Preparation And Characterization Of Granular Fe-Cu Binary Oxide Adsorbent And Their Phosphate Adsorption Properties

Phosphorus, as an essential nutrient element, may cause eutrophication or redtides if excessively exist in water, damaging the environment seriously and posing athreat to people and aquatic organisms. Currently, phosphate removal is an importantgoal for water treatment. Adsorption method was used to remove phosphate fromwater due to its high efficiency, fast and simple operation, and Fe-Cu compositeoxide as a phosphorus adsorbent, is environment-friendly with the excellentadvantages of high adsorption capacity and wide pH applied range. Powderedadsorbents are fit for situ production and dosing, whereas granular adsorbents arebetter for easily operation and maintain in columns. In order to expand the applicationscope of powdered Fe-Cu composite oxide, granular Fe-Cu composite oxide wasmade and phosphorus removal from aqueous solution on the granular adsorbent hasbeen carried out in the study. The following results were obtained:（1） Using the extrusion molding method, powdered Fe-Cu composite oxide wasmade into the granular adsorbent of the diameter of1mm²mm with PVA，anenvironmentally-friendly organic polymer, as the adhesive.（2） The granular Fe-Cu composite oxide retains high phosphate adsorptionability. The adsorption isotherm data is well described by Freundlich model withmaximal phosphate adsorption capacity of20.2mg/g at pH5.5, which is higher thanother granular adsorbents reported in literature.（3） The equilibrium can be achieved by about30h. The adsorption kinetic datacan be well described by both pseudo-second order model and intra-particle diffusionmodel.（4） The granular Fe-Cu composite oxide is effective in removing phosphate in awide pH rage （4⁷）. The presence of coexisting SiO₃^2-may decrease the phosphateadsorption and other coexisting anions (SiO₄^2-and HCO₃^-) have little effect onphosphate removal. Moreover, the coexisting cations such as Ca²⁺, Mg²⁺can promotethe adsorption of phosphate on granular Fe-Cu composite oxide.（5） EDS characterization showed that the surface layer and the inner layer of thegranular adsorbent have phosphate adsorption. The phosphate adsorption by the granular Fe-Cu composite oxide is a spontaneous endothermic process and non-monolayer chemical adsorption with the complexes occurred between the adsorbentand phosphate in aqueous.