【作者】 杨武；

【导师】 霍明昕；

【作者基本信息】 东北师范大学 ， 环境工程， 2014， 博士

【摘要】 控制饮用水中消毒副产物（DBPs）是饮用水水质安全保障的重要环节。DBPs前体物的控制被认为是最有效的DBPs控制方法。混凝技术作为最经济的前体物控制技术，几乎是所有水厂的必备工艺。但传统的铁、铝等金属盐类混凝剂对DBPs前体物的控制效果不佳。自2004年被发现以来，石墨烯就引起了科学界的研究热潮。作为石墨烯制备过程中的中间体，氧化石墨烯（GO）由于其分子结构中含有大量含氧官能团，已被证实对多价金属离子及部分有机物具有良好的吸附去除效果。GO在对高价态金属离子的吸附时会发生团聚，沉淀，这一现象与混凝剂的胶体脱稳现象类似。在GO制备过程中，已用强氧化剂对其进行了相对彻底的氧化，O3、Cl2、ClO2等常用消毒剂不会对其进行进一步氧化，即使在水中有残留，也不会与消毒剂反应产生DBPs。已有的毒理学研究表明，一定浓度下GO不会引起细胞毒性及遗传毒性，是一种绿色材料。此外，在实验室层面，GO的制备方法相对成熟，简单，成本相对较低。基于上述原因，本研究提出采用GO作为混凝剂，在考察其絮体形成影响的基础上，分别研究其对腐植酸配水、地表水、藻细胞及藻细胞胞外有机物的去除效率及相应的DBPs控制效果。本研究在采用密闭氧化法制备氧化石墨烯。经表征分析，制得的氧化石墨烯呈透明网状结构且具有明显褶皱，分子结构中碳氧原子质量比为1.63。红外分析显示制得的氧化石墨烯中含有羟基、C=O键、C-O-C等含氧官能团。200-400mg/L钙离子作用时，可以明显观察到GO絮体的产生。GO絮体的产生速率、大小及其沉降性能随pH的升高而增强。相同离子浓度下，钾、钠、镁离子作用产生的絮体大小及沉降性能不及钙离子，铝离子作用能产生更大更紧实的GO絮体。网捕作用是GO混凝去除有机物的主要作用，在pH5-9范围内GO对腐植酸均具有很好的去除效果。pH对GO去除腐植酸的影响较小，但对其去除地表水中有机物具有很大影响，pH≤5的条件下可获得最佳的有机物去除效率。初始pH4-10的地表水经GO处理后的pH稳定在6.3-7.7之间，这与GO表面丰富的含氧官能团有密切关系。经GO处理后，水样的SUVA值略微降低，说明GO对水样中腐植酸类，疏水性，大分子有机物去除较亲水性，小分子有机物的去除能力强。GO能够有效去除水体中DBPs尤其是卤乙酸的前体物，最多能够降低86.5%的三氯乙酸前体物。三维荧光分析表明GO混凝对腐植酸及富里酸类物质具有很好的去除效果，但对蛋白质类物质的去除效果不佳。藻类的控制近年来一直是饮用水水质安全保障的重要课题。传统的金属盐类混凝剂对藻类的控制效果不甚理想，以臭氧为代表的预氧化则会破坏藻细胞结构释放藻毒素等有机物。本研究采用GO混凝控藻，实验结果表明，GO对藻细胞有很强的网捕能力。在酸性及中性条件下，40mg/L的GO即可实现对叶绿素a的完全去除，对UV254的去除效率也可达到98.3%，消毒副产物前体物减少了97.5%-100%。碱性条件下GO与藻细胞间静电斥力增大，控藻效率明显降低，当pH=10时，对叶绿素a、浊度、DOC、UV254的去除率分别降低到13.8%、17.7%、42.1%、30.8%。硅藻土的投加不会使GO控藻效率发生变化，但会明显增强絮体的沉降性能，缩短沉降时间，减少絮凝污泥量。GO混凝沉淀对组成藻类胞外有机物（EOM）的有机物也有很好的去除效果，pH＜6时，TOC的去除率能达到61%。GO混凝能够有效去除EOM中消毒副产物尤其是卤乙酸的前体物，不添加溴离子时，最多能够降低90.1%的一氯乙酸前体物，溴离子存在条件下，能够使三氯乙酸前体物降低91.0%。进一步的分析表明，GO混凝对EOM中含苯环结构，类腐植酸类物质及含C=C双键和C=O双键的芳香族化合物具有一定的去除效果。此外，GO对EOM中的亲水性、大分子有机物的去除能力较疏水性、小分子物质去除能力强。对DBPs的终端控制是DBPs控制最直接的方式。本论文分别采用超声，石英砂及二者的联合作用对17种常见DBPs进行去除研究。结果表明，20kHz超声对logKow＞1.97的6种DBPs具有超过20%的降解效果，但其降解速率与logKow没有明显关系。KH及蒸汽压不是影响超声降解速率的主要因素，但在同类物质之间超声降解效率与物质的KH及蒸汽压呈正相关关系。官能团对物质的超声降解特性有重要影响，分子结构中含有硝基官能团更容易被超声降解，其次为含腈基官能团的化合物，超声对羰基和羟基的作用效果不甚明显。石英砂对17种DBPs中的9种具有12-80%的吸附效果。超声石英砂的联合作用对除卤乙酸外的12种DBPs均能达到50%以上的去除效果，其中对三氯硝基甲烷能实现100%去除。超声石英砂联合作用一方面增强了超声的空化作用效率，另一方面超声的存在加速了DBPs分子的传质速率，提高了石英砂对DBPs的吸附效率。此外，经超声或超声/石英砂处理后，溶液pH值略微降低，但都满足《生活饮用水卫生标准》的相关要求。三种处理方式下，除对DBPs有一定的去除效果外，对水中溶解性非DBPs有机物也具有一定的去除能力。更多还原

【Abstract】 Disinfection byproducts (DBPs) control is one of the most important parts ofprotecting the safety of drinking water. DBPs precursorcontrolis considered the mosteffective method of controlling DBPs. As the most economical technology for removingDBPs precursors, coagulation is one of the essential process of almost all water treatmentplants. However, the traditional iron and aluminum salts coagulant cannot efficientlyremove DBPs precursors.Graphene has gained intense interest in scientific communitysince it was discovered in2004.As the intermediate of graphene preparation, grapheneoxide (GO) has been confirmed has the ability of adsorption and removal