TiO_2光催化降解水中天然有机物富里酸的动力学模型

Kinetic model for fulvic acid degradation by TiO_2-photocatalysis in water

在天津地表水中天然有机物主要是富里酸,它是消毒副产物的主要前驱体,因此对于富里酸的控制非常重要.以粉末态TiO2为催化剂,在光催化超滤反应器中对水中天然有机物富里酸进行了光催化氧化研究,考察了富里酸氧化的主要影响因素,包括初始pH值、催化剂浓度、光强、添加剂浓度.结果表明:富里酸降解过程能够用一级反应动力学来表示;最佳的催化剂浓度为0.5g·L-1;在pH值减小、添加剂浓度和光强增大时有助于富里酸的去除.通过分析反应速率常数和影响因素之间的关系,得到富里酸光催化氧化总体动力学模型,试验值基本符合动力学模型.另外试验还表明该反应器可方便地实现有机物降解且具有较高的去除效率.

Fulvic acid (FA) is a natural organic matter existing in Tianjin surface waters as a major precursor of disinfection byproducts. So fulvic acid control is very important in surface water treatment. Degradation of FA in a photocatalysis-ultrafiltration reactor using TiO2 powder catalyst was studied in terms of UV254 and total organic carbon (TOC) concentration. The key effects of influencing parameters on the photocatalytic oxidation of FA, including pH values, photocatalyst concentration, additives concentration and light intensity were investigated. The results showed the reaction kinetics of FA could be reasonably represented by first-order kinetics. In addition, it was found that there was an optimal catalyst concentration of 0.5 g&middotL-1 and low pH value. Increasing additives concentration and light intensity were favorable for TOC removal. By analyzing the relationship between rate constant and influencing factors, an overall FA oxidation rate kinetic model was established. The theoretical prediction were in good agreement with the experimental data. This reactor was a convenient way to degrade the organic matter with high efficiency.