黏土矿物污染控制材料及其高效利用

黏土矿物具有特殊的纳米片层结构、含可交换性层间阳离子、微观结构及表面物理化学性质易调控;因此,黏土矿物及其改性产物对多种环境污染物有良好的吸附/催化性能,在污染控制领域有良好的应用前景。近年来,课题组以蒙脱石和层状双金属氢氧化物(LDH)为代表,研究了它们在污染控制领域的资源利用:1)研究了蒙脱石、LDH、LDO(LDH煅烧产物)对染料分子的吸附特征,发现它们对染料分子的吸附性能可优于活性炭;通过碳化处理废弃黏土矿物的方法,制备了系列类石墨烯纳米碳材料及多孔碳材料,所得碳材料显示了良好的电催化性能或吸附性能。2)研究了蒙脱石对重金属离子的吸附特征,并通过热处理实现了重金属离子的层间域/片层结构内的原位锁定。3)研究了羟基金属改性蒙脱石对重金属离子和含氧酸根的协同吸附机制,并发现吸附产物(如吸附了磷酸根和Cu2+的羟基铁柱撑蒙脱石)可用于光催化降解有机污染物。4)综合运用实验研究和分子模拟技术,研究了有机改性蒙脱石对疏水性有机污染物的吸附机制,发现表面活性剂堆垛密度是决定有机黏土吸附性能的关键因素,并采用阳离子聚合物来调控层间域表面活性剂堆垛密度,优化了有机黏土吸附性能。5)采用阳离子表面活性剂和羟基金属共同插层的方法,制备了有机-无机复合蒙脱石,发现了其能同时吸附有机物和含氧酸根离子。课题组的研究工作综合运用了实验研究和分子模拟,包括了基础理论研究和应用研究,涉及了黏土矿物及其改性产物的吸附、催化性能,并探讨多种废弃黏土矿物的资源回用技术。研究结果对实现黏土矿物在污染控制领域的高效资源利用提供了新信息。     

有机污染物在改性黄土中的吸附和迁移滞后性研究

用阳离子表面活性剂十六烷基三甲基溴化铵（HDTMA-Br）和阴离子型表面活性剂十二烷基苯磺酸钠（SDBS）对黄土进行改性处理，并制备了一系列土壤样品。比较了甲苯在天然黄土和改性土中的不同吸附特性，并探讨了它们不同的吸附机理。通过比较甲苯在两类土壤中的吸附特性可以发现，等温吸附曲线均符合弗德里希方程式．但改性黄土的吸附能力为天然黄土的3—6倍。当同时用阴一阳离子表面活性剂进行黄土改性，吸附能力比单独使用阳离子表面活性剂改性的黄土增强15％-20％。土柱实验证明改性黄土对有机污染物对硝基苯胺的迁移具有明显的滞后性，使污染带前锋到达土柱出水口的时间延迟了50倍，也使土柱被穿透的时间延长了3.5倍。可见用表面活性剂对黄土改性能有效地在包气带滞留污染物。在一定程度上延缓或防止地面石油泄漏对含水层的污染。     

坡缕石粘土的磷吸附机制及其铁负载效果研究

比较了3种天然坡缕石粘土对不同程度磷污染水体的吸附净化能力,通过等温吸附实验和吸附动力学实验探讨了坡缕石粘土的磷吸附机制,并研究了不同形态铁负载对坡缕石粘土吸附净化磷污染水体性能和机制的影响.结果发现,3种天然坡缕石粘土对不同程度磷污染水体均有一定的吸附净化能力,其中含白云石较多的坡缕石粘土的磷吸附能力最强,吸附等温曲线呈S型,且Freundlich方程(R2=0.977 6)比Langmuir方程(R2=0.924 9)拟合效果更好;准一级方程、冥函数方程、抛物线扩散方程、准二级方程均能较好地模拟坡缕石粘土对磷的吸附动力学过程,说明坡缕石粘土对磷的吸附可能属于不均匀介质的多分子层吸附.此外,不同形态铁负载均能显著增强坡缕石粘土对不同程度磷污染水体的吸附净化能力,吸附等温曲线呈L型,Langmnir方程(Fe2 :R2=0.96,Fe3 :R2=0.967 7)比Freundlich方程(Fe2 :R2=0.965 7,Fe3 :R2=0.936 1)能略好地拟合铁负载坡缕石粘土的磷吸附等温结果,说明铁负载坡缕石粘土的磷吸附过程可能是均匀介质的单分子吸附.适量白云石有助于提高坡缕石粘土的磷吸附净化性能,铁负载可能通过改变坡缕石的表面电荷和吸附活性位点来改变其磷吸附机制,从而提高其磷吸附性能.     

