利用零價鐵程序處理含銅、鎳及乙烯二胺四乙酸之研究

Simultaneous removal of Nickel, Copper and EDTA by Zero Valent Iron processes

金珮瑩(Pei-Ying Chin)

指導教授 ： 陳孝行

國立臺北科技大學/工程學院/環境工程與管理研究所/碩士(2008年)

https://doi.org/10.6841/NTUT.2008.00355

摘要

在工業製程中廣泛的使用EDTA，其應用於印刷電路板、造紙業、化妝品製造、及半導體製程…等，雖然EDTA在法規中並無明確訂定排放標準，但由於EDTA在使用後若被混入含有重金屬之工業廢水時，則會與重金屬離子形成穩定性極高之金屬螯合物（Metal-EDTA）大幅增加重金屬離子之溶解性，使重金屬離子無法利用混凝等程序去除，而Metal-EDTA被放流至自然水體後，對人類、生物具致病性、致癌性與環境污染之極大威脅。
本研究利用零價鐵（粒徑≦212μm）處理Metal-EDTA，本研究分為三部分，以批次式、流體化床及兩段式零價鐵程序處理Metal-EDTA廢水。以批次式零價鐵程序處理Cu-EDTA-Ni廢水，當零價鐵加藥量為15g（15g/100mL）初始pH為1.5時，反應180分鐘後Cu、Ni、EDTA去除率分別為100％、91.06％及94.34％，其反應速率常數為1.5415 min-1、0.0109 min-1及0.0151 min-1。
以零價鐵流體化床程序處理Cu-EDTA-Ni廢水時，在未曝氣的情況下，Cu的去除率皆可達100％，且可持續 40小時，但Ni及EDTA的去除率皆僅有20％~30％；當曝氮氣時Cu去除率也可達100％，Ni的去除率也僅有10％~20％，但EDTA完全沒去除；當曝空氣時Cu去除率可達100％，但僅只持續10小時，而Ni的去除率也僅有10％~20％，EDTA去除率增加至80％。因此本研究利用兩段式零價鐵流體化床程序處理Cu-EDTA-Ni廢水，第一段加入較多的零價鐵將Cu及Ni先進行處理，第二階段再以曝氣增加水中溶氧，增加EDTA之處理效率，於第一階段處理程序時Cu、Ni、EDTA去除率分別為100％、31％、27％；水樣經過第二階段處理程序時Ni及EDTA去除率提高至41％及80％。
利用反應速率常數推估本流體化床降解EDTA為假一階反應，反應速率常數會隨著系統中pH值、水力停留時間（HRT）、零價鐵加藥量及水中溶氧改變而改變，其中當水中溶氧增加時反應速率常數會大幅增加，當水中溶氧為17mg/L時，反應速率常數為17.77hr-1。

關鍵字

EDTA ； 銅 ； 鎳 ； 零價鐵 ； 流體化床 ； 溶氧 ； 兩段式

並列摘要

The wide application of ethylenediaminetetraacetic acid (EDTA) in pharmaceutical, agricultural and household industry results in the high deposits of chelating agent and heavy metal in the wastewater. The discharge standard for EDTA has not been enacted in the regulation, moreover, the product of the wastewater containing EDTA as compounded with heavy metal (Metal-EDTA) would prove difficult for regular wastewater treatment process.
In this study, the synthetic water samples containing EDTA 50 mg/L, Cu2+ 25 mg/L and Ni2+ 25 mg/L were treated at various pH, hydraulic retention time and ZVI dosage that carried out in batch system and continuous fluidized system with and without aeration. The removal rate of Cu2+, Ni2+ and EDTA, after 180 minutes in batch system, was 100 %, 91.06 % and 94.34 % with the observed pseudo-first-order rate constants (kobs) for EDTA removal of 1.5415 min-1, 0.0109 min-1 and 0.0151 min-1, respectively. In the zero valent iron fluidzed bed without aeration, Cu2+ removal rate was 100 %, Ni2+ and EDTA was 10% to 20% when retention time was over 40 hours. On the other hand, in the zero valent iron fluidzed bed with aeration under the same operating condition, the removal rate of Cu2+ was still 100%, and the removal rate of Ni2+ was 10% to 20%, but the removal rate of EDTA was increased to 80%.
Consequently, the Metal-EDTA wastewater was treated by the designed two-stage fluidized zero valent iron system. The removal rate of Cu2+, Ni2+ and EDTA was 100%, 31% and 27%, respectively in first stage, however, the removal rate of Ni2+ and EDTA was enhanced to 41% and 80% in second stage, respectively. The pseudo-first-order rate constant kobs for EDTA was enhanced with the increase of DO (dissolved oxygen concentration). The highest kobs was 17.77 hr-1 when DO was 17 mg/L in the aeration system.

並列關鍵字

Cu ； Ni ； EDTA ； Zero valent iron ； Fluidized bed, ； DO

參考文獻

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