Composite crosslinked chitosan beads with zeolitic imidazolate framework-67 as peroxymonosulfate activator for increased dye degradation

Abstract

In this study, a biodegradable cobalt-based peroxymonosulfate (PMS) activator for a dye degradation process was fabricated from crosslinked chitosan (CS) and zeolitic imidazolate framework-67 (ZIF-67) beads. Green synthesis of ZIF-67 produced a good yield, and its particles had an average size of 242 nm and a specific surface area of 1129 m2/g. These particles were then incorporated with the crosslinked CS beads at different loadings (2.5–10 %). The catalytic performance of these composite beads was evaluated for rhodamine B (RhB) degradation. Maximum degradation of 98 % was achieved with CS/7.5 %ZIF-67 and a PMS concentration of 0.15 g/L. The degradation equilibrium was obtained within 5 min, with a degradation rate of 0.957 min−1. The pH of the solution had no significant effect on the degradation extent. The predominant radical species in RhB degradation were sulfate radical anions, and a high concentration of coexisting anions decreased the degradation efficiency. The composite beads effectively degraded RhB over five cycles without any chemical recovery treatments. Furthermore, the PMS activating-composite beads effectively facilitated the degradation of various other dyes. This approach is a simple, practical, and cost-effective method for preparing a PMS activator that can efficiently increase dye degradation with ease of separation and recovery.