Fe_(3)O_(4)负载非晶态(碳酸)氧化锆复合材料对磷的吸附性能及机理

Fe_(3)O_(4) loaded amorphous zirconium (carbonate) oxides composite for phosphate adsorption: Performance, mechanism and treatment effect in real wastewater

有效控制富营养化和磷酸盐回收是近年来日益受到重视的问题。为此,采用溶剂热法合成了一种去除水中磷酸盐的Fe_(3)O_(4)负载非晶态(碳酸)氧化锆复合材料(MZCO),通过X射线衍射仪(XRD)、场发射扫描电镜(SEM)、高分辨率透射电镜(TEM)、傅里叶变换红外光谱仪(ATR-IR)、X光电子能谱仪(XPS)等对其进行了结构表征、吸附性能评价和吸附机理的探究。结果表明:MZCO为Fe_(3)O_(4)负载非晶态(碳酸)氧化锆复合产物,其比表面积高达478.28 m^(2)·g^(−1)。MZCO对磷酸盐的饱和吸附容量为68.16 mg·g^(−1),在前120 min的吸附量可以达到该饱和吸附量的87.2%。对于低浓度(2 mg·L^(−1))磷酸盐溶液,MZCO在pH为5~9内能保持稳定的吸附性能,相应的吸附容量为20 mg·g^(−1)左右,Mg^(2+)、Ca^(2+)、Cl^(–)、NO_(3)^(–)、SO_(4)^(2–)和HCO_(3)^(−)等共存离子和腐殖酸(HA)对磷酸盐吸附均无较大影响。对于低浓度实际废水(5 mg·L^(−1)),经5次吸附再生后MZCO吸附量可以保持初始吸附量的84.68%;当穿透值为0.1 mg·L^(−1)时,柱吸附量可达到~1500 BV(~34.05 mg·g^(−1))。MZCO吸附磷酸盐的主要机制为静电吸引、—OH和CO_(3)^(2−)与磷酸根之间的配体交换。

At present,the effective eutrophication control and phosphate recovery have attracted an increasing attention.In this study,a type of Fe_(3)O_(4) loaded amorphous zirconium(carbonate)oxides composite(MZCO)was synthesized by solvothermal method to remove phosphate from water.XRD,SEM,TEM,AFT-IR and XPS were used to characterize the micro-morphology and physicochemical properties of MZCO,and evaluate its adsorption performance and investigate the adsorption mechanisms towards phosphate.The results showed that MZCO consisted of Fe_(3)O_(4)loaded amorphous zirconium(carbonate)oxides and its large specific surface area was 478.28 m^(2)·g^(−1).The adsorption capacity of MZCO towards phosphate was 68.16 mg·g^(−1),and within the first 120 min its adsorption amount could reach 87.2%of this capacity.For the phosphate solution with an initial PO_(4)^(3−)-P concentration of 2 mg·L^(−1),MZCO could maintain a stable adsorption amount of about 20 mg·g^(−1)over a wide pH range of 5.0~9.0.Moreover,MZCO showed a strong selectivity to low-concentration phosphate in the presence of competing ions(Cl^(−),NO_(3)^(−),SO_(4)^(2−),HCO_(3)^(−),Ca^(2+),and Mg^(2+))and humic acid(HA).After 5 cycles of adsorption-desorption in real wastewater samples,the adsorption amount of regenerated MZCO still remained 84.68%of its maximum value.The column adsorption capacity of MZCO could reach~1500 BV(~34.05 mg·g^(−1))as P concentration decreased from 5 mg·L^(−1)to 0.1 mg·L^(−1).The mechanism of phosphate uptake onto MZCO could be mainly ascribed to electrostatic attraction and ligand exchanges between—OH and PO_(4)^(3-),CO_(3)^(2-)and PO_(4)^(3-).