Preparation Of Chitosan Based Membrane And Its Application In Printing And Dyeing Wastewater Treatment

Printing and dyeing wastewater,as a kind of wastewater which is not easy to treat,usually has deep color,high content of toxic pollutants and great harm.Azo dyes are widely used because of their carcinogenic precursors and their degradation products-aromatic amines,the decolorization of azo dyes has attracted much attention.Acid black 10 B and Congo red,as important dark diazo dyes,are widely used in the dyeing of natural and man-made materials because of their stable physical and chemical properties.However,the molecular structures of these two dyes contain aromatic rings,which are difficult to degrade in the water environment,and have "three hazards" to organisms.Therefore,acid black 10 B and Congo red are selected as special dyes to study the treatment of the dyes.Chitosan is a kind of natural alkaline polysaccharide with wide sources and abundant reserves in nature.It is non-toxic,harmless and no secondary pollution.Its special physical and chemical properties give it high adsorption capacity.As powder chitosan is used as adsorbent,it is easy to be lost after adsorption and difficult to be recycled.Considering the excellent film-forming properties of chitosan,different chitosan based membrane materials were prepared to study the treatment effects of typical bisazo dyes acid black 10 B and Congo red,and the mechanism was analyzed.In addition,the treatment effects of eight different adsorption materials on simulated wastewater and actual printing and dyeing wastewater were compared.The main contents of this project are as follows:(1)Single factor experiments were carried out to investigate the effects of experimental factors on the adsorption performance of four different chitosan based membranes for acid black 10 B and Congo red.The adsorption model was used to fit and the mechanism was analyzed combined with relevant characterization.(2)The optimal preparation conditions of chitosan polyaluminum chloride zeolite composite membrane and the interaction between operation parameters were investigated by orthogonal test and response surface method.The adsorption performance of the membrane was investigated by using D-optimal search function in Minitab software.(3)The reuse and regeneration effect of ternary composite membrane and the feasibility of using it to treat actual printing and dyeing wastewater were discussed.The adsorption effects of different adsorption materials on acid black 10 B and Congo red simulated wastewater and actual printing and dyeing wastewater were compared.The main conclusions are as follows:(1)The optimal preparation conditions of chitosan polyaluminum chloride composite membrane were as follows: the dosage of 3.2 g/L polyaluminum chloride solution was 4 m L,the reaction temperature was30 ?,the curing time of membrane solution was 24 h,the drying temperature of membrane solution was 75 ?,the drying temperature of membrane solution was 35 ? after washing with deionized water,and the film removal solution was 2.5 mol/L Na OH.The results showed that the optimal preparation conditions were as follows: the concentration of chitosan solution was 2%,the dosage of zeolite powder was 0.04 g(for acid black 10B)and 0.07 g(for Congo red),the optimal preparation parameters were as follows: 0.05 g and 0.08 g of zeolite powder,4 m L and 5 m L for 3.2 g/L polyaluminum chloride solution,reaction temperature was 30 ?,membrane solution curing time was 24 h.(2)The Langmuir model can be used to describe the adsorption behavior of four kinds of membrane materials for acid black 10 B and Congo red,and the adsorption of acid black 10 B and Congo red can be spontaneous;The quasi second order kinetic model can describe the adsorption process of four kinds of membrane materials for acid black10 B and Congo red,and the adsorption is a chemical speed controlling step.(3)There is a synergistic effect among chitosan,zeolite powder and polyaluminum chloride in the ternary composite membrane,and the ternary composite membrane has good treatment effect on Congo red and acid black 10 B in simulated wastewater and actual printing and dyeing wastewater,and can be regenerated and reused for many times.(4)For acid black 10 B,when the temperature was 63?,the initial concentration was 2807.44 mg/L,and the time was 339.5682 min,the maximum theoretical adsorption capacity was 5337.6644 mg/g;When the temperature was 58?,the initial concentration was 2807.44 mg/L,and the time was 405.3425 min,the maximum theoretical adsorption capacity of Congo red was 2534.29 mg/g.(5)After four cycles of adsorption,desorption and regeneration,the chitosan polyaluminum chloride zeolite composite membrane can still adsorb acid black 10 B and Congo red wastewater.