Zheng Shan, Cai Yong, O'Shea Kevin E
Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199.
J Photochem Photobiol A Chem. 2010 Feb 5;210(1):61-68. doi: 10.1016/j.jphotochem.2009.12.004.
Phenyl substituted arsenic compounds are widely used as feed additives in the poultry industry and have become a serious environmental concern. We have demonstrated that phenylarsonic acid (PA) is readily degraded by TiO(2) photocatalysis. Application of the Langmuir-Hinshelwood kinetic model for the initial stages of the TiO(2) photocatalysis of PA yields an apparent rate constant (k(r)) of 2.8 µmol/L·min and the pseudo-equilibrium constant (K) for PA is 34 L/mmol. The pH of the solution influences the adsorption and photocatalytic degradation of PA due to the surface charge of TiO(2) photocatalyst and speciation of PA. Phenol, catechol and hydroquinone are observed as the predominant products during the degradation. The roles of reactive oxygen species, •OH, (1)O(2), O(2) (-•) and h(VB) (+) were probed by adding appropriate scavengers to the reaction medium and the results suggest that •OH plays a major role in the degradation of PA. By-products studies indicate the surface of the catalyst plays a key role in the formation of the primary products and the subsequent oxidation pathways leading to the mineralization to inorganic arsenic. TiO(2) photocatalysis results in the rapid destruction of PA and may be attractive for the remediation of a variety of organoarsenic compounds.
苯基取代的砷化合物在禽类养殖业中被广泛用作饲料添加剂，这已成为一个严重的环境问题。我们已经证明，苯胂酸（PA）可通过TiO₂光催化轻易降解。将朗缪尔-欣谢尔伍德动力学模型应用于PA的TiO₂光催化初始阶段，得出的表观速率常数（k(r)）为2.8 μmol/L·min，PA的伪平衡常数（K）为34 L/mmol。由于TiO₂光催化剂的表面电荷和PA的形态，溶液的pH值会影响PA的吸附和光催化降解。在降解过程中，观察到苯酚、邻苯二酚和对苯二酚是主要产物。通过向反应介质中添加适当的清除剂来探究活性氧物种•OH、¹O₂、O₂⁻•和h(VB)⁺的作用，结果表明•OH在PA的降解中起主要作用。副产物研究表明，催化剂表面在初级产物的形成以及随后导致矿化生成无机砷的氧化途径中起关键作用。TiO₂光催化可快速破坏PA，对于多种有机砷化合物的修复可能具有吸引力。
