滨海地区不同质地土壤对垃圾渗滤液中氨氮的吸附作用

为了探讨粉砂、粉质粘土、粉土对垃圾渗滤液中NH4+-N的吸附作用,在室内做了吸附实验,实验结果表明,三种土样吸附NH4+-N的等温吸附曲线均符合Langmuir模式,且最大吸附量分别为粉砂1.3 034 ms/g,粉质粘土1.109 mg/g,粉土0.3 439 mS/S.不同土样吸附NH4+-N的能力差异较大,三种土样的吸附顺序为:粉砂>粉质粘土>粉土;三种土样的迟滞因子分别为粉砂27.939,粉质粘土21.782,粉土18.257,说明粉砂和粉质粘土的防污能力较粉土强.     

凹凸棒石、膨润土和活性炭吸附油中色素的研究

通过对凹凸棒石和膨润土酸活性点的测定和比较,以及对凹凸棒石、膨润土和活性炭的比表面积、孔径分布以及对油中叶绿素和胡萝卜素吸附的比较研究结果表明:凹凸棒石的B-、L-酸活性点均比膨润土高;对于膨润土和凹凸棒土,酸活性点多、孔径较大、比表面积大对叶绿素和胡萝卜素的吸附越有利,L-酸活性点主要吸附胡萝卜素;吸附剂在对叶绿素和胡萝卜的吸附过程中,起决定作用的是吸附剂与吸附质之间的相互作用力,只有在作用力较强时,比表面积和孔径分布才会对吸附效果产生影响。     

多离子体系中黄河沉积物对重金属的竞争吸附研究

以黄河包头段上游清洁河段的沉积物为吸附剂,以Pb2 + 、Cu2 + 、Zn2 + 、Cd2 + 4种离子的混合溶液体系为吸附质,开展了重金属离子在黄河沉积物中的竞争吸附及其影响因素等实验研究。结果表明,混合溶液体系中不同离子间的吸附竞争有显著的拮抗或协同效应关系,4种重金属离子在黄河沉积物中竞争吸附的能力依序为Pb2 + ≥Cu2+>Zn2 + ≥Cd2 + 。     

粉煤灰-粉质粘土对氟离子的吸附作用

不同土层对氟离子的吸附能力不同,在吸附能力较弱的土层建设贮灰场,会导致周边地下水中氟离子质量浓度较高,污染地下水。吉林市来发屯灰场运行多年来,地下水中氟离子质量浓度与背景环境未见明显差异,本文通过对来发屯灰场粉煤灰-粉质粘土和灰场外土层的比较分析,探究吸附机理,结果表明：粉煤灰-粉质粘土对氟离子有较强的吸附能力,能有效防止其对地下水的污染。     

粉煤灰/膨润土颗粒的制备与pb2+吸附实验

以天然钙基膨润土和燃料废弃物粉煤灰为原料,工业淀粉为致孔剂,采用挤出-滚圆技术,制备了粉煤灰/膨润土复合颗粒吸附剂,并用于含Pb~(2+)溶液的吸附。研究了吸附时间、pH、投样量和溶液初始浓度对吸附性能的影响。结果表明,采用挤出-滚圆法制得的复合颗粒吸附剂大小均匀,表面没有裂纹,具有良好的机械强度。吸附实验中,在投样量10.0 g/L,溶液pH为6,吸附时间120 min,溶液初始浓度100 mg/L时,复合颗粒吸附剂对Pb~(2+)的去除率达到97.40%,吸附量为9.74mg/g。热力学实验表明吸附剂对Pb~(2+)的吸附更符合Langmuir吸附等温模型。     

改性沸石对重金属离子竞争吸附特性研究

以钠型改性沸石为吸附剂,以含有单一的镉、锌、铅溶液以及镉、锌、铅的混合溶液为吸附质,开展了改性沸石中重金属离子的竞争吸附及其影响因素等实验研究。结果表明,当溶液中有多种二价重金属离子存在时,各离子之间存在竞争吸附,竞争能力为Pb2+>Cd2+>Zn2+;Zn2+-Cd2+表现出显著的协同吸附效应,而Zn2+-Pb2+、Cd2+-Pb2+表现出拮抗吸附。     

