Biosorption of hexavalent chromium from aqueous solutions using highly characterised peats

This research investigated the biosorption of hexavalent chromium (CrVI) from aqueous solutions by six highly characterised peats. Samples of the peats were tested both in unaltered condition and after being treated with hydrochloric acid (HCl) to free up any occupied exchange sites. Other variables tested were sample dose, contact time, mixing temperature, and the concentrations and pH of the CrVI solution. Desorption studies were also performed, and tests were done to determine whether the peats could be re-used for CrVI biosorption. The results indicate that all six peat types biosorb CrVI from aqueous solution well (42–100 % removal) and that their CrVI removal capacities are affected by manipulation of the various factors. The two factors that had the greatest impact on the CrVI removal capacities of the peats were the concentrations and pH of the CrVI solution. As the CrVI solution concentration and pH were increased, the percent of CrVI removed decreased dramatically (33–56 % decrease for concentration increase; 36–45 % decrease for pH increase with four of the six peat types). The desorption results indicate that it may be possible to recover up to 5 % of the removed CrVI. All of the peat types tested can be repeatedly re-used for additional CrVI biosorption cycles. Hence, their disposal should not become a hazardous waste problem

Perceived environmental uncertainty; PEU; REF 2014

NoAn important contribution to the literature on perceived environmental uncertainty (PEU) is Milliken’s distinction between state uncertainty, effect uncertainty, and response uncertainty. However, despite its appealing logic in capturing the types of uncertainty managers may experience as they seek to understand and respond to changes in an organization’s environment, there has been no full and rigorous psychometric development and testing of scales to measure the three constructs. Using a two-phase empirical study, this research seeks to develop and test such scales in terms of dimensionality, reliability, and validity (including nomological validity). The results suggest that managers do make a meaningful distinction between different types of uncertainty, that it is worthwhile measuring all three constructs (as they have differential impacts on outcome variables), and that there are linkages between them. Managerial contributions and implications for future research are also discussed

Atmospheric Escape and Evolution of Terrestrial Planets and Satellites

International audienceThe origin and evolution of Venus', Earth's, Mars' and Titan's atmospheres are discussed from the time when the active young Sun arrived at the Zero-Age-Main-Sequence. We show that the high EUV flux of the young Sun, depending on the thermospheric composition, the amount of IR-coolers and the mass and size of the planet, could have been responsible that hydrostatic equilibrium was not always maintained and hydrodynamic flow and expansion of the upper atmosphere resulting in adiabatic cooling of the exobase temperature could develop. Furthermore, thermal and various nonthermal atmospheric escape processes influenced the evolution and isotope fractionation of the atmospheres and water inventories of the terrestrial planets and Saturn's large satellite Titan efficiently