| 摘要: | 年來，有鑑於科技的快速發展，工商業快速的進步造就了現在多元文化的的物質享受，相對的也為環境帶來相當大的隱憂。環境品質的每況愈下是現今眾人有目共睹。隨著工業的發達，重金屬汙染對全球的危害已逐漸形成。存在於土壤及水體中的重金屬，會經有直接或是間接的管道對環境及人類早成一定的危害。如何有效處理水體重金屬汙染已成為現今環保的重要議題。復育(Remediation)是現今水體重金屬整治的技術之一，具有回復全球樣貌的特色，然而生物復育技術是利用天然微生物扮演著分解者的角色降解或破壞有害物，形成較低毒性或無毒性的物質。生物復育是安全，也較符合自然法則的淨化技術，是未來可以積極發展的復育技術。
生物高分子聚合物(Biopolymer)，具備微生物可分解的特色(Biodegradable Matierials)，成為未來研發的趨勢。幾丁聚醣是生物體經由加工製造成的天然陽離子型高分子，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。生物分解材料使用後會在自然界中進行循環，原料可在自然界中取得，此特性符合永續利用之原則，而幾丁聚醣得各種特性已經被廣泛利用在水體重金屬吸附實驗上。
本研究中使用幾丁聚醣為主要吸附材料，也利用氫氧化鐵及淨水廠汙泥作為吸附劑，也將幾丁聚醣以相同比例分別搭配氫氧化鐵和淨水廠汙泥兩種不同的物質製作成兩種吸附劑，進行不同濃度之二價銅離子(100-2000 ppm )的吸附批次實驗。研究結果得知，五種吸附劑對於二價銅離子具有一定的吸附效果。再分別以Langumir與Freundich兩種吸附模式探討，R均大於0.90以上，在Freundich模式下所有吸附劑其n直接大於1，證明了吸附劑對於二價銅離子具有吸附現象發生。在動力學模式下探討，各種吸附劑均屬於擬二階動力吸附。在不同之pH下進行吸附，具有不同的吸附量，在pH 2時各種吸附劑的吸附量為最小。
The rapid development of science and technology in recent years created a standard of living that caused serious deterioration in the environment. Heavy metal contamination in the soil, surface water and groundwater is one of the major environmental problems due to their non-biodegradability and toxicity. Presence of heavy metals in the surface water and groundwater environment is detrimental to human health and prevents any beneficial use of the water bodies. Therefore, it is important to treat and remove heavy metals from waste effluents before their disposal into the environment. Conventional technologies in heavy metal removal such as ion exchange, precipitation, reverse osmosis, and electro deposition are expensive, ineffective, and produce secondary pollutants like sludge that need proper disposal and confinement. On the other hand, adsorption is a physicochemical process that is easy to operate and can effectively treat effluents with high and low solute loadings. Commercialized adsorbents such as activated carbon are effective in removing heavy metals but remain costly.
Biological polymers or biopolymers have been gaining ground due to their selectivity, biodegradability and non-toxicity. In addition, biopolymers are economically-attractive due to their abundance in nature. Chitosan is a natural cationic polymer derived from chitin. It contains amino (-NH2) and hydroxyl (-OH) functional groups along its structural chain that serve as binding sites for heavy metals. It is known to have the highest metal chelating capacity among the biopolymers hence it has been widely utilized in the removal of heavy metals and organic dyes.
In this study, the removal of Cu(II) from aqueous solutions using chitosan, iron hydroxide, sludge, chitosan immobilized on sludge and chitosan immobilized on iron hydroxide was investigated under static conditions. The sludge was obtained from a water treatment plant. The effect of operating parameters like solution pH (pH 2 to pH 4) and initial concentration (100 mg/L to 2000 mg/L) on the % Cu(II) removal and adsorption capacity was examined. The isotherm data for all five adsorbents correlated well with the Langmuir model (R2 > 0.95). The Freundlich constant, n has a value of n > 1, indicating high affinity of Cu(II) adsorption for all five adsorbents. The kinetic data best fit the pseudo-second order equation, indicating that chemisorption is the rate-limiting step of the Cu(II) adsorption. At pH 2, it is observed that adsorption capacity is very low for the various five adsorbents. |
