膨润土对汞的吸附性能研究

试验了时间,ｐＨ,用量等对膨润土吸附汞效果的影响,还将有机膨润土与膨润土吸附絮凝对汞的处理作了比较,结果表明,利用廉价的天然膨润土作为吸附剂,用吸附混凝土法处理含汞废水有较高的应用价值。     

有机膨润土吸附硝基苯的性能及其在废水处理中的应用

分别用氯化十六烷基吡啶（ＣＰＣ）和溴化十六烷基三甲铵（ＣＴＭＡＢ）改性膨润，研究了有机膨润土吸附水中硝基苯的性能及其影响因素。２５℃时，ＣＴＭＡＢ－膨润土和ＣＰＣ－膨润土的饱和吸附容量分别为１１７．０ｍｇ／ｇ和８７．６ｍｇ／ｇ。比原土（５８．１ｍｇ／ｇ）有较大的增加，有机膨润土对水中硝基苯的去除率为５０～６０％，比原土（１０．５％）提高了４～５倍将Ａｌ２（ＳＯ４）３与有机膨润土联用处理废水，不但能     

膨润土处理废水中酚的吸附研究

膨润土在我省蕴藏丰富。目前对它的研究及开发利用尚未形成规模,尤其是它的吸附性的应用,报道甚少。本文应用其吸附特性,对工业废水、废渣中的高毒性物质酚类的吸附进行了探讨,并由大量实验数据得出等温吸附经验方程。1 实验部分1.1 水样及材料的处理 用分析纯苯酚与无酚水配制成两组水样,每组12个;膨润土先用氨水浸泡之,     

膨润土处理废水中酚的吸附研究

膨润土是一种具有硅酸盐结构的物质，蕴藏量丰富，但目前对其研究以及进一步开发利用尚未形成规模，尤其是对其吸附性的应用研究，所见甚少。本文就膨润土的吸附特性，应用其对工业废水、废渣中的高毒性物质酚类的吸附进行了探讨，并由大量实验数据得出等温吸附经验方程式。     

柱撑膨润土吸附水溶液中Cr6+的性能研究

研究了无机、有机和无机-有机柱撑膨润土对水中C r6 的吸附去除性能。结果表明:三种柱撑膨润土对C r6 的去除效果明显高于膨润土原土,当投土量为8 g/L时,对C r6 的吸附去除率分别为81.03%、95.41%和85.11%;三种柱撑膨润土对C r6 的吸附在60 m in达到平衡;溶液pH对C r6 的去除有一定的影响,在酸性条件下的去除率略大于中性和碱性;温度升高,C r6 的去除率略有下降。     

微波法制备的有机膨润土及吸附性能研究

研究了利用微波制备双阳型有机膨润土的适宜条件,对微波法制备有机膨润土的机理进行了分析,并与常规法合成的有机膨润土在结构与吸附性能方面进行了对比。结果表明,微波法制备双阳型有机膨润土的适宜条件为两种阳离子型表面活性剂总用量为100CEC,微波辐照能量210J/mL。与常规湿法的相比,有机膨润土的层间距、有机碳含量有所提高,对染料的去除率有较大提高。     

交联膨润土吸附磷行为研究

从热力学和动力学两方面讨论了交联膨润土吸附剂对磷的吸附特性。吸附等温式符合Ｌａｎｇｍｕｉｒ公式：Ｃ／ｑｅ＝０．１７Ｃ＋０．４１。吸附热力学模型为ｌｎＣ＝－４４０／Ｔ－０．１２６,吸附动力学特性可用下式描述：ｌｏｇ（ｑｅ－ｑ）＝ｌｏｇｑｅ－Ｋｔ／２．３０３,ｌｎ［１－（ｑ／ｑｅ）２］＝－Ｋｔ。其中,Ｋ＝（π／ｒ）２Ｄ,ｌｎＤ＝－２．５３－７４１．０７／Ｔ。扩散活化能为６．１６１ｋＪ／ｍｏｌ,表明吸附过程受扩散控制。     

PDMDAAC-膨润土对焦化废水的深度吸附处理研究

以聚二甲基二烯丙基氯化铵(PDMDAAC)和钠基膨润土为原料,制备了PDMDAAC-膨润土,发现PDMDAAC-膨润土对焦化废水具有较好的处理效果,PDMDAAC-膨润土在深度处理工业废水方面有广阔的前景。     

有机交联膨润土对预处理造纸黑液COD的吸附研究

主要探讨了有机交联膨润土吸附剂（简称TBC）对经酸化絮凝后的造纸黑液进行处理的研究。当pH=4．5,TBC用量为24g·1－1H2O,常温搅拌吸附60min后,其对COD的吸附效率可达61．5％,吸附容量为549．3mgCOD·g－1。     

