还原氧化石墨烯在NOM表面的沉积特性及混凝去除研究

发布时间：2018-06-01 12:35

  本文选题：还原氧化石墨烯 + 天然有机物　； 参考：《哈尔滨工业大学》2016年硕士论文

【摘要】：随着石墨烯系纳米材料(graphene family nanomaterials,简称GFNs)的发现、生产及广泛应用,其进入水环境系统的几率大大增加,可能会对水环境系统造成不利影响。但目前关于GFNs在水环境中的迁移转化行为及其对水环境系统的潜在污染的了解较少。为了进一步明确GFNs在水环境中的迁移转化行为及其对水生态系统的影响,研究以GFNs中的还原氧化石墨烯(reduced graphene oxide,简称r GO)为对象,首先主要利用耗散型石英晶体微天平(quartz crystal microbalance with dissipation,简称QCM-D)技术分析手段,分别考察了不同离子强度下r GO在天然有机物腐殖酸(HA)和富里酸(FA)表面的沉积特性并分析了其作用机理,并与其在有利条件PLL表面的沉积特性进行了对比。其次以铜绿微囊藻作为受试对象,首次探究了r GO进入水环境后对水生生物的影响;并在调查研究的基础上,以聚合氯化铝(PAC)作为混凝剂对r GO水处理过程中的混凝去除进行了初步探索。利用QCM-D手段考察了p H为7.4、不同浓度的Na Cl和Ca Cl2电解质溶液下r GO在HA和FA表面的沉积。表面总沉积量、初始沉积率和沉积效率的研究结果一致表明:随着Na Cl离子强度的增大,r GO的沉积作用呈现先增加后降低,低离子强度下(25m M)Na+的电荷屏蔽作用导致沉积作用的增加,符合经典的DLVO理论;高离子强度下(25m M)r GO的脱稳聚集导致其沉积作用的降低。二价阳离子Ca2+对r GO沉积的影响比一价阳离子Na+大。与HA相比,r GO在FA表面的沉积作用更强,但均比在PLL表面弱。这是由于FA表面具有相对较高含量的羧基官能团,能够与r GO表面少量的含氧基团发生作用。另外,HA对应较高的|ΔD/Δf|值表明,与FA相比,r GO在HA表面形成的沉积层更松散。另外,以铜绿微囊藻作为受试对象,首次探究了r GO对水生生物的影响。研究从铜绿微囊藻密度、表面形态、及叶绿素a含量变化进行了分析,结果表明r GO能够通过遮光效应和物理接触损伤效应抑制铜绿微囊藻的生长,对水生生态系统构成潜在污染。在分析了r GO对水环境系统潜在污染的基础上,进一步对r GO纳米颗粒从水系统中的去除做了初步的研究,并考察了HA对r GO颗粒混凝去除的影响,确定了两种条件下混凝剂的最佳投加量。初步研究结果表明,没有HA存在的条件下,聚合氯化铝的最佳投加量仅为3 mg/L,混凝作用机制主要为吸附架桥作用;HA存在情况下,聚合氯化铝的最佳投加量达40 mg/L,其主要混凝作用机制为电荷中和。
[Abstract]:With the discovery, production and wide application of graphene family nanomaterials (GFNs), the probability of its entry into water environment system has increased greatly, which may have a negative impact on water environment system. However, little is known about the transport and transformation behavior of GFNs in water environment and its potential pollution to water environment system. In order to further clarify the migration and transformation behavior of GFNs in water environment and its effect on water ecosystem, the reductive graphene reduced-graphene oxide (rgox) in GFNs was studied. Firstly, the deposition characteristics of r go on the surfaces of natural organic matter humic acid (HA) and fulvic acid (FA) under different ionic intensities were investigated by means of dissipative quartz crystal microbalance with dissipation, (QCM-D-) technique, and its mechanism of action was analyzed. The results are compared with the deposition characteristics on the favorable PLL surface. Secondly, using microcystis aeruginosa as the subject, the effects of r go on aquatic organisms after entering water environment were studied for the first time, and on the basis of investigation, The coagulation removal of r go water was studied with polyaluminum chloride (PAC) as coagulant. The deposition of r go on HA and FA surfaces with pH 7.4 and different concentrations of NaCl and Ca Cl2 electrolyte solutions was investigated by QCM-D. The results of total surface deposition, initial deposition rate and deposition efficiency show that with the increase of NaCl ion intensity, the deposition of rgo increases first and then decreases. The charge shielding effect of 25m M)Na at low ion intensity leads to the increase of deposition, which is in line with the classical DLVO theory, and the destability and aggregation of 25m MGo at high ionic strength results in the decrease of deposition. The effect of divalent cation Ca2 on r go deposition is greater than that of monovalent cation Na. Compared with HA, the deposition of PLL on FA surface is stronger than that on HA, but is weaker than that on PLL surface. This is due to the relatively high content of carboxyl functional groups on the surface of FA, which can interact with a small amount of oxygen-containing groups on the surface of r go. In addition, the higher value of 螖 D / 螖 F shows that the depositional layer formed on HA surface is looser than that of FA. In addition, microcystis aeruginosa was used to study the effect of RGO on aquatic organisms for the first time. The changes of density, surface morphology and chlorophyll a content of Microcystis aeruginosa were studied. The results showed that RGO could inhibit the growth of Microcystis aeruginosa by shading effect and physical contact damage effect. Potential pollution to aquatic ecosystems. Based on the analysis of the potential pollution of RGO to the water environment system, the removal of rgo nanoparticles from the water system was studied, and the effect of HA on the removal of rgo particles from the water system was investigated. The optimum dosage of coagulant was determined under two conditions. The preliminary results showed that the optimum dosage of polyaluminium chloride was only 3 mg / L without HA, and the coagulation mechanism was mainly under the condition of adsorption bridging action and the presence of HA. The optimum dosage of polyaluminium chloride is 40 mg / L, and the main coagulation mechanism is charge neutralization.
【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】：2016
【分类号】：O613.71;X52
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本文编号：1964201