Various
carcinogenic dyes in water bodies are difficult to degrade
due to their stability to light and oxidants, causing extended pollution.
In this study, MOF 1 ({[Co(tib)2]·(H2O)2·SO4}
n
) and MOF 2 ({[Cu(tib)2]·(H2O)2·SO4}
n
) (tib = 1,3,5-tirs(1-imidazolyl)benzene) were synthesized
by the solvothermal method. MOFs 1 and 2 were successfully characterized by single-crystal X-ray diffraction
(XRD) and powder X-ray diffraction (PXRD). Based on the structural
characteristics of MOFs 1 and 2, we designed
two cationic MOF material skeletons, namely, MOFs I and II ([Co(tib)2
2+]
n
and [Cu(tib)2
2+]
n
), which were obtained by calcination in combination with the
thermogravimetric curve to remove the free components in the lattice.
As expected, MOFs I and II showed an excellent
adsorption effect on sulfonic anionic dyes. Notably, the adsorption
capacity of MOF I can reach 2922.8 mg g–1 for Congo Red (CR) at room temperature (RT). The adsorption process
fits the pseudo-second-order kinetic model and Freundlich isotherm
model. Moreover, zeta potential tests and quantum chemical calculations
indicate that electrostatic interactions and hydrogen bond between
the hydroxyl group on the sulfonic acid group and the N atom on the
imidazole ring mainly promote the adsorption of CR dyes on MOF I. MOFs I and II are revealed as
a promising novel adsorption material to remove hazardous organic
aromatic pollutants with high efficiency in future endeavors.