The electrochemical reduction of CO2 in a KOH/methanol-based electrolyte was investigated with an indium (In) wire electrode at ambient temperature and pressure. Formic acid, carbon monoxide, and methane were the main products from the C()2. The formation of formic acid from the CO2 predominated in all the potential ranges studied. Under the optimum experimental conditions, 76.0% Faradaic efficiency formic acid, 41.4% CO, and 0.2% methane were produced from C02 by the electrochemical reduction. Hydrogen evolution, in competition with CO2 reduction, was observed at only 0.2% Faradaic efficiency. The partial current density for C02 reduction was more than 429 times larger than that for hydrogen evolution. This research can contribute to the application in the conversion of C02-saturated methanol into useful products and the large-scale removal of C02 from the atmosphere.

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Abstract.A preconcentration method for nickel in waters involving adsorption on tungsten foil, followed by electrothermal atomic absorption spectrometry (ETAAS) with a tungsten tube atomizer is described. The most suitable pH for nickel adsorption was 5 and the optimum immersion time was 2 rain. Severe interferences from co-existing elements (A1, Ca, Cu, Fe, K, Mg, Na, Pb and Zn) on the Ni AA signal were observed. Under optimal conditions, the preconcentration of nickel on W foil could eliminate interferences from these elements. The detection limit of nickel by preconcentration-ETAAS was 0.1 ng/ml (3S/N). The method with preconcentration on tungsten foil was applied to the determination of nickel in river water. The recovery of spiked nickel was 93-102%. The tungsten foil preconcentration method is sensitive, simple, and convenient. This adsorption method can be utilized in in situ-sampling of ultra-trace nickel in environmental samples (water). Furthermore, after sampling it is easy to carry and store the W-foil without contamination for long time.Key words: preconcentration, adsorption on tungsten foil, nickel, electrothermal atomic absorption spectrometry, water.Nickel, even in small concentrations, has severe shortand long-term effects on the health of individuals, e.g. carcinogenic and atopic dermatitis [1,2]. Trace nickel is present from natural sources as well as from contaminated water arising from manufactures. Many countries have established quality standards of drinking-water, for example 0.05 gg/ml for nickel in France * To whom correspondence should be addressed Tab'yankina [15] presented the determination of trace nickel by DC arc atomic emission spectrometry (AES) with 2-mercaptobenzthiazole/polyacrylonitrile fiber sorbent. Carboxymethyl cellulose 8-hydroxy-s-sulfo-7-quinolyl ester (oxine CM-cellulose) [16] and ICP-MS with I-8-HOQ column [17] have been used for Ni determination by ICP-mass spectrometry (MS). Most of these methods are, however, complicated and time-consuming. Adsorption on tungsten metal is a simple, conventional, low cost, and time saving preconcentration method. Wolff et al. [18] reported the preconcentration of Cd, Cu, Pb, Ag and Zn in water at the ng/1 level by adsorption onto tungsten wire. Hoshino et al. [19] and Newton et al. [20] described GFAAS with tungsten wire preconcentration for Ag, Cd, Co, Cr,