Application of chemometrics into simultaneous monitoring removal efficiency of two food dyes by an amine-functionalized metal–organic framework

Abstract

In this study, amine-functionalized of Fe-MIL-101 (NH2-Fe-MIL-101) was synthesized by the solvothermal method and applied for the removal of two food dyes amaranth (AM) and sunset yellow (SU). Due to the overlap of absorption peaks of these two dyes, it is impossible to measure and simultaneous monitor adsorption process of dyes. The principal component regression was assisted in overcoming this problem. To find significant parameters that can potentially influence the adsorption process, a fractional factorial design (26-1) was applied. To optimize the significant factors, the response surface methodology was implemented based on Box–Behnken design. The independent variables of sorbent dose (8–20 mg), solution pH (2–10), initial concentration (20–40 mg L−1) of dyes, and contact time (10–30 min) were considered in this study. The optimal conditions for each variable were achieved by the desirability function approach. The conditions were obtained as follows: adsorbent dosages (14 mg), pH (2), initial concentration (40 mg L−1), and contact time (30 min). Isotherm models of Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich were also studied. Under optimal conditions, the maximum adsorption capacities obtained were 131 and 116 mg g−1 for AM and SU, respectively. (a) There is a strong overlap between the absorption peaks of the two dyes. (b) Application of multivariate calibration method to overcome this problem and modeling with principal component regression (PCR). (c) The graph of the prediction against the actual values after modeling with PCR. (d) Preparation and application of NH2-Fe-MIL-101 for simultaneous adsorption of two food dyes. (e) Application of fractional factorial design to identify significant factors. (f) Optimization of significant factors with response surface methodology (RSM).