFP was 4.6 times lower than ECP. Furthermore, the results showed that EFP was an extremely efficient process for degradation and mineralization of a high concentration of MG (1000 mg/L) at a short reaction time (30 min).
This study investigated the performance of UVC/H 2 O 2 and UVC processes for the degradation and mineralization of ceftriaxone as an antibiotic. The highest ceftriaxone degradation was obtained at a solution pH of 5 and H 2 O 2 concentration of 10 mg/L. The apparent rate constant of ceftriaxone degradation was found to be 0.0302, 0.0165, and 0.0065 min −1 in the UVC/H 2 O 2 process for the initial ceftriaxone concentrations of 5, 10, and 20 mg/L, respectively. Degradation and mineralization efficiencies of ceftriaxone was obtained to be 100% and 58%, respectively, in UVC/H 2 O 2 process at reaction time of 120 min, whereas only 61% and 2.5% of ceftriaxone could be degraded and mineralized by UVC. The synergistic effect of UVC/H 2 O 2 was found to be 35%. The presence of anionic species improved the photolysis efficiency which degraded ceftriaxone from 61 to 83%, while, in the UVC/H 2 O 2 process, ability degradation declined from 100 to 70%. The efficiency of UVC/H 2 O 2 and UVC process was not greatly affected in real tap water. Besides, the reduction patterns in the UVC/H 2 O 2 and UVC processes were better described by pseudo-first-and second-order kinetics model with a reaction rate constant of 0.0165 and 0.0012 min −1 , respectively. The rate constant of ceftriaxone degradation in the UVC/H 2 O 2 process and at the presence of radical scavenger was found to be around 3.3 times lower than the one in its absence.
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