纳米水合二氧化锰氧化水中典型有机污染物的效能研究

发布时间：2018-01-10 21:11

本文关键词：纳米水合二氧化锰氧化水中典型有机污染物的效能研究　出处：《哈尔滨工业大学》2013年博士论文　论文类型：学位论文

【摘要】：锰元素是自然界中丰度较高的金属元素之一，它的氧化物不仅参与了自然环境中许多有机、无机成分的迁移转化，还在水质净化过程中发挥着重要作用。在水处理中，二氧化锰一般通过高锰酸盐的氧化还原原位产生，它不仅对高锰酸盐的氧化具有重要意义，自身还具有许多重要的除污染特性。磺胺和溴酚类化合物在水体中频繁检出，两类化合物与二氧化锰反应的特征官能团不同，分别为芳胺基和酚羟基。本文通过硫代硫酸钠还原高锰酸钾制得纳米水合二氧化锰（nHMO），模拟水处理中原位产生的二氧化锰，进而研究其对目标物的催化氧化特性。本文中制得的nHMO粒径分布在24.4~91.2nm之间，能够稳定存在40天以上。不同制备浓度、温度和混合方式对产生的nHMO的粒径均有影响，从而影响它的氧化活性。对混方式制得的nHMO比滴加方式制得的nHMO平均粒径小18.41nm。当pH为7.3时，前者氧化SMZ的效率要高出后者28%。制备液浓度越低、温度越高，制得的nHMO的平均粒径越小，它的氧化活性越高。为了考察nHMO的氧化活性，本文选取了磺胺二甲嘧啶（SMZ）、磺胺甲噻唑（SMZO）、磺胺甲VA唑（SMX）三种具有芳胺结构的药物进行研究。nHMO氧化三种磺胺的能力依次为：SMZSMXSMZO。相比其它常见的二价阳离子，锰离子对nHMO的氧化抑制最明显，当pH为6.0时，5μM锰离子就使SMZ的去除率下降22%。低浓度的磷酸根对SMZ的去除率影响较小，但是腐殖酸以及高浓度的磷酸根都表现出一定的抑制作用。nHMO氧化三种有机物的动力学曲线均不符合假一级动力学，反应后期存在明显的自抑制现象。本文通过引入两个动力学参数Sr和k，分别表示二氧化锰氧化有机物的活性位点数和基于该值的反应速率常数，建立了nHMO氧化SMZ的动力学模型。该模型能够很好的拟合整个氧化过程，其中，，随着SMZ初始浓度的增加，Sr值增加，k值减小；随着nHMO浓度的增加，Sr值增加，k值增加；pH值的增加导致Sr值和k值均降低。为了研究nHMO氧化卤代酚类有机物过程中的脱卤现象，本文选取了三种溴酚进行了研究。nHMO氧化三种溴酚的能力依次为：4-溴酚（4-BrP）2-溴酚（2-BrP）3-溴酚（3-BrP），氧化过程中的脱溴能力也遵循相同的次序。假一级条件下，nHMO氧化4-BrP的反应速率常数随着溴酚浓度的增加保持不变，表明表面络合物的电子转移是该氧化过程中的速控步骤。nHMO氧化溴酚过程中的脱溴指数（DN）随着pH的升高而逐渐减小，表明nHMO氧化溴酚的过程不仅仅遵循有机自由基耦合的机理。氮气曝气对溴酚的氧化及溴离子的释放均有一定的抑制作用，且pH5.0时的抑制效果比pH4.0时更明显。nHMO氧化溴酚的过程中，nHMO颗粒粒径不断增大，溴酚和nHMO初始浓度越大、pH越低，颗粒粒径增大的幅度越大。氧化过程中产生的锰离子大部分吸附在二氧化锰表面，溶液中锰离子浓度很低。鉴于nHMO的氧化活性和它的纳米粒径相关，本文还研究了nHMO氧化过程中的凝聚现象。锰离子引发的nHMO凝聚具有较低的临界浓度，在10-5M级别。随着pH值的升高，相同锰离子浓度引起的凝聚速率增大，因而引起扩散凝聚的临界浓度降低。nHMO氧化有机物过程中的凝聚速率主要取决于与有机物的反应速率，pH值升高，氧化速率降低，凝聚速率减慢。nHMO的氧化凝聚对氧化效能的影响很大，投加少量高锰酸钾可以有效控制nHMO氧化过程中的凝聚。nHMO/少量高锰酸钾组合体系氧化初始浓度为2.5~16.8μM的双酚A（BPA）时，自抑制现象消失，其假一级速率常数分别与nHMO单独氧化时初始阶段的速率常数一致，表明高锰酸钾在该体系中主要起氧化锰离子和维持nHMO纳米粒径的作用；而在氧化4-硝基酚（4-NP）时，高锰酸钾主要参与表面络合物的电子转移过程，从而强化4-NP的氧化去除，该组合体系主要表现为二氧化锰催化高锰酸钾氧化4-NP。二氧化锰对高锰酸钾氧化除污染具有非常重要的催化作用，本文选取了双键类污染物卡马西平（CMZ）以及酚类污染物双酚A（BPA）、苯酚（Phen）、2-氯酚（2-CP）、2,4-二氯酚（2,4-DCP）、2,4,6-三氯酚（2,4,6-TCP）等目标物，研究了高锰酸钾氧化以两种有机物形成的复合污染过程中nHMO和其它中间态锰物种的重要作用。在弱酸性条件下，CMZ能够促进Phen的氧化去除而自身不受影响；酚类化合物的氧化去除则表现为互相促进，且反应慢的酚的氧化去除受到的促进更大，nHMO的催化作用是造成这些现象的主导原因。弱碱性条件下，CMZ和Phen复合时，二者的氧化去除均不受影响；酚类污染物之间复合时，表现为与高锰酸钾反应速率常数较低的酚的氧化去除受到抑制，而反应速率常数较大的酚的氧化去除受到的影响很小。竞争动力学的研究表明，这种抑制作用主要是两种酚类污染物竞争了体系中除高锰酸钾及nHMO以外的其它氧化活性物种所致。由于CMZ的氧化机制和Phen不同，二者不存在竞争作用，因而二者的共存对各自的氧化均不构成影响。
