典型氟喹诺酮类抗生素在高岭土上吸附特征的实验研究

发布时间：2018-01-14 17:11

  本文关键词：典型氟喹诺酮类抗生素在高岭土上吸附特征的实验研究　出处：《中国地质大学(北京)》2017年博士论文　论文类型：学位论文

  更多相关文章： 氧氟沙星 氟甲喹 高岭土 溶解性腐殖酸 铜离子

【摘要】：氟喹诺酮类抗生素(Fluoroquinolone Antibiotics,FQs)在水-土壤/沉积物中已被频繁检出。吸附是控制其迁移转化的重要环节。环境中共存的溶解性有机质(Dissolved Organic Matter,DOM)与重金属离子会影响到抗生素的吸附。溶解性腐殖酸(Dissolved Humic Acid,DHA)是DOM的主要成分之一,而Cu(II)被广泛应用在工农业生产及动物饲料等方面,是水环境中受人关注的重金属离子。本文利用吸附批实验并辅助以微观表征和模拟计算方法研究了Cu(II)和DHA对氧氟沙星(Ofloxacin,OFL)和氟甲喹(Flumequine,FLU)这两种典型FQs在高岭土上吸附与解吸的影响。主要成果如下:(1)OFL主要通过氢键作用和阳离子交换作用吸附到高岭土上。溶液离子强度的增大对OFL+的吸附无影响,但会抑制OFL±的吸附,由此可以判断各形态的OFL与高岭土间的吸附亲和力大小顺序为OFL+OFL±OFL-。OFL吸附分配系数Kd(L/kg)随pH(4.0-10.0)变化呈现不对称的“钟形”,其最大值出现在pH=7.0左右。FLU在高岭土上的吸附机理主要为氢键和静电引力作用。溶液离子强度的增大降低了FLU的活度,导致其Kd值降低。FLU的吸Kd随pH(4.0-10.0)变化也呈现不对称的“钟形”,在pH=6.0左右达到最大。当OFL与FLU共存时,OFL与高岭土间较强的亲和力使其表现出了更强的竞争吸附能力。二者在高岭土上均容易发生解吸,且FLU比OFL解吸率高。(2)在溶液pH≤7.0时,游离态的Cu(II)会与OFL、OFL-Cu或FLU-Cu竞争吸附点位,从而抑制OFL或FLU在高岭土上的吸附。络合物Cu-OFL或CuFLU与高岭土间的亲和力均大于OFL或FLU,因而会促进OFL或FLU的吸附。Cu(II)的抑制或促进作用取决于二者的初始浓度。当溶液pH7.0时,Cu(II)会促进OFL和FLU在高岭土上的吸附,且促进作用随Cu(II)浓度的增大而增强。这是由于pH7.0时,未被络合的Cu(II)主要以Cu(OH)2的形式存在,不会竞争吸附点位。除此之外,Cu(OFL-)2(s)会沉淀到高岭土表面。在解吸过程中,Cu(II)会通过离子交换作用或者“络合拖拽”方式促进OFL在高岭土上的解吸,而Cu(II)对FLU解吸的促进作用是通过“络合拖拽”的方式。(3)在不同体系中,OFL或FLU与DHA的相互作用强度与溶液pH有关。DHA与OFL或FLU间的结合能力随着溶液pH的升高(4.0-10.0)而变弱。结合物DHA-OFL和DHA-FLU与高岭土间亲和力随着溶液pH的升高而降低,因此影响着OFL或FLU在高岭土上的吸附。在酸性条件下,共沉淀作用是目标组分从液相转移到固相的一个重要机理。在解吸过程中,DHA会与吸附到高岭土上的OFL或FLU结合,将吸附在高岭土上的目标污染物“拖拽”下来,从而促进OFL或FLU在高岭土上的解吸。
[Abstract]:Fluoroquinolone Antibiotics. FQs have been frequently detected in water-soil / sediment. Adsorption is an important step in controlling the migration and transformation of FQs. Dissolved Organic Matter. DOM) and heavy metal ions can affect the adsorption of antibiotics. Dissolved humic acid dissolved Humic acid (DHA) is one of the main components of DOM. CuPII is widely used in industrial and agricultural production, animal feed and so on. CuII) and DHA were used to study ofloxacin in Ofloxacin. OFLL and Flumequine. The effect of these two typical FQs on kaolin adsorption and desorption. The main results are as follows: 1). OFL was mainly adsorbed on kaolin by hydrogen bonding and cation exchange. The increase of ionic strength of solution had no effect on the adsorption of OFL. But it can inhibit the adsorption of OFL 卤. It can be concluded that the order of adsorption affinity between various forms of OFL and kaolin is OFL OFL 卤OFL-.OFL adsorption partition coefficient KDX L / kg with pH (. (4.0-10.0) the change presented an asymmetrical "bell shape". The adsorption mechanism of pH=7.0 on kaolin is mainly hydrogen bond and electrostatic gravitation. The increase of ionic strength decreases the activity of FLU. As a result of the decrease of K d value, the absorption of K d with pH = 4.0-10.0) also showed an asymmetric "bell shape", which reached the maximum around pH=6.0. When OFL and FLU coexisted. The strong affinity between OFL and kaolin makes them show stronger competitive adsorption ability. Both of them are easy to desorption on kaolin. Moreover, the desorption rate of FLU is higher than that of OFL. 2) when pH 鈮，

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