Kim Daeik, Petrisor loana G, Yen Teh Fu
Department of Civil and Environmental Engineering, University of Southern California, Los Angeles [corrected] CA, USA.
J Air Waste Manag Assoc. 2005 Jul;55(7):961-9. doi: 10.1080/10473289.2005.10464682.
Cathode ray tubes (CRTs) from computer monitors and television sets, which contain significantly high percentage of lead (Pb) by weight, represent an enormous and growing hazardous waste problem in the United States and worldwide. As a result, new technologies are needed to cope with current CRT waste stream and increased hazard and build new markets for its recycled components, developing commercially viable concrete composites, as well as minimizing CRT disposal problems. In this study, commercially available biopolymers, such as xanthan gum, guar gum, and chitosan, were used to encapsulate CRT glass waste, reducing the Pb leachability. The biopolymers utilized contain a number of useful functional groups, such as carboxyl (xanthan), hydroxyl (guar), and amino groups (chitosan), which play important roles in binding and stabilizing Pb onto concrete structures. The use of biopolymers in concrete systems can create a stable interpenetrating cross-linking composite that will last for many years. Results from these new composites show 30% higher compressive strength than standard concrete and a sharp decrease in lead leachability from several thousand milligrams per liter initially to an amount of three-tenths milligrams per liter or lower values (much lower than the U.S. Environment Protection Agency standard for hazardous waste of 5 mg/L by the toxicity characteristic leaching procedure test), and for some of the composites leachability is below even the standard for drinking water. This efficient and cost-effective CRT-biopolymer-concrete composite is a new class of biopolymer-modified material that can potentially perform a significant role in relieving the current CRT issue.
电脑显示器和电视机中的阴极射线管（CRT）含有重量占比相当高的铅（Pb），这在美国乃至全球都构成了一个巨大且日益严重的危险废物问题。因此，需要新技术来应对当前的阴极射线管废物流、降低危害，并为其回收部件开拓新市场，开发具有商业可行性的混凝土复合材料，同时尽量减少阴极射线管的处置问题。在本研究中，使用了市售的生物聚合物，如黄原胶、瓜尔胶和壳聚糖，来封装阴极射线管玻璃废料，降低铅的浸出性。所使用的生物聚合物含有许多有用的官能团，如羧基（黄原胶）、羟基（瓜尔胶）和氨基（壳聚糖），这些官能团在将铅结合并稳定在混凝土结构上起着重要作用。在混凝土系统中使用生物聚合物可以形成一种稳定的互穿交联复合材料，这种复合材料可以持续多年。这些新型复合材料的抗压强度比标准混凝土高30%，铅的浸出性从最初的每升数千毫克急剧下降到每升十分之三毫克或更低（远低于美国环境保护局通过毒性特性浸出程序测试得出的危险废物标准5毫克/升），对于某些复合材料，浸出性甚至低于饮用水标准。这种高效且经济高效的阴极射线管 - 生物聚合物 - 混凝土复合材料是一类新型的生物聚合物改性材料，有望在解决当前阴极射线管问题方面发挥重要作用。
