Electrodegradation of cyclophosphamide in artificial urine by combined methods.

The degradation of the chemotherapeutic drug cyclophosphamide in artificial urine was evaluated by Electrochemical Advanced Oxidation Processes (EAOP). The system consisted of an electrochemical flow reactor with a commercial DSA® electrode (nominal composition Ti / Ru0,3Ti0,7O2) and Ti-mesh cathode. In order to assess the best parameters, the effect of current density, time and flow rate were analyzed using an initial 23 factorial design. The chosen response variable was the energy efficiency to produce free chlorine species (HClO/ClO-). After obtaining the most significant factors, the Central Composite Design (CCD) was performed, where the optimum conditions were determined for the current density range (11.714 mA cm-2 and 66.57 mA cm-2), flow rate (31.33 mL min-1) and time range (19 and 37 min). Under an optimized condition, the efficiency of other combined methods (photo-assisted electrochemical, photochemical, sonoelectrochemical and photo-assisted sonoelectrochemical) was evaluated. The efficiency of degradation processes was determined by removal of Chemical Oxygen Demand (COD), creatinine and urea. Analysis by HPLC demonstrates that the cyclophosphamide was substantially removed during the treatment process of ∼77%. Based on these results, it can be observed that the coupling between electrochemical and photochemical processes is a promising alternative for the treatment of this effluent, as a marked reduction of organic matter is observed (63, 94% of creatinine, 29.62% of urea, 39.1% of TOC) and a low treatment cost ratio.

Treatment of real dairy wastewater by electrolysis and photo-assisted electrolysis in presence of chlorides.

The efficiency of electrolysis (EC/Cl2) and photo-assisted electrolysis (EC/UV/Cl2) methods, in the presence of chloride, for the abatement of real dairy waste from a producer in the Triangulo Mineiro region of Brazil, was evaluated. A complete 23 factorial design was performed for the variables time, pH and current. After determining the ideal pH, a Central Compound Design (CCD) was performed, where the applied current (533.42 mA) and treatment time (60.45 minutes) were maximized. The effluent was subsequently submitted to prolonged EC/Cl2 and EC/UV/Cl2 treatment in order to evaluate the behaviour of specific environmental parameters over time. The EC/UV/Cl2 method was more efficient than simple EC/Cl2 treatment. The EC/UV/Cl2 method resulted in a reduction of all environmental parameters investigated to levels within legal standards for effluent discharge. A relatively low cost of treatment is obtained with Energy per Order (EEO) values of 0.89 and 1.22 kWh m-3 order-1 for the EC/UV/Cl2 and EC/Cl2 treatments, respectively. The electrochemical production of free chlorine species followed by subsequent photolysis and production of radical species can convert a simple electrochemical process into an advanced oxidation process (AOP).