Oxidation Treatment Of Dye Wastewater By H₂O₂ Catalyzed By Activated Carbon In Fixed Bed

The quality of dyestuff wastewater has become very complex,resulting in a large amount of dye wastewater,serious pollution and difficult to deal with.At the same time,China's environmental awareness has been continuously strengthened,and the regulations and standards promulgated for printing and dyeing wastewater discharge become more stringent.Therefore,the research of effective printing and dyeing wastewater treatment technology is the future trend.Activated carbon as a commonly used adsorbent in industry,its catalytic performance is often neglected before.Activated carbon as a catalyst can combine activated carbon adsorption and catalytic ability.The active substances produced by advanced oxidation have good degradation effect on refractory organic matters,and have potential in solving the problem of self regeneration of activated carbon.By using granular activated carbon in a continuous flow fixed bed reactor to catalyze H₂O₂ degradation of simulated dye wastewater X-3B,the effect of catalytic performance of activated carbon on the degradation of pollutants and the feasibility of in situ regeneration of activated carbon by advanced oxidation technology were investigated.And elucidate the effect of enrichment of pollutants on the surface of activated carbon.The H₂O₂ degradation and catalytic performance of activated carbon combined with pyrite are studied.Fe²⁺is also introduced into GAC/H₂O₂ system to explore synergies.Through the analysis of the parameters of the catalytic oxidation reaction,the decolorization rate,COD removal rate and iron ion concentration of the dye wastewater were investigated.The catalytic mechanism of the activated carbon/H₂O₂ system and the combined system was initially discussed to provide technical support for the practical industrial application of activated carbon.The results obtained in this study are as follows:?1?when the H₂O₂ concentration of activated carbon/H₂O₂ system increases,the decolorization effect increases.Under the acid condition,the degradation effect is better.Acidified activated carbon can remove alkaline ash from activated carbon and maintain pH of effluent 3⁴.?2?the adsorption of pollutants on the surface of activated carbon has a negative effect on H₂O₂.The attached pollutants change the surface properties,occupy the active sites of activated carbon,and the continuous catalytic capability of GACs/H₂O₂ system is lower than that of GACn/H₂O₂ system.?3?through the analysis of the spectra of the dye reaction,a new absorption peak was found,indicating the production of the intermediate product;the methanol quenching experiment showed that the main active substance was OH.Titration results from Boehm showed that carboxyl groups increased after reaction,and the other groups remained unchanged.?4?the decolorization effect of pyrite/H₂O₂ system decreases with time,and finally maintains between 25%⁴0%.The change trend of COD removal rate is basically the same as that of decolorization.At the beginning,the dissolution of Fe²⁺reached 1175 mg/L^-1,and then decreased rapidly.When Fe²⁺was used repeatedly,the dissolution rate was also maintained at a low level.The concentration of iron ion in mineral dissolution is positively correlated with the rate of catalytic degradation.?5?when the volume ratio of activated carbon and pyrite is 2:1?V[AC]:V[pytire]=2:1?,the decolorization effect of the first reaction is better,and the decolorization rate drops to 56.5%at the end of the fourth reaction.The change trend of COD removal rate is basically the same as that of dye decolorization.Compared with pyrite alone,the removal efficiency increased slightly,but the sustained catalytic performance did not improve significantly.?6?according to n(Fe²⁺):n?H₂O₂?equal to 1:20,added to the system with activated carbon combined dynamic oxidation reaction.After 4 times of reuse,the decolorization rate is still 99.65%,the COD removal rate is 70.55%,and the TOC removal rate is 76.28%.It indicates that there is a synergistic catalytic effect of H₂O₂between activated carbon and ferrous sulfate.It is speculated that there are several processes in the reaction process:adsorption?synergistic catalytic oxidation?desorption?readsorption.