水中有毒有害有机污染物的处理问题一直都是环保领域的研究热点之一。光Fenton和光催化技术作为绿色高效的有机污染物去除技术得到越来越多的关注，在难降解污染物的去除方面具有重要意义。石墨相氮化碳（g-C₃N₄）和钒酸铋（BiVO₄）具有较窄的禁带宽度，并且g-C₃N₄的导带电位（-1.1 V vs NHE）和BiVO₄导带电位（-0.32 V vs NHE），都比O₂/H₂O₂（0.69 V）的还原电位更负，所以这两种半导体的导带电子都有足够的能量将O₂还原为H₂O₂。本文以环境有机污染物高效绿色去除为研究目标，分别采用g-C₃N₄和BiVO₄为光响应材料，比较研究光芬顿和光催化污染物降解的动力学及机理。发现在不同催化剂体系和不同有机污染物情况下，光催化过程总是表现出零级动力学特征而光芬顿过程符合一级动力学特征。论文的主要结论如下：

（1）将微量铁掺杂在剥离的层状g-C₃N₄中，制备了一系列不同浓度铁掺杂的光催化材料，并比较研究了该材料上的光芬顿与光催化罗丹明6G（Rh 6G）降解反应。当Fe负载量达到0.054 wt%并添加10 mmol/L H₂O₂时，Rh 6G的最佳移除效率在0.5 h光照下达到60%，在1 h光照下约为100%。然而，使用不掺杂Fe的g-C₃N₄作为对照组，光照0.5 h时Rh 6G染料的移除效率只有25%，1 h后移除效率也仅为55%。经过连续5次循环后，Rh 6G的光芬顿移除效率在1 h内仍超过88%。通过动力学模型验证了光芬顿反应符合一级动力学特征，而光催化反应符合零级动力学特征。由清除剂实验结果得到主要活性物种在Rh 6G降解过程中作用顺序为·O₂^->·OH>>h⁺，并推测了光芬顿降解反应机理的详细步骤。

（2）使用H₂SO₄插入B-g-C₃N₄层中并经过热剥离得到分层的TE-g-C₃N₄，剥离后的TE-g-C₃N₄可以在光照条件下原位产生H₂O₂。生成的H₂O₂可作为光芬顿降解罗丹明B（RhB）反应的自“启动按钮”，进而首次提出了无需添加H₂O₂的光芬顿降解反应。使用TE-g-C₃N₄和Fe³⁺作为催化剂，光照1 h的RhB染料移除效率为90%，2 h后移除效率可达到100%。与之形成强烈反差的是，在没有Fe³⁺的情况下，使用TE-g-C₃N₄光降解RhB的移除效率在光照1 h后约为55%，光照2 h后约为95%。循环5次后，光芬顿移除效率仍超过90%。由清除剂实验以及电子自旋共振谱（ESR）的结果可知，光芬顿降解RhB过程中主要活性物种的作用顺序为·OH>h⁺>>·O₂^-，而光催化降解过程的活性物种作用顺序为h⁺>>·OH>·O₂^-。在此基础上提出了光芬顿与光催化降解反应可能的详细机理。所提出的机理很好地解释了光芬顿反应比光催化反应更为迅速的原因。同时得到光芬顿反应符合一级动力学，光催化反应符合零级动力学。为了验证该规律性的普遍性，使用不同催化剂同一染料以及不同催化剂不同染料进行验证。利用B-g-C₃N₄以及第三章节制备的g-C₃N₄催化剂，降解结晶紫（CV），孔雀石绿（MG），亚甲基蓝（MB），在所有体系得到了符合一级动力学特征的光芬顿过程和符合零级动力学特征的光催化过程，说明该规律具有一定的普适性。

（3）通过水热法成功合成出具有类似于“冰糖”结构的八面体单斜晶BiVO₄催化剂，发现在该材料体系同样可以实现无需添加H₂O₂的光芬顿过程，以该材料为光吸收材料比较研究了光芬顿与光催化降解RhB、Rh 6G和诺氟沙星（NOR）。在光照20 min后，RhB、Rh 6G和NOR的光芬顿移除效率依次是80%、30%、85%，在光照1 h后，移除率分别达到100%、70%、98%。经过连续五个周期后，RhB的光芬顿移除效率仍超过90%。对比RhB和Rh 6G光芬顿降解曲线，发现在光照20 min后，RhB溶液的移除效率达到80%是Rh 6G移除效率的2.7倍，且两条降解曲线符合一级动力学特征，其速率常数依次为0.0437 min^-1，0.0136 min^-1，引起速率差异的原因可能是RhB或Rh 6G与Fe³⁺之间的配位差异。因此，推测RhB分子结构里的羧基比Rh 6G结构中的氨基更容易与Fe³⁺配位导致了RhB的降解反应速率远远高于Rh 6G速率。通过光芬顿与光催化降解RhB、Rh 6G、NOR反应，进一步验证了光芬顿过程符合一级动力学特征而光催化过程符合零级动力学特征。基于ESR和一系列清除剂的实验数据分析表明，活性物质在光芬顿降解Rh 6G中的作用顺序为·OH>h⁺>·O₂^-，并提出了详细的反应机理。

