Preparation Of SiO₂-based Composite Adsorbent From Yellow Phosphorus Slag And Its Copper Adsorption Performance

Yellow phosphorus slag--industrial waste produced in the process of producing yellow phosphorus by the electric furnace method at a high temperature of 1400?-1600?,in which the total content of SiO₂ and Ca O is more than 85%,and it can be used to prepare high value-added silicon and calcium products.Recycling the silica in the yellow phosphorous slag not only realizes the secondary utilization of resources,but also solves various problems such as waste of land resources and environmental pollution by the yellow phosphorous slag.In this thesis,yellow phosphorus slag was used as raw material to obtain a porous silica matrix through acid leaching.After chitosan modification,a SiO₂-based composite adsorbent(CS-SiO₂)was prepared for adsorpting Cu(?)in heavy metal wastewater.The adsorption performance of Cu(?)was taken as the main performance evaluation index,and its adsorption performance was studied.The structure and morphology of the SiO₂ matrix and CS-SiO₂ composite adsorbent were analyzed by infrared spectroscopy,scanning electron microscopy,X-ray diffraction,specific surface area and aperture analyzer,and laser particle size analyzer.Explored the optimal process conditions of the acid leaching,the compounding and adsorption process,and fitted its kinetic data with the pseudo-first and second-order kinetic equations,fitted the adsorption isotherm data with Langmuir adsorption isotherm model and Freundlich adsorption isotherm model.The results are as follows:(1)The optimal process conditions for the preparation of silica matrix material were:nitric acid concentration was 8%,liquid-to-solid ratio was 11:1,leaching time was 40min,leaching temperature was 30?,and rotational speed was 300r/min.The adsorption rate of the modified silica adsorbent prepared under the optimal technological conditions of the acid leaching process for Cu(?)in the simulated wastewater was 72.37%,and the adsorption capacity was 57.896mg/g.(2)The optimal process conditions for the preparation of CS-SiO₂ composite adsorbent were:the mass ratio was chitosan to silica is 1:5,the mass ratio of silica to acetic acid aqueous solution was 1:15,and the reaction time before adding Na OH was20min,the reaction time after adding Na OH was 20min,and the compounding temperature was 45?.The adsorption rate of Cu(?)in simulated wastewater by the silica modified adsorbent prepared under the optimal process conditions of the composite process was 94.78%,and the adsorption capacity was 75.824mg/g.(3)The optimal conditions for the adsorption of Cu(?)by CS-SiO₂ composite adsorbent were:adsorption temperature was 65?,adsorbent input was 1g/L,p H was4,Cu(?)initial concentration was 80mg/L,The adsorption time was 60min.Under the optimal adsorption conditions,the adsorption rate of CS-SiO₂ composite adsorbent for Cu(?)in simulated wastewater was 99.78%,and the adsorption capacity was 79.824mg/g.(4)The fitting result of adsorption kinetics experiment showed that the adsorption of Cu(?)in simulated wastewater by CS-SiO₂ composite adsorbent conforms to the second-order kinetic model,which indicated that the adsorption type of Cu(?)by the adsorbent was chemical adsorption.The fitting result of adsorption isotherm experiment showed that the adsorption of Cu(?)in simulated wastewater by CS-SiO₂ composite adsorbent was more in line with the Langmuir adsorption isotherm model,which showed that the adsorption of Cu(?)by the adsorbent was monolayer adsorption.The experimental results showed that the CS-SiO₂ composite adsorbent prepared with yellow phosphorus slag as the raw material and chitosan as the modifier had a good adsorption effect on the treatment of Cu(?),and provided a new method for the treatment of Cu(?)in industrial wastewater.