Mesoporous metal-organic framework PCN-222(Fe): Promising adsorbent for removal of big anionic and cationic dyes from water

Dyes are considered as harmful water pollutants because of their high water solubility, wide uses and toxicity. A highly mesoporous metal-organic framework PCN-222(Fe), together with commercial activated carbon (AC), was applied for the removal of both cationic (brilliant green (BG), crystal violet (CV), and methylene blue (MB)) and anionic (acid red 1 (AR 1), acid blue 80 (AB 80) and methyl orange (MO)) dyes from water through adsorption. The adsorptive performances of PCN-222(Fe) are much higher than AC for big dyes (BG, CV, AR 1, and AB 80). On the contrary, PCN-222(Fe) and AC show not very much different performances for the adsorption of small dyes (MB and MO). The maximum adsorption capacity of PCN-222(Fe) for BG, CV, AR 1, and AB 80 was higher than that of any reported adsorbent so far. The remarkably high adsorption capacity of PCN-222(Fe) for BG (854 mg·g⁻¹), CV (812 mg·g⁻¹), AR 1 (417 mg·g⁻¹) and AB 80 (371 mg·g⁻¹) could be explained by suitable pore size of PCN-222(Fe) together with electrostatic and π-π interactions. Moreover, PCN-222(Fe) could be successfully regenerated and reused for several cycles without any severe decrease in adsorption performance. Therefore, PCN-222(Fe) is suggested as an effective adsorbent for the dyes (especially with big size) removal from water.