ZnAl-LDHs覆膜改性湿地基质强化氮磷吸附性能

Performance of Enhanced Nitrogen and Phosphorus Adsorption Removal by Modified Wetland Substrate Coated with ZnAl-LDHs

传统湿地基质存在吸附作用单一的缺陷,采用LDHs覆膜定向改性具有一定氨氮吸附优势的人工湿地基质,通过冷场发射扫描电镜、X射线衍射仪对改性基质进行物理表征,研究无机磷(In-P)溶液初始浓度、吸附时间等因素对改性基质吸附In-P的影响,结合吸附等温线和吸附动力学分析除磷特性及吸附机理。结果表明,ZnAl-LDHs改性蛭石拟合得到的最大吸附量达74.239 mg/g,高于同类改性的沸石(4.133 mg/g)和砖渣(11.937 mg/g);吸附强度和吸附容量(K f=5.022)均大于改性沸石(0.633)和改性砖渣(0.971);ZnAl-LDHs改性基质对In-P的吸附动力学与准二级动力学模型拟合度(R2>0.980)更高,以化学吸附为控制步骤的吸附过程为主。利用蛭石进行ZnAl-LDHs覆膜改性可实现氨氮与In-P的同步高效吸附,有望弥补传统人工湿地基质吸附功能单一的不足。

The traditional wetland substrate has the defect of a single adsorption effect.LDHs was used to directionally modify the constructed wetland substrate with certain ammonia nitrogen adsorption advantage.The modified substrates were analyzed by scanning electron microscope and X-ray diffractometer.The substrate was physically characterized,and effects of initial concentration and adsorption time on the adsorption of In-P on the modified substrate were studied,and the phosphorus removal characteristics and adsorption mechanism were analyzed based on the adsorption isotherm and adsorption kinetics.The results showed that the maximum adsorption capacity obtained by fitting ZnAl-LDHs modified vermiculite was 74.239 mg/g,which was higher than similarly modified zeolite(4.133 mg/g)and brick slag(11.937 mg/g).Adsorption strength and adsorption capacity(K f=5.022)were greater than those of modified zeolite(0.633)and modified brick slag(0.971).Adsorption kinetics of ZnAl-LDHs modified substrates on In-P was more aligned with the quasi-second-order kinetic model(R2>0.980).The chemical adsorption was the main control step.The modification of vermiculite with ZnAl-LDHs can realize the simultaneous and efficient adsorption of ammonia nitrogen and In-P,which is expected to make up for the lack of a single adsorption function of traditionally constructed wetland substrate.