吸附离子对粉质粘土及改良土特性的影响

利用疏浚土有机质含量高、吸附能力强和低渗透性等特点,探讨将其作为填埋场黏土衬垫改性材料的可能性。针对粘土垫层所关心渗透性及强度两个基本问题,比较了粉质黏土、改良土（粉质黏土添加疏浚土）吸附离子前后的变化。吸附K+、Cu2+后粉质黏土、改良土的渗透系数随着土中离子含量的增加而增大,但对改良土渗透系数的影响要小于粉质黏土;吸附离子后,粉质黏土摩擦角增幅不大,黏聚力有较大增长,而改良土的黏聚力增长较少,摩擦角增长较快。总体而言,添加一定量的疏浚土能改善吸附离子对黏土垫层的影响。采用SEM电镜试验拍摄了离子吸附前后土体微观结构的变化,并从扩散双电层理论出发,解释了吸附离子对粉质黏土及改良土的影响。     

电气石对重金属离子Pb(Ⅱ)和Cu(Ⅱ)作用机理研究

<正>本文以河北灵寿电气石为吸附剂,以重金属离子Pb2+、Cu2+为吸附质,研究了电气石在水相中对吸附质吸附时的各试验条件与吸附效果之间的关系。结果表明,电气石对水中的Pb2+、Cu2+重金属离子有良好的吸附效果。Langmuir     

夏子街膨润土在碱性染料废水处理中的应用研究

以纳基和钙基夏子街膨润土为吸附剂,通过改变吸附时间、吸附剂用量、染料溶液浓度、初始pH值分析其对碱性红46和碱性兰41脱色率的影响,并对其吸附动力学、吸附热力学和吸附机理进行了研究.结果表明,2种膨润土对2种碱性染料废水的最佳脱色条件具有一定差异.准一级动力学模型对膨润土吸附碱性染料废水的过程描述更准确,膨润土对碱性红46的吸附是自发吸热反应,对碱性兰41的吸附是自发放热反应,膨润土对2种碱性染料废水的吸附既有物理吸附也存在离子交换吸附.     

高表面活性矿物对Zn~(2+)的吸附机理及其环境意义

本文利用高表面活性矿物蒙脱石、蛭石、沸石在一定的介质条件下对Zn2 +进行吸附实验研究。蒙脱石和蛭石对Zn2 +的等温吸附线呈双“S”型 ,而沸石对Zn2 +的等温吸附线则呈“Langmuir”型。三种矿物对Zn2 +的吸附容量大小顺序为 :蒙脱石 >蛭石 >沸石。运用粉晶X射线衍射、红外光谱、差热及热重分析等技术对矿物及矿物吸附Zn2 +后的结构特征进行了研究。结果表明 ,蒙脱石吸附锌后其层间域中吸附锌大量水解形成新的物相 ,而蛭石与沸石吸附锌后水解很少。这为利用高表面活性矿物控制和治理环境污染及其可循环利用提供了理论依据。     

循环荷载下粉质中液限黏土和粉煤灰土的动剪强度研究

通过对路基填料粉质中液限黏土和粉煤灰土的动力循环荷载试验,分析了粉质中液限黏土和粉煤灰土1: 2的动力特性,得出了动剪强度与循环荷载次数间的变化规律以及动模量与动应变的关系表达式。研究结果表明：粉煤灰土1: 2动剪强度优于粉质中液限黏土,可以作为路基填料。     

Reduction of Expansive Index,Swelling and Compression Behavior of Kaolinite and Bentonite Clay with Sand and Class C Fly Ash

Swelling behavior of expansive soil has always created problems in the field of geotechnical engineering. Generally, the method used to assess the swelling potential of expansive soil from its plasticity index, shrinkage limit and colloidal content. Alternative way to evaluate swelling behavior is from its expansive index (EI) and swelling pressure value. The present study investigates the reduction of EI and swelling pressure for kaolinite and bentonite clay when mixed with various percentages of Ottawa sand and Class C fly ash. The percentages of Ottawa sand and Class C fly ash used were 0–50 % by weight. The results show that there is a significant reduction in the swelling properties of expansive soil with the addition of Ottawa sand and Class C fly ash. The reduction in EI ranged approximately from 10 to 50 and 4 to 49 % for kaolinite and bentonite clay, respectively. Also the maximum swelling pressure of kaolinite and bentonite clay decreased approximately 93 and 64 %, respectively with the addition of various percentages of Ottawa sand and Class C fly ash. Standard index properties test viz., liquid limit, plastic limit and linear shrinkage test were conducted to see the characteristics of expansive soil when mixed with less expansive sand and fly ash. Also, for these expansive soils one dimensional consolidation test have been conducted with sand and fly ash mixtures and the results were compared with pure kaolinite and bentonite clay.     