The treatment of toxic and harmful organic pollutants in water has always been one of the research hot topics in the field of environmental protection. As a green and efficient technology for organic pollutant removal, photo-Fenton and photocatalytic technology have received more and more attention, and have important significance in the removal of refractory pollutants. Graphite phase carbon nitride (g-C₃N₄) and bismuth vanadate (BiVO₄) both have narrow band gaps, and the conduction bands potential of g-C₃N₄ (-1.1 V vs NHE) and BiVO₄ (-0.32 V vs NHE) are both more negative than the reduction potential of O₂/H₂O₂ (0.69 V), so the conduction band electrons of these semiconductors have enough energy to reduce O₂ into H₂O₂ . This paper focuses on the efficient and green removal of environmental organic pollutants, using g-C₃N₄ and BiVO₄ as light-responsive materials, respectively, and comparatively studied the kinetics and mechanism of photo-Fenton and photocatalytic degradation of pollutants. It was found that under different catalyst systems and different organic pollutants, the photocatalytic process always showed zero-order kinetic characteristics and the photo-Fenton process was first-order kinetic characteristics. The main conclusions of the paper are as follows:

(1) A series of photocatalyst materials doped with different concentrations of iron were prepared by doping trace iron in exfoliated layered g-C₃N₄, and the photo-Fenton and photocatalytic degradation reactions on this material were compare timely studied. When the Fe loading reached 0.054 wt% with 10 mmol/L H₂O₂ was added, the best removal efficiency of Rhodamine 6G (Rh 6G) reached 60% within 0.5 h and ~100% within 1 h of light illumination. However, using g-C₃N₄ without Fe dopping as a control experiment, the removal efficiency of Rh 6G was only 25% within 0.5 h and 55% within 1 h of light illumination. After 5 consecutive cycles, the photo-Fenton removal efficiency of Rh 6G still exceeded 88% within 1 h. The kinetic model verifies that the photo-Fenton reaction conforms to first-order kinetics, and the photocatalytic reaction conforms to zero-order kinetics. According to the experimental results of the scavenger, the sequence of the main active species in the degradation process of Rh 6G is: ·O₂^->·OH>>h⁺, and the detailed mechanical steps of the photo-Fenton degradation reaction were proposed.

(2) Layered TE-g-C₃N₄ was prepared by inserting H₂SO₄ into a B-g-C₃N₄ and thermal exfoliation.The exfoliated TE-g-C₃N₄ can generate H₂O₂ in situ under light illumination. Then the in situ generated H₂O₂ can be used as the "start button" for photo-Fenton degradation of Rhodamine B (RhB) reaction. Thus a novel H₂O₂-free photo-Fenton reaction was proposed for the first time. The removal efficiency reached 90% within 1 h and ~100% within 2 h of light illumination using TE-g-C₃N₄ with Fe³⁺ as catalyst. With strong contrast, the removal efficiency of RhB using TE-g-C₃N₄ without Fe³⁺ is just about 55% after 1 h and 95% after 2 h of light illumination, respectively. After 5 cycles, the removal efficiency of photo-Fenton degradation still exceeded 90%. Moreover, from the results of scavenger experiments and electron spin resonance spectroscopy (ESR) test, it can be seen that the order of main active species in the photo-Fenton degradation of RhB is: OH>h⁺>>·O₂^-, while the sequence in photocatalytic degradation is h⁺>>·OH>·O₂^-. On this basis, detailed steps of the possible mechanism of photo-Fenton and photocatalytic degradation reaction are proposed. The reason why photo-Fenton reaction is faster than photocatalysis can be well explained by the machnism steps proposed. Once more, it is obtained by data fitting that the photo-Fenton reaction conforms to first-order kinetics, but the photocatalytic reaction conforms to zero-order kinetics. In order to verify the universality of this regularity, we use the same dye with different catalysts and different dyes with different catalysts for confirmation. Using B-g-C₃N₄ and the g-C₃N₄ catalyst prepared in Chapter 3 as catalysts and dyes crystal violet (CV), malachite green (MG), and methylene blue (MB) as pollutants, we concluded that the photo-Fenton processes always conform to first-order kinetics but the photocatalytic processes conform to zero-order kinetics, indicating that the rule has certain universality.

(3) The monoclinic BiVO₄ catalyst with an octahedral structure similar to the "ice sugar" structure was successfully synthesized by hydrothermal method, and it was found that this material system can also realize the photo-Fenton degradation reaction without addition of H₂O₂ . Using the obtained BiVO₄ as a light absorbing materials, photo-Fenton and photocatalytic degradation of RhB, Rh 6G and norfloxacin (NOR) were compared. After 20 minutes of light illumination, the photo-Fenton removal efficiencies of RhB, Rh 6G and NOR were 80%, 30% and 85%, respectively, and the removal efficiencies within 1 h reached 100%, 70% and 98%. After five consecutive cycles, the removal efficiency of RhB still exceeds 90%. Comparing the photo-Fenton degradation curves of RhB and Rh 6G, we found that the removal efficiency of the RhB reached 80% after the light irradiation for 20 min, which was 2.7 times that of the Rh 6G, and the obtained kinetic rate constants were 0.0437 min^-1 and 0.0136 min^-1, respectively, which may be caused by the coordination difference between RhB or Rh 6G and Fe³⁺. Therefore, we speculate that the carboxyl group in the RhB molecular structure is easier to coordinate with Fe³⁺ than the amino group in the Rh 6G structure, which causes the degradation reaction rate of RhB to be much higher than that of Rh 6G. Again the rule that photo-Fenton conforms to first-order kinetics and photocatalysis does zero-order kinetics worked using BiVO₄ as photocatalyst and RhB, Rh 6G or NOR as pollutant, rspectively.The analysis of the experimental data based on ESR and a series of scavengers shows that the order of the active species in photo-Fenton degradation of Rh 6G is ·OH>h⁺>·O₂^-, and the corresponding reaction mechanism was proposed.