盐水中腐殖酸的光催化降解。第1部分。人工海水：二氧化钛、温度、pH值和气流的影响。

Photocatalytic degradation of humic acid in saline waters. Part 1. Artificial seawater: influence of TiO2, temperature, pH, and air-flow.

作者信息

Al-Rasheed Radwan, Cardin David J

机构信息

Department of Chemistry, The University of Reading, Whiteknights, Berkshire RG6 6AD, UK.

出版信息

Chemosphere. 2003 Jun;51(9):925-33. doi: 10.1016/S0045-6535(03)00097-3.

DOI:10.1016/S0045-6535(03)00097-3

PMID:12697183

Abstract

We report the first systematic study on the photocatalytic oxidation of humic acid (HA) in artificial seawater (ASW). TiO(2) (Degussa P25) dispersions were used as the catalyst with irradiation from a medium-pressure mercury lamp. The optimum quantity of catalyst was found to be between 2 and 2.5 gl(-1); while the decomposition was fastest at low pH values (pH 4.5 in the range examined), and the optimum air-flow, using an immersion well reactor with a capacity of 400 ml, was 850 ml min(-1). Reactivity increased with air-flow up to this figure, above which foaming prevented operation of the reactor. Using pure oxygen, an optimal flow rate was observed at 300 ml min(-1), above which reactivity remains essentially constant. Following treatment for 1 h, low-salinity water (2700 mg l(-1)) was completely mineralised, whereas ASW (46000 mg l(-1)) had traces of HA remaining. These effects are interpreted and kinetic data presented. To avoid problems of precipitation due to change of ionic strength humic substances were prepared directly in ASW, and the effects of ASW on catalyst suspension and precipitation have been taken into account. The Langmuir-Hinshelwood kinetic model has been shown to be followed only approximately for the catalytic oxidation of HA in ASW. The activation energy for the reaction derived from an Arrhenius treatment was 17 (+/-0.6) kJ mol(-1).

摘要

我们报告了第一项关于人工海水中腐殖酸（HA）光催化氧化的系统研究。使用TiO₂（德固赛P25）分散体作为催化剂，由中压汞灯照射。发现催化剂的最佳用量在2至2.5 g·l⁻¹之间；虽然在低pH值（在所研究的范围内为pH 4.5）时分解最快，并且对于容量为400 ml的浸没式反应器，最佳空气流量为850 ml·min⁻¹。在达到该数值之前，反应活性随空气流量增加，超过该数值则会产生泡沫，妨碍反应器运行。使用纯氧时，观察到最佳流速为300 ml·min⁻¹，超过该流速后反应活性基本保持恒定。处理1小时后，低盐度水（2700 mg·l⁻¹）完全矿化，而人工海水（46000 mg·l⁻¹）仍有痕量的HA残留。对这些影响进行了解释并给出了动力学数据。为避免因离子强度变化导致沉淀问题，腐殖质直接在人工海水中制备，并且考虑了人工海水对催化剂悬浮和沉淀的影响。结果表明，在人工海水中HA的催化氧化仅大致遵循朗缪尔 - 欣谢尔伍德动力学模型。通过阿仑尼乌斯处理得到的反应活化能为17（±0.6）kJ·mol⁻¹。