浸渍-煅烧法改性凹凸棒石对模拟废水中磷的吸附特性

The Adsorption of Phosphorus in Simulated Wasterwater by Immersing and Annealing Modified Attapulgite

为提升凹凸棒石对水溶液中磷的吸附性能,以凹凸棒石、氢氧化铝、熟石灰为原料,采用浸渍-煅烧法制备ATP-IA(改性凹凸棒石).通过吸附磷试验,探讨ATP-IA吸附性能以及投加量对吸附效果的影响;利用SEM(扫描电镜)、XRD(X射线衍射光谱)、XRF(X射线荧光光谱)和FTIR(傅里叶转换红外光谱)对ATP-IA表征,并结合吸附动力学、热力学和等温吸附试验探讨ATP-IA吸附磷机制.结果表明,ATP-IA平衡吸附容量为26.34 mg/g(凹凸棒石的平衡吸附量为0.88 mg/g),对磷的去除率可以达到99.36%;表征结果表明,改性可使部分凹凸棒石转变为钙沸石,改性能脱除凹凸棒石晶体内的结晶水,使凹凸棒石比表面积显著提升;动力学试验表明,ATP-IA吸附磷过程符合准二级动力学方程,说明ATP-IA吸附磷过程中反应控速步骤为化学反应;等温吸附试验结果符合Freundlich方程,表明吸附为多分子层不均匀吸附;热力学分析表明,ATP-IA吸附磷属于自发进行的吸热过程,且同时包含物理吸附和化学吸附.研究显示,浸渍-煅烧法改性会改变凹凸棒石部分理化性质,能显著提高凹凸棒石对磷的去除率及平衡吸附容量.

A series of calmogastrin and lime supported attapulgite(ATP-IA)prepared by immersing-annealing method were evaluated for the adsorption of phosphorus in wastewater.The effect of pH and dosage on the performance of ATP-IA were investigated.Scanning electron microscope(SEM),X-ray diffraction(XRD),X Ray Fluorescence(XRF)and Fourier Transform infrared spectroscopy(FTIR)were employed to characterize the physicochemical properties of the ATP-IA adsorbents.The mechanism of phosphorus adsorption was investigated by means of adsorption kinetics,adsorption thermodynamics and isothermal adsorption experiments.The results showed that ATP-IA exhibited an excellent adsorption capacity(26.34 mg g)and the removal efficiency of phosphorus could reach 99.36%.The results of XRD analysis indicated that parts of attapulgite were converted to scolecite after modification.The FTIR analysis showed that the crystalline water of attapulgite was reduced after modified,which significantly improved the surface area of attapulgite.The kinetic expression was conformed to the pseudo-second-order kinetics,which indicates a chemisorption of phosphorus by ATP-IA.The adsorption behavior of phosphorus by ATP-IA was well-fitted with Freundlich isothermal model,suggestive of a process of multi-layer adsorption.The thermodynamic analysis showed that the adsorption of phosphorus is a spontaneous endothermic process.