Experiments on the mineralization of oxytetracycline in aqueous solutions using UV/H 2 O 2 system were carried out. The mineralization process was monitored and measured as a function of total organic carbon (TOC) removal. Effect of five different water matrices on the mineralization efficiency, kinetics and the electrical energy per order was analyzed and reported. The present results showed that the percentage TOC removal, the rate constants and the electrical energy per order depend on the concentration of organics, inorganics and other impurities present in the water matrices. The value of electrical energy per order (EE/O) for the OTC mineralization is higher for more complex water matrices. Editorial responsibility: Binbin Huang.
Alkanolamines such as MEA, DEA, MDEA and DIPA in aqueous solutions is frequently used for scrubbing carbon dioxide from natural gas. High quantity of alkanolamine appears in the wastewater during cleaning and maintenance as well as shutdown of the absorption and desorption columns. The alkanolamines waste is toxic to the environment and this wastewater cannot be treated in the conventional wastewater treatment. Advanced Oxidation Process (AOP) named UV/H 2 O 2 is introduced to solve this problem. A laboratory set up of degradation MDEA waste using UV/H 2 O 2 was conducted and the degradation mechanism has been studied. Glycine, oxalic acid, acetic acid, nitrate ion, nitrite ion and ammonium ion are identified as degradation intermediate product.
The UV/H2O2 is one of the popular techniques in the advanced oxidation processes (AOPs) and has been applied in the wastewater treatment during recent two decades. UV exposure on the H2O2 generate highly reactive hydroxyl radicals (OH•), which are used to degrade organic contaminants through oxidation processes in wastewater. This present study involves the estimation of hydroxyl radical rate constants of methyldiethanolamine (MDEA) mineralization at different temperatures by using UV/H2O2 in aqueous solution. Laboratory experiments have been conducted and the profile of MDEA mineralization has been established. The hydroxyl radical rate constants and the activation energy of mineralization process have been calculated. The estimated hydroxyl rate constants and the activation energy are in good agreement with those reported in the literature.
Effluent containing high concentration of alkanolamine from a sweetening process of natural gas plant is commonly generated during maintaining, cleaning and scheduled inspection of the absorption and desorption column. The effluent is not readily biodegradable and cannot be treated in the conventional biological treatment. Advanced oxidation processes (AOPs) is a promising method for the treatment of recalcitrant organic contaminant. Most methods used are Fenton reagent, UV/Ozone and UV/H2O2. Based on the advantages of the UV/H2O2such as no formation of sludge during the treatment, high ability in production of hydroxyl radical and applicable in the wide range of pH, the UV/H2O2has been chosen to treat the effluent from refinery plant, which has high concentration of methyldietnaolamine (MDEA). The factors influencing in the degradation of refinery wastewater that contain MDEA were screened using response surface methodology (RSM). It was found that degradation process of the refinery effluent was highly dependent on oxidant concentration (H2O2) and initial pH. Temperature of oxidation process was found oppositely. Since the temperature gave insignificant effect on the TOC removal process, hence the independent factor temperature will be eliminated during the further optimization process condition of degradation. Thus, the optimization process condition of degradation will be more effective and simpler.
Oxytetracycline (OTC), a widely used antibiotic, was taken as the model contaminant to study the kinetic and thermodynamic parameters of mineralization using a UV/H2O2 system. Mineralization experiments were carried out at different initial OTC concentrations of 0.0156–0.0531 M, initial H2O2 concentrations of 0.043–0.116 M and at a temperature range of 20 − 50°C. The OTC mineralization process was monitored by measuring the total organic carbon as well as H2O2 consumption. The analysis of mineralization data showed two phases of mineralization: phase I: 0 ≤ t ≤ 30 min and phase II: 30 ≤ t ≤ 180 min. Based on this, the kinetic and thermodynamic parameters were established. The order of reaction obtained for organic C and H2O2 is 0.624 and 0.599 (phase I) and 0.954 and 0.062 (phase II), respectively. Based on this kinetic model, the OTC degradation rate constants were 0.0069 min−1 (phase I) and 0.0051 min−1 (phase II). The activation energy for phase I and phase II oxidation was 10.236 and 9.913 kJ mol−1, respectively. The estimated Δ#G and Δ#H values are positive, whereas negative Δ#S values were obtained.
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