of muti-valentmetal ion and organic compounds due to its molecular structure possesses large quantitiesof the oxygen-containing functional group. Agglomeration and settling will be found whenapplying GO for adsorption of multi-valent ions, this phenomenon is similar with that ofcolloidal destabilization of coagulant. Common disinfectants such as O3、Cl2、ClO2cannotfurther oxide GO because it was completely oxidase by strong oxidizers such asconcentrated sulfuric acid and potassium permanganate, thus DBPs cannot be formed evenGO remained in water. The existing toxicological data have shown thatGO cannot causecytotoxicity and genotoxicity, and was considered as a green materia. In addition, itrelatively simple and economic for preparation of GO in the laboratory. Based on thereasons mentioned above, GO was used as a coagulant to control DBPs precursors fromhumic acid water, surface water, algae solution and its EOM solution.GO was prepared with pressurized oxidation method and presents transparent meshstructure and possesses obvious fold, the C/O atomic ratio of is1.63. The FTIR spectra ofGO shows it contains hydroxyl, C=O and C-O-C functional groups.Coagulation constituent formed obviously when200-400mg/L Ca2+is added into thesolution. Sedimentation rate of GO, size of the floc properties and the forming rate ofcoagulation constituent increase with pH. Floc size generated by different ionsperformance better with Ca2+than Na+, K+and Mg2+under the same ion concentration,effect can produce.Larger and more compacted GO flocs was found whtn Al3+ion wasadded. The trap effect is the main function of GO to remove organic matter, GO showsgoodhumic acid removal efficiency within the pH5-9. It is proved that pH variation hasless effect on the trap flocculation of humic acid by GO, but it has great effects on theremoval of organic matter in surface water as the best removal efficiency was found whenpH≤5. The pH of surface water which initial pH is4-10will change after GO treatment andmaintain between6.3-7.7because of the rich oxygen-containing functional group on thesurface of GO. SUVA values of water samples are slightly lower after GO treatment, itshows that the GO has better removal ability on humic like matter in surface water samples.GO can effectively remove precursors of DBPs especially haloacetic acid (HAAs). At most86.5%of trichloroacetic acid (TCAA) precursors can be removed. EEM analysis showsthat GO has good removal efficiency on humic acid and fulvic acid like material, but thethe efficiency on protein like mater is not ideal.Algae control is a significant issue for guaranting the quality of drinking water for thelast decade.Traditional metal salt coagulants cannot effectivelyremoval of algaes.Chemicalpreoxidation shows good ability for controlling of algaes,but it will destroy the structure