Transformation and toxicity studies of UV filter diethylamino hydroxybenzoyl hexyl benzoate in the swimming pools.

Diethylamino hydroxybenzoyl hexyl benzoate (DHHB), an ultraviolet (UV) filter, can be found in sunscreens and other personal care products and thus can be introduced into swimming pools through the swimmers. In outdoor pools, DHHB will inevitably interact with free chlorine and sunlight. Therefore, the mechanism of solar­chlorine chemical transformation of DHHB, as well as the environmental risk, were investigated in this work. In chlorinated with solar (Cl + solar) process, free chlorine was the dominant contributor to 85% of the DHHB degradation, while hydroxyl radicals and reactive chlorine species contributed only 15% because of low free radical generation and fast DHHB and free chlorine reaction rates. Scavenging matrices, such as Cl-, NH4+, and dissolved organic matter (DOM), inhibited the degradation of DHHB in the Cl + solar process, while Br-, HCO3-, NO3-, and urea promoted DHHB degradation. DHHB degradation was inhibited in tap water swimming pool samples, while it was enhanced in seawater pool samples by the Cl + solar process. Seven transformation by-products (TBPs) including mono-, dichlorinated, dealkylate, and monochloro-hydroxylated TBPs were identified. Three degradation pathways, chlorine substitution, chlorine and hydroxyl substitution, and dealkylation were proposed for DHHB transformation in the Cl + solar process. Both Quantitative structure-activity relationship and Aliivibrio fischeri toxicity tests demonstrated increased toxicity for the chlorinated TBPs. A risk assessment of the DHHB and its TBPs suggested that both DHHB and its chlorinated TBPs pose a significant health risk.

Raman spectroscopic analysis of GeS2-Ga2S3-PbI2 chalcohalide glasses.

The structures of pseudo-binary GeS2-PbI2, Ga2S3(GaS)-PbI2 and pseudo-ternary GeS2-Ga2S3-PbI2 chalcohalide systems were investigated by Raman scattering spectroscopy. By evolving the vibrational bands as a function of PbI2 content, it was verified that the effect of addition of PbI2 to the glass network is threefold, namely: (i) the conversion of GeS4 tetrahedra to GeS3I and GeS2I2 structural units, (ii) the destruction of ethane-like S3Ga(Ge)-(Ge)GaS3 structural units and formation of GaS3I and GeS3I ones and (iii) formation of short S-S chains and [PbIn] structural units when the concentration of PbI2 is high.