引用本文:许海娟,王 锐,魏世勇,方 敦,杨小洪.蒙脱石-氧化铁复合体的表征及其对不同形态磷的吸附特性[J].土壤学报,2019,56(6):1381-1389.
XU Haijuan,WANG Rui,WEI Shiyong,FANG Dun,YANG Xiaohong.Montmorillonite-Iron Oxides Complex:Characterization and Features of Adsorbing Phosphates Different in Form Complex of Montmorillonite[J].Acta Pedologica Sinica,2019,56(6):1381-1389
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蒙脱石-氧化铁复合体的表征及其对不同形态磷的吸附特性
许海娟, 王 锐, 魏世勇, 方 敦, 杨小洪
湖北民族大学化学与环境工程学院,生物资源保护与利用湖北省重点实验室
摘要:
制备了蒙脱石-针铁矿复合体(Mt-Goe)和蒙脱石-非/弱晶质氧化铁复合体(Mt-HFO),研究了它们的结构、表面性质及其对无机磷酸盐(Pi)和植酸(IHP)的吸附特性。结果显示,Mt-Goe中少量羟基铁离子进入了蒙脱石晶层间导致其层间距增大,针铁矿颗粒较好地包被在蒙脱石外表面;Mt-HFO中蒙脱石层间则发生了Fe3+水解,生成了(羟基)铁氧化物,并在蒙脱石表面形成非晶质氧化铁颗粒。蒙脱石、Mt-Goe和Mt-HFO的比表面积分别为258.7、185.4和226.4 m2 ?g-1 ,其表面分形度、等电点和表面羟基含量均依次升高,pH5.5时的表面Zeta电位分别为-46.1、-13.6和-19.4 mV。3种样品对Pi和IHP的吸附模式以匀质性表面单层吸附为主,Langmuir饱和吸附量(qmax)和吸附亲和力均表现为由大到小依次为Mt-HFO、Mt-Goe、蒙脱石。3种样品对Pi和IHP的动力学吸附过程适合用准二级动力学模型描述,其速率常数由小到大依次为Mt-HFO、Mt-Goe、蒙脱石。与吸附Pi相比,3种样品吸附IHP的动力学速率常数明显减小,吸附量明显增大;Mt-HFO对IHP的吸附速率尤其缓慢,而吸附量远大于对Pi的吸附量。
关键词:  蒙脱石-氧化铁复合体  表面性质  吸附  磷酸盐  植酸
DOI:10.11766/trxb201902150626
分类号:
基金项目:国家自然科学基金项目(41561053)、生物资源保护与利用湖北省重点实验室项目(PKLHB1904)和湖北省“双一流”建设专项资金项目资助
Montmorillonite-Iron Oxides Complex:Characterization and Features of Adsorbing Phosphates Different in Form Complex of Montmorillonite
XU Haijuan, WANG Rui, WEI Shiyong, FANG Dun, YANG Xiaohong
School of Chemistry & Environmental Engineering, Hubei Key Laboratory of Biologic Resources Protection and Utilization, Hubei Minzu University
Abstract:
【Objective】In soils iron oxides often congregate with lamellar phyllosilicates into various complex-like structures, thus generating significant impacts on physical and chemical properties of the soils. Phosphorus is an essential nutrient for growth of organisms in ecosystems, but may lead to eutrophication and deterioration of water quality, once it accumulates excessively in the soils. In soils phosphorus tends to be adsorbed onto minerals, and hence its mobility and bioavailability is significantly affected. Its adsorption by iron oxide-phyllosilicates associate differs from that by iron oxides and phyllosilicates separately in behavior. Yet, little has been done to explore effects of iron oxides-montmorillonite complex on speciation and bioavailability of phosphorus in soils. 【Method】In this paper, Montmorillonite-goethite complex (Mt-Goe) and complex of montmorillonite with amorphous or poorly crystalline iron oxides (Mt-HFO) were prepared, separately, and analyzed for structure, surface properties and features of adsorbing phosphate (Pi) and myo-inositol hexakisphosphate (IHP). 【Result】In Mt-Goe a small amount of hydroxyiron ions entered into the layers of montmorillonite, thus expanding the interlayer space, while montmorillonite was covered with goethite particles on the surface. In Mt-HFO, Fe3+ in-between the layers of monymorillonite hydrolyzed into hydroxy iron oxide and formed a layer of amorphous iron oxides on the surface of monymorillonite. The specific surface area of montmorillonite, Mt-Goe and Mt-HFO was 258.7, 185.4 and 226.4 m2 ?g-1 respectively, with surface fractal, isoelectric point and surface hydroxyl contents being on a rising order; and when pH was 5.5, the surface Zeta potential of the three was -46.1, -13.6 and -19.4 mV respectively. Pi and IHP adsorptions on the three types of samples were all dominated by homogeneous surface mono-layer adsorption. In terms of Langmuir saturated adsorption (qmax) and adsorption affinity, the three samples followed a decreasing order of Mt-HFO > Mt-Goe > montmorillonite. The pseudo-second-order kinetic model could be used to well fit Pi and IHP kinetic adsorption processes of the three samples, with adsorption rate constant following an order of Mt-HFO > Mt-Goe > montmorillonite. Compared to Pi, IHP was significantly lower in adsorption kinetic rate constant on the three samples, but significantly higher in qmax, and particularly low in adsorption rate on Mt-HFO, but much higher in qmax. 【Conclusion】Compared to montmorillonite, Mt-Goe and Mt-HFO are both lower in Pi and IHP adsorption rate, but higher in adsorption capacity. Among the two complexes, Mt-HFO is lower in Pi and IHP adsorption rate, but higher in adsorption capacity. All the three types of samples, montmorillonite, Mt-Goe and Mt-HFO, are lower in IHP adsorption rate than in Pi one, but much higher in IHP adsorption capacity than in Pi one.
Key words:  Montmorillonite-iron oxides complex  Surface properties  Adsorption  Phosphate  Myo-inositol hexakisphosphate