四环素与含水层中常见铁氧化物矿物的相互作用机理研究

发布时间：2018-06-09 20:52

本文选题：四环素 + 铁氧化物矿物　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：四环素类抗生素由于具有抗菌广谱性和高效价廉的特点,已经成为目前使用最广泛、用量最大的抗生素种类之一。近年来,对其的滥用以及机体不完全吸收部分排出体外的现状使其在环境中不断积累,导致耐药基因的产生并对生物体造成危害,抗生素污染的高危害性引起了国际上的普遍关注。四环素是四环素类抗生素中元素组成较简单,具有代表性的一类,本文着眼于四环素在土水环境中的迁移转化,选取了三种土壤常见矿物针铁矿、水铁矿和赤铁矿作为研究对象,通过静态吸附批实验描述各矿物与四环素的吸附过程,辅以多种表征手段(XRD、SEM、TEM、BET、BJH、XPS、FTIR)刻画了相互作用前后矿物理化性质的差异性并进行分析,旨在研究四环素与不同类型常见铁氧化物矿物的相互作用机理。实验结果表明:(1)针铁矿和水铁矿对四环素的吸附平衡时间为4 d,其中水铁矿因其比表面积的绝对优势,吸附速率最快且平衡吸附量大于针铁矿,而赤铁矿由于晶体形态缺陷较多,在吸附过程中不断裂解,动力学曲线呈阶梯状,在实验时间4 d内未达到平衡;针铁矿和水铁矿的等温吸附量随初始浓度升高而增大直至饱和,赤铁矿因多阶段吸附,未达平衡,但实验时间4 d内,与针铁矿和水铁矿相比,其吸附量最大。(2)实验所采用的铁矿物均为三价铁,反应后上清液中可检测出二价铁,表明在铁矿吸附四环素的过程中,铁矿表面发生了化学反应导致了铁的还原,其中针铁矿反应体系的二价铁含量很低,化学反应所占比例有限。对反应前后的矿物表面进行红外光谱测试,发现其界面官能团有变化,证明三种铁矿与四环素相互作用过程中均存在络合作用。推测二价铁为四环素络合至矿物表面后发生电子转移而产生。(3)在水化学参数对吸附的影响研究中,随着离子强度的升高吸附量略有升高,表明四环素在此三种铁矿上的吸附主要为专性吸附;在pH的影响下,四环素在铁矿上的吸附量在某个pH值附近出现最大值,证明吸附过程中存在静电作用;常见阳离子类型对吸附无显著影响,而Cu2+作为键桥对四环素在三种铁矿物上的吸附量影响不同,推测与铁矿物结晶程度有关。
[Abstract]:Tetracycline antibiotics have become one of the most widely used and used antibiotics because of their wide spectrum and high efficiency and low price. In recent years, its abuse and incomplete absorption of the body have resulted in its accumulation in the environment, leading to the production of drug-resistant genes and causing harm to organisms, The high harmfulness of antibiotic contamination has aroused widespread concern in the world. Tetracycline is a simple and representative class of tetracycline antibiotics. Based on the migration and transformation of tetracycline in soil-water environment, three common minerals, goethite, are selected. The sorption process of each mineral with tetracycline was described by static adsorption batch experiments, and the physicochemical properties of minerals before and after interaction were characterized and analyzed by various means of characterization. The purpose of this study is to study the interaction mechanism of tetracycline with different types of iron oxide minerals. The experimental results show that the adsorption equilibrium time of tetracycline for goethite and water ore is 4 days, in which the adsorption rate of pyrite is the fastest and the equilibrium adsorption capacity is larger than that of goethite because of its absolute advantage of specific surface area. However, hematite, due to many defects in crystal morphology, cleavage continuously during the adsorption process, and the kinetic curve is in the form of a ladder, and the equilibrium is not reached within 4 days of the experimental time. The isothermal adsorption capacity of goethite and pyrite increases until saturation with the increase of initial concentration. Hematite is not balanced due to multi-stage adsorption, but the experimental time is 4 days, compared with that of goethite and pyrite. The divalent iron can be detected in the supernatant after the reaction, which indicates that the chemical reaction on the surface of iron ore resulted in the reduction of iron during the process of adsorption of tetracycline. The divalent iron content of goethite reaction system is very low and the proportion of chemical reaction is limited. The surface of the minerals before and after the reaction was tested by infrared spectroscopy, and it was found that the interfacial functional groups changed, which proved that the interaction between the three kinds of iron ores and tetracycline existed complexation. It is inferred that the divalent iron is produced by electron transfer after tetracycline complexing to the mineral surface. In the study of the effect of hydrochemical parameters on adsorption, the adsorption capacity increases slightly with the increase of ionic strength. The results show that the adsorption of tetracycline on these three kinds of iron ores is mainly specific adsorption, and the adsorption capacity of tetracycline on iron ore is maximum near a certain pH value under the influence of pH, which proves that electrostatic action exists in the adsorption process. The common cations have no significant effect on the adsorption, but Cu _ 2 acts as a bond bridge for different amounts of tetracycline adsorbed on the three kinds of iron ores, which may be related to the degree of crystallization of iron minerals.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X505;P579

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