Evidence of tautomerism in 2-aminopurine from fluorescence lifetime measurements

The fluorescence decay characteristics of 2-aminopurine (2AP) and 2-aminopurine riboside (2APr) have been investigated as a function of excitation and emission wavelength in aqueous and ethanolic solutions. Global analysis of the decay data shows that 2AP exists as two emitting species, whereas 2APr exists as a single species. This is attributed to 9H/7H tautomerism of 2AP. The proportion of 7H tautomer is estimated to be 20% in ethanol and 40% in water.</p

Drinking water distribution - improvements of the surface complexation model for iron corrosion

A previously presented theory for iron corrosion in the distribution networks for drinking water, the surface complexation model, was extended by the effect of natural organic matter and redox potential. The model calculations showed good agreement with measurements of the corrosion rate as obtained from coupon tests. A theory for the relation between the dissolved iron content in the water of the distribution networks and the corrosion rate is proposed. The model calculations also showed good agreement with the measured dissolved iron content.</jats:p

Pipe material selection in drinking water systems - a conference summary

A review is made of the oral presentations held at the conference “Pipe Material Selection in Drinking Water Distribution Systems - Sustainable Drinking Water Distribution Management”, held in Göteborg, Sweden on 5-6 September 2000. The topics discussed were: processes in the distribution network (microbiological activity and corrosion), water treatment and corrosion control, pipe material selection and structural design, and also the standardisation work within the European Union.</jats:p

Drinking water distribution: corrosion control in Swedish municipalities

Abstract Swedish action on corrosion control in drinking water distribution systems is evaluated. The extent to which chemicals are used and the costs of different processes are examined and the theoretical calculations of corrosion control effects are made. Improved measuring techniques and process evaluations are recommended with the objective of obtaining a more effective use of the chemicals. The content of copper and iron in water from different Swedish municipalities, before and after water treatment, was calculated using equilibrium models. The actions slightly decrease the iron corrosion in comparison with the drinking water without corrosion control, while the copper content in the water is somewhat increased.</jats:p

Corrosion control measures in Sweden and the effect of succession order

Corrosion control actions for drinking water distribution in Sweden are discussed. Several different processes are used. The water quality goals vary over a wide range both with respect to pH and alkalinity. None of the waters are supersaturated with respect to calcium carbonate. The results of the corrosion control action on copper and iron corrosion product release are calculated and discussed in terms of possibilities for improvements. The effect of water quality changes due to pipe material succession order is shown.</jats:p

Drinking Water Distribution - the Effect of Natural Organic Matter (NOM) on the Corrosion of Iron and Copper

The objective was to study the influence of natural organic matter (NOM) on the corrosion and by-product release of iron and copper. The corrosion was studied using potentiodynamic sweeps, coupon tests and field measurements in different Swedish municipalities. For iron it was found that the corrosion rate decreases in the presence of NOM. The results are explained in terms of surface complexation and a good correlation is found between theoretical calculations and experimental results. In the case of copper it was found that NOM both increases the corrosion rate and the content of copper in the water after one night of stagnation. The results are compared with equilibrium calculations and a good correlation is achieved.</jats:p

The influence of drinking water quality on the corrosion of stainless steel EN 1.4401 (SS 2347)

The corrosion and heavy metal release of stainless steel EN1.4401 (SS 2347) into drinking water was studied using potentiodynamic sweeps and chronoamperometry together with test rigs located in four Swedish municipalities. The influence of the drinking water quality on the corrosion was found to be very low. The corrosion increased with increasing total carbonate content and increasing content of natural organic matter. The results imply the action of surface complexation. Heavy metal release in stagnant water was in the vicinity of the detection limit. Nickel leaching was observed on some occasions shortly after installation. The nickel release disappeared after a few weeks. Surface analysis of the internal pipe surface after 9-12 months of exposure revealed no indication of local corrosion.</jats:p