使用幾丁聚醣固化於天然物質吸附水中銅金屬之研究

Adsorption of Copper（II） by Chitosan Immobilized on Sand

隨著工業快速的發展，重金屬污染已形成了一種全球性的危害。存在於土壤及地下水中的重金屬，經由直接或間接的管道，造成環境及人體的傷害，因此，如何有效的處理地下水之重金屬污染之問題，已成為現今環工界之重要課題。水中重金屬污染整治可分為「控制」及「處理」二個部分，而傳統的復育技術著重於化學物理處理方法，成本較高且易破壞污染現地；而生物復育技術是一經由管理或自然發生的過程中，以微生物將污染物降解或轉移成較低毒性或無毒性的型態，藉此降低或排除環境污染物，且處理技術本身不會造成環境二度傷害，是一成本低廉且政府、社會大眾接受度高的處理方式。生物高分子聚合物(Biopolymer)，為生物可分解材料(Biodegradable Materials)，已成為許多產業未來研發的趨勢。生物可分解材料的製成是以天然的生物材料為基質，如：微生物、植物與動物等。生物可分解材料於使用後，可用堆肥的方式回歸於大自然，滋養微生物、植物與動物，所以原料來源可不斷重複取得，符合「永續再生」的原則。有鑑於此，從昆蟲、水生甲殼類動物（蝦、蟹等）之外殼及真菌類之細胞壁中取得之幾丁質與幾丁聚醣，因其化學結構、反應特性及可塑性性質，已廣泛的被應用於重金屬之吸附試驗。本計畫以綠色設計為概念，使用生物可分解之材料，如：幾丁聚醣、黏土(Clay)及沙子(Sand)等，進行重金屬的吸附可行性研究。首先，找尋研製不同重量比的幾丁聚醣結合沙子為吸附劑之最佳化操作條件，並針對重金屬銅(Cu)進行吸附及等溫吸附模式之探討及評估。實驗結果顯示：沙子具有吸附銅金屬的能力（Langmuir等溫吸附之最大吸附量：3.27 mg/g）；基於經濟因素及實用性考量，選用沙子與幾丁聚醣之結合，當其重量比率為5%時具有最高的吸附容量(10.87 mg/g)，甚至高於幾丁聚醣單獨使用之最大吸附量(7.55 mg/g)，故5%的幾丁聚醣－－沙子聚合物可以考量作為廢水處理技術中吸附重金屬之生物吸附劑。

Because of the dramatic develop of industry, heavy metal pollution has become a global environmental considerations. The heavy metals in the soil and groundwater have endangered our environment and human body by direct or indirect pathway. Thus, how to solve efficiently the heavy metal pollution in groundwater has become the most essential issue around the world. Theoretically, the traditional remediation method is physicalchemical processes, which resulted in high capital cost and serious damage in contaminated sites. Currently, bioremediation is a developing biologic process that offers the possibility to destroy or render harmless various contaminants using natural biological activity. As such, it uses relatively low-cost, low-technology techniques, which generally have a high public acceptance and can often be carried out on site. Biopolymer is a biodegradable material, and becomes a newly developing tendency for many industries. Those materials can be degraded by landfill process, which provides the nutrient for microorganisms, plants and animals. Based on this concept, obtaining form insects, the shell of aquatic crustaceans (crab and shrimp), and the cell wall of fungus. Chitin and Chitosan have widely applied in the adsorption study of heavy metal based on their chemical structures, reaction characteristics and modification properties. This research is based on the ideal of green design and using biodegradable material (chitosan) coated with sand. Nature materials such as sand, soil, clay and chitosan used as adsorbent to examine by Cu(superscript 2+) adsorption capability and isotherms analysis using Langmuir isotherm. In the considerations of real scale and cost-effective applications, sand was immobilization on chitosan to uptake the Cu(superscript 2+) ions in aqueous solution. Moreover, the adsorption capacity of 5% chitosan-coated sand (10.87 mg/g) was a better adsorbent compared to chitosan used alone (7.55 mg/g), 1% (3.38 mg/g) and 2.5% (4.50 mg/g) weight percentages coasted with chitosan. It is suggested that using 5 % chitosan-coated sand as a bioadsorbent in wastewater treatment process.