Cyclodextrin-enhanced solubilization of pentachlorophenol in water

The solubilization of pentachlorophenol (PCP) by beta-cyclodextrin (beta-CD) and three of its most used derivatives, methyl-beta-cyclodextrin (MCD), hydroxypropyl-beta-cyclodextrin (HPCD) and carboxymethyl-beta-cyclodextrin (CMCD), has been investigated. The formation of soluble inclusion complexes between PCP and cyclodextrin (CDs) increases the aqueous solubility of PCP. Due to the ionizable nature of PCP, the effects of pH and ionic strength on the equilibrium complexation were evaluated. All CDs were found to form 1:1 inclusion complexes. Equilibrium constants calculated from solubility enhancement experiments revealed that the stability of the complexes was dependent on the polarity of the compound, on the ionic strength and on the cyclodextrin type. In general, weaker equilibrium constants were observed for PCP with beta-CD than with MCD or CMCD. For all CDs, the complexation or the solubilization efficiency of PCP (weak acid) depended on pH and ionic strength. Moreover, we observed that the solubility of the beta-CD/PCP complex was lower than that of the beta-CD molecule and dependent on the ionic strength of the solution. Although the equilibrium constant of PCP/CD complex was found to be higher at pH 3 than at pH 7 in water, extraction of PCP from porous media by a CD solution at neutral pH would be achievable due to the higher PCP aqueous solubility in neutral/basic media.     

Development of a method for predicting the ignition of explosive atmospheres by mechanical friction and impacts (MECHEX)

Mechanical friction and impacts is still today a main cause of ignition of explosive atmospheres (ATEX) in the industry and this trend seems to be stable in time. This situation certainly results from a significant gap of knowledge in the underlying mechanisms so that the parameters to play on are not precisely identified. In this programme of European dimensions, the process of degradation of the mechanical energy into heat during friction and impacts have been studied.

An extensive experimental programme is presented to this end. The mechanisms of dissipation of the mechanical energy into heat during friction has been studied with rubbing machines in which a slider equipped with temperature sensors rubs against a rotating wheel. For impacts, a new device has been developed using a special “air driven cannon” to propel a projectile accurately up to 50 m/s onto an inclined target. A very significant effort has been reserved to the investigation of the ignition mechanisms, not only for ATEX but also for dust accumulations.

Some “simple” modelling is proposed on purpose of practical applications. For frictional situations, a critical rubbing power is calculated without any limitations about any lower boundary concerning the rubbing velocity. For “impacts”, the relevant parameter for ignition is not the kinetic energy of the projectile but its velocity and the nature of the materials.     

Impact of emission control on regional air quality: An observational study of air pollutants before, during and after the Beijing Olympic Games

An observational study on trace gases and PM2.5 was conducted at three sites in and around Beijing, during the Olympic season from 2007 to 2009. Air quality improved significantly during the Olympic Games due to the special emission control measures. However, concentrations of the primary pollutants and PM were found to have risen significantly after the Games. Although the major O3 precursors （NOx and VOCs） were well controlled during the Olympic season, O3 was still found to be the highest in 2008, based on the data of ground-based observation. All this information suggests that while control of regional emissions for the Beijing Olympic Games did improved the air quality in Beijing, more efforts will be needed for the continuous improvement of regional air quality, especially for significant reductions of O3 and fine particulate pollution, and not only in Beijing, but also in the B eijing-Tianjin-Hebei region.     

Life cycle inventory for an organic swine waste treatment system

Journal of Material Cycles and Waste Management - The aim of this study was to analyze the efficiency of a system of treatment of organic swine waste as a management tool in the transformation of...     

Recycling of waste tire by pyrolysis to recover carbon black: an alternative reinforcing filler

Journal of Material Cycles and Waste Management - Thermal pyrolysis of waste tires is an industrially beneficial method for material and energy recovery. Pyrolytic carbon black (CBp) is considered...