TiO_2光催化降解乙酰甲胺磷

PHOTOCATALYTIC DEGRADATION OF O,S-DIMETHYL ACETYL PHOSPHORAMIDOTHIOATE

在TiO2悬浮体系中,利用光催化技术消除乙酰甲胺磷(DMAPT).探索了催化剂用量和目标物浓度对消除速率的影响.结果表明,催化剂的最佳用量为4g·l-1,DMAPT的光催化降解规律符合L-H模型,吸附常数和反应速率参数分别为2mmol-1·l和0.6mmol·l-1·min-1.反应中主要的活性物种为·OH.反应的主要中间产物和矿化产物有O,S-二甲基硫代磷酰胺酯,O,O',S-三甲基硫代磷酸酯和磷酸甲酯等.DMAPT的降解从C—N键的断裂开始,随后经过P—N,P—S,P—C键的氧化分解,生成低毒和无毒的中间产物,并随着反应的继续最终达到彻底矿化,最终产物为SO42-,NO3-,PO34-和CO2.

Photocatalytic degradation of DMAPT （O, S-dimethyl acetyl phosphoramidothioate ） in aqueous TiO2 suspensions is investigated. It is found DMAPT can be readily degradated and mineralized. The high degradation rate is obtained with TiO2 concentration of 4g ·l^-1. Moreover, Langmuir-Hinshelowood rate expression is employed for the degradation of DMAPT with 2.0 mmol·l^-1· min^-1 adsorption constant and 0. 6 mmol·l^-1· min^-1 reaction rate constant, respectively. Under acidic condition, the primary products are and phosphoramidothioic acid, O, S-dimethyl ester. It is suggested that DMAPT decomposition may origins from the destruction of C-N and P-N bond. Subsequently, the P-S, P-O, P-C bond may be oxidized gradually or simultaneously. Finally, the final products, such as, CO2, H3PO4 et al, are formed.