Study On Adsorption Performance And Application Of Phosphorus-containing Wastewater And Dye Wastewater By Steel Slag

Based on the unique physical and chemical properties and excellent adsorption properties of steel slag,the adsorption properties and adsorption mechanism of steel slag for phosphorus,acid dyes and basic dyes in wastewater were discussed.In order to improve the adsorption performance of electric furnace steel slag on dye wastewater and expand its application range,electric furnace slag was modified to prepare Layered Double Hydroxides（LDHs）,and its adsorption effect on methylene blue was verified,and its adsorption mechanism was analyzed.The main results of this study are as follows:1)The steel slag raw materials were characterized by scanning electron microscopy（SEM）,energy dispersive x-ray spectroscopy（EDS）,x-ray fluorescence spectroscopy（XRF）,fourier transform infrared spectroscopy（FTIR）and x-ray diffraction spectroscopy（XRD）.The contents of iron（Fe）,copper（Cu）,zinc（Zn）,selenium（Se）,arsenic（As）,mercury（Hg）,lead（Pb）and cadmium（Cd）in the leachate of steel slag all met the requirements of Class I standard of surface water,and the steel slag was safe and reliable.2)The influence of environmental factors on phosphorus removal by steel slag was discussed by the control variable method.When the adsorption time was 30 min,the removal rate of PO₄^3-with different concentrations by steel slag was over 97%.The effect of temperature on phosphorus removal by steel slag was not obvious.The adsorption capacity of steel slag to pyrophosphate was weaker than that for orthophosphoric acid.Combined with SEM,EDS,XRF and XRD,it was determined that the main mechanism of phosphorus removal by steel slag was chemical adsorption assisted by physical adsorption,and Ca HPO₄·2H₂O was the main precipitation substance.The removal rates of total phosphorus（TP）in the effluent of biological pond and wetland system by steel slag were98.36%and 93.33%,respectively.Compared with ceramsite and zeolite,steel slag has the best PO₄^3-removal characteristics.3)Steel slag showed excellent adsorption performance for acid fuchsin,Congo red and basic fuchsin,and the decolorization rate of these dyes can be over 94%under different experimental conditions,while the decolorization efficiency of steel slag for methylene blue was the worst.Adsorption time,initial concentration,adsorption temperature,particle size and dosage of steel slag were important factors affecting the adsorption effect of steel slag on different dyes,and different factors had different effects on different dyes.Combined with SEM,FTIR and XRD techniques and Freundlich isotherm model,acid fuchsin,Congo red and basic fuchsin were finally determined as chemical adsorption;New carmine,methyl orange and methylene blue were physically adsorbed.4)Multi-component LDHs material prepared from steel slag had high efficiency in removed methylene blue,and the decolorization rate of methylene blue solution with initial concentration of 10 mg·L^-1 can reached over 98%under suitable conditions.Adsorption time,initial concentration,p H and adsorbent dosage were important factors affected adsorption effect.The adsorption mechanism was mainly spontaneous chemical adsorption.