Phosphorus Removal From Water By Nano Lanthanum-contained Adsorbent

Phosphorus is the main pollutant in water,and excess phosphorus can lead to eutrophication.Therefore,phosphorus pollution has become an urgent problem to be solved.Adsorption method is widely used in wastewater treatment,because of simple operation and small amount of sludge.At the same time,an adsorbent can be recycled by regeneration and the phosphorus resource can be recovered.At present,there are several problems with adsorbent to be promoted:low adsorption efficiency and narrow pH stability range.For the purpose of solving these defects,the synthesis of the nano lanthanum carbonate is creative point of this title,then the adsorption process and adsorption mechanism are discussed by experiment and characterization.In this paper,the main dephosphorizationt of lanthanum carbonate was used in wastewater and prepared by crystal form control agent.After adsorbed,adsorbent was regenerated by NaOH solution,so as to effectively improved the utilization of lanthanum.Finally,the adsorbent was applied to the domestic sewage to further verify its value.The min contents are generalized as follows:Firstly,in ethanol/water mixed system,the lanthanum carbonate can be synthesized by changing quantity of ethanol,reactant concentration and reaction preparation temperature.As a result,an irregularity of the sheet structure and a smaller particle size of 55℃E-La was prepared.The XRD characterization results showed that it was lanthanum carbonate.For phosphorus adsorption research,the reaction reached equilibrium after 8h;the pH stability range was 3-7.Secondly,magnesium sulfate was utilized as another crystal form control agent.The optimal preparing condition was in 85℃,c(La3+)=0.04 mol/L,c(Mg2+)/c(La3+)=1,c(NaHCO3)/c(La3+)=4,ie,85℃Mg-La.Lanthanum carbonate was characterized by SEM、TEM、XRD,and proved that existed amorphous nanoparticle.And the TG results showed that it contained about 8 crystal water.In the phosphorus adsorption reaction,the equilibrium time about 2h,which is 6 h shorter than 55℃E-La;the maximum adsorption capacity of 85℃Mg-La was 113.1 mg/g,;and a high removal rate in the range of pH=3-11.The XRD and FTIR characterization showed that the adsorption process was chemical adsorption.Then,the lanthanum of 85℃Mg-La can be recovered by NaOH solvent method,and the optimum regeneration condition:NaOH solution concentration was 4mol/L,the liquid/solid ratio was 500:1,and the reaction temperature was at 100℃ for 5 h.Meanwhile,95.60%phosphorus recovery can be achieved.After four regenerations,more satisfying results may be expected.The XRD and SEM was confirmed that the regenerated materials was nano lanthanum hydroxide.Finally,lanthanum carbonate,ferric sulphate and bentonite were added together into the domestic sewage,with TP concentration of 0.609 mg/L.When the amount of mixture adsorbent was 0.04 g/L,the phosphorus concentration in the solution was less than 0.5 mg/L,which can meet the first-level emission standards.