Adsorption Characteristics And Mechanism Analysis Of Phosphorus Wastewater On The Synthetic Ferrihydrite

In recent years,the increasingly serious eutrophication problem,which has become one of the important environmental concerns at home and abroad.The main nutrient causing the eutrophication of water body is phosphorus.Therefore,the effective control of phosphorus in the water body becomes the key to solve the problem of eutrophication.At present,adsorption is widely used to remove phosphorus from water,so it is important to find a kind of high-performance adsorbent.The synthetic ferrihydrite,Ferror Mox?FM?,is used as adsorbent for removing phosphorus from waste water,adsorption theory is explored by static adsorption and dynamic adsorption experiments.At first,FM was applied to static adsorb phosphorus from wastewater,and the adsorption performance,influence factors and adsorption mechanism were investigated.The results obtained are as follows:SEM,EDS,XRD,FTIR and Raman were used to characterize FM,and the results indicated that FM was amorphous 2L ferrihydrite and was composed of Fe,O,Ca and Si,FM mainly exists in the form of hydroxyl iron;XPS was used to characterize before and after adsorption of FM,the results indicated tht the mainly forms of phosphorus adsorbed on the surface of FM are HPO₄^2-neutral condition),H₂PO₄^-?acidic condition?,HPO₄^2-and hydroxy calcium phosphate?alkaline condition?.Under the acidic condition,the growth of the phosphorus atom on the FM surface was the most,and it was proved that the adsorption effect of FM was relatively better under the acidic condition.The results through static adsorption experiment indicated the phosphorus removal rate reached 99.14% under the condition of adsorption time of 60 min,the initial pH phosphate solution of 2,relative dosing quantity of 7 g·L^-1,reaction temperature of 25 ?,the initial concentration of 10 mg·L^-1,and solution volume of 50 m L.Adsorption isotherms were well fitted with the Langmuir isothermal adsorption model at different temperature with the correlation coefficient reached above 0.95.The thermodynamic parameters showed that the phosphorus adsorption by FM was a spontaneous endothermic reaction.The phosphate removal kinetics well followed both pseudo-first-order model and pseudo-second-order model.About 99% of phosphate adsorbed on FM could be desorbed in 0.1 mol·L^-1 Na OH solution.Therefore,FM was a promising absorbent material for the removal of phosphate from waste water.Secondly,through dynamic experiment,parameters of adsorption column such as the adsorption velocity,column height,initial pH and the initial concentration of the solution,on the influence of the FM adsorption breakthrough curve,and dynamic adsorption model fitting curve of experimental data and the adsorption column regeneration performance.The results obtained are as follows:FM adsorption breakthrough curve with the increase of flow rate,the breakthrough curve becomes steeper,the water production gradually reduces;with the increase of the the adsorption column height,the adsorption breakthrough curve gradually flatten,the time to the breakthrough point and the exhaustion point increase gradually;with the increase of initial concentration of solution,the adsorption breakthrough curve moved to the left,the breakthrough time of adsorption curve and the saturation time will be shortened;under weakly acidic condition,the effect of FM removing phosphorus is better.Adam's-Bohart?Yoon–Nelson and BDST were used to fit the breakthrough curve by linear regression analysis.The results show that Adam's-Bohart model is better fitting effect on the initial stage of operation;Yoon-Nelson model is better to fitting effect on running later period;BDST model can successfully predict the velocity for reference to the engineering application.Through the experiments of adsorption column regeneration and reuse,FM is a regenerative performance is good,reusable adsorption material.