【作者】 王倩；

【导师】 田森林；

【作者基本信息】 昆明理工大学 ， 环境科学， 2014， 博士

【摘要】 纺织印染废水是处理难度最大的工业废水之一。用于纺织工业的助剂超过2000种,其中超过20%的纺织废水被直接排放到水体中。水体中含有大量的无机盐(例如硫酸铜)和表面活性剂,这些印染助剂来源于印染过程中的晕染和固色阶段。纺织废水因其对人体和生物具有毒害作用被视为水污染的重要来源,其特点是透光度低、毒性大、COD含量高,严重阻碍了水生生物的光合作用。高级氧化技术(Advanced oxidation processes,AOPs)是一类可高效处理有机废水的绿色方法。Fenton技术是高级氧化技术的一种,传统的Fenton体系由Fe2+和过氧化氢组成。在酸性条件下,Fe2+可催化过氧化氢分解产生羟基自由基。羟基自由基有很高的氧化性,仅次于氟原子,可以无选择的氧化水体中的有机物。pH为0时,其氧化电位为2.78V,pH为14时,其氧化电位为1.9V。羟基自由基还可使键能低于H-O(109kCal/mol)的化学键断裂,夺取C原子或其他原子上连接的氢原子使有机物分解,是一种强氧化性的自由基。Fenton具有反应速度快,设备简单,所使用的过渡金属催化剂环境友好等特点,但其弊端是铁盐消耗量大,反应后产生大量的污泥,造成二次污染,反应过程中所使用的催化剂难于回收重复利用。为解决传统Fenton的上述弊端,非均相Fenton体系应运而生。非均相Fenton技术是水处理领域研究的热点问题之一。它为解决传统Fenton技术中存在的催化剂不易回收、反应后产生铁泥造成二次污染以及pH适用范围小等工程应用核心问题提供了有效的途径。已有广泛研究聚焦在使用负载型催化剂催化的非均相Fenton体系上,但通常反应速率较慢,需要引入超声、紫外光等外部能量的辅助。为解决负载型催化剂活性组分负载量低、及活性组分溶出的问题,本研究提出以二茂铁和铁铁水滑石为催化剂的非均相Fenton体系。二茂铁具有良好的氧化还原可逆特性、催化特性和稳定性,且具有电子给受体结构和刚性骨架;铁铁水滑石具有较大的比表面积、稳定的层状结构,且制造简单,成本低廉,其骨架结构中的二价铁和三价铁在Fenton体系中均有较好的催化能力,二者均可作为非均相Fenton体系的优良催化剂。研究取得的创新性成果和结论如下：(1)证明了二茂铁具有氧化还原可逆性,可高效催化过氧化氢分解产生羟基自由基,进而构建了新型Fc/Fenton反应体系。最佳工艺条件是pH=3,二茂铁浓度为0.372g/L,30。C,[H202]/[MB]=3.16.反应120min后,染料可完全脱色,此时,其矿化率为63.75%。(2)提出并证实了Fc/Fenton反应降解MB的机理及途径。Fc/Fenton反应降解MB的反应活化能为82.708kJ/mol。随着亚甲基蓝的降解,溶液的pH降低,并测得了苯并噻唑。亚甲基蓝在Fc/Fenton体系中沿三条途径同时降解：亚甲基蓝脱氯后,沿两条途径降解：一是剩余结构发生去甲基化反应,而后C-N和S-C键断裂,并脱氨基,经过草酸和苯并噻唑后彻底降解；二是剩余结构中C-N键断裂,S发生氧化,然后脱除甲基和氨基,生成苯磺酸和苯酚后彻底降解；三是部分羟基和磺酸基连接到亚甲基蓝上生成大分子化合物。最终,这些中间产物完全降解为CO2和H2O。(3)明确了常见无机盐类及表面活性剂类印染助剂对Fc/Fenton降解MB的影响规律。低浓度CuSO4和PVA的加入对亚甲基蓝的降解有促进作用,反之,NaCl、Na2S、Na2SO4、Na2CO3、SDBS和Tween-80的加入对亚甲基蓝的降解有抑制作用。(4)探索出了强化Fc/Fenton降解MB效率的两条途径：加入低浓度草酸和分批投加H2O2对亚甲基蓝的降解均有促进作用。(5)载二茂铁树脂对水中亚甲基蓝及共存亚甲基蓝和铜离子的吸附作用机理及规律。二茂铁的负载极大的提高了亚甲基蓝在树脂上的饱和吸附量,将应用的pH范围拓宽到了2-12。二茂铁改性树脂能有效地同时吸附去除水体中的亚甲基蓝和铜离子,且该吸附过程为物理吸附。反应的最佳条件时pH=4-5。(6)研制出了可高效催化分解过氧化氢产生羟基自由基的铁铁类水滑石型非均相催化剂,构建了新型非均相FeFe-LDH/Fenton体系。亚甲基蓝在该体系中的降解效果表明：铁铁水滑石具有高效性和稳定性,其催化活性随制备过程中的[Fg2+]/[Fe3+]增加而增强。反应的最佳pH为3,且增加铁铁水滑石的用量对体系中亚甲基蓝的降解有促进作用。(7)推导出了FeFe-LDH/Fenton降解机理。随着亚甲基蓝的降解,溶液的pH呈下降趋势,并发现了亚甲基蓝降解的新产物—苯并噻唑,DL-正亮氨酸和Pleiocarpamine。推导出了亚甲基蓝沿着三条途径同时降解：亚甲基蓝首先脱去氯原子和甲基,然后剩余结构中的不同位置的C-N和S-C发生断裂,一是产生苯酚和DL-正亮氨酸；二是生成草酸和苯并噻唑；三是DL-正亮氨酸脱氨基后的产物与苯并噻唑在甲醛的作用下生成Pleiocarpamine。更多还原

【Abstract】 Textile and dyeing wastewaters are important sources of the refractory organic wastewaters. More than2000chemicals (dyes and agents) are used in textile industry, and20%of these are discharged in textile industrial effluents without pretreatment. Large amounts of inorganic salts (such as copper sulfate) and surfactants exist simultaneous with dyes in water, which come from the processes of the solidation of color and uniform the blooming. Textile effulents with low penetrations, high toxicity. and high COD has been focused on, not only for toxic to human beings but also for the resistant of photosynthesis.Advanced oxidation processes (AOPs) have