高含硫废水受控氧化及单质硫的形成特性研究

发布时间：2018-09-05 07:46

【摘要】：含硫废水不仅会对设备造成腐蚀,还会对水处理工艺系统造成影响,同时逸出的H2S还会对人体造成伤害。而针对高浓度的含硫废水,更是需要找到一种有效的处理方法,在减轻污染的同时实现污染物质的资源化回收利用。论文以模拟的含硫废水为研究对象,以S2-的去除率和单质硫的收率为指标,对Na2S2O5、Na2SO3和H2O2的脱硫效果进行评价,筛选出最佳氧化剂,考察了硫化物氧化动力学的影响因素,并在此基础上采用响应曲面法对其氧化反应条件进行优化。在最佳氧化剂的优化条件下,采用改变氧化剂的投加方式、控制反应体系的氧化还原电位(ORP)和反应分离耦合等手段强化单质硫的转化。利用X射线衍射仪(XRD)、扫描电镜(SEM)和粒度分析仪对体系中固相产物的结构、形态特征进行了表征。结果表明： (1)在Na2S2O5投加量为9g/L,初始pH值为6,反应时间为30min的最佳条件下,S2-的去除率和单质硫的收率分别为95.16%和42.32%。在Na2SO3投加量为5g/L,初始pH值为5,反应时间为20min的最佳条件下,S2-的去除率和单质硫的收率分别为78.71%和26.68%。在H2O2投加量为10mL/L,初始pH值为6,反应时间为14min的最佳条件下,S2-的去除率和单质硫的收率分别为95.68%和60.78%。H2O2是脱硫效果最好的氧化剂。H2O2氧化硫化物遵循表观二级反应动力学,表观反应速率常数为K=1.0669L.g-1.min-1。其反应速率常数受H2O2的投加量、反应温度和反应初始pH的影响。氧化剂投加量增加,反应速率常数增大；温度升高,反应速率常数增大；初始pH增大,反应速率常数减小。 (2)采用响应曲面法对H2O2氧化含硫废水的反应条件进行优化,优化后的反应条件为：初始pH为6.5,投加量为9mL/L,反应时间为15min。此条件下得出的单质硫的收率为65.85%,相对于优化前提高了5.07%。 (3)在H202氧化含硫废水的过程中,相对于一次性投加,H2O2的分次投加使单质硫的收率降低了8.25～26.05%,与预期的效果相反；采用反应分离耦合的方式强化单质硫的转化,在分离因数为1082的条件下,单质硫的收率达到了74.98%,相对于未强化前提高了9.13%；控制体系中的ORP值强化单质硫的转化具有最好的效果,当ORP值控制在(30±5)mV时,单质硫的收率达到了76.35%,相对于未控制前提高了10.50%。 (4)XRD分析表明,H2O2氧化含硫废水所得的固相产物为室温下结构稳定的S8。SEM及粒度分析仪对液相中的单质硫进行分析表明,体系中的单质硫颗粒逐渐增大,由纳米硫颗粒组成的层状逐渐变成团聚卷积在一起的微米级颗粒状；增大的机理为晶体的生长和纳米颗粒的团聚,并由此推断单质硫的S8结构的形成机制是以Sx2-为中间产物。
[Abstract]:The sulfur-containing wastewater will not only corrode the equipment, but also affect the water treatment process system. At the same time, the H _ 2S released from the wastewater will also cause harm to the human body. It is necessary to find an effective treatment method for high concentration sulfur-containing wastewater, which can reduce the pollution and realize the recycling of pollutants. In this paper, the desulfurization effect of Na2S2O5,Na2SO3 and H2O2 was evaluated with the removal rate of S2- and the yield of elemental sulfur as the index, and the optimum oxidant was screened out. The factors influencing the oxidation kinetics of sulfides were investigated. On this basis, the reaction conditions were optimized by response surface method. Under the optimum conditions of oxidant, the conversion of elemental sulfur was enhanced by changing the way of adding oxidant, controlling the redox potential (ORP) of the reaction system and the coupling of reaction separation and so on. The structure and morphology of solid products in the system were characterized by (XRD), scanning electron microscope (SEM) and particle size analyzer. The results showed that: (1) under the optimum conditions of Na2S2O5 dosage of 9 g / L, initial pH value of 6 and reaction time of 30min, the removal rate of S2- and the yield of elemental sulfur were 95.16% and 42.32%, respectively. Under the optimum conditions of Na2SO3 dosage of 5 g / L, initial pH value of 5 and reaction time of 20min, the removal rate of S2- and the yield of elemental sulfur were 78.71% and 26.68%, respectively. When the dosage of H2O2 is 10 mL / L, the initial pH value is 6, and the reaction time is 14min, the removal rate of S2- and the yield of elemental sulfur are 95.68% and 95.68%, respectively. The oxidant, H2O2, which is the best oxidant for desulfurization, follows the apparent second-order reaction kinetics. The apparent reaction rate constant is KN 1.0669L 路g-1.min-1. The reaction rate constant is affected by the dosage of H2O2, the reaction temperature and the initial pH. With the increase of oxidant dosage, the reaction rate constant increases; the temperature increases, the reaction rate constant increases; the initial pH increases and the reaction rate constant decreases. (2) the reaction conditions for H2O2 oxidation of sulfur-containing wastewater are optimized by response surface method. The optimized reaction conditions are as follows: the initial pH is 6.5, the dosage is 9 mL / L, and the reaction time is 15 min. Under these conditions, the yield of sulfur is 65.85, which is 5.07% higher than that before optimization. (3) in the process of oxidation of sulfur-containing wastewater by H202, Compared with the one-off addition of H _ 2O _ 2, the yield of elemental sulfur decreased by 8.25% 26.05, which was contrary to the expected effect, and the reaction separation coupling method was used to strengthen the conversion of elemental sulfur under the condition of separation factor of 1082. The yield of elemental sulfur reached 74.98%, which was 9.13% higher than that before strengthening, the ORP value of control system enhanced the conversion of elemental sulfur had the best effect, when the ORP value was controlled at (30 卤5) mV, The yield of elemental sulfur reached 76.35, which was 10.50% higher than that before control. (4) XRD analysis showed that the solid phase product of H _ 2O _ 2 oxidation of sulfur-containing wastewater was S8.SEM with stable structure at room temperature and the analysis of elemental sulfur in liquid phase by particle size analyzer. The elemental sulfur particles in the system gradually increased, and the layers composed of nano-sulfur particles gradually became micron-sized particles of agglomeration and convolution, and the mechanism of the increase was the growth of crystals and the agglomeration of nanocrystalline particles. It is inferred that the formation mechanism of S _ 8 structure of elemental sulfur is Sx2- as the intermediate product.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X741

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