傳統上已有許多物化方法可用來移除溶液中之重金屬，然而工業廢水的多樣性，要得到較佳的金屬離子去除率是相當困難而且成本昂貴的。目前已有許多研究致力於發展低成本、可再利用且對環境友善之生物吸附劑來移除溶液中的有害物質。
本研究利用台灣濕地常見浮水植物 (布袋蓮、水芙蓉及浮萍)，探討其對金屬離子之吸附成效。本研究主要分為兩個部分，一為將植物製備成吸附劑並對其進行改質探討其對金屬離子之吸附成效；二為水耕試驗，將植物栽種在含銅工業廢水之溶液中，觀察其生長情形與水溶液中銅離子濃度之變化。
由實驗結果可得知植物所製備而成之吸附劑表面羧基與氫氧基含量越多，對金屬之吸附效果越好，經過 NaOH 改質活化後之吸附劑較其他改質劑效果佳，因 NaOH 可移除植物表面雜質使羧基與氫氧基得以裸露，由 FTIR 圖譜可看出具有明顯羧基與氫氧基之吸收波峰。經過吸附後，羧基與氫氧基之吸收波峰明顯消減許多，表示吸附劑主要是藉由表面羧基與氫氧基使重金屬鍵結於其上而達到移除重金屬的目的。
浮生植物在 20 mg/L 之 Cu2+ 溶液中生長，隨著時間的增加，水溶液中 Cu2+ 濃度逐漸下降，大約在第 4 ~ 5 天該濃度已降至銅之放流水標準 3 mg/L 以下。經質量平衡得知水溶液中減少的 Cu2+ 與植物體內增加的量大約一致，但植物體內若累積過多的 Cu2+ 時則會造成浮生植物的毒害，甚至死亡。

Traditionally, there are a lot of chemical and physical methods to remove heavy metal ions from industrial sewage. Due to the variety of industrial effluent, it is very difficult to get inexpensive good removal efficiency. Presently, many studies are devoted to develop low cost and reusable biosorbent to get rid of harmful substance in the solution.
In this study we use common floating macrophytes in Taiwan ( Eichhomia crassipes, Pistia stratiotes, Lemna minor ) as the raw materials to investigate their adsorption capacity of metal ions. The experiments include two parts, one is to prepare the adsorbent and use different chemicals to modify it, and to compare the capacity of adsorption of heavy metal. Another is to plant the plants in industrial discharge which contained the metal ion, observe the growth of plants and the metal ions concentration change in solution during the plant’s growth.
The experimental results show that the adsorbent prepared from the plants contained more carboxyl and hydroxyl group has higher capacity to adsorp the heavy metals. The FTIR spectra showed that there are carboxyl groups and hydroxyl groups in biosorbents, which are able to react with heavy metal ions obviously in aqueous solution. The adsorbent modified using NaOH is better than other modifier, due to NaOH.
Three species of floating plants were planted in industrial discharge which contain copper ion. In 20 mg-Cu/L system, the copper concentration decreased with the plant growth. The copper concentration decreased under the effluent standards 3 mg/L after 3 to 5 days. By the mass balance, we know that the amount of copper decrease in solution is equal to the amount increase in the plants. If plants accumulate too much copper, it will be poisoned even leads to fatal.

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