| 摘要: | 生物高分子聚合物又稱生物可分解材料(Biodegradable Materials)，符合綠色設計概念，不易形成二次污染；此項研究重點主要著眼於利用生物高分子聚合物，如：甲殼素，處理地下水的重金屬污染問題。幾丁聚醣是甲殼類生物體經由萃取、加工製造成的天然陽離子型高分子聚合物，結構中含有大量的胺基、羥基之官能基，對重金屬容易進行螯合及吸附作用，可應用於處理汙染水體中的重金屬離子之吸附；但因幾丁聚醣成本較高，若用於大面積之重金屬汙染場址則將大幅提升處理成本，因此，本研究選擇適宜之可回收物質作為承載幾丁聚醣之基質，作為實廠應用之基礎設計。
本研究使用幾丁聚醣為主要吸附材料，將幾丁聚醣依不同比例(1：100、2.5：100、5：100)固定於回收之淨水廠汙泥形成生物吸附劑，並進行不同濃度之二價銅離子(50-1000 ppm )之吸附批次實驗。研究結果得知，不同比例之吸附劑對於二價銅離子具有良好之吸附效果，吸附平衡時間為6 小時。此外，等溫吸附模式分析驗證：不同吸附劑之Langmuir 等溫吸附模式分析均較Freundlich 等溫吸附模式為佳；以Langmuir 等溫吸附模式分析在平衡時間時，不同比例之吸附劑在pH=3 之最大吸附量Cmax(mg/g)分別為1:100-CIS (11.20)、2.5:100- CIS (16.644)、5:100-CIS (19.12)，在pH=4 之最大吸附量Cmax(mg/g)分別為1:100-CIS (12.35)、2.5:100-CIS (17.64)、5:100-CIS (18.92)。動力吸附模式分析亦驗證：本實驗所用之吸附劑皆符合擬二階動力學模式，為化學性吸附模式(Chemical Adsorption)。
Chitosan is a product of the partial N-deacetylation of chitin, which has several desirable properties like biodegradability, hydrophilicity, anti-bacterial, and non-toxicity, which is known to be biodegradable material, non-toxic, efficient, inexpensive, and highly competitive with ion-exchange resins and activated carbon. Such a structure has chemically active functional groups viz. hydroxyl (-OH) and amino (-NH2) as efficient sites to bind metal ions. It can be apply to in-situ remediation of heavy metal contaminations in groundwater. However, the procedure of contaminated waste stream remediation would be costly if chitosan were to be used alone. Filters must be constructed along the stream requiring large quantities of material but much lower amounts are needed if chitosan is immobilized on low-cost material.
Experiments were conducted batchwise as a function of different Immobilization ratio to sludge (1：100、2.5：100、5：100), different copper concentration (50-1000 ppm), solution pH (3 and 4), and contact time (0.5, 1,2, 4, 6, 12 and 24 h). Langmuir and Freundlich adsorption models were used to describe static isotherms and constants. The data fitted well with Langmuir model at six hours contact time. The Cmax(mg/g) at pH=3 and pH=4 were confirmed at 1:100-CIS (11.20), 2.5:100-CIS (16.644), 5:100-CIS (19.12), and 1:100-CIS (12.35),2.5:100-CIS (17.64), 5:100-CIS (18.92), respectively. Kinetic studies followed the pseudo-second order reaction which indicated that the chemical sorption is the rate-limiting step. Results of desorption process signified potential for recovering metal ions from CIS. |