不同表面活性剂修饰TiO2柱撑粘土的制备及其光催化活性研究

本文分别采用阴离子、非离子、阳离子三种不同类型的表面活性剂对河北蒙脱石进行改性修饰,并以酞酸丁酯和盐酸分别为前驱物和酸催化剂,采用溶胶-凝胶法（Sol-gel）制备了不同表面活性剂修饰TiO2柱撑粘土催化剂.用X射线粉末衍射（XRD）和场发射扫描电子显微镜（SEM）等手段表征了催化剂的微观结构,以2,4,6-三氯苯酚（2,4,6-trichlorophenol, TCP）和甲基橙染料的吸附、降解为模型反应,考察了改变溶胶和表面活性剂的不同添加顺序对阳离子表面活性剂所修饰的催化剂性质的影响,以及不同类型的表面活性剂修饰所得的催化剂的光催化活性.实验结果表明,通过添加不同的表面活性剂能够不同程度地改变柱撑粘土的BET比表面积,并使其对不同目标污染物具有不同的吸附能力和光催化活性.阴离子表面活性剂十二烷基苯磺酸钠（DBS）修饰的TiO2柱撑粘土具有较好的光催化活性,其次是非离子表面活性剂聚乙烯醇（PVA）修饰的TiO2柱撑粘土,而阳离子表面活性剂十六烷基三甲基溴化铵（CTMAB）修饰的柱撑粘土光催化活性较差.     

改性硅藻土对水中DDTs的吸附机理

采用阳离子表面活性剂(十六烷基三甲基溴化铵)对硅藻土进行改性, 并以优选的改性方案为基础, 研究了该有机硅藻土对水中有机氯农药DDTs(p, p'-DDT、p, p'-DDE和p, p'-DDD)的吸附过程及增强机理.结果表明, 十六烷基三甲基溴化铵能有效改变硅藻土的Zeta电位、比表面积和表面疏水性质, 从而提高硅藻土吸附有机氯农药的能力.改性硅藻土对水中3种有机氯农药的吸附能力依次为: p, p'-DDT>p, p'-DDE>p, p'-DDD.基于模型的准确性(R2值)考虑, Redlich-Peterson方程能更好地用于拟合DDTs在改性硅藻土上的等温吸附曲线.      

坡缕石对直接耐酸大红4BS的吸附动力学特征

研究了坡缕石对水中直接耐酸大红4BS的吸附动力学,在初始质量浓度为30~50 mg/L,转速为100~200 r/min,以及温度为303~348 K的范围内,坡缕石对直接耐酸大红4BS的吸附动力学数据均符合准二级速率方程。结果表明,坡缕石对直接耐酸大红4BS的吸附是外表面吸附,吸附表观活化能为11.92 kJ/mol,说明此吸附是由液膜扩散控制的物理吸附过程。     

铁氧化物改性坡缕石粘土对Cr(Ⅵ)的吸附性能

以铁氧化物对坡缕石粘土进行包覆改性,通过静态吸附实验研究了改性坡缕石吸附Cr(Ⅵ)的特性,探讨了吸附的动力学特征、吸附平衡、热力学参数和吸附机理。结果显示,改性坡缕石对Cr(Ⅵ)的吸附随溶液初始pH值的升高显著减弱,在初始pH值为4.0时,吸附90 min可达平衡,吸附过程能较好地符合pseudo-second-order动力学方程,速率常数k₂随温度的升高增大,表观活化能为18.90 kJ/mol;吸附平衡能较好地符合Langmuir方程,吸附过程吸热,ΔH为28.29 kJ/mol,ΔG为-25～-20 kJ/mol,是物理吸附和化学吸附并存的过程。     

