Study On The Adsorption Performance Of Modified Metal Oxide/hydroxide For Phosphorus Removal

Phosphorus is one of the important nutrients in biological growth and chemical processes.However,when a large amount of phosphorus enters the water body with domestic sewage and industrial wastewater,it will lead to eutrophication of the water body,algal blooms,and water quality deterioration.Therefore,the research and development of wastewater phosphorus removal technology has important scientific research value and practical application significance for solving environmental pollution problems such as water eutrophication.Among many phosphorus removal methods,adsorption method has received extensive attention due to its low cost,high efficiency and simple operation.Among the currently prepared adsorbents,La（OH）₃and Mg O have high specific surface area and high affinity for phosphate,but they have the problems of easy agglomeration and low adsorption capacity.Therefore,in this study,La（OH）₃and Mg O were modified by caragana and melamine foam,respectively,and two adsorbents with excellent phosphorus removal performance were prepared.The main research contents and conclusions are as follows:（1）A low-cost,environmentally friendly and efficient phosphate adsorbent（La/CK-DETA）was prepared by in situ loading La（OH）₃by amine-modified caragana.Among them,the amino group can anchor and disperse La（OH）₃,and at the same time,the amino group is positively charged after protonation,and can electrostatically adsorb negatively charged phosphate radicals.The thermodynamic and kinetic studies of the adsorbent show that its adsorption behavior conforms to the Langmuir adsorption isotherm,and the maximum adsorption capacity for phosphate is 173.32 mg P g^-1;the kinetic model conforms to the pseudo-second-order kinetic equation,The adsorption equilibrium was reached within 50 min.Furthermore,when coexisting anions are present,the adsorbent is not affected by the coexisting anions in the solution,indicating its excellent phosphate selectivity and anti-interference ability.The adsorption regeneration experiment shows that the phosphorus removal rate can still reach 85%after four cycles of regeneration experiments,which proves that it has good regeneration performance and is beneficial to the application in practical wastewater treatment.（2）Mg O/MF phosphate adsorbents with high dispersion,hierarchical porous structure and abundant oxygen vacancies were prepared by choosing melamine foam as the sacrificial template.Density-functional theory calculation reveals that the phosphate prefers to adsorb on hollow sites rather than top sites of Mg O when oxygen vacancies exist,which improves the intrinsic adsorption ability of Mg O/MF.The Mg O/MF-1 adsorbent displays excellent phosphorus removal properties in water within a wide p H range of 2 to 12,and the maximum adsorption capacity of phosphate reaches as high as 400 mg P g^-1.In particular,the phosphate adsorption capacity of Mg O/MF-1 adsorbent can be restored to 100%after calcination and activation.After six adsorption cycles,the Mg O/MF-1 with a high phosphate content of 117.5 mg P g^-1serves as a potential high-quality fertilizer.This work provides a promising strategy for the construction of efficient adsorbent for wastewater treatment as well as resource recovery.