Dyes wastewater treatment by reduction-oxidation process in an electrochemical reactor packed with natural manganese mineral.

A novel technology which combined electrochemical process catalyzed by manganese mineral with electro-assisted coagulation process was proposed in this study. The mineralization of organic pollutant from simulated dye wastewater containing an azo dye Acid Red B (ARB) was experimentally investigated using this method. It was found that the manganese mineral could catalyze the electrochemical process dramatically. The TOC removal percentage of electrochemical treatment catalyzed by manganese mineral was 43.6% while the TOC removal percentage of the process using the manganese mineral alone and using the electrolysis alone were 9.3% and 20.8%, respectively. Moreover, it was found that combined electroxidation with electro-assisted coagulation process could more effectively eliminate ARB. After a period of 180 min electrooxidation and 300 min electroreduction, almost 66.9% of TOC was removed, and the dissolved Mn2+ could be effectivly removed. The effects of the order of oxidation and reduction, the proper ratio electrooxidation/reduction time, and current density on the removal efficiency were investigated in detail. In addition, a proposed mechanism of manganese-mineral-catalyzed electrooxidation-reduction process was discussed in this paper.

[Preparation of triolein-embedded CA membrane and its characteristics].

Triolein is successfully embedded into cellulose acetate (CA) by phase inversion. This prepared flat membrane can effectively remove trace lipophilic organic pollutants from water. Structure of hybrid membrane is mainly observed by scanning electron microscope (SEM). Triolein dispersion by mechanical rabbling and ultrasound are investigated. Ultrasound can more effectively strengthen triolein dispersion than mechanical rabbling. Effect of casting membrane temperature (room temperature, 0 degrees C) shows low temperature can help to forming smaller triolein droplets. In addition, interaction between triolein and CA belongs to physical mixing by the observation of FT-IR, accordingly triolein structure is not changed and adsorptive capacity for persistent organic pollutants is not affected. Triolein in hexane is analyzed by fluorometric measure. The results show that triolein is completely embedded into membrane, so it is impossible that triolein leaks into water in the process of the adsorption.

Double catholyte electrochemical approach for preparing ferrate-aluminum: a compound oxidant-coagulant for water purification.

Ferrate is an excellent water treatment agent for its multi-functions in oxidation, disinfection, coagulation and adsorption, but its coagulation ability depends on its dosage and is after its oxidation. This paper focuses on preparing a new kind of ferrate combined with alum to enhance its coagulation function for water purification. An effective electrolysis reactor was designed and employed in the test. Some key parameters in the process of electrolysis concerning the preparation efficiency, such as the current density, temperature and alkalinity were also investigated. The proper conditions for ferrate-alum preparation were determined. Under the condition of 5 V given voltage, 6 h electrolyzing interval, below 2% alum concentration (in weight), a combined liquid ferrate-alum products was successfully prepared, which contained 0.0294 mol/L FeO4(2-) and 0.0302 mol/L total soluble ferron with 2% Al2O3. There was no insoluble ferron produced by controlling an optimum electrochemical condition.