坡缕石黏土负载铁锰复合氧化物吸附磷的性能

以氧化还原共沉淀的方法将铁锰复合氧化物负载于坡缕石黏土表面,制备负载型吸附剂,由静态吸附实验研究了吸附剂对磷的吸附性能,探讨了吸附的动力学特征、热力学参数和吸附机理。结果显示,吸附剂对磷的吸附受溶液初始pH值、吸附时间及温度的影响,在中性条件下吸附平衡时间为90 min,pseudo-second-order吸附动力学方程能较好描述吸附过程,吸附表观活化能为11.76 k J/mol;吸附等温线与Freundlich方程的拟合结果略优于Langmuir方程,由Langmuir方程得到最大吸附量为26~31 mg/g。吸附焓变为9.29 k J/mol,吸附熵变为正值,自由能变为-4.3~-5.8 k J/mol,吸附作用有多层不均匀吸附的性质,同时包含物理作用和化学作用,但不属强的化学键作用。     

混合表面活性剂对长石、石英浮选分离的影响

采用单矿物浮选、Zeta电位和芘荧光探针,研究由DDA和SDS组成的阴阳离子混合表面活性剂在不同的浮选条件下对长石、石英分离效能影响以及表面活性剂在矿物表面的吸附行为。结果表明:在相同浓度阴阳离子混合表面活性剂中,长石的疏水性要强于石英;Zeta电位在DDA∶SDS=1∶1时主要由阳离子决定,在DDA∶SDS=1∶2、1∶3时由阴离子决定。芘荧光探针结果表明:在pH=2.0,长石和石英表面极性在低浓度混合表面活性剂中与浓度呈负相关;在DDA∶SDS=1∶1、浓度为4×10-4 mol/L时,混合表面活性剂在矿物表面形成半胶束,且长石表面形成半胶束浓度低于石英。当DDA∶SDS=1∶2、1∶3时,长石表面形成半胶束浓度提高,而石英未能在实验条件内形成胶束。综合而言,在同一混合表面活性剂条件下,长石表面疏水性强于石英。     

坡缕石吸附水中阳离子桃红FG染料的热力学研究

研究了纯坡缕石对水中阳离子桃红FG染料的吸附热力学及其机理。结果表明：在298．328K和实验浓度范围内,纯坡缕石对水中阳离子桃红FG染料的吸附是吸热过程,吸附等温线符合Langmuir方程。根据热力学函数关系计算出坡缕石对阳离子桃红FG的吸附焓变为0．49kJ／mol,吉布斯吸附自由能改变量为-27．48-30．29kJ／mol,吸附自由能的变小是阳离子桃红FG染料在纯坡缕石上吸附的推动力,吸附熵变为93．85J／rnolK。     

Adsorption of reactive dyes from aqueous solutions by tannery sludge developed activated carbon: Kinetic and equilibrium studies

Adsorption kinetic and equilibrium studies of two reactive dyes, namely, Reactive Red 31 and Reactive Red 2 were conducted. The equilibrium studies were conducted for various operational parameters such as initial dye concentration, pH, agitation speed, adsorbent dosage and temperature. The initial dye concentration was varied from 10 - 60 mg/L, pH from 2–11, agitation speed from 100–140 rpm, adsorbent dosage from 0.5 g to 2.5 g and temperature from 30 °C -50 °C respectively. The activated carbon of particle size 600 μm was developed from preliminary tannery sludge. The dye removal capacity of the two reactive red dyes decreased with increasing pH. The zero point charge for the sludge carbon was 9.0 and 7.0 for the two dyes, respectively. Batch kinetic data investigations on the removal of reactive dyes using tannery sludge activated carbon have been well described by the lagergren plots. It was suggested that the Pseudo second order adsorption mechanism was predominant for the sorption of the reactive dyes onto the tannery sludge based carbon. Thus, the adsorption phenomenon was suggested as a chemical process. The adsorption data fitted well with Langmuir model than the Freundlich model. The maximum adsorption capacity(q⁰) from Langmuir isotherm were found to have increased in the range of 23.15–39.37 mg/g and 47.62–55.87 mg/g for reactive dyes reactive red 31 and reactive red 2, respectively.     

