Degradation Of Dye Wastewater With Persulfate Catalyzed By Tourmaline

Large amounts of discharged dye wastewater have caused serious water pollution, and brought great threaten to the environment and human security. Azo dyes are most widely applied among them. Due to the characteristics of high chemical oxygen demand and degradation-resistant, azo dyes have attracted many researchers’ focus. Tourmaline, as a kind of very beneficial minerals to the environment has been widely used in pollutants removal, and the common methods to utilize the tourmaline are adsorption and advanced oxidation process.The p HZPC of tourmaline is 6.17, and the surface of tourmaline is full of pores structures. Fe2+ and Fe3+ are easily dissolved out in acidic aqueous, this characteristic provides possibility for tourmaline being a catalyst in advanced oxidation process. The tourmaline in this article was analyzed by XPS and the ratio of Fe(II) and Fe(III) was found to be 50.47%:49.53%. According to the XRD analysis of tourmaline, the crystal structural formula of tourmaline is Na Fe3Al6[Si6O18][BO3]3(OH)4.According to the kinetic analysis of following systems: TM only、PS only、PS/US、TM/PS、TM/PS/US-10 min,we found that they were belonged to second order kinetics reaction. Ultrasound can promote the degradation of dye waste water, the removal rate can be up to 92%. Compared with different catalyst utilized in Direct Red 23 degradation by persulfate under ultrasound and no ultrasound conditions respectively, tourmaline had more advantages because of its high removal rate and easily obtained. Meanwhile, according to measuring the content of Fe2+ in different systems, we found that the content of Fe2+ is consistent with the removal efficiency by catalyst. The systems of TM/PS and TM/PS/US-10 min were respectively applied for the degradation of three dyes waste water, and the results show that the catalytic oxidation method with tourmaline has applicability in different dyes wastewater. According to the study of the effect of different inorganic salt ions on DR23 degradation, we found that the influence degree of the reaction of the inorganic salt as Na Cl O4≈Na NO3< Na2SO4<Na Cl<Na2HPO4. From above on we know that Na2HPO4 affect the degradation greatest, some reports have suggested that HPO42- can consume the amount of SO4-·. The time and power can affect the catalytic oxidation efficiency of DR23 degradation by tourmaline. Tourmaline catalyzes persulfate to oxidate DR23 can not only decolorization of the dye wastewater, but also remove the COD and ADMI of the dye wastewater. The results of the study suggested the removal of COD in different three dye waste water could be up to over 90%. According to the study of wavelength scan conducted during the process of DR23 degradation, the absorption peaks at 504 nm and 310 nm gradually varies from steep to slow, the height of the peak become lower, this is because the –N=N- group of the azo dye at 504 nm and the benzene ring linking to-N=N- group were damaged respectively.The regeneration test of tourmaline shows that tourmaline used in advanced oxidation experiments is reusable. As the increase of tourmaline reused times, the efficiency of DR23 oxidative degradation decreased. When the tourmaline was reutilized four times, the degradation efficiency of DR23 was 43%.