Demonstrating Aqueous-Phase Low-Molecular-Weight-Gel Wicking of Oil for the Remediation of Oil Spilled into Surface Water

Oils spilled into surface water require effective and timely treatment. In this paper, we report on a low-molecular-weight gelator that can form gels in organic and aqueous phases. The aqueous gel was observed to absorb oils, which is proposed as a new class of materials for remediating oil spilled into surface water. The gels and the low molecular-weight gelator have both fundamental and applied significance. Fundamentally, identifying the mechanisms that govern the formation of these gels and their resultant mechanical properties is of interest. Subsequently, these fundamental insights aid in the optimization of these gels for addressing spilled oil. First, we briefly compare the organic and aqueous gels qualitatively before focusing on the aqueous gel. Second, we demonstrate the ability of the aqueous gel to wick oils through experiments in a Hele-Shaw cell and compare our results to the Washburn equation for porous media. The Washburn equation is not entirely adequate in describing our results due to the change in volume of the porous media during the wicking process. Finally, we investigate mechanisms proposed to govern the formation of low-molecular-weight gels in the literature through rheological shear measurements during gel formation. Our experiments suggest that the proposed mechanisms are applicable to our aqueous gels, growing as anisotropic crystal networks with fractal dimensions between one and two dimensions from temporally sporadic nucleation sites

Cyanide ion-selective electrode measurements in the presence of copper

The response of a cyanide ion-selective electrode (ISE) in the presence of copper has been investigated. The interferences of metal ions, like copper, on the response of the cyanide ISE prevents its use for routine direct analysis of metal cyanide containing waste water. In this work an improved understanding of the chemistry at the electrode, and the effects of different cyanide and copper concentrations and matrix pH values on the electrode response, has been developed. Based on this insight, a semi-empirical approach is described to allow calibration of the ISE enabling the estimation of total cyanide. While not as robust as, for example, total cyanide distillation, it provides an inexpensive, rapid and convenient approach for more frequent and widespread screening of industrial waste waters.Peer reviewed: YesNRC publication: Ye

Health Hazards and Socio-Economic Status: A Neighbourhood Cohort Approach, Vancouver, 1976–2001

This paper lays the foundation for a research program concerned with the geographical patterning of environmental and population health at the urban neighbourhood scale. Based on the Vancouver metropolitan region, the aim is to better understand the role of neighbourhoods as epidemiological spaces where environmental and social characteristics combine as health processes and outcomes at the community and individual levels. With respect to procedure, this paper builds a cohort of commensurate neighbourhoods across all six census periods from 1976 to 2001, assembles neighbourhood air pollution (total particles) data, and provides an initial analysis to demonstrate how air pollution systematically and consistently maps onto neighbourhood socio-economic markers, specifically education and family status. We conclude with a discussion of how the neighbourhood cohort can be further developed to address emergent priorities in the population and environmental health literatures, namely the need for temporally matched data, a life-course approach and analyses that control for spatial scale effects

Photo/electrocatalytic hydrogen exploitation for CO2 reduction toward solar fuels production

This chapter discusses the transformation of CO2 to value-added products, with a focus on the exploitation of sun-driven water splitting for generation of hydrogen protons (H+) that can be used in situ for the CO2 reduction reaction. It starts by introducing CO2 as a raw material for the production of fuels or chemicals by conventional (thermocatalytic) conversion processes or emerging sun-driven technologies. It then gives a background about the different figures of merit that must be considered and identifies the opportunities for syngas production. Different architectures for syngas production are presented, considering the photo-driven systems and with particular emphasis on the electrochemical systems. It proceeds by extensively discussing various catalysts for these two kinds of systems. Finally, it tackles the promising solvent-less route for the electrochemical conversion of CO2 to value-added products