微波法制备的有机膨润土及吸附性能研究

有机膨润土应用于废水处理的研究较多，有望成为一种高效吸附剂，有机膨润土是利用表面活性剂改性膨润土而成。传统湿法制备有机膨润土，存在费时、能耗高等缺点。微波具有较强的热效应与非热效应，已应用于新型材料制备、膨润土钠化改型的研究。     

壳聚糖改性膨润土处理实验室废水的研究

利用脱乙酰度为90％、浓度为0．5％的壳聚糖溶液对膨润土进行改性,制备了壳聚糖改性膨润土,并应用于实验室废水,对水处理影响因素进行了优化,在pH=6、投加量为1．2g／mE,搅拌时间分别为10、12rain条件下,改性后膨润土对实验室     

天然沸石FMA吸附剂对磷吸附能力的研究

天然沸石基材经镁、铝等修饰并活化而制得的FMA吸附剂,对磷有较高的吸附能力,其静态吸附量为9.94mg/g,动态吸附量为17.64mg/g。     

改性膨润土在废水处理中的应用

概述了膨润土的主要特性，研究了膨润土的主要改性方法以及改性膨润土在废水处理中的应用，讨论了改性膨润士用于废水处理中存在的问题和今后的研究方向。     

Interaction of bentonite with supercritically carbonated concrete

Bentonite and concrete are essential components in construction of a geological high level nuclear waste (HLNW) repository. Conventional Ordinary Portland Cement (OPC) used for concretes gives a pore water leachate with a pH as high as 13.5 in contact with ground water. This alkaline plume of leaching waters might perturb the engineered barrier system, which might include bentonite buffer, backfill material or the near-field host rock. The accepted solution to maintain the bentonite stability, which is controlled by the pH, is to develop cementitious materials with pore water pH around 11. Four lixiviation experiments representative of long-term interaction of solids and pore fluids at the concrete/bentonite interface were performed with two types of cement paste, Portland and calcium aluminate cement, before and after being carbonated under supercritical conditions, with granite water at 80 °C. The evolution of the pH indicates that the supercritical carbonation reduced the alkalinity of the cement pastes and calcite likely controls the equilibrium of Ca at the end of the experiments. The bentonite helps to buffer the alkalinity of concrete leachates through several reactions such as dissolution of montmorillonite and precipitation of secondary products as trioctahedral smectite, zeolites (gismondine), and presumably Mg hydroxides and amorphous gels. Carbonation may reduce propagation of the alkaline plume and enhance the barrier performance.     

Experimental study on ethanol/bentonite slurry injection into synthetic rock fractures: Application to seepage control

Transmissive fractures or rock discontinuities (micro and macro) are mostly encountered when shafts and tunnels are excavated during the construction stage of underground space development or repositories for high level radioactive waste (HLW) disposal. These fractures may become flow paths to groundwater seepage and affect the stability of the excavated structure. For safe, effective construction and operation of such facilities, these fractures need to be sealed. In this study, the effect of ethanol on the injection characteristics of bentonite slurry as an effective grouting material is investigated. Various levels of ethanol concentrations (60%, 50% and 40%) were mixed with bentonite at liquid/solid ratios L/S (10, 8 and 6) by weight, w/w and injected into synthetic fracture of aperture sizes 100, 80 and 60 µm to investigate the penetrability of various concentrations of ethanol/bentonite slurries (EBS) into fractures of small aperture. Viscosity tests were also carried out to characterize the effect of ethanol on the rheological characteristics of the slurries. The results indicate that EBS is an effective grouting material capable of penetrating fractures of aperture sizes (100 µm–60 µm) and effectively sealing them for seepage control in the construction and operation stages of HLW repository. The results also showed that dynamic injection is more effective than static injection as it was able to inject high dense slurry into fractures better than static injection.     

Simplified evaluation on hydraulic conductivities of sand–bentonite mixture backfill

Sand–bentonite mixtures are planned for use as backfill materials for high-level nuclear waste disposal in Japanese project. Sand–bentonite mixtures are attracting greater attention as backfill materials because they offer properties of very low permeability and high swelling. We must investigate the hydraulic properties by experiments and evaluate quantitatively the hydraulic-conductivities of sand–bentonite mixtures to design specifications, such as dry density and bentonite content, of backfill materials.For that purpose, this study investigated hydraulic conductivities at different bentonite contents and dry densities by experimentation. In addition, we discussed the relationship between hydraulic conductivity and bentonite content from the viewpoint of bentonite swelling in backfill voids. Furthermore, this study proposed simplified evaluation for hydraulic conductivity using a parameter proposed by the author: swelling volumetric strain of montmorillonite. This evaluation method can obtain hydraulic conductivity of backfill materials at various dry densities and bentonite contents. Therefore, this evaluation method can be used for designing bentonite content and compaction density to achieve very low permeability.     

