| At present,a lot of textile wastewater treatment process using chemical or biochemical method,these methods can reach the emission requirements,but according to the current emissions standards,emissions will still have a certain amount of pollutants in textile wastewater,and the pollutant concentration in the water.It is a threat to water environment,Therefore it is necessary to advanced processing of these pollutants.This study intends to synthesize a kind of material as a dynamic membrane material to form a dynamic membrane in the dynamic membrane reactor which designed and developed by our research group for the advanced treatment of textile wastewater.By ultrasonic assisted chemical co-precipitation method,this study used silica,Fe3+,Fe2+and the precipitation synthesis magnetic silica in sodium hydroxide solution.By Field emission scanning electron microscope（SEM）,Field emission transmission electron microscope（TEM）,X-ray diffraction（XRD）,Automatic rapid specific surface and porosity analyzer（BET）,Vibrating sample magnetometer（VSM）,Fourier infrared spectrum（FT-IR）,and X-ray photoelectron spectroscopy（XPS）characterization technique,to explore the magnetic silica morphology and the composition of physical properties and specific surface area and pore diameter size.The adsorption kinetics and equilibrium of dye in aqueous solution and the removal effect and mechanism of textile wastewater were investigated by adsorption experiments.The main conclusions of this study are as follows:（1）Magnetic silica was successfully prepared by ultrasound-assisted chemical co-precipitation method.The nano-structure on the magnetic silica was found to be within the range of 10-20nm by Field emission transmission electron microscopy,and through various characterization techniques proving the magnetic nanoparticles were Fe3O4.The adsorption-desorption isotherm of magnetic silica is a typical type IV isotherm.The specific surface area of magnetic silica is 309.1m2/g,and the pore diameter is mainly distributed at 5-23 nm,which belongs to magnetic mesoporous materials.（2）Magnetic silica can efficiently remove cationic textile wastewater.pH value has a great influence on the removal of textile wastewater by magnetic silica.When the initial pH value is 3.0,the removal effect is poor.The removal mechanism of magnetic silica on cationic dyes is mainly electrostatic.The removal rate of textile wastewater can be kept higher after 5 times of pickling and desorption.（3）The removal ability of the synthesized magnetic silica on textile wastewater is significantly improved,because on the one hand,the specific surface area of the synthesized magnetic silica increases,which can provide more adsorption sites to adsorb dyes;on the other hand,the synthesized magnetic silica has synergistic adsorption effect on dyes.（4）Kinetic data fitting showed that the adsorption process of magnetic silica on cationic dyes was more in line with the Pseudo-second-order kinetic equation.At25℃,pH=7.0 under the condition of using Langmuir isothermal adsorption equation fitting,magnetic silica is obtained for the biggest monolayer adsorption of methylene blue and malachite green quantity respectively 115.2 mg/g and 151.5 mg/g.The adsorption of methylene blue is more in line with the Langmuir model,more accord with the Freundlich adsorption model of malachite green.Thermodynamic data in the delta△G<0,delta△S<0,and delta△H<0 analysis can be obtained magnetic silica adsorption of methylene blue adsorption process is exothermic spontaneous.（5）The magnetic silica slurry mixed with a certain amount of water into membrane.The membrane plasma input dynamic membrane formed in the dynamic membrane reactor,and then simulated textile wastewater treated with dynamic membrane reactor,got a great treatment of methylene blue wastewater.The removal efficiency can reach 100%in two hours,and the treatment effect of malachite green is no good as methylene blue,it may the adsorption of methylene blue is mainly uniform monolayer adsorption,adsorption of malachite green non-uniform surface adsorption. |
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