| 摘要: | 水生植物具有吸收及累積重金屬的特性，故本研究利用浮水性植物（布袋蓮、大萍、青萍及槐葉蘋）處理含重金屬（銅、鎘、鉛、鎳、鋅）之溶液使其含量能有效降低。
本研究利用浮水性植物去除水中重金屬可分為兩個部份；一為盆栽試驗乃利用浮水性植物以栽種方式去除水中重金屬的實驗。二為吸附試驗利用廢棄的水生植物為吸附體對含銅、鎘、鉛、鋅、鎳的實驗室配製溶液進行動力學、等溫吸附平衡實驗之研究且達到以廢棄物處理污染物之目的。
第一部分研究結果發現四種水生植物以混合重金屬溶液處理後，植物皆會產生受害的病徵，濃度越高處理天數越多生長狀況越差，且葉綠素的含量明顯下降，但重金屬攝取量因濃度及處理天數增加而上升，四種植物對五種重金屬吸收之趨勢皆約為鎳金屬最大，布袋蓮含1.186 mg-Ni/g；大萍含1.754 mg-Ni/g、青萍及槐葉蘋則含4.883及7.912 mg-Ni/g。
第二部份布袋蓮、大萍、青萍及槐葉蘋的吸附平衡時間均約為60~90分鐘，以鉛金屬的吸附量為最大，依序分別為16.66、16.79、16.48及15.44 mg-Pb/g。動力學實驗結果吻合二階動力學模式，等溫吸附模式較符合Langmuir。利用Freundlich等溫吸附曲線推估的經驗常數（n）皆為正值，當 n ﹥1表示非線性但有利吸附。
Aquatic plants have been shown having the ability to uptake heavy metals from the surrounding environment. This study used floating macrophytes（Eichhornia crassipes,Pistia stratiotes,Lemna perpusilla and Salvinia natans） to remove the heavy metals（Cu,Cd,Pb,Ni andZn） from the prepared solution containing metal effectively.
In this study, the experimental work heavy metals removal from aqueous solution by floating macrophytes could divide into two parts. In one set of the experiments, plants were exposed to heavy metals solution. In the second set, the wasted aquatic plants were use to study adsorption kinetics in the prepared solution containing metals. The purpose of this part of work was to study the treatability of metals using wasted aquatic plants.
The results from the first part or research work, four species of aquatic plants to treat mixed metals solution, indicated that all plants looked unhealthy and deteriorated. The growth condition was getting worse with increasing metals concentrations. Even chlorophyll content conspicuous was decreased after several days, but the heavy metals uptake was increased. Among the five tested metals, nickel was removed most efficiently by the four species of plants. The metal contains in each species are 1.186 mg-Ni/g for Eichhornia crassipes, 1.754 mg-Ni/g for Pistia stratiotes, 4.883 mg-Ni/g for Lemna perpusilla, and 17.912 mg-Ni/g for Salvinia natans.
In the second part or research work, the adsorptions of metals by Eichhornia crassipes、Pistia stratiotes、Lemna perpusilla and Salvinia natans were achieved equilibrium within 60~90 minutes. Lead was found to be adsorbed the most, and the adsorbing capacities by these species were 16.66, 16.79, 16.48, and 15.44 mg-Pb/g, respectively. The adsorption kinetic was found following the second-order reaction, and the Langmuir isothermal equation can be well-fitted. Freundlich model can be used to demonstrate when n ﹥1 show non-linear but favorable for adsorption. |
