Degradation Of Dye Wastewater With Permonosulfate Activated By Activated Carbon

Dye wastewater has increased attention on the decolorization of dyes solution due tomany characteristics, such as high COD and high colority. Activated carbon adsorptiontechnology can deal with dye wasterwater, but the physical method can’t degradatepollutants thoroughly and the saturated AC requires regeneration to use. AC/peroxide（hydrogen peroxide and persulfate） combined system which can generate·OH and SO₄^-todegradate organic pollutants and regenerate AC in situ. PMS as a kind of peroxide can beactivated by cobalt ion, alkali. However, using cheap AC to activated PMS is still limited.From this, the paper carried the following research from three aspects.1)Study activation ability of three different types of activated carbon, We choosecoconut shell AC to make further research. Results show that, after two hours, theAC/PMS combined system can degradation20ppm organge G, the discoloration rate canreach90%. At the same time, some inorganic ions which were presence in the dyewastewater for organge G degradation were examined in batch experiments. It wasspeculated that Cl-and CO₃^2-can enhance the reaction to some extent, the effect of NO3-and HPO₄^2-was not obervious, and SO₄^2-would inhibit the degradation of organge G.2) Research the effect of AC diameter and surface groups for AC activation. Thediameter of AC which was milled and sieved decreased from2mm to0.355mm. Theresults proved that after treatment AC can improve adsorption and degradation efficiencysignificantly. It is evident that AC oxidated with HNO3（AC₁） presents low adsorption andcatalytic activity while AC after thermal treated with N2（AC₂） show better adsorption andcatalytic activity. The textural of AC was obtained by BET, results revealed there were nomajor differences between AC₁and AC₂. And surface chemical properties of AC sampleswere characterized by many techniques, such as Bohem titration and FT-IR. The resultsshowed that compared to AC₂, AC₁had higher amount of surface oxygen-containinggroups. Taking these observations into consideration, The surface chemical properties of AC have essensial effect on catalyst activity.3) In addition, this work discussed mechanism of organge G degradation by AC/PMS.It speculated that the active species in the combined system is SO₄^-, which can producethrough PMS obtaining electrons. Therefore, to quantify the reducing sites we usedidometric titrations, observed that the concentration of reducing sites on the activatedcarbon surface was correlation with the reaction rate. As a result, the electrons transferfrom the surface of AC seems to be involved on the mechanism.