H.B. Krop

n-Octanol-water partition coefficients, aqueous solubilities and Henry's law constants of fatty acid esters

Abstract The aqueous solubility and n-octanol-water partition coefficient of fifteen fatty acid esters are determined by the RP-HPLC method. Aqueous solubilities decrease from 5.7 × 10 −5 M for methyl caprate to 5.3 × 10 −12 M for methyl behenate while the log K ow s increase from 4.4 to 10. Special attention is given to satisfying the statistical assumptions underlying the establishment of the calibration line. Residual plots show that in this case small systematic errors are introduced rapidly even if the selected substances for the calibration line are similar in their physical properties to the fatty acid esters. Combining previously determined vapour pressure data with the estimated solubility values allows for the estimation of Henrys law constants. Although the calculated values are not very accurate, it can be concluded that they are in general lower than those of the halogenated hydrocarbon solvents.

Life cycle assessment of flame retardants in an electronics application

PurposeFlame retardants are added to plastics and textiles to save lives. However, certain brominated flame retardants (BFRs) form an environmental hazard and should be replaced by less harmful alternatives. In the recently completed European research project ENFIRO, we examined which alternatives are most suitable from a technical and environmental perspective. This study describes the LCA comparison of BFRs and halogen-free flame retardants (HFFRs) in an electronics product, in order to compare their environmental impacts over the whole life cycle and identify where in the life cycle the main impacts occur.MethodsThis cradle to grave LCA used the complete life cycle of a laptop computer as the functional unit. Specific attention was paid to often neglected aspects, including emissions of flame retardants in all life cycle phases, emissions during accidental fire and improper waste treatment. New characterization factors for toxicity of flame retardants were calculated using USES-LCA2 and included in the impact assessment.Results and discussionThe largest differences in impact were found to occur in the waste phase due to an increased dioxin emission formed out of BFRs during improper waste treatment. Minor human toxicity and ecotoxicity impacts of FRs are present due to volatilization in the use phase. FR emissions during accidental fire vary with the FR’s mode of action (active in the gaseous or solid phase). The BFR scenario has a higher impact than the HFFR scenario due to a higher rate of smoke formation and a higher terrestrial ecotoxicity score. In most phases of the life cycle of FRs, fossil energy use related impact categories dominate the LCA score, i.e. climate change, fossil depletion, and particulate matter formation. Over the full life cycle, the BFR scenario has a slightly higher environmental impact than the HFFR scenario, mainly through the contribution of human toxicity in the waste phase.ConclusionsThe study shows that for improvements of the life cycle environmental performance of FRs, the waste treatment phase is critical. Export and improper treatment of WEEE have the highest impact of all waste treatment options for both the BFR and HFFR scenarios, and efforts should be intensified to reduce the amount of WEEE ending up in this scenario. The study further shows that processes which are often ignored in LCA can give relevant insights into the environmental performance of a product. It is therefore recommended to broaden the scope and system boundaries of future LCA studies to include unofficial scenario options (specifically in the end-of-life phase) to provide a more complete description of the full environmental impact of a product’s life cycle and thereby contribute to relevant discussions in society and policy.

Prediction of Redox Potentials and Isomer Distribution Yields for Reductive Dechlorination of Chlorobenzenes

Abstract Gibbs free energies of reductive dechlorination processes of chlorobenzenes are calculated from thermodynamic data. The results are utilized to predict redox potentials and isomer distribution yields. The model predicts a standard redox potential of 0.680 V for the reduction of hexachlorobenzene to pentachlorobenzene, tapering off to 0.535 V for the reduction of monochlorobenzene to benzene. It is shown that under anaerobic conditions, reductive dechlorination is more likely to occur, while aerobic conditions favour the formation of chlorophenols. An isomer distribution yield is predicted for each of the reductive dechlorination processes of chlorobenzenes. Predicted yields correspond to experimental values within 10%. The model includes a possibility to establish a temperature dependence of the relative isomer yields.