Studies on Quantitative Distribution and Removal of Heavy Metals in Rice

Abstract

In this paper, the quantitative distribution of cadmium (Cd), copper (Cu) and zinc (Zn) in brown rice polluted with Cd, and the removal of these elements by means of various eluting agents were described.
1) Cd, Cu and Zn in brown rice were distributed very evenly.
2) The brown rice or polished rice was crushed in a grain mill, and mixed with an eluting solution such as water, ethanol, inorganic acid, organic acid or chelating agent.
After filtration of the mixture, the filtrate and the residues were analyzed by atomic absorption spectrometry.
Efficiency of the elution was calculated as the ratio of metal found in the eluted solution to those values found in rice before elution.
More than 90% of the Cd and Zn in the crushed brown rice was removed with tartaric acid solution. The value of Cu was comparatively lower. Stirring, immersing time and pH largely influenced the elution of Cd, Cu and Zn.
3) From brown rice grain, efficiency of the elution of Cd, Cu and Zn with 0.1M tartaric acid solution after 150 hours was about 98%, 40% and 90%, respectively, and from polished rice grain about 74%, 90% and 68%, respectively.