Search Results (2)

Cadmium sulfide (CdS)-based photocatalysts are prepared following a hydrothermal procedure (with CdCl₂ and thiourea as precursors). The HydroThermal material annealed (CdS-HTa) is crystalline with a band gap of 2.31 eV. Photoelectrochemical investigation indicates a very reducing photo-potential of −0.9 V, which is very similar to that of commercial CdS. CdS-HTa, albeit having similar reducing properties, is more active than commercial CdS in the reductive dehalogenation of 2,2-dichloropropionic acid (dalapon) to propionic acid. Spectroscopic, electro-, and photoelectrochemical investigation show that photocatalytic properties of CdS are correlated to its electronic structure. The reductive dehalogenation of dalapon has a double significance: on one hand, it represents a demanding reductive process for a photocatalyst, and on the other hand, it has a peculiar interest in water treatment because dalapon can be considered a representative molecule of persistent organic pollutants and is one of the most important disinfection by products, whose removal from the water is the final obstacle to its complete reuse. HPLC-MS investigation points out that complete disappearance of dalapon passes through 2-monochloropropionic acid and leads to propionic acid as the final product. CdS-HTa requires very mild working conditions (room temperature, atmospheric pressure, natural pH), and it is stable and recyclable without significant loss of activity. Full article

While disinfection ensures the destruction of pathogenic microorganisms, the disinfectant substances used react with some organic and inorganic substances in water, causing the formation of disinfection by-products. Some disinfection by-products have been classified as carcinogenic by the Environmental Protection Agency (EPA). Haloacetic acids are one of the disinfection by-product groups that have been detected in drinking water and are carcinogenic. It is commonly believed that bottled water, which is being increasingly consumed worldwide, does not contain environmental pollutants. For this reason, research on bottled water is limited. In this study, the amount of 9 haloacetic acids and dalapon were investigated in 28 different branded bottled water samples collected from a market. As a result of the study, the total haloacetic acid concentrations were found to be from 2.13 to 7.56 μg/L, and the dalapon concentration was < detection limit-12.47 μg/L. At least three different haloacetic acids were detected in each sample analyzed. It was determined that the threshold values given by the EPA and the World Health Organization (WHO) were not exceeded. It has been observed that bottled waters, which are generally considered to be of higher quality than mains water, contain haloacetic acids and dalapon at low concentrations. A health risk assessment was performed for dalapon and trichloroacetic acid (TCAA). A low non-carcinogenic risk and tolerable carcinogenic risk were determined. Care should be taken to counter the negative health effects of HAAs and dalapon. Full article