Fabrication of EDTA modified silica gel toward highly efficient adsorptive removal of copper ions from methanol

With the rapidly growing demand of high-purity methanol, developing high-efficiency adsorbents has become urgent to completely remove metal ions from methanol. Herein, a novel adsorbent, ethylenediaminetetraacetic acid (EDTA) modified silica gel (EDTA-2N-Silica) was successfully prepared for copper ions deep removal from methanol. EDTA-2N-Silica was constructed by using 3-(2-amino-ethylamino) propyl-trimethoxysilane (Silicone A-1120) to graft the EDTA molecules onto the silicon hydroxyl groups over silica gel. Dynamic adsorption experiments revealed that copper ions could be effectively removed from methanol prior to breakthrough point, with almost complete elimination achieved before adsorption column exhaustion. Correspondingly, the breakthrough and equilibrium adsorption capacities of copper ions over EDTA-2N-Silica-0.375 achieved 0.159 and 0.846 mmol g −1 at 40 °C, respectively. According to the density functional theory calculation, the enhanced copper ions capture performance of EDTA-2N-Silica was mainly attributed to the copper ions complexation with N-containing and the O-containing groups from EDTA. Furthermore, after the fifth regeneration, the equilibrium adsorption capacity of EDTA-2N-Silica-0.375 toward copper ions could retain 87.82 % that of the fresh sample, indicating its satisfactory regeneration performance. Considering its excellent adsorption and regeneration performance, EDTA-2N-Silica adsorbent is expected to be employed for efficient removal of trace copper ions from methanol.