[Abstract]:Manganese is one of the metal elements in high abundance in nature, it is not only involved in oxides in natural environment of many organic, inorganic composition of migration transformation, play an important role in the process of water purification. Still in water treatment, the manganese dioxide by permanganate oxidation and reduction of in situ generated, it not only has important significance to permanganate oxidation, also has many important characteristics. In addition to pollution of sulfonamides and bromophenol compounds are frequently detected in water medium, two characteristic functional group compounds and manganese dioxide reaction were different, aromatic amino and phenolic hydroxyl. The sodium thiosulfate reduction Potassium Permanganate nanoscale hydrous manganese dioxide (nHMO), manganese dioxide produced in situ simulated water treatment the object of the research of catalytic oxidation properties.
This paper prepared nHMO particle size distribution between 24.4~91.2nm, can be stable in more than 40 days. Prepared by different concentration, influence of temperature and mixing methods on nHMO size were, thus affecting its reactivity. The mixing mode of the prepared nHMO than dropping made nHMO average particle size. Small 18.41nm. when pH is 7.3, the efficiency of oxidation of SMZ is up to the preparation of 28%. solution concentration is low, the higher the temperature, the average particle size of nHMO was smaller, its higher oxidation activity.
In order to study the activity of oxidation of nHMO, this paper selects the sulfamethazine (SMZ), sulfamethoxazole (SMZO), sulfamethoxazole (SMX) with VA three with aromatic amine structure of drug.NHMO oxidation of three sulfonamides were SMZSMXSMZO. compared with the other two common divalent cations, oxidation of manganese ion on nHMO the most obvious inhibition, when pH is 6, 5 mu makes M manganese ions decreased the removal rate of SMZ 22%. phosphate in low concentration has little effect on the removal rate of SMZ, but high concentration of humic acid and phosphate showed inhibition of.NHMO oxidation kinetics curves of three kinds of organic matter were not consistent with the false the first-order kinetics, the late reaction existed since significant inhibition. Through the introduction of the two kinetic parameters of Sr and K, respectively, manganese dioxide oxidation of organic active sites and the reaction rate constant value based on nHMO is established. The kinetic model of SMZ oxidation can be well fitted to the whole oxidation process. With the increase of SMZ initial concentration, Sr value increases and K value decreases. With the increase of nHMO concentration, Sr value increases, K value increases, and Sr value and K value decrease with pH value increasing.
