Adsorption of neutral red onto MIL-100(Fe) from solution: Characterization, equilibrium, kinetics, thermodynamics and process design

Abstract

Metal organic frameworks are attracting scientific interest in adsorption applications owing to their large surface area and controllable pore size or shape over both microporous and mesoporous domains. Based on this, an iron(III) trimesic acid MIL-100(Fe) was facilely synthesized by hydrother-mal treatment and used as adsorbent to remove neutral red (NR) from aqueous solution. MIL-100(Fe) was characterized using X-ray diffraction, scanning electron microscopy and transform infrared spec-troscopy. MIL-100(Fe) was studied in view of the adsorption isotherms, thermodynamics, kinetics, and regeneration of the adsorbent. The adsorption kinetics data of NR were found to be in agreement with pseudo-second-order model. Temkin model was observed to be more suitable than Freundlich and Langmuir models in describing the adsorption isotherm. The maximum adsorption quantity was 333 mg g–1 at 313 K from Langmuir model. Thermodynamic parameters indicated that the NR adsorption process was endothermic and spontaneous. The NR-loaded MIL-100(Fe) adsorbent was regenerated and reused using pH = 2, 75% ethanol. A single-stage batch design for NR adsorption onto MIL-100(Fe) was also presented based on Temkin isotherm model equation. Based on the findings, MIL-100(Fe) is a promising adsorbent for the removal of cationic dyes from solution and thus can be used in practical application.