Efficient removal of cationic dye using ZIF-8 based sodium alginate composite beads: Performance evaluation in batch and column systems

The environmental and health risks associated with dye contamination in water sources are alarming. Recently, researchers have been focusing on developing an innovative and susceptible solution using composite beads that effectively combat this issue. In this paper, beads were synthesized using a sodium alginate (SA) and zeolitic imidazolate framework-8 (ZIF-8) through a simple dipping process. Several characterization tests were performed including XRD, FTIR, BET, TGA, and SEM-EDX. The SEM images confirmed that SA effectively coated the cubical structure of the ZIF-8, ensuring optimal performance. The efficiency of the resulting SA@ZIF-8 composite beads was tested on both synthetic malachite green dye and real industrial wastewater samples using batch and fixed bed column reactors. The findings revealed that maximum adsorption of 95.5% was achieved at pH 6 in 120 min of reaction time. FTIR and SEM analysis also confirmed the adsorption of MG dye onto the beads. The Freundlich isotherm model (R2 > 0.99) has a better fit than the Langmuir (R2 > 0.96) for describing the adsorption process. The PSO model predicted the kinetics of the system, whereas the intraparticle diffusion study supported the system's mechanistic analysis. Furthermore, the study also investigated the efficacy of the beads in treating real wastewater effluent samples collected from the dye industry. Overall, using sodium alginate-coated ZIF-8 beads was found to have many advantages over powdered ZIF-8, including higher selectivity, stability, reusability, and practicality, making them a promising alternative for adsorption applications. Therefore, these composite beads have the potential for the removal of the dye from wastewater, which could be widely applied in various industries.