Model water disinfection with electrolysis using TinO2n-1 containing ceramic electrodes

Water treatment with electrolysis was performed in a specially made electrolytic cell containing TinO2n-1 ceramic anode and Escherichia coli was used as a model organism for disinfection tests. The results showed that even relatively low energy input (0.5-2.5kWh*m-3, depending on water conductivity) in water samples with chloride ions concentration below 50mg*l-1, TinO2n-1 ceramic electrodes generated active chlorine in the range of 0.4-3.5mg Cl2*l-1, which is the level of chorine used for water disinfection. The results also confirmed that disinfection effect is a result of generation of oxidant species from chlorine rather than effect of electricity per se, or formation of radicals in water. At chloride ion concentration about 7mg*l-1 E. coli is not culturable, not able to divide and not respiring. Results showed that increase of the current above 0.02A at chloride ion concentration of 7mg*l-1 was sufficient to inactivate both culturable and viable but nonculturable (VBNC) E. coli. Notably, the ability of bacteria to divide (DVC positive) was lost more rapidly than their ability to respire. Kinetics of disinfection was studied in water sample which was treated with 0.02A at chloride ion concentration of 7mg*l-1. After about 15 minutes of exposure no culturable or able-to-divide E. coli were detected in the sample. Using the TinO2n-1 electrode in the electrolysis process with the presence of chloride ions, in concentration range which is common in raw waters, one can create a level of active chlorine that kills more than 99% of E. coli within 15 minutes. A practically applicable simple model for prediction of disinfection efficacy with electrolytic cell has been proposed

Žemės ūkis ir tarša : distancinio mokymo kurso Žemės ūkis ir tarša medžiaga

Vytauto Didžiojo universitetasŽemės ūkio akademij

Fast Proton Conduction Facilitated by Minimum Water in a Series of Divinylsilyl-11-silicotungstic Acid-co-Butyl Acrylate-co-Hexanediol Diacrylate Polymers

Studies of proton transport in novel materials are important to enable a large array of electrochemical devices. In this study, we show that heteropoly acids (HPAs) when immobilized in polymer matrixes have highly mobile protons. Divinyl-11-silicotungstic acid, an HPA, was copolymerized with butyl acrylate and hexanediol diacrylate at various weight percentage loadings from 25% to 85% using UV initiated polymerizations. The resultant films were tan colored flexible sheets of ca. 120 μm thickness. The morphology of these films varied with loading, showing phase separation into clustered HPA above a 50 wt % loading and lamella morphologies above an 80 wt % loading. Water uptake was strongly associated with the HPA clusters, which facilitated transport of protons. This was realized by proton conductivities as high as 0.4 S cm–1 at 95 °C and 95% RH and 0.1 S cm–1 at 85 °C and 50% RH. Pulse field gradient spin echo NMR measurements indicated that water self-diffusion was fast (1.4 × 10–5 and 4.4 × 10–5 cm2 s–1 for 50% and 100% RH, respectively) at 80 °C. We show that the water in these systems is highly associated with the HPA clusters and that fast proton transport is facilitated by as few as 3 water molecules per proton