Feasibility of using fly ash,lime, and bentonite to neutralize acidity of pore fluids

Acidic groundwater resulting from the poorly planned use of acid sulfate soils has become a major environmental issue in coastal Australia over the last several years. Use of permeable reactive barriers (PRBs) designed to generate alkalinity by promoting sulfate reduction has recently become popular as an alternative solution to this problem. However, recent studies have also revealed that the long-term performance of such PRBs can be significantly undermined by chemical precipitation and clogging of pore space, which would decrease the buffer capacity and hydraulic conductivity of the reactive material. This study seeks to explore the feasibility of using bentonite in addition to lime and fly ash to form mixtures with a high buffer capacity and permeability that would enable groundwater flow through PRBs over a substantial period of time. A series of laboratory experiments, including buffer capacity and leaching tests, were performed on different mixtures of fly ash with lime and bentonite using acidic fluids of low pH. It was found that the ability of such mixtures to neutralize acidic fluids was mostly controlled by the content of lime. Laboratory data also showed that an addition of bentonite to lime—fly ash mixtures could decrease the buffer capacity of soil. Compaction tests indicated that the presence of bentonite would increase the dry density of mixtures at the optimum moisture content. A series of hydraulic conductivity tests were carried out to study changes in the coefficient of permeability of lime—fly ash mixtures with different contents of bentonite permeated with acidic liquids. The obtained results revealed that the coefficient of permeability of the specimens tended to increase over a period of time, likely due to the changes in the diffuse double layer of bentonite particles.     

粉煤灰土冻融循环后的动力特性试验研究

为研究粉煤灰土作为路基填料的可行性，把易液化的粉煤灰和易冻胀的粉质黏土按干重1：2混合，通过冻融循环后的动三轴试验，研究了粉煤灰土的动力特性，得出了动强度和循环荷载次数及冻融循环次数的数量关系，以及动模量与动应变及冻融循环次数的关系曲线。研究表明，粉煤灰土经过3次冻融后的动力性能指标优于粉质黏土，具有良好的抗冻性及稳定性，可以作为季冻区路基填料。     

武汉地区粉煤灰和膨润土双掺合剂水泥土性能改良试验研究

近年来,水泥土被广泛应用于土体加固工程,其强度与加固效果密切相关。为研究膨润土和粉煤灰掺量对水泥土性能的影响,对25组不同膨润土和粉煤灰掺量的水泥土进行基本力学性能试验。通过抗压强度试验,发现当粉煤灰和膨润土掺量分别为40%和11%时,28 d的水泥土抗压强度最大,为7.30 MPa;当粉煤灰和膨润土掺量分别为20%和7%时,90 d的水泥土抗压强度最大,为7.19 MPa。通过室内直接剪切试验,发现当粉煤灰和膨润土掺量分别为20%和11%时,28 d的水泥土抗剪强度参数粘聚力c最大,为1144.8 kPa;当粉煤灰和膨润土掺量分别为30%和5%时,90 d的水泥土抗剪强度参数粘聚力c最大,为1753.71 kPa。研究成果可以为武汉地区的粉煤灰和膨润土双掺合剂改良水泥土的现场施工提供参考依据。     

