Enhancing Cationic Dye Removal Efficiency through Factorial Design Analysis using ZIF-8 and Fe-BTC Metal-Organic Frameworks

In the present study, we examine the adsorption of the cationic dye Malachite Green (MG) onto two metal-organic frameworks: ZIF-8 and Fe-BTC. The preparation of beads was effectively carried out through the polymer coating process utilizing sodium alginate. To study the effect of different factors on adsorption capacity and removal %age of Malachite Green in a batch process, we employed a 2³ factorial design study analysis. The investigation involved three primary factors, each with two levels: MOF type (A: Fe-BTC and ZIF-8), MOF bead dosage (B: 50 mg to 100 mg), and initial concentration (C: 5 mg/L to 17 mg/L). The primary effects of these variables and their interactions were examined using Response Surface Methodology (RSM), main effect, interaction effect, and Pareto chart. The factorial design analysis, conducted using analysis of variance (ANOVA), revealed that the most significant factor influencing adsorption capacity was the initial concentration of MG, followed by the dosage of MOF beads and the type of MOFs. The study demonstrates that SA@ZIF-8 beads have achieved the highest removal rate of 96%, in comparison to SA@Fe-BTC which reaches 90%. Notably, the initial concentration of MG demonstrates a positive effect, MOF dosage exhibits a negative effect, while the MOF type presents a positive effect, favoring SA@ZIF-8 for higher adsorption capacity. Moreover, significant two-way and three-way interactions were identified. The optimum conditions for the maximum removal of MG dye using SA@ZIF-8 were reported as follows: adsorbent dosage = 50 mg; MG initial concentration = 17 mg/L. The R2 value > 98.8% for MG dye underscores the potency of the factorial design model, thereby encouraging further exploration and application of SA@ZIF8 metal-organic framework to eliminate pollutants from aqueous solutions.