been considered a green efficient method, coping with organics in wastewater. Fenton is a kind of AOPs, consisting of Fe2+species and hydrogen peroxide. Under acidic conditions, H2O2can be catalyzed decompose, generating hydroxyl radicals(-OH), which is the most oxidizing chemical species except fluorine atoms. Hydroxyl radical is such a powerful species for the non-selectively in water to oxidize organics, and the oxidation potential has been estimated as2.78and1.90V at pH0and14. respectively. Hydroxyl radicals can also abstract one hydrogen atom from hydrocarbons and other organic substrates, under the condition that the hydrogen bond to be broken has bond energy lower than109kcal/mol. which is the energy of the H-O bond energy.-OH is considered a general oxidant which is able to attack any kind of organics. Fenton is considered a benignity process, with a minimum dosage of reagents used and all transition metals used in Fenton process were environmental friendly, but with drawbacks of the comsumption of a large amount of Fe salts, iron sludge generated after the reaction as a kind of second pollution. Also, catalyst used in Fenton is hard to be recovered and reused, leading to a waste of reagents. Heterogeneous Fenton established using solid catalyst is a promising alternative to solve or minimize these problems in traditional Fenton system.Heterogeneous Fenton has been focused on for waterwater treatment. It is effect in dissolving the disadvantages of traditional Fenton, such as the impossible of the recycling of catalysts, generation of iron sludge, and small pH window. Heterogeneous Fenton catalyzed by metal loaded catalysts has already been focused on, but with drawbacks of slow reaction rate and the introduction of extra energies, such as sonic, ultraviolet. In this study, Ferrocene(Fc) and FeFe-LDH were occupied as catalyst to establish new heterogeneous Fenton systems. Fc which possesses electron donor-acceptor conjugated structure is of good oxidation redox character, catalytic activity and stability. FeFe-LDH with layered structure is of large surface area, and it can be easily prepared. The ferrous and ferric ion in FeFe-LDHs is of good catalytic activity. Thus, both Fc and FeFe-LDH can be used as catalyst to establish heterogeneous Fenton processes. The main research contents and conclusions are listed as follows:(1) Fc was verified to be of good reversible redox characteristic, and H2O2can be catalyzed to decompose, forming hydroxyl radicals(-OH), effectively. Based on the characters of Fc mentioned above, Fc was occupied to establish the new heterogeneous Fenton-Fc/Fenton. The optimal condition was determined to be pH3,0.372g/L Fc,23.58mmol/L H2O2at30℃。100%discoloration was reached at120min, with63.75%COD removed.