金属氧化物纳米颗粒对磷的吸附及回收潜力

Phosphate adsorption from solution by metal oxide nanoparticles and the potential on phosphate capture

比较4种金属氧化物纳米颗粒(nMgO,nAl_2O_3,nTiO2和nFe_2O_3)对水体P的吸附性能,并探讨了pH、吸附时间、共存离子等因素对nMgO吸附P的影响,用XRD和XPS分析了nMgO对P的吸附机制,最后通过小青菜盆栽实验法探讨nMgO从养殖废水中吸附回收P的应用潜力.结果发现,在pH3.0~8.0范围内,nMgO对P的吸附量显著高于nAl_2O_3、nTiO_2和nFe_2O_3,4种纳米颗粒对P的吸附量分别可达40、31.77、15.93和13.08mg/g.吸附后P的解吸可逆性较差.nMgO对P的吸附能在0.5h内达到吸附平衡,P的吸附符合准二级动力学过程.体系共存的等量F^-、Cl^-、NO_3^-、SO_4^(2-)、Na^+、K^+和NH_4^+离子对nMgO吸附P无显著影响,Mg^(2+)和Ca^(2+)离子对P吸附具有促进作用.nMgO对P的吸附等温线可用Langmuir模型描述,最大吸附量达139.3mg/g.XRD和XPS分析表明,nMgO对P的吸附是伴有静电吸引的以表面络合沉淀反应为主的吸附过程.nMgO能有效地从养殖废水中吸附回收P,吸附P的nMgO作为肥料,能使小青菜干物质量从0.31g/kg土增加到0.96g/kg土.

Effects of four different metal oxide nanoparticles(nMgO,nAl2O3,nTiO2and nFe2O3)on phosphate adsorption were compared in the batch experiment.The influences of solution pH,contact time and coexist ions on phosphate adsorbed by nMgO were examined.Further,the phosphate adsorption mechanism onto nMgO was evaluated by XRD and XPS analysis.And the potential of recovered phosphate by nMgO from pig breeding wastewater on fertilzer was assessed by pot experiment.The results showed that nMgO had higher phosphate adsorption ability than nAl2O3,nTiO2and nFe2O3.The phosphate amount reached40、31.77、15.93and13.08mg/g in the range of pH3.0to8.0for nMgO,nAl2O3,nTiO2and nFe2O3,respectively.The phosphate adsorption was a inreversible process.The phosphate sorption onto nMgO could reach equilibrium within0.5h,the adsorption process fitted the pseudo-second order kinetic model.The equal content of coexisted F-,Cl-,NO3-,SO42-,Na+,K+and NH4+ions had no negative influence on phosphate adsorbed onto nMgO,while the existence of Mg2+and Ca2+ions could promote the phosphate adsorption.Langmuir model could be used to describe the adsorption isotherm,by which the maximum phosphate adsorption capacity was around139.3mg/g.Based on the results of XRD and XPS analysis,it can be concluded that phosphate adsorption was dominated by chemical precipitation reaction combined with electrostatic attraction process.nMgO particles effectively recovered phosphate from piggery wastewater,in turn the phosphate loaded nMgO nanoparticle could be used as a potential substitute for phosphate-based fertilizer,which significantly improved the cabbage dry biomass from0.31to0.96g/kg soil.