| Excessive phosphorus in the water can cause water eutrophication,damage to the water environment,leading to water deterioration.Adsorption method for low concentration of wastewater treatment has a low cost,simple operation,high phosphorus removal efficiency and no secondary pollution and so on.Steel slag is a kind of industrial waste discharge in the steel-making process,the comprehensive utilization of low efficiency,large accumulation will pollute the ecological environment.The steel slag has certain adsorption capacity because of the physical characteristics,but the large size low surface area of steel slag,phosphorus slag powder,the effect is not ideal,in the practical application due to the size of particles small,easy to plug the pipeline and reach the adsorption effect theory,and there is a risk of loss of filter media.The modified steel slag ceramsite is made of steel slag as the base material,adding modifier,adhesive and reaming agent,mixing,granulating and molding,and then sintered at high temperature.In this paper,two modifiers are used to prepare two Modified steel slag ceramsite with a certain particle size,hardness and porosity.The effects of various conditions on the removal efficiency of modified steel slag and the isothermal adsorption and dynamic adsorption of phosphorus removal were studied.The removal mechanism of modified steel slag was studied by specific surface area and pore size distribution tester,scanning electron microscope and X-ray powder diffractometer.The conclusions of this paper are summarized as follows:(1)The effects of dosage,reaction time,initial phosphorus concentration and p H value on the removal efficiency of two kinds of modified steel slag were discussed by static adsorption experiment.The optimum operating conditions of phosphorus removal of modified steel slag were determined: 0.5mg/L simulated wastewater was treated with 5g/L,and the removal rate of aluminum modified ceramic was 91.82% at 60 min,When the grain size is30 min,the removal rate is 98.72%,and the removal efficiency is better in the short time.When the p H value is between 5 and 11,the two kinds of modified materials can maintain the better phosphorus removal effect.(2)The phosphorus removal process of the two composites is more consistent with theLangmuir model,and the linear correlation coefficients of the aluminum and calcium modified steel slag are 0.9962 and 0.9790,respectively,which belong to the single molecular layer adsorption model and have typical chemical adsorption.The adsorption of phosphorus on the composite is in accordance with the Lagergren secondary kinetic adsorption rate equation,which can reflect the adsorption process of phosphorus more accurately.(3)The removal rate of phosphate in water was 91.82% when the dosage of aluminum and calcium modified steel slag was 5g/L,and the removal rate of phosphate in water was91.82% and 98.72%,respectively.The removal rate of phosphate in water was 93.37% and95.63% respectively when the dosage of aluminum and calcium modified steel slag was10g/L,and the removal rate of modified steel slag was The removal efficiency of the waste water is not as good as that of the simulated wastewater,but the addition of the modified steel slag can also achieve good phosphorus removal effect.(4)by scanning electron microscopy and X-ray diffraction analysis,the modified steel slag than the steel surface area of large,the gap structure more.The structure of the composite adsorbable material can obviously detect the existence of the reaction product,and the product is mainly calcium phosphate.The adsorption of phosphates by modified steel slag is mainly through physical adsorption,ion exchange and chemical precipitation.The phosphorus removal process of Al-loaded steel slag is mainly the exchange of phosphates in the aqueous solution with the active components containing Si and Al in the adsorbent,and also contains chemical precipitation,accompanied by electrostatic adsorption and physical adsorption.The process of Ca-loaded steel slag is mainly due to the chemical precipitation in the phosphate and the active components containing Ca in the aqueous solution,accompanied by physical adsorption and electrostatic adsorption.(5)the modified steel slag 2 as an example,in the modified steel slag adsorption adsorption,the use of Na OH as a regenerant,the amount of material after regeneration 5g/L,the initial concentration of phosphate solution 0.5mg/L,The removal rate of phosphate was about 90% after 30 min reaction.The optimum regeneration conditions were as follows: theoptimum concentration of 3mol/L Na OH and the regeneration time was 30 min.Compared with the previous studies,the preparation of steel slag into granular composite adsorbent material not only avoid the blockage of the pipe and recycled,but also can improve the removal efficiency of steel slag.The modified steel slag has high physical and chemical adsorption and chemical precipitation properties due to its chemical and physical properties(surface functional groups,surface area,porosity).The adsorbent is not affected by the p H value of the water body.The adsorption effect is good and the phosphorus removal efficiency is high.It can be used for the treatment of low concentration phosphorus-containing wastewater,such as eutrophication of water,and can be used directly in rivers and lakes,artificial wetlands and conventional Wastewater treatment works such as the depth of treatment.And a wide range of raw materials,low prices,the preparation method is simple,green technology,operable,with a wide range of industrial applications. |
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