Modeling Ionic Strength Effects on Hollow-Fiber Nanofiltration Membrane Mass Transfer.

In this research, we investigated the influence of feedwater ionic strength on diffusion of divalent ions through a hollow-fiber nanofiltration membrane. The results indicated that solute flux of magnesium was increased as a result of elevating the ionic strength in the feedwater. Specifically, the feedwater ionic strength was observed to have a nonlinear impact on the diffusion of magnesium during the nanofiltration process, which was under-predicted by the homogeneous solution diffusion (HSD) model.

Nonsingular adsorption/desorption of chlorpyrifos in soils and sediments: experimental results and modeling.

At environmentally relevant concentrations in soils and sediments, chlorpyrifos, a hydrophobic organic insecticide, showed strong adsorption that correlated significantly with organic matter content. Chlorpyrifos desorption followed a nonsingular falling desorption isotherm that was estimated using a memory-dependent mathematical model. Desorption of chlorpyrifos was biphasic in nature, with a labile and nonlabile component.

Adsorption and desorption of chlorpyrifos to soils and sediments.

Chlorpyrifos, one of the most widely used insecticides, has been detected in air, rain, marine sediments, surface waters, drinking water wells, and solid and liquid dietary samples collected from urban and rural areas. Its metabolite, TCP, has also been widely detected in urinary samples collected from people of various age groups. With a goal of elucidating the factors that control the environmental contamination, impact, persistence, and ecotoxicity of chlorpyrifos, we examine, in this review, the peer-reviewed literature relating to chlorpyrifos adsorption and desorption behavior in various solid-phase matrices.

Mobility and recalcitrance of organo-chromium(III) complexes.

Hexavalent chromium [Cr(VI)] is a major industrial pollutant. Bioremediation of Cr(VI) to Cr(III) is a viable clean-up approach. However, Cr(VI) bioreduction also produces soluble organo-Cr(III) complexes, and little is known about their behavior in the environment.

Estimating the dual-enzyme kinetic parameters for Cr (VI) reduction by Shewanella oneidensis MR-1 from soil column experiments.

Hexavalent chromium (Cr (VI)) contamination of soil and groundwater is considered a major environmental concern. Bioreduction of Cr (VI) to trivalent chromium (Cr (III)) can be considered an effective technology in remediating Cr (VI) contaminated sites. Among the Cr (VI) reducing bacteria, Shewanella oneidensis MR-1 (MR-1) is relatively effective.

Kinetics of phenol biodegradation in high salt solutions.

Biological treatment of high-salinity industrial wastewaters using halophilic bacteria can be used to remove organic compounds without first decreasing the salt concentration. While halophilic degradation of phenol and other organics has been investigated, there exists a general absence of kinetic data in current literature to allow evaluation of this treatment alternative. Liquid, soil and sediment samples were collected from three distinct saline environments in the western United States.