Metal accumulation rates in northwest Atlantic pelagic sediments

Measurements of ²³⁰Th, ${}^{87}\text{Sr}{}^{86}\text{Sr}$ and twenty-four metals were made on cores from the Nares Abyssal Plain. The sediment is characterized by slowly-accumulating (0.3–0.7 g/cm² 10³ yr) pelagic red clays and rapidly deposited grey clays transported by turbidity currents. Despite their colour differences and the enrichment of Mn, Fe, Cu, Co, Ni, Zn, V and, to a lesser degree, the rare earths in the red clays, Sr isotope evidence demonstrates that the clays have the same terrigenous origin. The excesses of metals in the red clays have been attributed to metal removal from the water column and a comparison with the grey clays has enabled the authigenic fluxes of metals to be estimated. The fluxes obtained are in the ranges 20–50 μmol/cm² 10³ yr for Mn and Fe, 0.1–0.4 μmol/cm² 10³ yr for Cu, Co, Ni, Zn, V, Sr and Ce, 10–20 nmol/cm² 10³ yr for La and Nd, and 0.5-3 nmol/cm² 10³ yr for Sm, Eu, Gd, Dy, Er and Yb. Authigenic fluxes of Y, Nb, Cr, Zr, Rb, U and Th were not resolvable. Fluxes appear to be near constant on the Plain but comparison with other areas shows that they are quite variable both between and within ocean basins. The chief factor controlling authigenic fluxes is the geochemical abundances of the elements but fractionation within both the transition element and rare earth series can be recognized from inter-element comparisons and from differences in fluxes between Atlantic and Pacific red clays corresponding to the oceanic reactivities of the elements.     

Assessment of raw clays from Maghnia (Algeria) for their use in the removal of Pb<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> ions from industrial liquid wastes: a case study of wastewater treatment

Homogenized samples of raw clays resulting from two (2) different lots of natural clays from Maghnia (Algeria) have been assessed for their potential use in the removal of Pb²⁺ and Zn²⁺ ions from industrial liquid wastes (LW). Raw and acid-activated samples have been characterized by powder X-ray diffraction, FT-IR spectroscopy, electron microscopy (SEM), and X-ray fluorescence (XRF) and used as adsorbents for the removal of Pb²⁺ and Zn²⁺ ions from aqueous system using adsorption method under different conditions. The effect of factors including contact time, pH, and dosage on the adsorption properties of Pb²⁺ and Zn²⁺ ions onto clays was investigated at 25 °C. The obtained results revealed that the removal percentages of Pb²⁺ and Zn²⁺ ions, from both aqueous solution (AS) and LW, were varying between 90 and 98% for 40 min and optimal pH values ranged from 5 to 6 for Pb²⁺ and Zn²⁺ ions, respectively. The kinetics of both Pb²⁺ and Zn²⁺ ion adsorption fitted well with the pseudo-second-order model. Langmuir, Freundlich, and Temkin adsorption isotherms were used, and their constants were evaluated. The values of thermodynamic parameters, ΔH°, ΔS°, and ΔG° indicated that the adsorption of Pb²⁺ and Zn²⁺ ions was spontaneous and exothermic process in nature. The adsorption and desorption isotherms indicated that Pb²⁺ and Zn²⁺ adsorption to raw clays was reversible. The experimental results obtained showed that the raw clays from Maghnia (Algeria) had a great potential for removing Pb²⁺ and Zn²⁺ ions from industrial liquid wastes using adsorption method.     