Wall friction measurement and compaction characteristics of bentonite powders

This paper presents a new method (referred to as direct method) for measuring wall friction during powder compaction and ejection. The accuracy for wall friction force measurement by both new and conventional methods (referred to as indirect method) were first studied according to the theory of error propagation. The error sources for compact density measurement in both methods were also examined. Based on the accuracy in the measurement of wall friction force and compact density, the direct method is compared favorably to the indirect method. Two bentonites, Black Hills bentonite and Zhi-Hsing bentonite which were considered as the candidate buffer materials for the geological disposal of high-level radioactive wastes were adopted to conduct a series of compaction and ejection tests. The compaction characteristics of bentonite blocks were expressed in terms of compressibility curve, wall friction ratio and friction index. The Gurnham's equation was used to describe the compressibility curve. The effects of the aspect ratio of block on the friction ratio and friction index are discussed from both experimental and theoretical point of views. Ejection profiles of the compacted bentonite blocks during ejection phase were presented. The proposed measuring method is validated by comparing the readings of ejection force recorded by both upper load cell and ring-type load cell.     

Influence of temperature on the hydro-mechanical behaviour of a compacted bentonite

This paper reports the results on the influence of temperature (between 20 and 80 °C) on some hydro-mechanical properties of a compacted bentonite. The water retention capacity at higher temperature, both in confined and unconfined conditions, is lower, especially when suction is low. At high temperatures, the swelling capacity of clay decreases, although the influence of temperature is less evident when the applied stress is high. Furthermore, a decrease in swelling pressure as a function of temperature was observed. On the other hand, the measured increase in permeability with temperature is lower than expected on the basis of thermal change in water kinematic viscosity. The transfer induced by temperature between intra-aggregate adsorbed water and inter-aggregate free water may explain most of the features observed, taking into account that the physical characteristics (density, viscosity) of water in each one of these two states are different.     

Gas migration properties through a bentonite/argillite interface

Among diversified industrial uses, see for instance Koch [Koch, Appl. Clay Sci., (21) 2002], and following positive in situ experiments, compacted bentonite blocks are potential candidates for sealing nuclear waste repositories, thanks to their swelling ability in a wet environment.As requested by Andra (French Agency for Nuclear Waste Management) and complementarily to in situ experiments, an original experimental laboratory set-up was designed in order to reproduce the introduction and swelling of bentonite plugs inside an argillite host rock. Once the argillite/bentonite interface is established, an increase in storage tunnel gas pressure is simulated and the interface gas migration pressure (or gas critical pressure) is evaluated. More precisely, a first experimental set-up provides bentonite swelling pressure and kinetics (i.e. mainly hydraulic cut-off, time to reach asymptotic swelling pressure and value of asymptotic swelling pressure) at given initial compaction and saturation rate. This phase is preparatory to reproducing the introduction and subsequent swelling of a bentonite plug inside the argillite host rock, which uses a similar test rig. Experimental results of water permeability and gas critical pressure are provided for MX80 compacted bentonite associated to Bure Callovo-Oxfordian argillite.     

Role of different types of water in bentonite clay on hydrate formation and decomposition

The equilibrium and kinetic of hydrate in sediments can be affected by the presence of external components like bentonite with a relatively large surface area. To investigate the hydrate formation and decomposition behaviors in bentonite clay, the experiments of methane hydrate formation and decomposition using the multi-step decomposition method in bentonite with different water contents of 20%, 40% and 60% (mass) were carried out. The contents of bound, capillary and gravity water in bentonite clay and their roles during hydrate formation and decomposition were analyzed. In bentonite with water content of 20% (mass), the hydrate formation rate keeps fast during the whole formation process, and the final gas consumption under different initial formation pressures is similar. In bentonite with the water contents of 40% and 60% (mass), the hydrate formation rate declines significantly at the later stage of the hydrate formation. The final gas consumption of bentonite with the water contents of 40% and 60% (mass) is significantly higher than that with the water content of 20% (mass). During the decomposition process, the stable pressure increases with the decrease of the water content. Hydrate mainly forms in free water in bentonite clay. In bentonite clay with the water contents of 20% and 40% (mass), the hydrate forms in capillary water. In bentonite clay with the water content of 60% (mass), the hydrate forms both in capillary water and gravity water. The bound water of dry bentonite clay is about 3.93% (mass) and the content of capillary water ranges from 42.37% to 48.21% (mass) of the dry bentonite clay.