PERFORMANCE OF PHOSPHATE ADSORPTION BY MgFe-LDHs MODIFIED DREDGING SLUDGE PERMEABLE BRICK
In this work,modified sludge was prepared by adding a certain proportion of dredging sludge in the process of synthesizing functional material layered double hydroxides(LDHs).It was used as one of the raw materials to prepare four kinds of water permeable bricks for sponge city construction with different mass mixing ratios.The surface morphology,chemical composition,and crystal structure of permeable bricks before and after mixing modified sludge were characterized by a field emission scanning electron microscope(SEM),energy dispersive spectrometer(EDS),and X-ray diffractometer(XRD).Through the detection of compressive strength and water permeability,combined with the results of purification experiments,the optimum blending ratio of modified quality was determined.Isothermal adsorption,adsorption kinetics,and thermodynamics experiments were carried out to explore the adsorption performance and mechanism of phosphate on permeable bricks before and after mixing modified sludge.The results showed that:1)the modified dredged sludge permeable brick with a blending ratio of 1∶1 was more practical than several other mass blending ratios.When the initial phosphate concentration was 32 mg/L,the dosage of water permeable brick was 1.2 g,and the adsorption time was 360 min,then the adsorption capacity of phosphate reached 2.08 mg/g;2)the adsorption process of phosphate by permeable brick before and after mixing modified sludge conformed to Langmuir isothermal adsorption model and pseudo-second-order kinetic model,and the maximum saturated adsorption capacity of phosphate by permeable brick increased by 25％after mixing modified sludge;3)the addition of modified sludge reduced the energy required for the permeable brick to adsorb phosphate,and enhanced the spontaneity,which helps the permeable brick to purify rainwater in practical applications.
lake sludgepermeable brickMgFe-LDHsadsorptionphosphate
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