The geochemistry and mineralogy of the Permian red beds of Southwest England

Detailed mineralogical and chemical examination of some hundred rock samples representing the Permian red bed sequence of Southwest England has been carried out. Mineral—element correlations are presented and factor analysis of the chemical data shows that 80% of the variance can be explained by seven factors. Among these are recognised a clay factor; detrital minerals versus carbonate factor; halide and sulphate factors and a volcanic enrichment factor. The behaviour of elements in the strong oxidising environment associated with red bed deposition is discussed. In particular, zirconium is shown to be enriched in red bed clays, reflecting solution from the source area. Cerium, in its oxidised state as Ce⁴⁺ is shown to be strongly correlated with the carbonate phase, indicating its tendency to form relatively stable carbonate complexes. Strontium is positively correlated with the clays and negatively correlated with carbonate, while sulphur (as SO₄^2?) is associated with carbonate usually in the form of barytes. The origin of the red pigment is also discussed.     

Stabilization of swelling clays by Mg(OH)2. Changes in clay properties after addition of Mg-hydroxide

Stabilization of the swelling clay structure is attempted by intercalation of Mg(OH)₂ and the development of a brucite interlayer between the clay layers. The properties of the product obtained by applying the technique, formulated as described in a previous work, are considered here. The materials used were Wyoming bentonite (USA), Fuller's Earth (UK), kaolinite, illite, lignite, and silica gels. The Mg(OH)₂-clay products were examined by the methylene blue dye test, X-ray diffraction analysis (XRD), differential thermal analysis (DTA), and derivative thermogravimetry analysis (DTGA). From the results obtained it is concluded that: the Mg-hydroxide is adsorbed by swelling clays both on their external and internal surface, whereas it is adsorbed on the external surface by non-swelling clays. The internally adsorbed phase of Mg-hydroxide forms an ill-defined interlayer of brucite, retarding swelling, whereas the external phase covers the particles modifying drastically their surface properties, like the adsorption of the MB dye. The material produced after precipitation of Mg-hydroxide on swelling clays (smectites) did not re-expand on wetting or after glycolation. The adsorption of MB dye was also reduced by some 80–90%, due to coating effect, preventing the measurements of the external surface area of the clay by polar molecules. The principal forces involved in the process are believed to be physical adsorption on the external surface, along with chemisorption and some chemical bonding, mostly in the internal surface. Cementation due to crystallization and, in the long term, some pozzolanic reactions take also place. Internal adsorption of the Mg-hydroxide is postulated to be in the form of positively charged mono- and/or small polymers and it is, chiefly, diffusion controlled. Since Mg-hydroxide is internally adsorbed by swelling clays, whereas Ca-hydroxide(lime) is not, and the (Mg, Ca)-clay aggregates are more stable than the Ca-clay or the Mg-one, the combination of the two hydroxides could give better results in soil stabilization than each hydroxide alone.     

不同粘土矿物对赖氨酸的吸附行为对比研究

以皂石、高岭石、绿泥石和伊利石为原材料,分别与赖氨酸进行反应,研究赖氨酸在上述粘土矿物上的吸附行为, 并运用粉末X-射线衍射技术（XRD）、傅里叶变换红外吸收光谱术（FTIR）和热重（TG）等分析方法,表征反应前后粘土 矿物的变化。实验结果表明,不同粘土矿物对赖氨酸的吸附等温线均符合Freundlich等温方程,且不同粘土矿物对赖氨酸的 饱和吸附量大小顺序为：皂石>蒙脱石>绿泥石>高岭石>伊利石;XRD结果表明皂石对赖氨酸的吸附发生在矿物层间,而绿 泥石、高岭石和伊利石对赖氨酸的吸附主要在矿物表面进行;FTIR和TG结果表明赖氨酸主要取代粘土矿物层间吸附水,以 氢键的形式与Si-O-Si(IVAl)键合。实验结果将有助于进一步探明环境中粘土矿物对有机质的吸附机理。     

