Removal of heavy metals from contaminated water using nano-magnetic Prussian blue based on graphene oxide sorbent

The aim of this study was to modify magnetite nanoparticles (Fe₃O₄) with Prussian blue and graphene oxide and further employ it to remove Cu (II), Co (II), Ni (II) and Pb (II) ions. The batch studies were performed in order to simulate experimental data in treatment of contaminated waters. Nano-magnetic Prussian blue based graphene oxide (MPBGO) sorbent was synthesized from a mixture solution of Fe(II)/Fe(III) salts, K₄[Fe(CN)₆] and graphene oxide via in situ co-precipitation method. Adsorption experiments were performed by mixing known amount of nano-sorbent with a 10ml metal ions solution. The pH of the solutions was adjusted with HCl and NaOH solutions using a pH meter. The sorption experiments in multimetal solutions (when Cu (II), Co (II), Ni (II) and Pb (II) are in one solution) were performed as well. For desorption study, the metal ion-loaded sorbent was collected from the sorption experiments and washed with water to remove the unsorbed metal ions. Then, solid nanoparticles were mixed with HNO₃ solution at pH 4.0. The effect of sorbent dosage was investigated when using 10-30mg MPBGO sorbent for 10ml aqueous heavy metal solution. Results showed that the maximum sorption capacities for Cu(II), Co(II), Ni(II) and Pb(II) using magnetic Prussian blue based graphene oxide sorbent were: 138 mg/g, 115 mg/g, 460 mg/g and 443 mg/g respectively. Uptake has increased about 1.5 times, upon increasing sorbent dosage: 40.6%, 67.7% and 97.4% for 10 mg, 20 mg and 30 mg. Synthesized magnetic nanosorbents can be used several times - the MPBGO sorption efficiency reached 60% after third sorption cycle.