廢電池不同前處理程序還原六價鉻之可行性探討

Using spent alkaline batteries by various pretreatment processes for chromium removal in wastewater

曾俞鈞(Yu-Chun Tsen)

指導教授 ： 李柏青

淡江大學/工學院/水資源及環境工程學系碩士班/碩士(2009年)

https://doi.org/10.6846/TKU.2009.00261

摘要

本研究是針對廢鹼性電池陽極添加物中之鋅粉以不同前處理程序還原六價鉻廢水之可行性探討。此外，也期望能界定出不同殘餘電壓下鋅粉中零價鋅含量。前處理方式包含：純水水洗系統、硫酸水洗系統及碳酸水洗系統。六價鉻廢水為人工合成廢水，此實驗採用批次瓶杯反應。
陽極添加物中鋅粉經不同前處理程序後，藉由鋅粉之水洗液pH值、XRD、FE-SEM及BET等分析觀察其特性變化。研究中發現，改變前處理程序並不會影響鋅粉中氧化鋅與零價鋅含量比例，並根據實驗結果統計得知鋅粉中零價鋅含量與殘餘電壓有一關係式，可用來說明不同殘餘電壓下，鋅粉中零價鋅含量。
在經過批次瓶杯反應後，發現以硫酸水洗系統對還原六價鉻廢水具有最佳的效果（0.84∼3.12 mg Cr6+/g zinc powder/30 min），其次為碳酸水洗系統（0.59∼1.84 mg Cr6+/g zinc powder/30 min）最後為純水水洗系統（0.23∼2.40 mg Cr6+/g zinc powder/30 min）。研究中發現經過三種系統處理後之鋅粉中零價鋅的利用率皆很低，分別為硫酸水洗系統0.37∼28.61％、碳酸水洗系統0.33∼13.27％及純水水洗系統0.26∼5.99％，這是因為六價鉻還原反應系統中之氫離子濃度有限，隨著pH上升使氧化還原反應停止所導致。如持續提供氫離子於反應系統中，將有助於還原反應進行以提高鋅粉中零價鋅利用率，且反應後廢水中總鉻濃度亦會下降，將有助於達到工業廢水放流水標準。

關鍵字

鹼性電池 ； 零價鋅 ； 氧化鋅 ； 六價鉻 ； 氧化還原反應

並列摘要

In this project, the feasibility of the zinc powders from the spent alkaline batteries anode by using various pretreatment to reduce the hexavalent chromium in wastewater has been studied. And we expect to define the amounts of the zero-valent zinc in the zinc powders from various residuary voltages. The hexavalent chromium wastewater was prepared by artificial synthetize wastewater, and the redox reaction experiments were conducted by the batch reaction. The pretreatments include the pure water system, the sulfuric acid system and the carbonic acid system.
After going through various pretreatments, the properties of zinc powders have been examined by XRD、FE-SEM and BET, respectively. And the pH values of the rinsed solution were also measured in the study. According to the result, it showed that switching of pretreatment condition will not alter the weight ratio between zinc oxide and zero-valent zinc in the zinc powders. It also presented that there is a regression equation to indicate the relation between the residuary voltage and the amount of zero-valent zinc in zinc powders via statistics.
The results of the batch test suggest that the optimum pretreatment for reducing chromium was the sulfuric acid system (0.84~3.12 mg Cr6+/g zinc powder/30 min); followed by carbonic acid system (0.59~1.84 mg Cr6+/g zinc powder/30 min), and the pure water system was the last (0.23~2.40 mg Cr6+/g zinc powder/30 min). However, the utilization of zero-valent zinc in the zinc powders was low in reacting with Cr(VI). The utilization of zinc in the sulfuric acid system ,the carbonic system ,and the pure water system were 0.37∼28.61％, 0.33∼13.27％ ,and 0.26∼5.99％ respectively. It is because that the concentration of the hydrogen ion in the Cr(VI) redox reaction system was finite, and Cr(VI) reduction efficiency was reduced as pH increased. If keep providing hydrogen ion in the solution may either increase Cr(VI) removal or enhance the utilization of zero-valent zinc in zinc powders. In summary, the concentration of total chromium and hexavalent chromium in wastewater can be reduced by the way of using spent alkaline batteries, and it helps to meet the industrial effluent requirement.

並列關鍵字

alkaline batteries ； zero-valent zinc ； zinc oxide ； hexavalent chromium ； redox reaction

參考文獻

30. 洪儷瑋, 2006, 以廢鑄鐵還原電鍍廢液中高濃度六價鉻之研究. 國立台北科技大學環境規劃與管理研究所碩士論文.

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