Sponge Iron Reduction Coupled With GAC Adsorption And Microwave Regeneration For The Elimination Of Dyes Wastewater

With the rapid development of dyestuff industry, the environment pollution taken by dyewastewater has stepped up in the meanwhile. It has high chromaticity, strong toxicity anddifficulty to degrade. It has caused people‵s wide attention. Aimming at these problems, thisthesis summarizes the sort feature of printing and dyeing wastewater and their hamrs toenvironment, introduces the treatment methods of printing and dyeing wastewater and theirevolvements，and analyzes advantages and disadvantages of different methods respectively.In the present paper is systematically researched the removal effieiency and effects ofriphenylmethane dyes and azo dyes by sponge iron. The kineties of d yes removal by spongeiron was also analyzed. Through Scanning electron microscope, high-resolution transmissionelectron microscopy, X-ray diffraction, X-ray photoelectron spectra, and BET method, thesurface characteristics and chemistry of sponge iron in reaction system were analyzed.Toexplore triphenylmethane dyes decolorizing mechanism by sponge iron (s-Fe~0) reductionunder ultrasound condition, Moreover, in view of TOC, toxicity and iron ion concentration ofdye wastewater after decoloring is still higher, the treated solution was further treated by GACadsorption coupled with MW-based regeneration. Investigated the variation of GACadsorption capacity before and after microwave radiationFor this research, five typical cationic triphenylmethane dyes(BG、MG、CV、EV and RhB)and one azo dye (MO) have been chosen for model wastewater dyes, and investigated theeffects of s-Fe~0dosage, particle size, dyes concentration and ultrasonic power on theelimination process. The results showed that (1) sponge iron has good effect on decolorizationof BG、MG、CV and EV, and has poor effect on decolorization of RhB. For example, thedecolorization rate of BG, MG, CV and EV was more than90%after2h treatment with theparticle size of s-Fe~0as1～3mm and the dosage as30g/L, the initial concentration as20mg/L and with the ultrasonic power as200w. However, the RhB decolorization rate lessthan20%;(2)In order to effective degradation of RhB, this paper further modified the spongeiron with metal copper to obtain s-Fe~0-Cu bimetallic particles. The experiment resultsdemonstrated that s-Fe~0-Cu bimetallic particles can significantly improve the decolorizationrate of RhB. For example, the decolorization rate of RhB was more than90%after1htreatment with s-Fe~0-Cu bimetallic particles, and the dosage as20g/L, Cu loading5%, theinitial concentration as20mg/L, pH=4.0and with the ultrasonic power as200w.(3)Spongeiron also has the very good decoloring effect of MO. When5g/L of sponge iron, dyeconcentration100mg/L, after1h, and with the ultrasonic power as200w decoloration rate canreach90%. Moreover, the treated solution was further treated by GAC adsorption coupled withMW-based regeneration (800W,1min). The results indicated that the GAC-based adsorptionsuccessfully eliminated biotoxicity and total organic carbon (TOC), as well as the residuedyes of the treated solution. Furthermore, MW radiation could effectively regenerate the spentGAC basically maintaining the BET area, pore volume and pore size of GAC, andregenerative effect is good.Accordingly, it was feasible to effectively, rapidly and thorough removaltriphenylmethane dyes(BG、MG、CV、EV and RhB) and one azo dye (MO) solution over s-Fe~0(or s-Fe~0-Cu) combined with GAC adsorption and microwave regeneration process, Effective,rapid and thorough removal, and there is a very good application prospect.