来源网址：http://www.rsoau.com 2020-05-15 16:27:12
Biodegradable materials include polymer materials directly prepared by biotechnology, such as polyhydroxyalkanoate (PHA); a class of materials obtained by polymerization of raw materials prepared by biotechnology, such as polylactic acid (PLA), polybutylene succinate (PBS), polyamino acid, etc.; in addition, starch based biodegradable plastics, carbon dioxide copolymer aliphatic polycarbonate (APC) Wait.
Starch based biodegradable plastic is a kind of plastic product made by blending starch with other polymers after modification and grafting reaction. It can replace general plastics in industry, and can be used as packaging material, shockproof material, mulch film, food container, toy, etc.
PLA is a high molecular material polymerized from lactic acid. It has the characteristics of non-toxic, non irritating, high strength, easy processing and good biocompatibility. The products can be completely degraded after use. Therefore, PLA is a kind of bio environmental protection material that can truly achieve the double effects of ecology and economy. It is the most active and fastest-growing biodegradable plastic in recent years.
Poly (butylene succinate) is a kind of biodegradable plastics with the best comprehensive properties, which is produced by polycondensation of succinic acid and butanediol. Due to its excellent comprehensive performance, reasonable cost performance and wide application, PBS can be used in packaging, tableware, cosmetic bottles and drug bottles, disposable medical supplies, agricultural film, pesticide and chemical fertilizer slow-release materials, biomedical polymer materials and other fields.
生物降解螯合剂（BC）有较强的络合能力和较低的成本，在重金属污染土壤修复的应用中有希望代替常规洗涤剂。但是，对于生物降解螯合剂的应用仍然存在很大的挑战，如影响金属去除效率的因素及金属去除机理的了解还存在不足。因此，本研究使用分批洗涤法评价4种生物降解螯合剂对污染土壤中Cd、Pb和Zn的去除潜力。研究分析了洗涤前后土壤的光谱特征。结果表明，亚氨基芥酸（ISA）和谷氨酸-n，n-二乙酸（GLDA）是替代常用的不可生物降解的乙二胺四乙酸的理想选项，而葡萄糖醛酸（GCA）和聚天冬氨酸（PASP）的效率较低。考虑到金属去除效率和成本，生物降解螯合剂的参数为：浓度为50 mmol·L1，pH值为5.0，接触时间为120 min，固液比为1:5。一次洗涤对土壤Cd、Pb、Zn的去除率分别为52.39%、71.79%、34.13%，对农田土壤Cd、Pb、Zn的去除率分别为98.28%、91.10%、90.91%。洗涤后，重金属与土壤胶体的结合强度增加，而生物降解螯合剂去除的弱结合组分降低了金属迁移率。使用生物降解螯合剂的土壤洗涤结果表明，金属去除的可能机制包括酸溶解、离子交换和表面络合。本研究结果强调了ISA和GLDA作为洗涤剂去除污染土壤中潜在有毒元素的应用价值。
The biodegradation chelating agent (BC) has strong complexing ability and low cost. It is hopeful to replace the conventional detergent in the application of heavy metal contaminated soil remediation. However, there are still great challenges for the application of biodegradable chelating agents, such as the factors affecting metal removal efficiency and the understanding of metal removal mechanism. Therefore, batch washing method was used to evaluate the removal potential of CD, Pb and Zn from polluted soil by four kinds of biodegradable chelators. The spectral characteristics of soil before and after washing were studied. The results show that isa and glda are ideal alternatives to the commonly used non biodegradable ethylenediaminetetraacetic acid, while GCA and PASP are less efficient. Considering the metal removal efficiency and cost, the optimal parameters of the chelating agent are: concentration of 50 mmol · L1, pH value of 5.0, contact time of 120 min, solid-liquid ratio of 1:5. The removal rates of CD, Pb and Zn in soil by one-time washing were 52.39%, 71.79% and 34.13% respectively. The removal rates of CD, Pb and Zn in farmland soil were 98.28%, 91.10% and 90.91% respectively. After washing, the binding strength of heavy metal to soil colloid increased, while the weak binding component removed by biodegradation chelating agent reduced the metal mobility. The results of soil washing with biodegradable chelating agents show that the possible mechanisms of metal removal include acid dissolution, ion exchange and surface complexation. The results of this study emphasize the application value of ISA and glda as high-efficiency detergents to remove potential toxic elements in polluted soil.
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