铁碳复合材料催化内电解技术处理模拟农村铅污染水体效果

为考察基于新型铁炭复合填料的催化内电解技术处理模拟农村铅污染水体的特性,该文采用单因素试验设计和八因素三水平(考虑交互作用)正交试验设计,研究了初始pH值(1.0~8.0)、反应时间(10~90 min)和曝气量(0~12 L/h)对Pb~(2+)去除效果的影响。结果表明:初始pH值从1.0升高到8.0,铅(Pb~(2+))去除率先缓慢上升后急剧降低;反应时间从10 min提高到60 min,Pb~(2+)去除率稳步上升,继续延长至90 min,去除率趋于稳定;曝气量从0增大到12 L/h,Pb2+去除率先快速增加后缓慢降低;3个因素对Pb~(2+)去除效果的显著影响大小依次为:曝气量初始p H反应时间,最佳反应条件是:初始p H值3.0、反应时间60 min、曝气量6 L/h。按照一级动力学模型对反应阶段进行拟合,采用电子扫描显微镜(scanning electron microscope,SEM)观察了反应前后铁炭填料表面形态和结构变化,并利用X射线衍射(X-ray diffraction,XRD)分析了反应后溶液组分,推断得出催化内电解去除铅的机理是氧化还原和化学沉淀。当初始Pb~(2+)浓度为1.0 mg/L,在最佳试验条件下,处理后Pb~(2+)浓度降至0.037 mg/L,满足《地表水环境质量标准》(GB 3838-2002)Ⅲ类水体限值要求。研究结果可为农村铅污染水体修复提供理论和设计依据。

Study on characteristics of catalyzed internal electrolysis treating simulated rural lead pollution water

Lead may cause a series of health problems which ranged from behavioral problems, learning disabilities to seizures or even death. The conventional treatment methods adopted for removing lead from wastewater included chemical precipitation, electro-chemical reduction, ion exchange process and adsorption method. However, these methods had certain disadvantages, such as high cost, technical sophistication, generation of sludge, or other waste products that needed to be processed. Therefore, it was necessary to research and develop a treatment method which had the advantage of relative high efficiency and low operating cost. On the basis of above considerations, an emerging lead removal system, namely, the catalyzed internal electrolysis based on advanced ferric-carbon filler, was applied to treat lead-containing wastewater, especially the lead pollution water in rural areas. To investigate the effect of catalyzed internal electrolysis based on advanced ferric-carbon filler treating water that simulated lead pollution in rural area, this study adopted single factor experimental design and orthogonal experimental design that included eight factors and three levels, making study on initial pH(1.0~8.0), reaction time(10-90 min) and aeration quantity(0-12 L/h). The results showed that the removal rate of Pb2+rose slowly at first and then dropped sharply when pH value rose from1.0 to 8.0. The removal rate of Pb2+rose steadily when the reaction time increased from 10 min to 60 min and tended to be stable when the reaction time kept extending to 90 min. The removal rate of Pb2+rose sharply at first and then dropped slowly when aeration quantity increased from 0 to 12 L/h. The influence of the three factors on removal efficiency of Pb2+were as follows: aeration quantity>initial pH value>reaction time, the best reaction condition occurred when the initial pH value was at 3.0, the reaction time was 60 min and aeration quantity was 6L/h. This paper fitted the reaction stage according to the first-order kinetic model, observed the surface feature and structure changes of the ferric-carbon filler before and after the reaction by using scanning electron microscope (SEM) and analyzed the components of solution after the reaction by using X-ray diffraction (XRD) and inferred that the mechanism for catalyzed internal electrolysis removing lead was oxidation-reduction and chemical precipitation. In optimum experimental conditions, the concentration of Pb2+could fall to 0.037 mg/L after treatment when initial Pb2+concentration was 1.0 mg/L, which could meet the requirement on limiting value of the case-Ⅲ water specified in Environment Quality Standards for Surface Water (GB3838-2002). This research results may provide theoretical foundation and design basis for the remediation of the lead pollution water in rural areas.