In order to study the phenomenon of dehalogenation of nHMO oxidation of halogenated phenolic compounds in the process, this paper selects three kinds of brominated phenols were investigated for the ability of oxidation of.NHMO three bromophenol were 4- bromophenol (4-BrP) 2- (2-BrP) 3- bromophenol bromophenol (3-BrP), bromine removal ability during oxidation follow the same order. Pseudo first order conditions, nHMO 4-BrP oxidation reaction rate constant with the increase of bromine phenol concentration remained unchanged, indicating that electron transfer surface complexes is the oxidation process in the speed control of debromination step.NHMO index in the process of oxidation of bromophenol (DN) with the increase of pH decreased gradually. Show that the mechanism of nHMO oxidation of bromophenol not only follow the coupling of organic free radicals. The inhibition of release were oxidized and bromide ion nitrogen aeration on the process of bromophenol, inhibitory effect and pH5.0 is more obvious than pH4.0.NHMO oxidation of bromophenol in nHMO particle size The larger the initial concentration of Bromphenol and nHMO, the lower the pH. The larger the particle size is, the more the manganese ions are adsorbed on the surface of manganese dioxide. The concentration of manganese ion in solution is very low.
In view of the oxidation activity of nHMO nanoparticles and its size, this paper also studies the phenomenon of condensation in the oxidation of nHMO. The manganese ion induced nHMO condensation with critical concentration is low, at the 10-5M level. With the increase of pH value, concentration of manganese ion by the same condensation rate increases, and the critical concentration of diffusion aggregation decreased.NHMO oxidation of organic matter in the process of condensation rate mainly depends on the reaction rate of organic compounds and caused the increase of pH value, the rate of oxidation reduction, oxidation condensation rate slowed down the condensation of.NHMO has great influence on the oxidation efficiency, adding a small amount of Potassium Permanganate.NHMO/ Potassium Permanganate combination system can unite the small oxidation initial concentration of effective control of nHMO oxidation in the process of bisphenol A M 2.5~16.8 (BPA), self inhibition phenomenon disappeared, the pseudo first-order rate constants are consistent with the rate constants of nHMO alone when the initial stage of oxidation, table Potassium Permanganate in the system mainly from the oxidation of manganese ion and maintain nHMO nanoparticles; and in the oxidation of 4- nitrophenol (4-NP), Potassium Permanganate is mainly involved in the electron transfer process of surface complexes, thereby strengthening the 4-NP removal, the combined system mainly for manganese dioxide catalytic oxidation of 4-NP. Potassium Permanganate
In addition to Potassium Permanganate manganese dioxide catalytic oxidation of pollution is very important, this paper selects the double pollutant C Masi Bing (CMZ) and phenol bisphenol A (BPA), phenol (Phen), 2- (2-CP), 2,4- two chlorophenols, chlorophenols (2,4-DCP) 2,4,6- three chloro phenol (2,4,6-TCP) as the object, study the important role of nHMO compound pollution of Potassium Permanganate oxidation formed with two kinds of organic matter and other intermediate state manganese species. Under acidic condition, CMZ can promote the oxidation of Phen and its removal is not affected; the oxidation of phenols removal performance and promote each other, and the slow oxidation of phenol removal by to promote greater catalytic effect of nHMO is the leading cause of these phenomena. In alkaline conditions, CMZ and Phen composite oxide, two removal is not influenced; between phenols compound, manifested with permanganate The oxidation reaction rate constant K low phenol removal was inhibited, while the oxidation rate constant of phenol removal by the impact is very small. The competitive kinetics shows that this inhibition is mainly two kinds of phenols in the competition system in addition to Potassium Permanganate and other nHMO species caused by oxidation activity due to oxidation. The mechanism of CMZ and Phen, two are not competitive, so the coexistence of two of their oxidation are not affected.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU991.2

【参考文献】