Degradation Of Pollutants In Wood Dyeing Wastewater With Oxidation Technology Based On Peroxide

Wood dyeing belongs to wood chemical processing category,a large amount of waste water generated in the production process has become one of the main pollution source of the wood processing industry waste water,the waste water containing dyes,wood extractives and other pollutants,high chemical oxygen demand,chroma large,composition is very complex,these organic pollutants with carcinogenic,teratogenic,mutagenic effects,threatening human health and ecological environment.Therefore,it is urgent to solve the problem that wood dyeing waste water must be treated to meet the standards before discharged.Advanced oxidation technology based on peroxide treatment has many advantages,such as strong oxidation ability,no selectivity,fast reaction speed,good treatment effect and so on.It is a common oxidation technology in wood processing waste water treatment,however,it is rarely used in the treatment of wood dyeing waste water.Fe²⁺ catalyzed H₂O₂ production · OH and thermal activated Na₂S₂O₈ production SO₄^-· can be used for fast oxidation degradation of organic pollutants in wastewater.Therefore,in this study,two kinds of different free radicals were used to study the oxidation degradation process of wood reactive dye wastewater.With the help of UV-Vis,HPLC,FTIR and,Raman spectra and other means,in-depth analysis of the degradation mechanism of dyeing wastewater produced by activated Na2S28 SO₄^-· oxidation of reactive dyes on wood.The following research work has been carried out:?1?Study the activation of H₂O₂ oxidation wastewater by Fe²⁺.The results showed that the order of influencing factors from large to small was pH value>oxidant H₂O₂ dosage>reaction temperature>reaction time>FeSO4 · 7H2O concentration.In the orthogonal experiment,the optimal process conditions were 30%H₂O₂ concentration is7.5ml/L,FeSO₄·7H₂O is 0.9g/L,initial pH value of 2.5,reaction temperature was 50 ?,and reaction time was 80min.Under this optimized conditions,the removal rates of COrCrand chroma were 90.5%and 99.99%.?2?Study the activation of Na₂S₂O₈ oxidation wastewater by thermal.The results showed that the removal rate of CODcr increased with the increase of temperature,Na₂S₂O₈ dosage and the extension of reaction time,and the CODcr removal rate was up to 90?,50g/L and stay unchanged 150min later.The initial pH value had no significant effect on CODCr removal rate.The optimized process conditions were the reaction temperature was 90?,the dosage of Na₂S₂O₈ was 50g/L,the reaction time was 150min,the initial pH was not adjusted.Under the condition of the treatment,the CODCr removal rate was up to 91.06%.?3?To further optimize the activation of Na₂S₂O₈ oxidation wastewater by thermal treatment process using response surface analysis,the optimal process parameters are determined as the reaction temperature is 90?,the Na₂S₂O₈ dosage is 51.3g/L,the reaction time is 2.00h,and the initial pH is not adjusted.After treatment,the average removal rate of CODCr was 98.36%,the average removal rate of TN was about 89.33%,and the average removal rate of aniline was about 95.64%.?4?Adapting UV-Vis spectroscopy,HPLC,IR spectra and Raman spectra to analyze the changing of functional groups in wood dyeing waste water,the results show that the thermal activation of Na₂S₂O₈ produces SO₄^-·,which makes the-N=N-of the conjugated chromophore in the reactive dye molecules in the dyeing waste water break and break down into a colorless,small molecular substance.At the same time,benzene ring and naphthalene ring generate ring opening reaction,So make the dye waste water decolorization,And the degradation rate of naphthalene ring was higher than that of benzene ring..The degradation rate of-N=N-bond was in accord with the first-order kinetic equation.The rate constant is 0.033 min-1,and the activation energy of Ea is about 29.22kJ/mol.