Study on Treating Stench Wastewater Containing Dodecyl Mercaptan by Electrolyzing Sodium Sulfate Solution
This paper suggests a technological process to oxidize stench sulfide wastewater containing dodecyl mercaptan with electrolyzing Na2SO4 in the presence of active carbon. Preliminary experiments were conducted and good results were obtained. Under the condition that electrolyzing 1%(m/V)Na2SO4 with 1A current and the reaction temperature remains 30 and the reaction time lasts 10 ~ 30 s, the stench dodecyl mercaptan was eliminated.
Electrochemical Destruction of Aniline and 4‐Chloroaniline for Wastewater Treatment Using a Carbon‐PTFE O 2 ‐ Fed Cathode
The electrochemical degradation of 100 ppm aniline and 4-chloroaniline in basic aqueous solutions of pH ranging between 10.1 and 12.7 has been studied at constant current intensity using a Pb/PbO{sub 2} anode and a carbon-polytetrafluoroethylene O{sub 2}-fed cathode. Under these conditions, hydrogen peroxide was electrogenerated in the cell via a two-electron reduction of oxygen gas fed to the cathode. The current efficiency for H{sub 2}O{sub 2} generation depended on the applied current intensity and the background electrolyte used. The concentration decay for each contaminant with electrolysis time was followed by high pressure liquid chromatography (HPLC). Kinetic analysis of these data showed a pseudo first-order decomposition reaction for both substrates at anodic current densities of 30 mA cm{sup {minus}2} or higher, as well as a decrease, of their half-lifetimes when current intensity increased. A gradual decrease in total organic carbon (TOC) for 0.05 mol/dm{sup 3} NAOH solutions with electrolysis time was always found. Product analysis of these electrolyzed solutions by gas chromatography-mass spectroscopy (GC-MS) and HPLC allowed the detection of nitrobenzene and 1-chloro-4-nitrobenzene proceeding from the anodic decomposition of aniline and 4-chloroaniline, respectively. Maleic acid was also detected as intermediate and ammonia was found as final product. Destruction of initial pollutantsmore » and intermediates is explained by their oxidative reactions with OH and HO{sub 2} radicals at the anode reaction layer. The effect of HO{sub 2} upon decomposition pathways of anilines is discussed.« less
Electrochemical production of NH2• radicals by the system Cu2+/VO2+/NH2OH and their reactions with benzene and toluene
Abstract Electroinitiated production of NH2. radicals was demonstrated to occur in aqueous acid solution when in the system Cu2+/VO2+/NH2OH Cu2+ is reduced to metallic copper on a mercury cathode. The first stage of this process involves the reduction of vanadyl to V3+ by metallic copper. The electrochemical system Cu2+/VO2+ was demonstrated to follow a depolarization scheme of the type of the catalyzed electrode process. For the reaction Cu+2 VO2+k1 → Cu2++2 V3+ a k1 value of 32 M−1 s−1 at 50°C was calculated. The second stage of the process is the reduction of NH2OH by V3+ to give aminyl radicals. In presence of benzene and toluene these radicals add to the aromatic ring to give new radicals which are oxidized by Cu2+ to the corresponding amines. The cuzrent yield of this process attains values as high as 70%. The yield dependence on H2SO4 concentration, electrolytic current and dioxane concentration is discussed.