English abstract
Graphene oxide (GO) was prepared from graphite via oxidative exfoliation. GO was
surface functionalized using ethylene diamine and GO-NH2 was produced. EDTA (H form) was immobilized onto GO-NH2 via an amide coupling process to produce GO EDTA. Nitrogen content, FTIR, and TGA showed evidences of successful
functionalization process. Pb(II), Cu(II) and Zn(II) solutions were tested for their
sorption onto GO-EDTA (Na-form) in terms of sorbent mass, initial pH, contact time,
metal concentration, and temperature. pH 6.0 was found optimum for metal sorption
that took place via chelation. The kinetic sorption data were found to fit well pseudo
second order model with better performance at a higher temperature. The activation
energy (Ea) of metal adsorption was less than 40 kJ/mol indicating the occurrence of
physisorption. Equilibrium sorption data followed well the Langmuir isotherm with
metal uptake following the order of Pb(II) > Cu(II) > Zn(II) with better performance
at a higher temperature. Adsorption capacity was 72.4, 46.5 and 28.0 mg/g at 25 oC
while it was 86.2, 56.8 and 31.95 mg/g at 35 oC for Pb(II), Cu(II) and Zn(II),
respectively. Metal sorption followed the order: GO-EDTA > GO-NH2 > GO. Metal
sorption was found to be endothermic and spontaneous. GO-EDTA proved from this
study that it is an effective sorbent for heavy metals and can be reused efficiently.
