Self-cross-linking of metal-organic framework (MOF-801) in nanocellulose aerogel for efficient adsorption of Cr (VI) in water

Chromium (Cr) poses significant hazards to both human health and the natural environment. Therefore, in this study, metal-organic framework (MOF-801) was compounded with nanocellulose aerogel for the first time. And a nanocellulose/metal-organic framework composite aerogel was developed for efficient chromium ion adsorption. The resulting aerogel has an ultra-low density (0.017 g/cm3) and high porosity (98.87%). The removal efficiency of this aerogel for Cr (VI) (93.86%) was measured to be higher than that of cellulose nanofiber aerogel (TCNF: 50.08%) and MOF-801 powder (59.86%). It was also higher than the cellulose nanocellulose aerogel prepared without MOF-801 (TMPA: 70.58%). This is because MOF-801 cross-linked with nanocellulose increased its porosity and provided a large number of adsorption sites. The maximum adsorption of Cr (VI) by this aerogel was 350.64 mg/g (5.96 mg/cm3). The adsorption mechanism was investigated by adsorption isotherms, adsorption kinetics, XPS, and FT-IR analysis. The aerogel has good reusability, with no significant loss of adsorption performance over 6 cycles. It is worth mentioning that 0.69 g (V: 7.363 cm3) of aerogel could effectively remediate 3710 mL of chromium-containing wastewater in a fixed-bed column adsorption experiment. In addition, the aerogel can effectively remove many metal ions from wastewater. As a result, the aerogel made in this study has the ability to be an effective adsorbent for metal ion removal.