吕梁山西麓复兴剖面红黏土的磁性地层学研究

吕梁山西麓中上新世的一套厚层红黏土层记录了吕梁山前盆地的演化和吕梁山新近纪的隆升。山前不同的构造部位,各异的古地貌特征导致红黏土的堆积特征差别较大,柳林复兴地区黏土层的下部常含有数层化石层和薄厚不等的砾石层。本文对复兴地区的红黏土进行了岩石磁学和磁性地层学研究,得出了复兴地区红黏土及所含砾石层和化石层的古地磁年龄,并通过野外沉积特征以及粒度等指标探讨了复兴地区红黏土的形成过程。岩石磁学结果表明,红黏土中特征剩磁的载体为磁铁矿和赤铁矿。古地磁和生物化石显示复兴剖面的年龄为7.1～2.6Ma。其中所含厚层砾石层的古地磁年龄约为5.2Ma。两层化石层的年龄分别为～6.8Ma和～7.1Ma。剖面野外沉积特征和粒度变化显示柳林复兴地区红黏土堆积初期有水流作用的参与。     

Mobility of arsenic and trace element inventories in sediment cores from Masuda City,southwestern Japan

The vertical distribution of arsenic and other trace and major elements has been studied in four sediment cores from Masuda City, Nagashima and Okite in the Shimane Prefecture of southwestern Japan. The sediment cores were also subjected to leaching techniques and ¹⁴C dating. The stratigraphic sequences in the cores consist of silt and sandy silt at top, passing downward into gray to black clays. Elevated values of As, Pb, Zn, Cu, Ni, Cr, and V are present in several horizons while abundances of these elements tend to be higher in the black and gray clays, probably due to adsorption onto clay sediments. Higher concentrations of Fe and total sulfur (TS) occur in black clays. The correlations of the trace metals with iron suggest their adsorption onto Fe (oxy)hydroxides, whereas correlations with sulfur in some cores indicate that they were precipitated as Fe-sulfides. Age determinations suggest that clay horizons at ∼5 m depth were deposited at around 5,000 and 6,000 years BP (¹⁴C ages) during the transgressive phase of sea level change. The results of the leaching techniques in the core samples show that higher amounts of As were extracted with deionized water. Even at neutral pH, As can be released from sediments to groundwater, and therefore groundwater pollution is a concern in Masuda City and the surrounding area.     

Partition of radiotracers between suspended particles and seawater

Distinctive uptake mechanisms of different radiotracers by red clays in seawater are elucidated from the magnitude and change of distribution coefficients (K_d) for up to 17 γ-emitting radiotracers as functions of equilibration time, suspended particle concentration and compositions of solids and seawaters. The adsorption of ionic metals onto colloids and subsequent coagulation of colloids onto larger particles are the dominant removal processes of metals in the aquatic environments of low suspended particle concentration.     

江西泰和第四纪红色粘土的矿物特征

第四纪红色粘土在我国南方分布很广,最典型的分布在华中岗地上,土层较厚,上部土质均匀,下部具有红白网纹并含砾石,大都是中更新世的洪积-冲积或残积-坡积物,笔者认为可能是间冰期比较暖热气候条件下的产物。熊毅早就指出:各地环境殊异,地形复杂,母岩不同,其理化特征将随之而异。第四纪红色粘土来自不同的堆积相,和经受不同的风化和成土过程,这将在矿物组成方面反映出来。土壤普查的结果表明,第四纪红色粘土按其分布的地形部位,成因和物质来源,可分成两类:一类是残积坡积相，为中更新世较早的暗红色沉积物，即Q₂另一类是冲积相，为中更新世较晚的红化程度较轻的淡红色沉积物。它们都经历了中更新世至今的成土过程1)”。为了查明它们的差异，并有助于第四纪沉积物的研究，笔者用部分标本进行矿物分析，并对初步结果进行讨论。