γ-FeOOH-草酸系统中橙黄I的光化学脱色

以8 W黑光灯为光源,γ-FeOOH为催化剂,加入草酸构成光化学Fenton体系,研究了这一体系中橙黄Ⅰ的光化学脱色动力学;考察了橙黄Ⅰ的初始浓度、初始pH值和草酸初始浓度对橙黄Ⅰ光化学脱色降解的影响.结果表明,草酸能显著促进橙黄Ⅰ的脱色与降解,橙黄Ⅰ光化学脱色一级动力学常数随草酸浓度的增大呈先升后降的趋势,最佳草酸初始浓度为1.8 mmol·L-1;溶液pH值的变化也显著影响橙黄Ⅰ的脱色.光化学反应过程中Fe2+和总Fe的浓度也随草酸浓度与反应时间的变化而变化.

The photochemical bleaching for Orange I in the lepidocrocite-oxalate complex system

The lepidocrocite powder was prepared by means of hydrothermal method and characterized by means of XRD, SEM, BET methods. The results showed that powder should be pure lepidocrocite with rose-like morphology and its specific surface area was up to 125.6m2/g. Dark adsorption experiments were carried out and the adsorption equilibrium constant (1.52×105L?mol-1) and saturated adsorption amount(4.202×10-5mol?g-1) of Orange I were obtained based on Langmuir theory. The photochemical bleaching of Orange I was investigated in the photo-Fenton-like system, which consisted of lepidocrocite as catalyst, oxalic acid and an 8 watt black lamp as light source. A series of experiments were carried out to investigate the dependence of photochemical bleaching kinetic of Orange I on the different initial concentration of Orange I, pH value and the initial concentration of oxalic acid (COX). The results showed the addition of oxalic acid could promote the photochemical bleaching of Orange I, and first-order kinetic constant of Orange I photochemical bleaching increased firstly and then decreased with the increase of COX. The optimal COXwas 1.8mmol?L-1. The first-order kinetic constant also depended strongly on the pH value and the initial concentration of Orange I. The concentration of Fe2+ and total ferric ions (Total-Fe) with reaction time also depended on the COX. The photochemical mechanisms of photobleaching and photodegradation for Orange I were discussed in the presence of oxalic acid.