| 摘要: | 電鍍、礦業及金屬加工處理業廢水中含有重金屬離子。水中金屬離子不能被生物分解且易累積蓄存在水體生物，經食物鏈進入人體中造成各種疾病(如痛痛病、水侯病等)。纖維素是自然界最豐富之生物聚合物(biopolymer)。食品加工廢棄物(茶葉渣)中含有豐富纖維素、幾丁質、兒茶素、腐質酸、黃酸等，因微生物對其分解速度不夠迅速，如直接丟棄在環境中易造成環境污染問題。本研究擬以化學處理法修飾茶葉萃取殘渣成吸附劑，提升應用茶葉萃取殘渣去除水中重金屬離子(Cu2+、Zn2+和Ni2+)的效能，此舉將可同時處理食品加工廢棄物和廢水二種環境污染問題，並有助於綠色產業無廢棄物之推廣，助於整體環境之永續利用。
本研究針對九種化學修飾化法製備之吸附劑進行一系列重金屬離子吸附試驗，包括吸附劑吸附量受pH值、接觸時間、溫度、重金屬離子種類之影響，並進行等溫吸附平衡、及吸附動力試驗探討修飾化吸附劑效能，對推廣修飾化吸附劑將有助益。
實驗結果顯示，對Zn2+、Ni2+及Cu2+的最大實驗觀測吸附值(QH)依序為：硫脲加磷酸化修飾處理法(一)＞磷酸化修飾處理法(一)＞硫脲提升纖維素架橋作用＞磷酸化修飾處理法(二)＞硫代硫酸鈉修飾處理法＞甲醛修飾處理法(一) ＞甲醛修飾處理法(二)＞醋酸修飾處理法＞檸檬酸修飾處理法。其中硫脲加磷酸化修飾處理法(一)修飾吸附劑具有對Zn2+、Ni2+及Cu2+最佳吸附量為256.28、241.56、229.96mg/g，效果最差之檸檬酸修飾處理法亦有40.32 mg、37.9 mg、34.64 mg/g。各種修飾改良法茶葉渣吸附劑吸附能力為Zn2+＞Ni2+＞Cu2+。設未經修飾過茶葉渣比表面積(0.3391 m2/g)之相對比值為1，其餘九種化學修飾化法製備之吸附劑比表面積相對比值分別為硫脲加磷酸化修飾處理法(一)24.7，磷酸化修飾處理法(二) 12.2，磷酸化修飾處理法(一) 6.7，硫脲提升纖維素架橋作用6.5，硫代硫酸鈉修飾處理法6.1，甲醛修飾處理法(一) 5.9，甲醛修飾處理法(二) 5.8，醋酸修飾處理法5.4，檸檬酸修飾處理法4.9。各種修飾改良法吸附劑對Zn2+、Cu2+及Ni2+最大實驗觀測吸附值(QH)皆大於Langmuir的QL值且Freundlich的n值也都大於1顯示複雜之吸附模式。
Many industrial waste-water contaminated with heavy metals, such as metal plating facilities, mining operations and tanneries. Heavy metals are not biodegradable and tend to accumulate in living organisms through food chain, causing various diseases and disorders. Cellulose is the most abundant natural biopolymer in the world. Food processing waste, hereafter abbreviated as FPW, contained cellulose, humic acid, catechin, fulvic acid, and chitin. FPW also considered as an environmental problem because of difficult degradation with microorganism. The aim of this study is to use the chemical process to modify the tea extracted residual into adsorbent which could enhance the removal efficiency of metal ions (Cu2+, Zn2+, and Ni2+) from water solution with food processing waste. The heavy metal pollution problem and FPW can be expected to solve in the same time. The utilization of modified adsorbent can help the development of green industry with zero waste and the sustainability of environment.
The experimental design for adsorption of heavy metals with 9 kinds of modified adsorbents includes pH of heavy metals solution, reaction temperature, reaction time, and kinds of heavy metals. The isothermal adsorption and adsorption kinetic experiment for adsorbent also did.
The modified adsorbent with highest experimental observed adsorption capacities (QH) were 256.28(Zn2+), 241.56(Ni2+), 229.96(Cu2+)mg/g and made from the thiocarbamide plus phosphorylation (1) process. Inversely the QH of the adsorbent from process of citric acid modification was only 40.32(Zn2+), 37.9(Ni2+), 34.64(Cu2+) mg/g. The chemical process for enhancement of metal adsorption in adsorbent ordered decreasingly as thiocarbamide plus phosphorylation (1), phosphorylation (1), thiocarbamide modification, phosphorylation (2), sodium thiosulfate modification, formaldehyde (1), formaldehyde (2), acetic acid modification, and citric acid modification. The adsorption capacity for each kinds of adsorbent was Zn2+ï¼Ni2+ï¼Cu2+. If the specific surface area (0.3391 m2/g) of non-modified tea extracted residual was set as 1, the specific surface area of 9 adsorbents, modified with optimized condition, will be 24.7 (thiocarbamide plus phosphorylation (1), 12.2 (phosphorylation (1), 6.7 (thiocarbamide modification), 6.5 (phosphorylation (2)), 6.1 (sodium thiosulfate modification), 5.9 (formaldehyde (1), 5.8 (formaldehyde (2), 5.4 (acetic acid modification), and 4.9 (citric acid modification). The highest experimental observed adsorption capacities (QH) was larger than QL, derived from Langmuir adsorption model, and the n value derived from Freundlich adsorption model also larger than 1.0 for adsorption reaction between Zn2+, Ni2+, Cu2+ and 9 kinds of modified adsorbents. |
