Photo- and electro-catalysis for solar disinfection of Escherichia coli-contaminated water using Ag–TiO2/graphite

A titanium dioxide film on a graphite substrate was synthesized by chemical bath deposition from TiCl₄ as precursor and with the surfactant cetyl trimethyl ammonium bromide as a linking and assembling agent. Silver was loaded on the TiO₂ film by electrodeposition at 0.025?A. Water contaminated with Escherichia coli was disinfected under sunlight irradiation by photolysis (Lys), photocatalysis (PC), photoelectrocatalysis (PEC), and electrocatalysis (EC). The highest rate constant, k, was achieved with EC; k was 5.1?×?10^?2 colony forming units (CFU) mL^?1?min^?1. However, auto-oxidation of Ag occurred during EC and PEC. Meanwhile, the rate constant of disinfection by means of PC was lower than EC and PEC, and k was 3.82?×?10^?2 CFU?mL^?1?min^?1. Nevertheless, the auto-oxidation of Ag in the Ag–TiO₂/graphite tablet did not occur during the disinfection process.     

Sulfamethoxazole removal from polluted water by immobilized photocatalysis

The photocatalytic activity of TiO₂ deposits (Degussa P25 and Millennium PC500) has been studied using sulfamethoxazole (SMX) as a model water pollutant and a UV fluorescent lamp as a light source (365 nm). Both catalysts have shown very similar properties in the photocatalytic degradation of SMX. Special attention has been given to the effect of the irradiation time, pH, and pollutant concentration. No mass-transfer limitations are observed. The degradation of SMX is accelerated at low concentration, and the photocatalytic degradation kinetics obey the Langmuir–Hinshelwood model, allowing the adsorption and apparent rate constants to be determined for both catalysts.     

Scaling up site disputes: strategies to redefine ‘local’ in the fight against fracking

Plans to replace an aging diesel backup energy plant with liquid natural gas (LNG) generators in Whitehorse, Yukon, resulted in a public outcry, involving community meetings, massive petitions, and demonstrations. Are these civil society protests just a case of a local siting dispute – a response to an unwanted industrial site in an urban neighborhood? Here, it is argued that siting debates are not the driver of these campaigns, but instead are harnessed by activists to advance a broader environmental movement. By linking the LNG project to more distant extraction, involving hydraulic fracturing (‘fracking’), movement leaders portray the entire territory as part of the ‘local’ for Whitehorse residents. Movement leaders rely upon two key mechanisms: claiming insider status, and identifying visible symbols. This case reveals the strategic use by environmental movements of local concerns to recruit support for broader campaigns, and the value of local, place-based activism for broader environmental movements.     

COMPARISON BETWEEN SOLID–PHASE EXTRACTION METHODS FOR THE CHROMATOGRAPHIC DETERMINATION OF ORGANOPHOSPHORUS PESTICIDES IN WATER

A solid-phase microextraction (SPME) procedure has been developed to ex tract eight organophosphorus pesticides (OPs) in water and the method was compared with a conventional solid phase extraction (SPE) technique. The extracted OPs were analyzed by gas chromatography using thermionic specific detection. Both extraction methods presented linear calibration at least over the concentration range investigated (100 to 1000 ng.mL^?1 for SPE and 1 to 100 ng.mL^?1 for SPME). SPME method presented higher sensitivity than SPE. The quantitation limits were between 0.1 to 1.0 ng.mL^?1 for SPME depending upon the analyte, and 100 ng.mL^?1 for SPE. The precision, as measured by the standard deviations (RSD), were in the range 3.6 % to 5.8 % for SPME and 2.4 % to 9.2 % for SPE.

Along with the feature of being a solvent – free sampling technique, SPME offers additional benefits due to its high sensitivity, simplicity, and small size sample required (typically: SPE – 500 mL, SPME – 5 mL).     

The siting puzzle: Balancing economic and environmental gains and losses

Traditional approaches to the siting of potentially hazardous but regionally necessary facilities are often ineffective and lead to drawn-out legal disputes ultimately satisfactory to none of the parties. Research at MIT over the last decade has indicated five factors that may solve the siting puzzle. Application of these principles do not guarantee that a decision will not be disputed but may enhance the possibility of a wise and durable agreement.     

A comparative study of countries’ responsibilities for carbon dioxide emission in an open economy

In an open economy, embodied carbon dioxide emissions in international trade should be taken into consideration to scientifically define each country’s emissions responsibility. In this study, a multiregional input–output model is constructed to calculate the embodied carbon dioxide emissions of 25 World Trade Organization members, including China, according to the producer–consumer shared responsibility principle. The study indicates that: it is fairer and more efficient to identify each country’s carbon dioxide emissions responsibility according to the shared responsibility principle; China’s producer responsibility is 1.4 times that of the USA, while China’s consumer responsibility is only one-tenth that of the USA; according to the producer responsibility principle, China shoulders the greatest responsibility. According to the producer–consumer shared responsibility principle, China’s responsibility shows a large decrease. Resource endowment, economic development stage, and trade structure account for the abovementioned changes in China’s emissions responsibility.     

Oxidation of Toluene on γ-Al2O3 Supported Copper–Manganese Catalysts

Abstract Catalytic incineration of toluene over γ-Al2O3-supported copper–manganese oxide catalysts in the temperature range of 433?K–553?K was investigated using a fixed-bed flow reactor. Catalysts were characterized using Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy, temperature-programmed reduction, temperature-programmed oxidation, X-ray photoelectron spectroscopy, and X-ray diffraction. Incineration of toluene was achieved at temperatures up to 553?K and it was found that the weight ratio of reactants (Cu:Mn) was optimized to be 15:10. Brunauer-Emmett-Teller surface area results had no correlation with the activity of the catalysts. Results of temperature-programmed reduction/temperature-programmed oxidation and X-ray photoelectron spectroscopy showed that the redox peak of the 15Cu-10Mn catalyst shifted at lower temperatures and the binding energy shifted toward higher oxidation levels. These results show that high binding energy and high redox capacity are the causes of...