Investigation of ultrasound assisted regeneration of Ni–bentonite with response surface methodology (RSM)

This paper assesses the potential of ultrasonic desorption of toxic heavy metal Ni(II) from bentonite for regeneration purposes. Response surface methodology (RSM) was employed to optimize the desorption of Ni(II) retained on bentonite by varying the amount of adsorbent, contact time, pH and ultrasound time. The results indicated that in the present experimental setup, the pH and the ultrasound time were the most significant variables affecting Ni(II) desorption from bentonite. Based on statistical analysis, the Ni(II) desorption model was highly significant with very low p-values (< 0.0001) and the optimal control parameters were determined as follows: solid/liquid ratio (0.5 g/mL), contact time (6 h), pH (3.37) and ultrasound time (30 min). The experimental value of desorption percentage (59.4%) for regeneration of bentonite under the optimum conditions is in agreement with the predicted value of 64.5%.     

CPAM/膨润土体系中剪切力对细小纤维-碳酸钙共絮聚影响的研究

以杨木P-RC APMP为原料,对其进行筛分,并对P-RC APMP细小纤维与轻质碳酸钙（PCC）进行共絮聚,研究了CPAM/膨润土微粒助留体系下,剪切力对细小纤维-PCC共絮聚团大小、颗粒结构的影响;结果表明：随着剪切力的增大,细小纤维-PCC絮聚团的尺寸不断减小;在高转速下,絮聚团虽然被打碎,但悬浮液中单独的白色颗粒很少（PCC）,体系中还是有许多小的絮聚体.     

膨润土K—JT在活性染料净洗工艺中的应用

通过分析膨润土K—JT在净洗工艺中的用量、净洗温度、净洗时间等因素对活性染料染色净洗后的K／S值、水洗牢度的影响,确定膨润土K—JT作活性染料染色净洗剂的最佳工艺条件为：用量3．0g／L,温度95℃,时间为16分钟。自制膨润土K—JT和常规净洗剂净洗后的织物水洗牢度几乎相同,但经自制膨润土K—JT净洗后,净洗残液的CODCr值下降幅度很大。因此,膨润土K—JT是一种很有实用价值的纯棉织物活性染料染色净洗剂。     

钙基膨润土活化工艺的研究

以低品位钙基膨润土为原料,研究了酸法活化制备活性膨润土的最佳工艺参数,主要包括硫酸和盐酸的活化效果、酸浓度和活化时间对产品质量的影响。结果表明,以盐酸为活化剂时,活化反应速度较快;在相同条件下,盐酸的活化效果优于硫酸。成功地制备了脱色率大于99%、活性度为220～225的活性膨润土。     

膨润土理化性能对球团性能影响的研究

根据国内的质量标准和检测方法测定了六种膨润士的理化性能,并将其与冀东铁精矿混合造球。进行球团焙烧试验。通过对试验数据进行回归处理,找到了膨润士理化性能与球团性能之间的关系。     

湿型砂膨润土烧损的数学模型

湿型砂膨润土的烧损量可以通过生产统计分析，实验室测定结果计算，以及传热学微分方程高斯误差函数等方法测定，其结果基本一致。膨润土烧损的数学模型由高斯误差函数公式而得。     

ELECTROOSMOTIC DEWATERING BY A “NEW” METHOD USING A “GATE” ELECTRODE: FIELD EFFECT TRANSISTOR (FET) MODEL OR SIMPLY A MULTISTAGE DEWATERING?

Recently some workers in the field of electrostatics have proposed a “new” method of electroosmotic dewatering (EOD) in which a third electrode (called the “gate” electrode) is placed between the anode and the cathode to enhance the EOD. These authors present a conceptual analysis in terms of the notions of a field-effect transistor (FET). We show here that the proposed method is simply a variation of the multistage EOD already practiced by the workers in this field. It is further demonstrated that an analysis based on the FET model is not applicable to the phenomena involved in the proposed EOD method.     

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.     

Thermal loading of smectite-rich rocks: Natural processes vs. laboratory experiments

Changes of physico-chemical properties of smectite-rich rocks (used as an engineered barrier in the nuclear waste repository) are studied. Two different genetic types of clays are evaluated—bentonite representing the residual weathering type and sedimentary montmorillonite-rich clay. Cation exchange capacity and specific surface area were determined for bulk samples (after heating experiments) and results were compared to a natural analogue (Ishirini deposit, Libya).Structural changes of clay minerals were studied using XRD, TG and DTA. Two main transformation processes (illitization and kaolinization) of smectite-rich rocks followed by deterioration of physico-chemical properties were observed after heat treatment. Cation exchange capacity drops significantly with increasing temperature and so does S_micro. However, S_BET values increased when heat treatment was applied.     

Physicochemical characterisation and flow properties of some bentonite muds

In civil engineering technologies, bentonites mixed with water are commonly used as bentonitic mud. The choice and the definition of criteria for mud selection are a difficult problem for industrials. This paper proposes a data set obtaining from the physicochemical and rheological investigation of 16 different commercial bentonites. Several analytical techniques are used to determine the mineralogical composition of those powders including X-ray diffraction, DTA and chemical analysis. Physical parameters such as particle size, specific surface area, swelling index, cationic exchangeable capacity and exchangeable bases are also studied. The viscosity of the mud is tested, thanks to the classic Marsh funnel viscometer and the rheological properties (yield stress, plastic viscosity and thixotropy) are measured by a high-resolution rheometer (Stresstech). Mineralogical data show that the bentonite appellation covers a very large variety of materials. Even if the main mineral is smectite, the global analysis of the powders shows that commercial bentonites contain secondary minerals, salts and sometimes polymers. Rheological data obtained for established flow allow to define two families of bentonite mud which difference seems to be due to industrial treatments. In fact, each bentonite develops its own behaviour depending on multicriteria. The results from this study show that it is necessary to characterize the mud from mineralogical and rheological points of view and to take into account, the nature of the excavated soils in order to choose the best bentonite.