Selective Removal of Pb From Aqueous Phase by HGMS and Ion-Imprinted Magnetic Adsorbent

Abstract

A selective removal of certain ions from aqueous phase containing common ions is very useful in engineering aspect because the process allows removal of toxic substances only or recovery of valuable ion species. The ion imprinting technology has shown great potential in the synthesis of materials that are capable of adsorbing a metal ion selectively. In current study, a Pb (II) imprinted magnetic polymer was synthesized using surface imprinting technique employing Pb (II) as template, polyethyleneimene functionalized magnetic Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> as functional monomer and epoxy chloropropane as cross-linker. The magnetic adsorbent was successfully imprinted, and the ion imprinted sorbent was used for selectivity test for Pb (II). Through the imprinting process, the shape of sorbent has changed, and the magnetic properties have decreased. This is an adverse effect of the polymer formed on the surface of the sorbent by the imprinting. The synthesized magnetic adsorbent was recovered from aqueous phase by a high gradient magnetic separation (HGMS) system with a superconducting magnet. The magnet is a cryo-cooled Nb-Ti superconduction magnet. Magnetic filter (SUS 403, 10 mesh) was used for the magnetic separation. The synthetic polymer with small particle size and weak magnetic properties successfully recovered the by the HGMS system and the recovery efficiency was improved with increased magnetic field of the superconducting magnet. By the magnetic separation, the adsorbent could be recovered and reused after the selective adsorption process for a heavy metal removal. The prepared Pb (II) imprinted magnetic adsorbent was also characterized by transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). Batch selectivity studies were performed to evaluate the influence of competing ions such as Cd (II), Ni (II), and Cu (II). The selectivity coefficients of Pb (II)/Cd (II), Pb (II)/Ni (II) and Pb (II)/Cu (II) were calculated as 1.89, 3.57 and 11.23 respectively.