Investigation of Copper Sorption Using Plant Materials

Abstract

Abstract An attempt was made to describe the mechanisms of copper sorption by plant materials such as canola meal, pine bark and moss in terms of the compositional analysis of the sorbents and the electron spin resonance tests. The compositional analyses showed that lignin and carbohydrates from bark and moss, and proteins, carbohydrates and phytic acid from canola meal were the major components responsible for the sorption of heavy metals. The roles of the car-boxyl and amino groups in the sorption process were also examined. It was found that the esterification of the carboxyl or the methylation of the amino groups in canola meal, bark and moss resulted in a lower metal uptake by these sorbents. Furthermore, sorption with the de-esterified sorbents resulted in the same uptake as that of the control. Electron spin resonance tests demonstrated that free radicals from the sorbents played a significant role in the sorption processes. The increase in copper uptake by moss was associated with a decrease in the concentration of free radicals in this sorbent.