Compacted and water saturated bentonite will be used as an engineered barrier in deep geological repositories for radioactive waste in many countries. Due to the high dose rate of ionizing radiation outside the canisters holding the nuclear waste, radiolysis of the interlayer and pore water in the compacted bentonite is unavoidable. Upon reaction with the oxidizing and reducing species formed b...

BACKGROUND The dispersion-aggregation behaviors of suspended colloids in rivers and estuaries are affected by the compositions of suspended materials (i.e., clay minerals vs. organic macromolecules) and salinity. Laboratory experiments were conducted to investigate the dispersion and aggregation mechanisms of suspended particles under simulated river and estuarine conditions. The average hydrod...

E. coli bacteria move in streams freely in a planktonic state or attached to suspended particulates. Attachment is a dynamic process, and the fraction of attached microorganisms is thought to be affected by both bacterial characteristics and particulate properties. In this study, we investigated how the properties of cell surfaces and stream particulates influence attachment. Attachment assays ...

Controlled-release herbicide formulations have been shown to decrease the leaching potential of several herbicides under laboratory and Ðeld conditions. The utility and efficacy of these formulations may be improved by combining several herbicides and a fertilizer source in a single formulation. The objective of these studies was to develop granular alginate formulations that were composed of a...

The sorption capacity of montmorillonite clay minerals for small cations, such as Ni , can be greatly enhanced by modifying the clay mineral with Al(III). In this study, the mechanisms of Ni uptake by Al-modified montmorillonite were studied using extended x-ray absorption fine structure (EXAFS) spectroscopy of powders and polarized EXAFS spectroscopy of self-supporting clay films to delineate ...

novel collagen-based hydrogel nanocomposites were synthesized by graft copolymerization of acrylamide and maleic anhydrid in the presence of different amounts of montmorillonite, using methylenebisacrylamide (mba)and ammonium persulfate (aps) as crosslinker and initiator, respectively. the optimum amount of clay on the swelling properties of the samples was studied. it was found that the hydrog...

Adsorption of three sulfonamide antimicrobials to clay minerals was investigated as a function of pH, ionic strength, and type of exchangeable cation. Sulfonamide antimicrobial adsorption exhibited pronounced pH dependence consistent with sorbate speciation and clay properties. Sulfonamide antimicrobials did not intercalate into montmorillonite, and surface charge density influenced sorption by...

Adsorption-desorption of the herbicide glyphosate (GPS) onto the clay mineral montmorillonite has been studied in presence of copper, in order to clarify the effects that this strongly complexing metal could have on the availability and mobility of GPS in soil environment. In contrast with previous findings, GPS adsorption on montmorillonite decreases in the presence of Cu, in solution or adsor...

Nanoporous sodium montmorillonite clay (Na+-MMT) was used as a support for the immobilization of 1-methyl-3-(trimethoxysilylpropyl)-imidazolium hydrogen sulfate (Na+-MMT-[pmim]HSO4). This catalyst showed excellent catalytic activity for the preparation of 2-amino-3-cyano-5-oxo-5,6,7,8-tetrahydro-4H-benzopyrans via three-component reactions betw...

Background: Ramsar, a northern city in Iran, lies on the coast of the Caspian Sea. This city has areas with some of the highest levels of natural radiation measured to date. The radon concentration in some areas of Ramsar is up to 3700 Bq m–3. On the other hand, due to high level of humidity, damp-proof barriers should be used in construction of new buildings in radon prone areas of this cit...