具污染潛勢農地土壤重金屬分布及移除研究

Separation and removal of heavy metals from potential contaminated farm land.

黃士澤(Shih-tze Huang)

指導教授 ： 張益國

中臺科技大學/健康科學院/安全與防災科技研究所/碩士(2012年)

https://doi.org/10.6822/CTUST.2012.00068

摘要

本研究應用多種溶出試驗，包括 pH 對初始酸鹼添加之溶出影響等溶出行為試驗(pH-dependent test)、管柱試驗(Percolation test)驗證農地土壤重金屬溶出特性，研判重金屬溶出或穩定之可能機制。隨後搭配水力分離技術開發，以水力漩流分離器(Hydrocyclone)分離重金屬污染農地之顆粒大小，再以重金屬於pH 依存度之溶出行為為基礎，酸洗及螯合萃洗濃集農地土壤重金屬。
研究結果顯示，農地土壤樣本一及樣本二中分別為78.8%及45.1%顆粒徑<63μm；另由微波消化金屬總量分析結果可知，Cu、Pb、Zn為農地土壤中含量較高之重金屬。以水力漩流分離器分離細顆粒農地土壤可將樣本一及樣本二分別分離細顆粒(<63μm)為84.7%及78.6%，具一定分離效果。再以HCl、H2SO4、EDTA、Citric acid等試劑對農地土壤中Cu、Pb、Zn重金屬進行移除試驗，樣本一Cu之萃取率分別為67.2%、40.1%；對於Pb之萃取率為11.4%、1.32%；對於Zn之萃取率分別為60.2%、19.3；樣本二>63μm及<63μm Cu之萃取率分別為66.8%、51.1%；64.5%、78.0%；對於Pb之萃取率分別為70.5%、65.3%；67.1%、63.7%；對於Zn之萃取率分別為82.1%、72.5%；60.2%、64.2%，其中以HCl效果最好，EDTA效果次之。惟EDTA可有效萃洗Cu、Pb、Zn，但亦增加農地土壤中Cu、Pb、Zn重金屬離子之移動性，因此殘存之重金屬變得容易溶出。

關鍵字

重金屬 ； 農地土壤

並列摘要

Contaminated soils in the environment remain being a significant issue during land application. Numerous methods have been suggested in recent years for remove, treating and beneficial uses of heavy metal-containing soils. In this research, the basic characteristics and the geochemistry of metals in the soils were studied, and which were subjected to pH-dependent leaching test, percolation test. The results of experimental leaching tests was used to predict the metal concentrations and the pH of leaching solution at equilibrium.
The result of laboratory research showed that the content of heavy metals contaminants is primarily governed by the gain size. The optimum separation process was approached through hydrocyclone separation and sieving. The corase particles (d>63μm) of sample-1and sample-2 was 21.2% and 54.9%, respectively, which could be directly reused. On the other hand, the contaminated fine particles with silt and clay fraction (d<63μm)) of sample-1and sample-2 was 78.8% and 45.1%, respectively. Heavy metal contaminant tends to be adsorbed on the fine particles, and thus further treatments such as chemical washing and stabilization/modification are needed before deposition and recycling.
Results form the chemical washing (extraction) technique revealed that under 0.3N HCl and 0.1N EDTA as reagents with a sample-1 particle/reagent ratio of 1/10, contact time of 30, 120 minutes, the Cu removal efficiency 67.2% and 40.1%；the Pb remove efficiencywas 11.4% and 1.32%；the Zn remove efficiency was 60.2% and 19.3%, respectively. The upon results revealed that the HCl reagent was effective for metal removal than the EDTA reagent. This research provided a basic understanding, and the statistic correlation among the particle characteristics,metal concentration and the possible controlling factors.

並列關鍵字

heavy metals ； farm land

參考文獻

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