偕胺肟化二氧化硅的制备及其吸附铀、铅的试验研究

发布时间：2018-09-02 09:01

【摘要】：废水中的铀离子具有放射性,若进入人体会造成内辐射,严重危害人体健康。尤其是儿童饮用含铅超标的饮用水虽然没有放射性,但会对儿童的健康和智力发育产生严重影响,因此,寻找一种处理含铀、铅废水的高效方法迫在眉睫。而目前研究最多的含铀、铅等重金属的处理方法是吸附法。本研究以二氧化硅材料为载体对其进行有机改性,进而探讨其对铀、铅离子的吸附性能及机理。通过功能化修饰将对铀具有优异选择性的偕胺肟基和刚性有机基团乙烷基接入二氧化硅材料,合成偕胺肟基乙烷桥键介孔二氧化硅材料(AO-PMOs)。通过静态吸附实验,研究了p H值、初始溶液浓度、吸附剂投加量等因素对AO-PMOs吸附铀、铅的影响,并对吸附过程进行了吸附等温线模型、吸附动力学模型拟合分析,采用红外光谱、扫描电镜对材料吸附前后的基团、形貌进行表征,分析探讨其吸附机理。实验结果表明:(1)AO-PMOs对水溶液中铀的吸附适宜p H值为5-7,其中以p H=5为最佳。吸附过程的前10min能够迅速吸附,30min之后吸附速率逐渐减慢即达到吸附平衡。吸附平衡时能使99%以上的铀离子被吸附去除。对铀离子的吸附量受其初始溶液的影响比较小,不同浓度的含铀溶液基本都可以用其进行吸附。(2)利用等温吸附模型对实验数据进行拟合分析,结果表明Langmuir模型可以用于描述AO-PMOs对铀的吸附过程,用Langmuir模型拟合30℃、40℃下的实验数据,经过分析计算可得到这两种温度下的吸附容量分别可以达到151.98mg/g和153.84mg/g,此结果表明随着温度的升高其吸附量也在增加,即其对铀的吸附过程为吸热反应,且以单层吸附为主。而动力学拟合结果显示AOPMOs吸附铀过程遵循准二级动力学模型,其对铀离子的吸附主要是胺肟基团与铀的配位作用。(3)AO-PMOs吸附铅在p H值为6.0时的效果最好,在60min后吸附基本处于平稳状态,平衡时对铅的去除率最高到80%以上。材料对铅的吸附遵循Freundlich等温线模型,说明以多层吸附为主。可以用准二级动力学模型描述材料吸附铅的过程。通过材料吸附铅前后红外光谱图分析可知吸附铅起主要作用的是胺肟基团,主要以化学吸附为主。
[Abstract]:The uranium ion in the wastewater is radioactive, and it will cause internal radiation if it enters the human body, which seriously endangers human health. Especially, children drinking water containing lead has no radioactivity, but it will have serious influence on children's health and intellectual development. Therefore, it is urgent to find an efficient way to treat waste water containing uranium and lead. At present, adsorption is the most widely studied method for treating heavy metals such as uranium and lead. In this study, silicon dioxide was used as the carrier to study the adsorption properties and mechanism of uranium and lead ions. The amidoxime group and rigid organic group ethyl group with excellent selectivity for uranium were added to the silica material by functionalization to synthesize the amidoxime ethane bridged mesoporous silica material (AO-PMOs). Through static adsorption experiments, the effects of pH value, initial solution concentration and adsorbent dosage on the adsorption of uranium and lead by AO-PMOs were studied. The adsorption isotherm model and the adsorption kinetics model were used to fit the adsorption process. The group and morphology before and after adsorption were characterized by IR and SEM, and the adsorption mechanism was analyzed. The experimental results show that: (1) the suitable pH value of AO-PMOs for the adsorption of uranium in aqueous solution is 5-7, among which pH 5 is the best. The adsorption rate of pre- 10min could decrease gradually after 30 minutes of rapid adsorption, and the adsorption equilibrium could be reached. More than 99% of uranium ions can be removed by adsorption equilibrium. The adsorption amount of uranium ion is less affected by its initial solution, and it can be used to adsorb uranium ions in different concentrations. (2) the experimental data are fitted and analyzed by isothermal adsorption model. The results show that the Langmuir model can be used to describe the adsorption process of uranium by AO-PMOs, and the experimental data at 30 鈩，

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