氧化铁改性沸石对Se(Ⅳ)的吸附性能及试验废物再利用研究

为解决天然沸石去除废水中Se（Ⅳ）能力低的问题，采用氯化铁对天然沸石进行改性，制备表面负载氧化铁的改性沸石，即氧化铁改性沸石，并将其应用于去除水体中Se（Ⅳ）.首先对比天然沸石和氧化铁改性沸石的结构特征，研究二者对Se（Ⅳ）溶液的吸附特性，并通过X射线荧光光谱（XRF）、X射线衍射图谱（XRD）、扫描电镜（SEM）和氮气吸附孔径分布测试（BET）对二者进行表征；其次进行吸附试验，考虑接触时间、pH、吸附剂投加量、初始溶液反应浓度的影响，并通过天然沸石和氧化铁改性沸石的吸附动力学及吸附等温线对吸附的机理进行阐述.结果表明:①氧化铁改性沸石表面形成细碎的球状颗粒，分布在沸石的表面.②氧化铁改性沸石能够高效地吸附水体中的Se（Ⅳ），且在pH为3时吸附效率最高，其对Se（Ⅳ）溶液的去除率最高达97.7%，其理论最大吸附量为46.901 mg/g.③氧化铁改性沸石对Se（Ⅳ）的吸附过程符合准二级动力学模型和Langmuir等温吸附模型.④添加负载Se（Ⅳ）后的氧化铁改性沸石土壤均达到富硒土壤标准（>0.4 mg/kg）.研究显示，氧化铁改性沸石吸附Se（Ⅳ）的效果较好，显著优于天然沸石的吸附效果，且吸附Se（Ⅳ）废水后的废弃氧化铁改性沸石还可应用于土壤改良方向. 

Adsorption Characteristics of Se(Ⅳ) on Iron Oxid Modified Zeolite and Waste Reuse

In order to solve the problem of low adsorption efficiency of natural zeolite for Se(Ⅳ) in wastewater, ferric chloride was used to modify the natural zeolite, and iron oxide was loaded on the modified zeolite surfacefor Se(Ⅳ) removal, which is named iron oxide modified zeolite. The structural and the adsorption characteristics of Se(Ⅳ) were compared between natural zeolite and iron oxide modified zeolite. The zeolite and iron oxide modified zeolite were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction pattern (XRD), scanning electron microscope (SEM) and nitrogen adsorption pore size distribution test (BET). Next, perform adsorption experiments, the influence of contact time, pH, adsorbent dosage, initial solution reaction concentration were considered, and the adsorption mechanism was described by adsorption kinetics and adsorption isotherms. The results show that: (1) The surface of the iron oxide modified zeolite formed finely divided spherical particles, which are distributed on the surface of the zeolite. (2) The adsorption efficiency of iron oxide modified zeolite for Se(Ⅳ) was high, especially at low pH. When pH was 3, Se(Ⅳ) adsorption was up to 97.7%. The theoretical maximum adsorption capacity was 46.901 mg/g. (3) The adsorption kinetic results of Se(Ⅳ) on iron oxide zeolite was consistent with the quasi-secondary kinetics, and the equilibrium adsorption could be described by Langmuir isotherm equation. (4) The soil added with Se(Ⅳ) modified zeolite all reached the standard of selenium-rich soil (>0.4 mg/kg). The results show that the adsorption capacity of iron oxide modified zeolite is higher than natural zeolite, and the modified zeolite loaded with Se(Ⅳ) can be used for soil improvement.