Modelling the sorption of Zn and Ni on Ca-montmorillonite

In some previous work titration and Ni/Zn sorption edge/isotherm measurements carried out under a wide variety of experimental conditions on purified Na-montmorillonite were modelled in terms of cation exchange and surface complexation mass action equations. A major objective of the experimental/modelling programme is to understand and predict sorption in commercial bentonite systems. Since montmorillonite is the dominant clay mineral in bentonite and is often present in a mixed Na/Ca form, a natural extension to the previous investigations was to study Ni/Zn sorption on a conditioned Ca-montmorillonite. An important open question was whether the same basic parameters such as site types, site capacities, and acidity constants could be used for both materials and to see to what extent the Ni and Zn surface complexation constants were influenced by the form of the montmorillonite. Sorption edges for Ni and Zn at different Ca(NO₃)₂ background electrolyte concentrations, together with sorption isotherms measured over a range of pH values, are presented and modelled using the MINSORB code. The parameters characterising the sorption of Ni and Zn on Na- and Ca-montmorillonite systems are compared. Finally, examples are given that illustrate how the modelling can provide insight into the sorption processes.     

Studies on Hydraulic Conductivity of Fly Ash-Stabilised Expansive Clay Liners

Earthen barriers or clay liners are a major concern in geo-environmental engineering. They are designed to preclude or reduce leachate migration. Hence, a low hydraulic conductivity (k) is an important parameter in the design of clay liners. Materials such as bentonite and lateritic clays, which have a low hydraulic conductivity at high dry densities, are used in the construction of clay liners. Compacted expansive clays which are high in montmorillonite content also have a very low hydraulic conductivity. When expansive clays are blended with fly ash, an industrial waste, the hydraulic conductivity further reduces as the ash-clay blends result in increased dry densities at increased fly ash contents. Hence, fly ash-stabilised expansive clay can also be proposed as an innovative clay liner material. It is, therefore, required to study various physical and engineering properties of this new clay liner material. Liquid limit (LL) and free swell index (FSI) are important index properties to be studied in the case of this clay liner material. The hydraulic conductivity of this new clay liner material depends on the fly ash content in the blend. Further, parameters such as solute concentration and kinematic viscosity also influence hydraulic conductivity of clay liners. This paper presents experimental results obtained on hydraulic conductivity (k) of fly ash-stabilised expansive clay liner at varying fly ash content and solute concentration. The tests were performed with deionised water (DIW), CaCl₂, NaCl and KCl as permeating fluids. Fly ash content in the blend was varied as 0, 10, 20 and 30 % by weight of the expansive clay, and the solute concentration was varied as 5 mM (milli molar), 10, 20, 50, 100 and 500. It was found that hydraulic conductivity (k) decreased with increasing fly ash content, solute concentration and kinematic viscosity. Further, hydraulic conductivity (k) was correlated with LL and FSI of the clay liner material for different fly ash contents and solute concentrations. Useful correlations were obtained.     

Batch and column experiments to support heavy metals (Cu,Zn and Mn) in alluvial sediments

Laboratory batch sorption and column transport experiments were performed on heterogeneous alluvial soils with a wide range of physical characteristics from wells that are located in the region between Mogan Lake and Eymir Lake, Gölba??, Ankara. The mean values for the K _d of Cu were found to be highest in clay (32550.350 L/kg) and lowest in loamy sand (18170.76 L/kg). The minimum and maximum sorption capacity values (mean values) for Zn were found to be in clay (10985.148 mg/kg) and in silty loam (8597.14 mg/kg) units, respectively. Similarly, the minimum and maximum values for Mn were found in loamy sand (4908.695 mg/kg) and clay (7587.391 mg/kg) units. The non-linear least-squares optimization code “CXTFIT” was used to determine transport parameter values by curve-fitting. The results of the column experiments demonstrate dispersivity values within the range of 0.024–1.13 cm for soil samples.     

Development of synthetic soil mixture for experimental shaking table tests on building frames resting on soft soils

In this study, a synthetic soil mixture has been developed and proposed for experimental soil-structure interaction shaking table tests on building frames with shallow foundations resting on soft soil deposits. The proposed mix provides adequate undrained shear strength to mobilise the required shallow foundation bearing capacity underneath the structural model while meeting both criteria of dynamic similarity between the model and the prototype to model soft soils in shaking table tests. To find the most appropriate mixture, different mixes with different proportions of mix components were examined in the soils laboratory. Performing bender element tests, the shear wave velocity of the soil specimens was acquired at different cure ages and the results were examined and compared. Based on the test results, a synthetic clay mixture consisting of kaolinite clay, bentonite, fly ash, lime and water has been proposed for experimental shaking table tests.