Multi-active-site UiO-66-NO₂-based carboxymethyl cellulose-sodium alginate composite aerogel: Efficient adsorption of...

This study developed a multi-adsorption-site UiO-66-NO₂ gel@CMC/SA (carboxymethyl cellulose and sodium alginate) composite using an in-situ growth approach. The CMC/SA aerogel carrier was combined with a metal-organic gel (MOG) to enable the highly effective removal of methylene blue (MB) and methyl orange (MO). Experimental results showed that under specific pH conditions, the maximum adsorption capacities of the composite for MB and MO reached 658.8 mg/g and 183.2 mg/g, respectively. Even in complex systems with multiple coexisting ions, its adsorption of the two dyes still exhibited a certain degree of resistance to ionic interference. Notably, the UiO-66-NO₂ gel@CMC/SA still maintained high adsorption performance after four consecutive adsorption-desorption cycles. The adsorption capacity of UiO-66-NO₂ gel@CMC/SA for MB decreased from 398.2 mg/g to 329.5 mg/g, while that for MO declined from 158.9 mg/g to 116 mg/g. The determined ΔH⁰ (MB: -21.19 kJ/mol; MO: -15.99 kJ/mol) and ΔG⁰ (MB: -5.34 kJ/mol; MO: -2.67 kJ/mol) values at 303 K demonstrate that the adsorption of both dyes onto the composite is spontaneous and exothermic. In conclusion, this study provides a practical technical approach for improving the recycling efficiency and adsorption performance of MOF materials, and holds significant reference value for promoting the application of MOF-based materials in dye wastewater treatment.