Amine-Functionalized Membrane Adsorbers to Purify Copper from Acidic Solutions

Amine-functionalized membrane adsorbers are synthesized to adsorb Cu2+ from acidic solutions (pH 2 HCl). Putrescine (C4) and ethylenediamine (C2) are covalently attached to poly(glycidyl methacrylate) films coated on commercial poly(vinylidene fluoride) membranes. The presence of poly(glycidyl methacrylate) and amines on the membrane was supported by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Amine content was quantified using X-ray photoelectron spectroscopy (XPS). Amine-functionalized membranes have a permeabilities ranging from 300 to 2650 LMH bar–1 depending on the polymerization reaction time: 0.5 to 6 h. High permeabilities led to filtration times of <2 min for 50 mL of water through a single membrane at 100 kPa. Equilibrium adsorption experiments revealed maximum capacities of 1.65 and 1.59 mg/g for putrescine- and ethylenediamine-functionalized membranes, respectively─which are statistically the same. The similar capacities and Langmuir constants imply that the chain length of the amine (C4 vs C2) does not affect the binding affinity for Cu2+. This research takes the first steps toward developing membrane adsorbers for use in medical isotope purification.