Metal uptake properties of silica gel-immobilized aminophenol and aminobenzoic acid and their application for heavy metal removal from sugar cane molasses

Silica gel was modified with 3-chloropropyltrimethoxysilane. To this modified silica gel, ortho-aminophenol, ortho-aminobenzoic acid and their para-isomers were added to yield the corresponding new phases. The capability of these phases for the extraction of Fe (III), Co (II), Ni (II), Cu (II) and Pb (II) as a function of pH and time was evaluated and discussed on the basis of the batch equilibrium technique. These phases showed their highest affinity towards Fe (III) and their lowest affinity towards Co (II). The range of metal uptake capacity values is 0.50-0.54 and 0.04-0.09 mmol.g(-1) for the extraction of Fe (III) and Co (II), respectively. In addition, the extraction equilibrium of Fe (III) was found to be the fastest among all tested metal ions. The column application of these immobilized chelates as cation exchangers to remove different metal ions from sugar cane molasses revealed that these phases have higher preference towards heavy metals rather than alkali and alkaline earth metals.