BENTONITE PERFORMANCE MATERIALS

Abstract Coupled THM simulation of the FEBEX, which is the full-scale in-situ Engineered Barrier System Experiment performed in Grimsel Test Site in Switzerland, is one Task in the international cooperation project DECOVALEX III. In the Task, the simulation of the thermal, hydraulic and mechanical behaviour in the buffer during heating phase is required, e.g. the evolutions and the distributions of stress, relative humidity and temperature at the specified points in bentonite buffer material. 

The objective of this work is to synthesize and characterize zeolite-bentonite hybrid catalysts and perform test reactions in the pyrolysis of woody biomass in a dual-fluidized bed reactor. The aim is to produce catalytic materials which have good mechanical strength and are still able to de-oxygenate the pyrolysis oil. 

Initially, Oz diffuses through the bentonite and granitic domains, controlling the redox state of the system. Once 02 is exhausted, granitic groundwater controls the redox state of the system. The results of these calculations performed with the PHREEQC geochemical code (Parkhust Appelo 1999) clearly indicate that there is a substantial variability in pH/pe space along the temporal and spatial evolution of the near field of a repositoiy. This has clear consequences for the subsequent interactions with the Fe canister material and finally with the spent fuel matrix. 

In a comparative study of sorbing additives for soil/bentonite slurry walls, Adu-Wusu et al. (1997) identified a natural humus material as an attractive candidate in terms of cost and sorption capacity. Subsequently, column experiments were performed by Khandelwal and Rabideau (2000) using an SB mixture containing 5 percent humus. To account for possible... 

The material properties were obtained from various field and laboratory tests that were performed before the emplacement of the buffer and heaters. For example, the inflow into the open drift was utilized to calibrate the in situ hydraulic properties of the rock mass and Lamprophyre dykes. Moreover, several laboratory tests were utilized for numerical back-analyses of coupled THM properties of the bentonite. The properties of the bentonite and rock are listed in Tables 1 and 2. 

In the present study, we show an example of the application of this experimental methodology to the investigation of adsorption characteristic of local bentonite clay. Adsorption / desorption experiment were performed at laboratory scale with model-contaminated gaseous stream containing o-xylene that has been selected as rep resentative VOC because it is environmentally relevant regarding industrial concern. The work aimed to help further development of low cost materials involved in environmental engineering control. 

Stability can be said as the protection of polymeric materials from which lead to deterioration of properties [9]. In literature, there are different and sometimes contradictory reported papers concerning the effect of the nanoparticles on polymer thermal stability. There are papers suggesting that nanoparticles have no obviously effect on thermal stability, some of them suggested a small to substantial enhancement and some others suggested acceleration of thermal decomposition. In a study performed by Ollier et al. [10], the author incorporated 5 % weight of bentonite in unsaturated polyester (UP) matrix. They noted that the addition of bentonite... 

SBS-BentoNAT presents the worst FPI index, because of the negative effect of bentonite on the performance of the material, mainly caused by the shortening of the TTI. Clay/organoclay-SBS composites present similar FIGRA indices, and this behavior is essentially due to a balance between a lower TTP and a lower PHRR. SBS-BentoDEDMEL shows a decrease in PHRR similar to that for SBS-BentoNAT and SBS-BentOTAB, with a satisfactory TTI compared with SBSBentoNAT. 

For this reason, sodium bentonite might not be the most appropriate barrier material. Furthermore, other materials may be available more readily and might be more cost-effective to use. Therefore, much research has been directed at other low-permeability materials that might be used for active containment. Thornton et al. present results from a study of a high-attenua-tion liner material constructed from low-cost natural and industrial waste available in the UK. Laboratory column experiments were used to assess the performance of this and other potential liner materials to contain mobile organic and inorganic components by chemical means. Results of the experiments are discussed and linked to important landfill liner design issues. For example, additives could be included within the main liner material, or a separate liner could be placed beneath the main liner to act as a secondary chemical containment system. 

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