High-efficient double-cross-linked biohybrid aerogel biosorbent prepared from waste bamboo paper and chitosan for wastewater purification

This work prepared a double-cross-linked biohybrid aerogel (DCBA) bead biosorbent from waste bamboo paper and chitosan by sequential physical (hydrogen bonding and electrostatic interaction between -COO- and-NH3+ groups) and chemical (polymerization reaction between-COOH and-NH2, dehydration condensation between Si -OH and-OH) cross-linkings. The resulting DCBA bead was applied to remove cationic (Methylene blue, MB) and anionic (Congo red, CR) dyes in both single and binary systems. The MB and CR adsorption capacities of DCBA bead increased with increasing adsorbent dosage, contact time, temperature and initial dye concentration. With increasing solution pH, the MB adsorption capacity increased, while that for CR increased first and then decreased. The maximal adsorption capacities for MB and CR were 653.3 and 559.6 mg/g, respectively, in the single system. The thermodynamic analysis results showed a spontaneous and endothermic adsorption process. DCBA bead had a good stability and reusability with the removal efficiencies of 49.4% and 60.6% for MB and CR, respectively, after five cycles of adsorption-desorption. In the binary system, the adsorption of MB was inhibited by CR, while the removal of CR was enhanced by MB.

Automated summary

A double-cross-linked biohybrid aerogel (DCBA) bead biosorbent was prepared from waste bamboo paper and chitosan. The DCBA bead showed increased adsorption capacities for cationic and anionic dyes with various conditions and exhibited good stability and reusability. In the binary system, the adsorption of one dye was inhibited by the other, indicating an interactive effect between the dyes.