Preparation And Properties Of The New Types Of Phosphate Removal Adsorbent

Phosphorus is considered as an essential element in agriculture and industry,but the release of excess phosphorus into natural water can lead to eutrophication,which not only poses risks to aquatic ecosystems,but also leads to economic losses.Therefore,it is very necessary to study the technology of removing phosphate from water.Although many methods have been used to remove phosphate from wastewater,the adsorption process is more economical and efficient,especially for the low concentration of phosphate.For the selection of adsorbents,the search and preparation of low-cost,high-efficiency,high-capacity adsorbents is the direction of researchers.In this study,the following two aspects are studied:?1?Preparation of cobalt-containing spinel oxide and its phosphate removal performance.In this paper,the cobalt-containing spinel oxides?MgCo₂O₄,MnCo₂O₄ and CuCo₂O₄?were prepared as phosphate removal adsorbents by solution combustion method.The study found that MgCo₂O₄ adsorbed the highest amount of phosphate?90.02 mg/g?among the three adsorbents.The Langmuir isotherm model and the pseudo-second-order kinetic model can better fit the adsorption process.The phosphate adsorbed by MgCo₂O₄ was endothermic and non-spontaneous.The presence of coexisting ions CO₃^2-significantly interfered with the adsorption of phosphate on MgCo₂O₄.MgCo₂O₄ still maintained a high removal rate of phosphate after three adsorption-desorption cycles,indicating that the adsorbent had the excellent stability and recyclability.Adsorption mechanisms involved precipitation,electrostatic interaction and ligand exchange.?2?Preparation of functionalized polyvinyl chloride materials and research on phosphate removal performance.In this paper,ethylenediamine functionalized polyvinyl chloride?PVC-EDA?,magnetic ethylenediamine functionalized polyvinyl chloride?MPVC-EDA?and magnetic Ce???-coordinated ethylenediamine functionalized polyvinyl chloride?MPVC-EDA-Ce?as phosphate removal adsorbents were prepared.Among the three adsorbents,MPVC-EDA-Ce adsorbed the largest amount of phosphate.The Langmuir isotherm model and the pseudo-second-order kinetic model can better fit the experimental data.MPVC-EDA-Ce exhibits excellent adsorption performance over a wide pH range and almost no release of Ce???into the solution.After the addition of competitive anion(SO₄^2-)in the phosphate solution,the adsorption capacity of MPVC-EDA-Ce towards phosphate decreased from 27.28 mg/g to 18.41mg/g,while the adsorption capacity of MPVC-EDA and PVC-EDA towards phosphate decreased to close to 0,indicating that the phosphate adsorbed by the Ce???site was a specific adsorption process with strong inner-sphere complexation;the ammonium functional group adsorbed phosphate as a non-specific adsorption process with a relatively weak electrostatic attraction effect.