Electrochemical disinfection using boron-doped diamond electrode--the synergetic effects of in situ ozone and free chlorine generation.

This work investigated the capability of using a boron-doped diamond (BDD) electrode for bacterial disinfection in different water matrices containing varying amounts of chloride. The feed water containing Pseudomonas aeruginosa was electrochemically treated while applying different electrode conditions. Depending on the applied current density and the exposure time, inactivation between 4- and 8-log of the targeted microorganisms could be achieved. The disinfection efficiency was driven by the generation of free chlorine as a function of chloride concentration in the water. A synergetic effect of generating both free chlorine and ozone in situ during the disinfection process resulted in an effective bactericidal impact. The formation of the undesired by-products chlorate and perchlorate depended on the water matrix, the applied current density and the desired target disinfection level. In case of synthetic water with a low chloride concentration (20 mg L(-1)) and an applied current density of 167 mA cm(-2), a 6-log inactivation of Pseudomonas aeruginosa could be achieved after 5 min of exposure. The overall energy consumption ranged between 0.3 and 0.6 kW h m(-3) depending on the applied current density and water chemistry. Electrochemical water disinfection represents a suitable and efficient process for producing pathogen-free water without the use of any chemicals.

Serial coupling of RP and zwitterionic hydrophilic interaction LC-MS: suspects screening of diclofenac transformation products by oxidation with a boron-doped diamond electrode.

The presence of pollutants and their transformation products (TPs) in the water system is a big concern because of possible adverse effects on the aquatic environment. Their identification is still a challenge that requires the combination of different chromatographic techniques. In the current research, serial coupling of RPLC and zwitterionic hydrophilic interaction LC with TOF-MS was investigated as a single separation technique for the screening of suspected TPs from electrochemical oxidation of diclofenac using a boron-doped diamond electrode. Diclofenac oxidation was performed in three water matrices in order to study its transformation in different chemical contexts. 47 TPs resulting from similar oxidation methods were selected from the literature. As in most cases standards were not available, an identification procedure based on accurate mass data and chromatographic behavior was proposed. According to this procedure, 11 suspected TPs, previously analyzed by LC, GC, or ion chromatography, were detected in a single injection. The method was proved to be reliable and versatile and it could be efficiently employed as a comprehensive analytical tool for the simultaneous analysis of compounds in a wide polarity range.