Original Articles: 2011 Vol: 3 Issue: 2
Abatement of Cu (II), Pb (II) and Zn (II) from highway runoff using agricultural byproduct rice bran
Abstract
The rice bran has been used as biosorbent to remove heavy metal ions from highway runoff. It is noted
that increase in Pb2+ concentration and pH, caused the increase in adsorption capacity of rice bran. In
relation to this, a decrease in rice bran dose results in a higher metal loading on the rice bran. The
adsorption isotherms of heavy metals fit the Langmuir and Freundlich model reasonably well. The order
of heavy metal adsorption is Pb2+ > Cu2+ > Zn2+. A high concentration of co-existing ions such as Ca2+
and Mg2+ depresses the adsorption of heavy metal. Dissolved organic matter (DOM) has a significant
influence on metal adsorption. In studies involving column, a long breakthrough time is observed for
heavy metals according to the ion selectivity on rice bran. The metal adsorption capacity per rice bran
mass in column is lower than that obtained in batch equilibrium tests, which is possibly due to the
insufficient residence time and diffusion limitation of the metal. Flushing of the column saturated with
heavy metals by 0.1M CaCl2 solution results in the elution of a highly concentrated metal within
shortened pore volumes, implying that rice bran could be re-used for the treatment of heavy metals.