【作者】 王晴晴；

【导师】 邰超；

【作者基本信息】 河南理工大学 ， 环境工程， 2010， 硕士

【摘要】 氯酚类化合物常见于各种化工废水,易在环境介质中积累,在环境各介质中均检测到以较高浓度存在,对人类健康及生态环境构成长期威胁。由于其高毒性和难降解性,美国环境保护局将氯酚类污染物列为最优先控制的污染物。偶氮染料是指分子中含有偶氮基(-N=N-)的一类染料,种类很多,色谱齐全,是最大的一类工业合成有机染料,仅在生产过程中就有近15%排入水体。绝大多数偶氮染料具有很强的生物毒性和致癌性。所以,对氯酚和偶氮染料的降解研究具有重要的现实意义。近年来,纳米金属以其独特的性能优势,已成功应用于地下水及土壤环境污染物的修复处理,显示出良好的应用前景。本论文采用液相还原法制得分散纳米金属Fe,并采用阳离子交换树脂为载体,液相还原法制得负载纳米金属Fe、Ni、Fe-Ni及Fe-Pd,采用扫描电子显微镜(SEM)对合成的纳米金属进行表征,显示出纳米粒子均为球形且粒径在10-200 nm。以三氯酚(TCP)和偶氮染料作为目标污染物降解,考察了溶液pH,温度,H2O2浓度,纳米金属粒子的加入量,及复合金属中Ni(或Pd)的含量百分比、盐度等对TCP和偶氮染料降解率的影响。研究结果表明:1.在实验优化条件下,50 mL的反应体系(含10 mL 1.10 mmol/L的TCP,10mL 50 mmol/L HClO4,1.0 mL 80 mmol/L的H2O2,0.4 mL 7 mmol/L纳米铁),经过20 min超过95%的TCP被降解。酸性条件下,TCP的降解效果较好,pH=3时最佳。反应温度对H2O2发生均裂产生?OH的影响较大,随着温度的升高,TCP的降解率随之增加。2.负载纳米零价金属Fe、Ni、Fe-Ni、Fe-Pd均能够较好的降解偶氮染料。酸性条件下,负载纳米Fe降解偶氮染料,除橙黄I、酸性嫩黄G、酸性黄17的降解率分别为96.1%、53.3%、39.3%,其他各染料的降解率均达100%。尤其是复合金属Fe-Ni、Fe-Pd比Fe、Ni具有更快的降解率。3.溶液pH、温度、盐度、负载纳米金属的加入量,及负载纳米金属中Ni(或Pd)的含量都是影响反应降解率的重要因素。溶液的酸度越大、温度越高、投加的纳米金属量越大、及Ni(或Pd)的含量越高,降解率越高;盐度对偶氮染料的降解有一定的抑制作用,盐度越高,偶氮染料的降解率越低。4.本研究采用阳离子交换树脂作为载体负载纳米零价金属,然而其不只是载体,还是反应产物Fe2+的收集者,可以大大减少释放到水溶液中的Fe2+的含量,避免其对环境造成不利影响。所制备的纳米材料经过活化再生,可循环使用,仍具有较高活性及较长的使用寿命。更多还原

【Abstract】 Chlorophenols can be found in various chemical waste waters and can exist in various media of the environment with relatively high concentration. They are easy to accumulate in the surroundings and endangered human as well as ecological environment over a long period of time. Azo dyes, which contain one or more azo bonds (-N=N-), have many different types and full range of chromatography, are a major class of synthetic, colored organic compounds. During the dyeing production process, about 15% of them end up in wastewaters. Most azo dyes are highly carcinogenic and toxic. Therefore, the degradation research of chlorophenols and azo dyes has important practical significance. Recent years, for the unique property advantages, nano-metals have been used to remedy groundwater and soil pollutants, and show a good prospect.Dispersed nanoparticles Fe0 was obtained through chemical reduction, and using cation exchange resin as carrier, through chemical reduction we obtained loaded nanoparticles Fe、Ni、Fe-Ni、Fe-Pd. The degradation of 2,4,6-trichlorophenol (TCP) by hydrogen peroxide catalyzed by dispered nano-iron and the degradation of azo dyes in aqueous solutions by loaded nanoscale Fe、Ni, and Fe-Ni、Fe-Pd bimetallic nanoparticles were investigated. Scanning electron microscopy (SEM) of as-synthesized nanoparticles showed the presence of spherical particles having a size of 10-200 nm.The influences of pH, temperature, the concentration of H2O2, ionic strength, the amount of nanoparticles Fe、Ni、Fe-Ni、Fe-Pd and Ni (or Pd) loading in the bimetallic metals on the degradation of TCP and azo dyes were investigated. Batch experiments showed that:1. Under optimal conditions of the experiment: 50 mL of the reaction system (containing 10mL 1.10mmol/L of the TCP, 10mL of 50 mmol/L HClO4, 1.0 mL 80 mmol/L of H2O2, 0.4 mL 7mmol/L nano-iron), over 95% of TCP can be degraded in 20min. In acidic condition the degradation of TCP showed high degradation activity. Reaction temperature had a great impact on the occurrence homolysis of H2O2, as the temperature rised, the chlorophenol degradation efficiency increased.2. Zero-valent metal particles Fe, Ni, Fe-Ni, Fe-Pd could well degraded azo dyes. Under acidic conditions using Fe, in addition to Orange I, Acid Yellow G, Acid Yellow 17 which degradation rate were 96.1%, 53.3%, 39.3%, the degradation rate of other dyes was complete 100% within 60min. Especially using Fe-Ni, Fe-Pd had even better degradation efficiency. The bimetallic Fe-Ni、Fe-Pd nanoparticles demonstrated an enhanced degradation rate compared to Fe、Ni nanoparticles.3. The results showed that the solution pH, the addition of Fe(or Ni, Fe-Ni, Fe-Pd), and the Ni (or Pd) loading in Fe-Ni (or Fe-Pd) nanoparticles were the main factors that influenced the degradation rate of azo dyes. With increasing acidity, temperature, nanoparticles addition, the Ni (or Pd) loading, the degradation rate increased rapidly. The existence of Na2SO4 could inhibit the decolorization of azo dyes in some extent.4. In this study, cation exchange resin as a carrier loaded zero-valent nano-metal particles, but it was not just a carrier, but also collectors of the reaction product Fe2+, which could significantly prevent Fe2+ releasing into the solution, to avoid its adverse impact to the environment. More importantly, after the activation of renewable, these nanoparticles showed a significantly long life span with sustained reactivity.更多还原