Extraction of lithium ions from acidic solution using electrochemically imprinted membrane

A novel lithium ion imprinted membrane (Li+-IIM) was synthesized by unipolar pulsed electropolymerization, using lithium ion as template ion, 2-hydroxymethyl-12-crown-4 ether as capture agent, pyrrole as conductive agent and crosslinking agent. The morphology and structure of the products were characterized by using field emission scanning electron microscopy and Fourier transformation infrared spectroscopy. The adsorption behaviors were detected by inductively coupled plasma-optical emission spectrometry. At pH = 1.0, the maximum adsorption capacity of Li+-IIM towards lithium ion reached 16.40 mg g−1 in 40 mg L−1 Li+ solution, within 80 min. The resulting Li+-IIM exhibited excellent selectivity for Li+ because the selectivity coefficients of Li+ with respect to Na+, K+, Mg2+, Al3+ and Fe3+ are 4.20, 4.11, 4.13, 4.30 and 4.28, respectively. After five adsorption-desorption cycles, the adsorption capacity of Li+-IIM still maintained 95.88%, indicating that the obtained imprinted membrane has excellent regeneration ability.