Purification of astrazon pink FG and brilliant Red B contaminated water using zeolitic imidazolate framework enhanced potassium ferrite

Abstract

Adsorption and photocatalysis are known methods for removing dyes from aqueous systems. However, they may suffer from shortcomings like poor dye removal, high cost, poor adsorbent/catalyst regeneration and poor adsorbent/catalyst recovery. Therefore, a zeolitic imidazolate framework enhanced potassium ferrite (KFe₂O₄@_monoZIF-8) was prepared to remove astrazon pink FG (AP) and brilliant Red B (BR) dyes from the water system. The characterization results of KFe₂O₄@_monoZIF-8 revealed a well-structured diffraction pattern with a crystallite size of 31.24 nm and an energy bandgap of 1.87 eV. The scanning electron micrograph image revealed a homogeneous surface with similarly shaped particles of different sizes. At the same time, the energy-dispersive X-ray spectroscopy and elemental mapping confirmed the component elements to be K, Fe, O, C and Zn. Interestingly, KFe₂O₄@_monoZIF-8 functions as an adsorbent and a photocatalyst. The adsorption of AP and BR by KFe₂O₄@_monoZIF-8 in the absence of visible light revealed an equilibrium sorption capacity of 17.85±0.8 and 15.00±0.8 mg g^-1, respectively, in a process described by pseudo-2nd-order kinetic model. Furthermore, when subjected to photocatalytic degradation under visible light irradiation, the removal efficiencies towards AP and BR became 98.80±1.20 and 95.2 ± 1.30 %, respectively. KFe₂O₄@_monoZIF-8 in a binary mixed solution of AP and BR exhibited a photodegradation efficiency of 78.00±1.10 and 70.00±1.10 % towards AP and BR, respectively. In addition, KFe₂O₄@_monoZIF-8 exhibited a regeneration capacity above 70 % at the 7th regeneration treatment cycle. KFe₂O₄@_monoZIF-8 compared favourably with previously published materials for removing dyes in an aqueous solution. This study revealed KFe₂O₄@_monoZIF-8 as a promising material for removing dyes from the water system.