Photocatalytic oxidation of VX-simulation substance

Abstract

Experimental studies of photocatalytic oxidation (PCO) of VX-gas simulation substance cysteamine-S-phosphate sodium salt (NaHPO3S-CH2-CH2-NH2, CPSS) at various initial concentrations and pH were undertaken. PCO ultimately resulted in complete mineralisation of CPSS. The PCO byproducts of CPSS include acetate, oxalate and trace amounts of formate ions. The formation rates of acetate and phosphate were equal to the rate of degradation of CPSS, which indicates easy breakage of P-S, C-S and C-N bonds. Sulphate was formed more slowly due to stepwise oxidation of reduced sulphur. Amino group, generally transformed to ammonia, was partially oxidised to nitrite and nitrate in alkaline media. The fastest mineralisation in terms of both TOC degradation and phosphate formation was observed in neutral media. Under neutral media conditions, the PCO rate increased linearly with the CPSS concentration increase. The maximum efficiency by TOC degradation was observed as large as 77 mg per Wh of incident UV flux with quantum efficiency 3.8%.

Titanium dioxide-mediated heterogeneous photocatalytic degradation of terbufos: Parameter study and reaction pathways

“…The formation of terbufos-oxon (compound II) is attributed to oxidative desulfuration by • OH attack (Scheme 1, route A). Terbufos-oxon represents one of the most expected intermediates since previous studies showed that the oxidant attack of the • OH radicals on the P S bond occurs firstly in the case of phosphorothioates, resulting to the formation of the oxon derivatives [30,34,49,50].…”