【作者】 欧阳秀欢；

【导师】 陈国华；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2005， 硕士

【摘要】 目前环境污染越来越严重,因此环境清洁和环境补救成为一个急迫的任务。在各种净化环境技术中,高级氧化技术作为一种新环境净化技术受到越来越多的关注。高级氧化技术对水体中有毒有害难降解的污染物具有较强的应用优势,具有高效、快速、无二次污染等众多优点,因而有着广阔的应用前景。高级氧化技术的关键是产生高度活性的·OH,按所用的氧化剂及催化条件的不同,通常可以分为三大类:Fenton试剂法及类Fenton试剂法,臭氧及组合臭氧氧化法,半导体光催化氧化法。本文选取了其中的Fenton试剂法和半导体光催化法进行探讨。 首先,选取有机磷农药之一久效磷以及褐藻胶生产废水作为研究对象,利用Fenton试剂法对它们进行了研究。 对于久效磷,本文采用正交实验和单因素实验分别考察了pH值,H₂O₂用量,Fe²⁺浓度,反应时间,反应温度等5个因素在Fenton氧化久效磷过程中对COD去除率的影响。在选用的试剂用量中,由正交实验得出5个因素的影响主次顺序为H₂O₂浓度>反应温度>反应时间>pH值>Fe²⁺浓度,COD去除率最高为78.8%。通过单因素实验得出最佳反应条件是2.0ml H₂O₂,70℃,pH值为3,0.50mmol/l Fe²⁺,经过反应10h后,溶液中的有机物全部被矿化为无机物,COD去除率达100%,并基本符合准一级动力学反应。另外,还考察了过渡金属离子Cu²⁺、Mn²⁺、Co²⁺、Zn²⁺对Fenton试剂的协同催化作用。经实验证明,在一定浓度下,它们都对Fenton反应具有很好的促进作用,其中Cu²⁺的作用最佳,其原因是过渡金属离子有助于H₂O₂分解为羟基自由基,从而提高了反应效率。最后,借助GC-MS测定了Fenton法反应过程中久效磷的残留量,发现30min后溶液中已经检测不出久效磷。 对于褐藻胶生产废水,首先采用了正交实验考察了5个因素对Fenton法降解褐藻胶生产废水的影响,在选用的试剂用量中,影响的主次顺序为Fe²⁺浓度>反应时间>反应温度>pH值>H₂O₂浓度。然后采用单因素实验分别探讨了以上5个因素的影响,确定了最佳反应条件是0.5ml H₂O₂,40℃,pH值为3;4.0mmol/1 Fe²⁺,经过60min后,Fenton反应达到了平衡,COD去除率最高为62.9%,出水COD值为67mg/l。更多还原

【Abstract】 The issue of environmental pollution is currently more and more serious, so that the environmental cleaning and environmental remediation is an urgent task. Among various techniques for purifying environment, advanced oxidation processes （AOPs） are paid greater attention as new environment-purifying technique. AOPs have high efficiency, have no pollution after treatment, so it is a prospective technique for treating toxic contaminations in water. The key of the AOPs technology is to produce hydroxyl radical（ · OH）. According to the conditions of oxidants and catalytical, AOPs can be dvided into Fenton reagent and like-Fenton reagent, ozone and combined ozone oxidation, photocatalytic degradation. The method of Fenton reagent and photocatalytic degradation are choosed to discuss in this paper.Firstly, monocrotophos and wastewater from algin production are selected to be the target object degradated by Fenton reagent.For monocrotophos, the five important factors, pH value, dosage of H₂O₂, Fe ²⁺ concentration, temperature and reaction time are designed by orthogonal experiments or single experiments. The result from orthogonal experiments show that the order of the five factors was: dosage of H₂O₂>tempreture>reaction time> pH value>Fe²⁺ concentration. The COD removed is 78.8%. The result from single experiments indicate that the optimal conditions are as following: 2.0ml H₂O₂, 70℃, 0.50mmol/l Fe²⁺, pH=3. After 10 hours, the organics in the solution are completely minerized to inorganics, and the COD removed is 100%. The kinetics of this reaction is first order kinetics. Moreover, we investigate the catalysis of four transition metal ions Cu²⁺, Mn²⁺,Co²⁺ and Zn²⁺ on the Fenton reaction. The results indicate that the degradation efficiency has been great improved when the concentration of the metal ions achieve certain value. The reason is that transition metal ions are helpful to decompose H₂O₂ and produce more hydroxyl radical. Among these four transitionmetal ions, Cu2+ has the highest catalysis efficiency. Finally, the result of GC-MS shows that monocrotophos can not be determined after 30min.For wastewater algin from production, we firstly carry out orthogonal experiments to discuss the influence of five facor on the decomposition of Fenton reagent. And the result is Fe + concentration >reaction time>tempreture>pH value >dosage of H2O2. Single experiments show that the optimal conditions are: 0.5ml H2O2, 40°C, 4.0mmol/l Fe2+, pH=3. After 60 min, Fenton reaction balanced. Finally, the COD removal ration is 62.9% and the COD value of the solution is 67mg/l after degradation.Secondly, we study photocatalyzed 2,4-dichlorophenol by TiO2-CS prepared as catalyst. The dosage of TiO2-CS, original pH value, dissolved oxygen, concentration of 2,4-dichlorophenol and irridation time are studyed.The dosage of TiO2-CS has vital effect on the removal of 2,4-dichlorophenol. In the light system without TiO2-CS, the maximal remaval rate is 80.4%. The optimal dosage of T1O2-CS is 0.1 g/1, the maximal removal rate is 95.4%. With same dosage of TiO2 powder and T1O2-CS, the removal rate of TiO2-CS in 30min is higher than TiO2 powder by 14%, literature1"91 by 36.6%.The original pH has an important effect on the removal rate, absorbance and pH value changes during the oxidation. In the system of pH=12.5, the removal rate is the highest, 94.8% in 30minutes. With different original pH value, the color of the solution are getting deeper quickly, and slowly lighter after get to the deepest. If the original pH value is too low or too high, the pH value of the solution during the oxidation has little change because of buffer ability of the solution. In the weak acid or weak alkaline system, the pH decrease rapidly to 3 in the first 30 minutes, and then become stable, because organic acids are formed during the photocatalytic reaction.Dissolved oxygen in the solution plays an important role on the photocatalytic oxidation confirmed by three control experiments. The result indicats that oxygen mainly affects the absorbance of the solution. With enough oxygen, absorbance of the solution lower rapidly after 30min, or it will not lower at all untill the oxygen isintroduced.During the oxidation, the concentration of chlorine ion has a linear relation with the reaction time, so its kinetics is zero order kinetics. The velocity constants of three solutions （25 mg/1, 50 mg/1, 100mg/l）are 0.4987, 0.9496, 1.7674 min"1, respectively.更多还原