BENTONITE PERFORMANCE

In low sohds muds, vinyl acetate—maleic anhydride copolymers were once used to extend or enhance the viscosity of bentonite suspensions (141). This function is largely performed by polyacrylamides. The vinyl acetate—maleic anhydride copolymers can also have a flocculating effect on drill sohds. Concentrations generally are quite low (0.14—0.57 kg/m (0.05—0.2 Ib/bbl)). 

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. 

Chemat and his collaborators [92] reported the UV- and MW-induced rearrangement of 2-benzoyloxyacetophenone, in the presence of bentonite, into l-(o-hydroxy-phenyl)-3-phenylpropane-l,3-dione in methanol at atmospheric pressure (Sch. 14.2). The reaction, performed in the reactor shown in Fig. 14.7, was subject to a significant activation effect under simultaneous UV and MW irradiation this corresponded at least to the sum of the individual effects (Fig. 14.11). The rearrangement, however, was not studied in further detail. Such competitive processes can be described by the diagram in Fig. 14.9, because the product obtained from both types of activation was the same. 

Lund E, Nissen B (1986) Low-technology water purification by bentonite clay flocculation as performed in Sudanese villages virological examinations. Water Res 20 37-43... 

The reverse osmosis performance of the two membranes under typical brackish water conditions is shown in Figure 2 (I, reference membrane III, with bentonite). At a rejection of 85 % the flux is almost doubled (from 2000 to nearly 4000 l/m d), the effect becoming smaller when going to higher rejections. Maximum brackish water rejection of the bentonite membrane is 97 % as against 98 % for the reference membrane. 

Figure 2. Effect of hydrophilic bentonite incorporation on the reverse osmosis performance of asymmetric cellulose diacetate membranes I, reference membrane III, with hydrophilic bentonite.

Membrane Properties. The reverse osmosis performance of the bentonite-doped membrane under brackish water conditions is compared to that of the reference membrane in Figure 5 (I, reference membrane II, with organophilic bentonite). At low salt rejection the bentonite membrane again shows a higher initial flux than the reference membrane, the performance of the two becoming identical at the high rejection limit. 

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. 

Bradbury, M. H. Baeyens, B. 2002a. Near-Field Sorption Data Bases for Compacted MX-80 Bentonite for Performance Assessment of a High Level Radioactive Waste Repository in Opalinus Clay Host Rock. Nagra Technical Report NTB 02-18, Nagra, Wettingen, Switzerland. Also issued as PSI Bericht Nr. 03-07, Paul Scherrer Institut, Villigen, Switzerland. 

Borja and Banks also performed a kinetic study of the anaerobic digestion of soft drink wastewater using bioreactors containing various suspended supports. Again, bentonite, zeolite, sepiolite, saponite, and polyurethane foam were used as substrata onto which the microorganisms affecting purification were immobilized. Similar results were noted. Vieira et al. also studied the kinetics of anaerobic sludge immobilization in the matrix of a polyurethane foam.- ... 

Eq. 4 is amenable to solution techniques based on the numerical inversion of Laplace-transformed equations these calculations can be performed rapidly and are therefore suitable for calibration. In Figure 1, typical soil/bentonite column predictions are shown to highlight the effect of the influent mixing zone on the spatial contaminant distributions for low-flow systems. The simulation results, which were generated for column conditions described by Khandelwal et al. (1998), indicate that the mixing zone has a significant influence on the shape of the spatial contaminant distribution and, therefore should be considered explicitly in estimating sorption parameters from spatial column data. 

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... 

Khandelwal, A., and Rabideau, A. J. (1998). Enhancement of soil/bentonite barrier performance by the addition of natural humus, Proceedings of the 4th International Symposium on Environmental Geotechnology, Boston, MA, 9-12 August, 1998. 

The most important industrial example of cation exchange is the preparation of sodium-montmorillonite/bentonite from calcium bentonite. As seen in Table 2.2, calcium ions have greater affinity to the layer charge than sodium ions, so the calcium-sodium cation exchange must be performed in the presence of carbonate ions. It means that calcium-montmorillonite/bentonite is suspended in sodium carbonate solution. Calcium ions precipitate with carbonate ions, so sodium ions can occupy the interlayer space. This process is known as soda activation of bentonite. The disadvantage of soda activation is that sodium-montmorillonite is contaminated with calcium carbonate. 

Hydroxyl-Zr bentonite catalyst for esterification was prepared. Effects of the preparation conditions (calcination temperature, calcination time and ageing time) on interlayer distance, specific surface area and surface total acidity of catalyst have been studied. XRD, BET method and potentiometric titration were respectively used to detennine interlayer distance, specific surface area and surface total acidity of catalyst. Scanning Electron Microscopy was performed to observe the images of samples. 

Kwon, S.W. (2004). Profiling of soluble proteins in wine by nano-high-performance liquid chro-matography/tandem mass spectrometry. J. Agric. Food Chem., 52, 7258 - 7263 Lee, T. (1986). Protein instability nature, characterization and removal by bentonite Leiper, K.A., Stewart, G.G., McKeown, I.P., Nock, T, Thompson, M.J. (2005). Optimising beer stabilisation by the selective removal of tannoids and sensitive proteins. J. 1. Brewing, 111, 118-127... 

---