摘要
As a bio-recalcitrant organic pollutant in paper mill effluent, lignin is generally removed by an advanced oxidation process, such as a TiO2/H2O2 photocatalytic technique under irradiation with ultraviolet light, which only accounts for less than 5% of sunlight. Herein, we reported a TiO2/H2O2-based thermally-assisted photocatalytic process that allows lignin to be efficiently degraded under visible/near-infrared light at an elevated temperature. Adsorption of H2O2 on TiO2 nanoparticles and an increase of temperature facilitate the production and separation of charge carriers under near-infrared and visible light irradiation, accelerate carrier transfer at the TiO2-electrolyte interface and promote the production of hydroxyl radicals, A higher level of H2O2 addition results in an increased degradation rate of lignin,while the optimal temperature for the thermally-assisted photodegradation of lignin is 70℃. A charge carrier excitation and transfer process was proposed for the TiO2/H2O2, thermally-assisted photocatalytic process. This work describes a new method for the photodegradation of organic pollutants,such as residual lignin in paper mill effluent, using wide band gap semiconductors under visible and near-infrared light irradiation.
木素是一种生物难降解有机物.造纸工业废水中的木素通常利用诸如TiO_2/H_2O_2紫外光催化技术之类的高级氧化技术去除,但紫外光在太阳光中的份额不足5%.本文提出了一种TiO_2/H_2O_2热辅助可见/近红外光催化技术,利用该技术可在可见/近红外光照射下将木素有效地催化降解.H_2O_2在TiO_2上的吸附及提高温度可促使光生电子在近红外光和可见光照射下向导带跃迁,并与H_2O_2反应促进光生载流子的分离及羟基自由基的形成.因此,提高H_2O_2浓度和适当提高温度有助于提高木素的近红外光催化降解速率,并在70℃时获得最大木素降解速率.本文还根据实验与分析提出了TiO_2/H_2O_2热辅助光催化体系降解木素时光生载流子的产生与传递机制.
基金
funded by the National Natural Science Foundation of China (31270625)
