Selective adsorption of heavy metal and ionic dye on superparamagnetic particles

Abstract

Effects of surface functional groups of silica coated superparamagenic nanoparticles (SCPs) on selective adsorption of ionic dyes (Acid Blue 45 and Methylene Blue) and heavy metal (Cu(II), Cd(II) and Pb(II)) from synthetic wastewater have been evaluated base on adsorption kinetic and isotherms in single and bi solute. Nano-size magnetite (Fe₃O₄) was coated by silica matrix and modified by grafting 3-aminopropyltriethoxy- and 3-mercaptopropyl- groups (AM-SCP and MP-SCP, respectively). Physico-chemical characteristics of adsorbents were investigated by nitrogen adsorption isotherm (BET), FT-IR, acid-base titration, SEM, etc. MP-SCP had highest adsorption capacities of Cu(II), Cd(II) and Pb(II) at pH 5 about 13, 6 and 5 mg/g, due to chemical bonding. AM-SCP had highest adsorption capacities of acid blue 47 at pH 5 about 50 mg/g. MP-HMS had highest adsorption capacity of methylene blue at pH 9 about 90 mg/g. Increasing to pH 5 could enhance the adsorption capacities of Cu(II), Pb(II) and Cd(II) on SCP, AM-SCP and MP-SCP. Electrostatic interaction caused by pH of solution effect to adsorption capacity of acid blue 45 and methylene blue on synthesized SCPs. The presence of the heavy metals didn’t affect to adsorption capacity of the ionic dyes significantly. Magnetic filed could enhance sedimentation efficiency of all SCPs. The presence of the heavy metals and the ionic dyes on the surfaces did not affected to the sedimentation efficiency of all synthesized SCPs.