(147e) Membrane Adsorbers to Capture Cu from Mixed Metal Acidic Solutions in Support of Radiopharmaceuticals

Radiopharmaceuticals offer promising new approaches for both imaging and treating cancerous tumors in personalized medicine. An emerging isotope for use in radiopharmaceuticals is copper-67 (⁶⁷Cu) which can provide treatment (via beta decay) and imaging (via gamma rays). Currently, ⁶⁷Cu is purified using resin-packed columns, which exhibit (1) low column flow rates, (2) high elution volumes and (3) long purification times—all of which contribute to the bottleneck in the sustained supply of ⁶⁷Cu. Due to the short half-life (2.58 days) of ⁶⁷Cu, rapid purification from competing isotopes (⁵⁷Ni, ⁶²Zn, ⁶⁵Zn, and unreacted ⁶⁸Zn) is key for increasing the availability of the isotope for clinic trials and use. Membrane adsorbers are well-positioned to meet that need.

In this study, glycidyl methacrylate (GMA) brushes are grafted from commercial polyvinylidene fluoride and electrospun chloromethyl styrene membranes using AGET ATRP, a controlled polymerization technique. After grafting poly(GMA), diamine ligands (4-picolylamine, putrescine, or ethylene diamine) are attached to the poly(GMA) brushes by an epoxide ring-opening reaction. Membranes are washed with methanol/DI water, EDTA at pH 10 and HCl at pH 2 to remove residual Cu catalyst from AGET ATRP. Membranes are characterized by ATR-FTIR and x-ray photoelectron spectroscopy (XPS) to support functionalization. Permeability was calculated from pure-water flux experiments in dead-end filtration mode (unmodified PVDF: 5166 LMH/bar, GMA grafted: 4692-648 LMH/bar, and amine-functionalized: 4124-175 LMH/bar). Membrane morphology was examined using scanning electron microscopy (SEM). The binding capacity for Cu, Ni, and Zn were calculated by fitting the Langmuir isotherm to equilibrium adsorption data collected at pH 2. Binding capacity was calculated to be 1.65 and 1.59 for putrescine and ethylenediamine, respectively. Though low, this capacity is 2 orders of magnitude higher than the amount of radiocopper in solution. Dynamic binding experiments were conducted to calculate membrane productivity. The results of this research are laying the groundwork for implementing membrane absorbers as a new separation material for medical isotope purification.