Highly effective and fast removal of Congo red from wastewater with metal-organic framework Fe-MIL-88NH2

Highlights: • Fe-MIL-88-NH₂ is a promising adsorbent for removing of organic pollutant Congo red from wastewater. • The main adsorption sites of Fe-MIL-88NH₂ are on its heterogeneous surface. • Congo red is mainly removed from wastewater through chemisorptions by using the Fe-MIL-88NH₂ as adsorbent. • The adsorption of Congo red on Fe-MIL-88-NH₂ is a spontaneous endothermic process. In the present investigation, the applicability of the adsorption and removal of the toxic organic dye Congo red (CR) from industrial wastewater using metal organic framework (MOFs) Fe₃O(OH₂)₃Cl(NH₂-BDC)₃·9.5H₂O (Fe-MIL-88NH₂) was evaluated. The influence of contact time, initial CR concentration, adsorbent dosage, ionic strength and temperature on the adsorption properties of Fe-MIL-88NH₂ were investigated. The Langmuir and Freundlich and Tempkin isotherm models have been used to discuss the adsorption behavior of CR on Fe-MIL-88NH₂. Tempkin adsorption isotherm model was found to be most suitable for the adsorption of CR. Different kinetic parameters were obtained by studying of adsorption kinetics on the basis of the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic equations. The pseudo-second-order kinetic equations is most suitable for adsorption of CR on Fe-MIL-88NH₂, which indicates that the removal of CR are mainly carried out by chemical adsorption process.