草酸促进光助Fenton催化氧化深度处理炼化废水工艺研究

发布时间：2018-04-03 06:43

本文选题：光催化氧化　切入点：草酸　出处：《哈尔滨工业大学》2015年硕士论文

【摘要】：炼化废水产量大,污染成分复杂,采用传统的“老三套”处理工艺,出水仍无法达到国家排放新标准,因此有必要对炼化废水进行深度处理。由于二级处理后的炼化废水可生化性较差,本文利用光催化氧化法进行处理,并针对普通光-Fenton法产生铁泥量大以及适用p H范围有限的特点,引入草酸提高了对炼化废水的处理能力,并探讨了反应机制。本文采用沉淀法制备的针铁矿为光催化剂,考察了Fe3+来源、反应方式、陈化温度及陈化时间等因素对合成针铁矿的影响,并利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对不同因素制备的针铁矿矿相及微观形貌进行表征,确定了适宜的催化剂制备条件。选用双酚A(BPA)为目标污染物,研究了针铁矿的光催化性能。结果表明,采用将Na OH溶液逐滴滴加至Fe(NO3)3溶液中,在60 o C条件下陈化12 h以上可以得到结晶度高、呈现均匀棒状的针铁矿,对BPA的去除率达90%以上。以BPA为目标污染物,建立了草酸促进光助Fenton催化氧化水处理工艺,考察了各种因素对去除BPA的影响,得到最佳工艺条件为:草酸浓度为0.33 mmol/L,针铁矿投加量为0.7 g/L,过氧化氢浓度为5.5 mmol/L,无需调节p H(约为6),在100 W紫外灯下反应120 min,BPA去除率可以达到96.4%。考察了催化剂的稳定性和重复使用性,使用五个周期,针铁矿催化剂对BPA的去除率可以保持在90%以上。对实验数据进行动力学拟合,反应符合准二级动力学模型,在最优工艺条件下,反应动力学速率常数为0.0225 L/(mol·min),半衰期为4.44 min。比较了不同工艺条件下BPA去除率以及·OH生成量的不同,探讨了草酸促进针铁矿光催化氧化反应机理。认为在紫外光作用下针铁矿与H2O2之间产生协同作用,使BPA去除率显著提高;草酸的加入可以促进体系分解H2O2生成·OH,进一步提高BPA的去除率。设计了草酸促进光助Fenton催化氧化深度处理炼化废水的两段式动态工艺装置,系统由预处理段和光化学反应段组成。考察了草酸浓度、Fe2+浓度、H2O2浓度、p H及预处理时间等因素的影响,确定了最佳工艺条件:草酸浓度为0.11mmol/L,H2O2浓度为6.6 mmol/L,Fe2+浓度为0.11 mmol/L,p H为6时,预处理15 min后在100 W紫外灯下反应5 min,体系TOC的去除率可以达到70%以上。增加预处理段可以提高TOC去除率,降低药剂使用量。
[Abstract]:Because of the large output of refinery wastewater and complex pollution composition, the effluent can not reach the new national discharge standard by using the traditional "old three sets" treatment process, so it is necessary to carry out advanced treatment of refinery wastewater.Due to the poor biodegradability of the secondary treated refinery wastewater, the photocatalytic oxidation process is used to treat the wastewater. The characteristics of the ordinary photo-Fenton process are the large amount of iron sludge produced and the limited application range of pH.Oxalic acid was introduced to improve the treatment capacity of refinery wastewater and the reaction mechanism was discussed.In this paper, the influence of Fe3 source, reaction mode, aging temperature and aging time on the synthesis of goethite was investigated by using goethite prepared by precipitation method as photocatalyst.X-ray diffractometer and scanning electron microscope (SEM) were used to characterize the phase and micromorphology of goethite prepared by different factors. The suitable preparation conditions of the catalyst were determined.The photocatalytic activity of goethite was studied with bisphenol A (BPA) as the target pollutant.The results show that the goethite with high crystallinity and uniform rod shape can be obtained by adding NaOH solution to Fe(NO3)3 solution one by one at 60 o C for more than 12 h, and the removal rate of BPA is more than 90%.With BPA as the target pollutant, the process of oxalic acid promoting photocatalytic oxidation of Fenton was established. The effects of various factors on the removal of BPA were investigated.The optimum technological conditions are as follows: oxalic acid concentration is 0.33 mmol / L, goethite dosage is 0.7 g / L, hydrogen peroxide concentration is 5.5 mmol / L, and the removal rate of BPA can reach 96.4g / L at 120 mins under 100W UV lamp without adjusting pH (about 6g 路L ~ (-1)).The stability and reusability of the catalyst were investigated. The removal rate of BPA of goethite catalyst was over 90% when used for five periods.The experimental data were fitted to the quasi-second-order kinetic model. Under the optimum conditions, the kinetic rate constant of the reaction was 0.0225 L/(mol / min and the half-life was 4.44 min.The mechanism of oxalic acid promoting photocatalytic oxidation of goethite was discussed by comparing the removal rate of BPA and the yield of OH under different conditions.It is concluded that the synergistic effect between goethite and H2O2 under ultraviolet light can increase the removal rate of BPA, and the addition of oxalic acid can promote the decomposition of H2O2 and further increase the removal rate of BPA.A two-stage dynamic process for advanced treatment of refinery wastewater using oxalic acid to promote photocatalytic oxidation of Fenton was designed. The system consists of pretreatment stage and photochemical reaction stage.The effects of oxalic acid concentration, Fe _ 2 concentration, H _ 2O _ 2 concentration and pretreatment time on H _ 2O _ 2 concentration and pretreatment time were investigated. The optimum conditions were determined as follows: oxalic acid concentration was 0.11 mmol / L ~ (-1) H _ (2) H _ 2O _ 2 was 6.6 mmol / L ~ (-1) Fe _ (2) concentration was 0.11 mmol / L ~ (-1) H _ (6),After pretreatment for 15 min, the removal rate of TOC was over 70% under 100W UV lamp for 5 mins.Increasing the pretreatment stage can increase the removal rate of TOC and reduce the dosage of medicament.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X742

【参考文献】