(2) Mechanism of Fc/Fenton reaction and the degradation pathways of Methylene Blue was proposed, and the reaction active energy was determined to be82.708kJ/mol. pH decreased as MB degraded and Benzothiazole was detected. MB degraded in three pathways simultaneously:Cl was first removed from MB, and the the residual structure decomposed in two ways:oxalic acid and benzothiazole generated after the removal of methyl and the broken of C-N and S-C Benzenesulfonic acid and phenol generated after the broken of C-N in residual structure, the oxidation of S and the removal of methyl and amino; macromolecular compounds generated as the connection of-OH and-SO3to the residual structure. Finally, all the intermediates were oxidized to CO2and H2O.(3) The effects of inorganics including NaCl, Na2S, Na2SO4, Na2CO3, CUSO4and surfactants including PVA, SDBS and Tween-80on the efficiency of Fc/Fenton was investigated. The results indicated that the degradation of MB in Fc/Fenton was accelerated with the addition of low concentrations of CUSO4and PVA, but resisted with the addition of NaCl, Na2S. Na2SO4, Na2CO3, SDBS and Tween-80.(4) Two methods were proposed in order to enhance the efficiency of Fc/Fenton. The results indicated that the degradation of MB can be accelerated with the presence of low concentraitons of Oxalic acid or adding H2O2in multi-steps.(5) The mechanisms of the adsorptive removal of MB and the simultaneous adsorptive removal of MB and Cu2+on to ferrocene mofied cation exchange resin(FMCER) were proposed. The adsorption capacity of MB was improved a lot and the pH window for the adsorption of MB onto resin was expanded from2-4to2-12. MB and Cu2+in water can be removed effectively using FMCER. The adsorption of MB and Cu2+on FMCER were physicosorptive, and4-5is optimum.(6) FeFe-LDH, which can catalyzed the decompositon of H2O2to from·OH was synthesized, was used as catalyst to establish a new kind of heterogeneous Fenton. The degradation of MB in FeFe-LDH/Fenton indicated that FeFe-LDH is of good stability and high efficiency. The catalysis activatity was improved as the [Fe2+]/[Fe3+] increased in preparation. The optimal condition was pH3, and the degradation of MB can be accelerated by increasing the dosage of FeFe-LDH.(7) Mechanism of the degradation of MB in FeFe-LDH/Fenton process was proposed. pH of solution decreased as MB degraded, and Pleiocarpamine. DL-Norleucine and Benzothiazole that have rarely been detected previously were observed. MB decomposed through three pathways simultaneously. Cl and methyl were first removed from MB, and then C-N and S-C in the residual structure broken: phenol and DL-Norleucine generated; oxalic acid and benzothiazole generated; DL-Norleucine reacted with benzothiazole after-NH3been removed, to from pleiocarpamine.更多还原