ZIF-8 modified polyvinyl alcohol/chitosan composite aerogel for efficient removal of Congo red

Developing inexpensive adsorbent with high removal efficiency is an important strategy to solve the issue of dye residues in wastewater. Zeolitic imidazole framework-8 (ZIF-8) modified polyvinyl alcohol (PVA)/chitosan (CS) composite aerogel ([email protected]/CSA) was prepared through freeze-drying and in situ growth. The introduction of PVA enhanced the mechanical properties of CSA. Experimental results showed that [email protected]/CSA had superior compression resilience and water stability, with a maximum adsorption capacity on Congo Red (CR) of 1216.5 ​mg ​g−1, which was obviously higher than most different adsorbents in previous reports. The adsorption process was consistent with pseudo-second-order kinetics and Langmuir isotherm model, revealing chemisorption was the rate-determining step and adsorption process was monolayer adsorption. After 5 adsorption-desorption cycles, [email protected]/CSA still showed excellent stability and reusability to remove CR with a removal rate above 91%. This study provided a new idea to remove CR from dye wastewater by the combination of ZIF-8 and polysaccharide aerogels.