Preparation and characterization of a new class of starch-stabilized bimetallic nanoparticles for degradation of chlorinated hydrocarbons in water
Preparation and characterization of a new class of starch-stabilized bimetallic nanoparticles for degradation of chlorinated hydrocarbons in water
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DOI：
10.1021/es048743y
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发表时间：
2005-05-01
影响因子：
11.4
通讯作者：
Zhao, DY
中科院分区：
文献类型：
--
作者：
He, F;Zhao, DY
近年来，利用双金属纳米颗粒对三氯乙烯和多氯联苯的脱氯越来越受到人们的关注。然而，由于纳米粒子具有极高的反应性，使用现有方法制备的纳米粒子往往要么与周围的介质反应，要么结块，导致形成更大的絮体，导致反应性的显著丧失。为了克服这些缺点，我们开发了一种简单、绿色的方法来合成钯化铁(Fe-Pd)纳米颗粒。我们对传统方法进行了改进，使用了一种水溶性淀粉作为稳定剂。与未加稳定剂的纳米颗粒相比，上浆后的纳米颗粒团聚小得多，但脱氯力更强。透射电子显微镜分析表明，上浆的纳米粒子是以离散的粒子形式存在的，而非上浆的粒子则是树枝状的絮状物。平均粒径为14.1 nm，标准偏差为11.7 nm，比表面积约为55m(2)g(-1)。虽然上浆的纳米颗粒在水中悬浮了几天，但非上浆的颗粒在几分钟内凝聚和沉淀。当用于水中三氯乙烯或多氯联苯的脱氯时，上浆的纳米颗粒表现出明显更高的反应活性。在0.1g L-1剂量下，1 h内可破坏98%的三氯乙烯(C-0=25 mg L-1)，在降解初期(20分钟)检测到微量的1，1-二氯乙烯，未检测到其他中间产物如氯乙烯、顺式和反式二氯乙烯。在接近1g L-1的条件下，淀粉纳米粒子在100h内对80%以上的多氯联苯(C-0=2.5mgL-1)的转化率超过80%，而未淀粉纳米粒子的转化率仅为24%。一种无害的稳定剂的应用可以大大提高钯纳米铁在环境应用中的性能。
Dechlorination of TCE and PCBs using bimetallic nanoparticles has received increasing interest in recent years. However, due to the extremely high reactivity, nanoparticles prepared using current methods tend to either react with surrounding media or agglomerate, resulting in the formation of much larger flocs and significant loss in reactivity. To overcome these drawbacks, we developed a simple and green approach for synthesizing palladized iron (Fe-Pd) naroparticles. We modified the conventional methods by applying a water-soluble starch as a stabilizer. The starched nanoparticles displayed much less agglomeration but greater dechlorination power than those prepared without a stabilizer. TEM analyses indicated that the starched nanoparticles were present as discrete particles as opposed to dendritic flocs for nonstarched particles. The mean particle size was estimated to be 14.1 nm with a standard deviation of 11.7 nm, which translated to a surface area of similar to 55 m(2)g(-1). While starched nanoparticles remained suspended in water for days, nonstarched particles agglomerated and precipitated within minutes. The starched nanoparticles exhibited markedly greater reactivity when used for dechlorination of TCE or PCBs in water. At a dose of 0.1 g L-1, the starched particles were able to destroy 98% of TCE (C-0 = 25 mg L-1) within 1 h. While trace amounts (< 25 mu g L-1) of 1,1-DCE were detected in the initial stage (< 20 min) of degradation, no other intermediate byproducts such as vinyl chloride, cis-, or trans-dichloroethene were detected. The starched nanoparticles at similar to 1 g L-1 were able to transform over 80% of PCBs(C-0 = 2.5 mg L-1) in less than 100 h, as compared to only 24% with nonstarched Fe-Pd nanoparticles. The application of an innocuous stabilizer may substantially enhance the performances of palladized iron nanoparticles for environmental applications.