Degradation Of Reactive Red X-3B With Persulfate Activated By Modified Activated Carbon

Azo dye wastewater has increased attention on the decolorization of dyes solution due to many characteristics, such as high COD,high colority and weak biodegradability. Activated carbon adsorption technology can deal with dye wasterwater, but the physical method can’t degradate pollutants thoroughly which just transmit from the acqeous to the supersurface by non-mineralization. In addition the saturated AC requires regeneration to use. AC/peroxide(hydrogen peroxide and peroxymonosulfate)combined system which can generate·OHand SO4·to degradate organic pollutants and regenerate AC in situ.SPS as a kind of peroxide can be activated by transition ion, alkali,light and heat etc. However, using cheap AC to activate SPS is few studied. From this, the paper carried the following research from two aspects.1)Make surface chemical modification of coconut shell AC.Study the changes of activated AC ability before and after the preparation. Modified granular activated carbon was synthesized with citrate, ferric nitrate, Na2S2O3 and HN03 via a impregnation, reduction-oxidation of aqueous-phase synthesis method treatment. The prepared efficient activated carbon catalyst is researched in the subject of the reactive red X-3B for the catalytic capability to the persulfate.Find that the absorption rate and degradation rate of unmodified GAC is relatively 13% and 70%,whereas those of the modified GAC is relatively 5% and 95%.2) Researsh the law of decomposition of the reactive red X-3B persulfate according to persulfate catalyzed by modified coconut shell GAC.Furthermore make a preliminary analysis of the reaction kinetics and reaction mechanisms.At the same time study the reuse of the catalyst in order to application.The research is carried from the following six aspects,initial pH,initial dye concentration,initial SPS concentration,catalyst dosage,temperature and reuse of catalyst.The results show that in the situation of the temperature 25 ℃, ambient pH and the initial dye concentration 200mg/L, the optimal SPS concentration is 0.042mol/L (corresponding to 19:1 at PS/reactive red X-3B molar ratio).Then the degradation rate of reactive red X-3B is highest.The results for reusability of the catalyst are shown that the efficiencies of reactive red X-3B removal for each reusing time gradually decreased. At the reaction time of 3 h, the final reactive red X-3B removal rate was decreased to 93%、91%、 87%、81%、72% of catalyst 1st,2nd,3rd,4th and 5th use,respectively. Compared to 95%(OG removal rate) of the first use,the catalyst capacity of the modified GAC reduced littlely. The oxidative processes were fitted for first order reaction kinetics: lnCt=lnC0-kt.