稳定型纳米铁球构建可渗透反应墙去除电镀废水中重金属的研究

There are a great many of heavy metals in the electroplating wastewater. Due to the unreasonable discharge of the electroplating wastewater, surface water is contaminated by heavy metals. Heavy metals are enrichmented and nondegradable, which even cause both short term and long term adverse effects to humans, animals and plants. A great number of studies have shown that Fe0-nanoparticles (NZVI) are effective to remove heavy metals from wastewater. However, NZVI are easily oxidized and to agglomerate, which limit the application of NZVI. According to the problem, NZVI and chitosan (CS) have been introduced to prepare the stable CS-NZVI beads in the study. The mechanical strength and stability of these beads are enhanced by chemical modifications. In permeable reactive barriers（PRB），modified CS-NZVI beads will be used to remove heavy metals from the wastewater taken from an electroplate factory. In the sight of hydroxyl, carboxyl and amino groups attached to these modifiers, the changes of the microscopic structure of these beads will be studied, as well as the effects of the changes on the interaction mechanism of the specific sorption of heavy metals. The kinetics, thermodynamics and mechanism will be also studied. The remediation effect is tested in the application of these ourselves-made PRB system. We expect that an efficient removal and controllable remediation will be implemented, which can reduce the hazard of heavy metals to organisms and improve the health conditions of mankind.

电镀废水中含有大量的重金属，不当处理和排放会造成地表水环境的严重污染。由于重金属具有富集性和难降解性，进而会危害动植物和人类的健康。近年来，研究表明纳米铁（NZVI）对重金属有明显的去除效果。但是，纳米铁在污水介质中容易被氧化和易团聚，使得纳米铁在实际应用中受到很大局限。针对以上问题，本项目拟以壳聚糖固定纳米铁制备成壳聚糖-纳米铁球，以期解决纳米铁易被氧化和团聚问题。另外，此纳米铁球的机械强度不高，需要通过表面改性来提高其机械强度。利用制备的稳定型壳聚糖-纳米铁球构建PRB反应器去除电镀废水中的重金属，从化学改性剂分子链上的羟基、羧基和氨基等官能团的角度，研究该壳聚糖-纳米铁球内部微观结构的变化及其对重金属吸附作用的影响机理；探明该纳米铁球去除重金属的反应动力学、热力学及其机理，从而研究该PRB反应体系在实际运用中的除污性能。以期实现对重金属污染的有效控制，降低其对生物体和人类的危害。

电镀废水中含有大量的重金属，不当处理和排放会造成地表水环境的严重污染。由于重金属具有富集性和难降解性，进而会危害动植物和人类的健康。本项目以壳聚糖固定纳米铁制备成壳聚糖-纳米铁球，很好地期解决纳米铁易被氧化和团聚问题，通过表面改性来很好地提高其机械强度。利用制备的稳定型壳聚糖-纳米铁球构建PRB反应器去除电镀废水中的重金属，研究了该壳聚糖-纳米铁球内部微观结构的变化及其对重金属吸附作用的影响机理；探明了该纳米铁球去除重金属的反应动力学、热力学及其机理。EGDE-CS-NZVI-PRB对电镀废水中的重金属有很好的去除效果，连续进样6小时候，Cr(VI)、Cu(II)、Cd(II)和Pb(II)去除率都在95%以上；10小时后，各种金属的去除率都在89%以上。pH 对Cr(VI)、Cu(II)、Cd(II)和Pb(II)的去除率有明显的影响，在pH为2.96-9.17，Cr(VI)、Cu(II)、Cd(II)和Pb(II)的去除率都在91%以上。该体系能连续稳定运行35天，对电镀废水中各种重金属的去除效率都在85%以上，是一个利用纳米材料整合传统废水处理工艺解决实际废水污染问题的明智选择。