ofalgaes and resulting in releasing some organics such as algal toxin.This dissertationinvestigated the algae removal efficiency by GO. It shows that GO has good ability oftrapping algaes. Under the condition of acid and neutral, could chlorophyll a will becompletely removed under40mg/LGO, the removalefficiency of UV254and DBPsprecursors could reach at98.3%, and97.5%-100%, respectively. Under alkalcondition, theelectrostatic repulsion increases between GO and algal cells and resulting in reducingefficiency of algaecontrol.At pH10, the removalefficiency of chlorophyll a, turbidity, DOC,UV254dramatically reduced to13.8%,17.7%,42.1%,30.8%, respectively. Addingdiatomite to the system couldn’t change the algaes removal efficiency, but it could reducethe sedimentation time and the amount of sludge. GO coagulation also has a good effect onremoving organic matter of EOM of algae, when pH<6, the efficiency of removing TOCcould reach61%. It showed that GO could remove the DBPs precursors of EOM,especially those of HAAs. It could remove the precursors of Monochloroaceticacid by90.1%in the absent of Br-, while remove those of trichloroaceticacid by91.0%in the present ofBr-. It showed that GO hasthe ability of removing organic mattere which containedbenzene ring structure, kind of humic acid substances and aromatic compounds, whichcontain C=C, C=O. Morever, GO has a better ability of removing hydrophilic thanhydrophobic organic maters.To the best of our knowledge, little information is available on the combined use ofultrasound (US) and quartz sand (QS) in the removal of DBPs from drinking water. Thisstudy investigates the removal efficiency for17DBPs from drinking water by20KHz sonolytic treatment, QS adsorption, and their combination. Results indicate that DBPs withlogKow≤1.12could not be sonolysized; for logKow≥1.97, more than20%removalefficiency was observed, but the removal efficiency was unrelated to logKow. DBPscontaining a nitro group are more sensitive to US than those that comprise nitrile, hydroxyl,and hydroxyl groups. Among the17investigated DBPs,9could be adsorbed by QSadsorption. The adsorption efficiency ranged from12%for1,1-dichloro-2-propanone to80%for trichloroacetonitrile. A synergistic effect was found between the US and QS on DBPsremoval, and12DBPs could be effectively removed by the combined use of US and QS.In the presence of US, part of the QS particles were corroded into small particles whichplay a role in increasing the number of cavitation bubbles and reducing cavitation bubblesize and then improve the removal efficiency of DBPs. On the other hand, the presence ofUS enhances the DBP mass transfer rate to cavitation bubbles and quartz sand. In addition,sonolytic treatment led to a slight decrease of pH, and TOC values decreased under all thethree treatment processes.更多还原