Nanosized Spinel Ferrites Synthesized by Sol‐Gel Autocombustion for Optimized Removal of Azo Dye from Aqueous Solution

Abstract

Nanosized spinel ferrites MFe2O4(M = Ni, Co, and Zn) have been prepared by sol-gel autocombustion method using citric acid as a fuel agent. The materials are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The spinel ferrites have been applied for Congo-Red (CR) dye adsorption using batch technique. Different kinetic and equilibrium models have been fitted by nonlinear regression to analyze the adsorption data. In accordance with Langmuir isotherm, the maximum adsorption capacity at 293 K is 14.06 mg/g for CoFe2O4and 17.13 mg/g for NiFe2O4. The values of mean free energy determined from Dubinin-Radushkevich isotherm are higher than 8 (kJ mol−1), indicating a chemisorption mechanism. Based on the calculated thermodynamic parameters (free energy, enthalpy, and entropy) the adsorption of CR onto ferrites is a spontaneous and endothermic process. Response surface methodology has been applied to construct the multiple regression models for prediction of the adsorption capacity and removal efficiency. The model-based optimization has been performed using genetic algorithms and desirability function approach. The single-objective optimization has yielded a maximum value of color removal efficiency of 98.995%, using NiFe2O4adsorbent. The multiobjective optimization has resulted in the improvement of both removal efficiency and adsorption capacity.

Enhanced visible light photocatalysis with E‐waste‐based V2O5/zinc–ferrite: BTEX degradation and mechanism

“…The bands at 726 and 837 cm −1 are attributed to asymmetric stretching vibrations of the V&bond;O&bond;V group. The band at 993 cm −1 is due to the presence of VO stretching vibrations and peaks at 3499 and 3576 cm −1 are due to OH stretching vibration . The coherence of the obtained XRD peaks with JCPDS no.…”

“…The FTIR spectrum (Fig. 3(a)) of zinc–ferrite exhibited specific bands for metal–oxygen stretching vibration in the tetrahedral site (584–540 cm −1 ) and at 674 cm −1 . The band observed at 516 cm −1 in the spectra of pure V 2 O 5 and ZFV composites can be attributed to symmetric stretching vibrations of the V&bond;O&bond;V group.…”

“…The band at 993 cm −1 is due to the presence of V O stretching vibrations and peaks at 3499 and 3576 cm −1 are due to O H stretching vibration. 24,25 The coherence of the obtained XRD peaks with JCPDS no. 09-0387 in addition to the h k l attributions of 200, 001, 110, 400, 011, 310, 002, 411, 600, 601, 121, 420 and 710, as seen in the XRD pattern of V 2 O 5 indicate the crystalline nature of the synthesized photocatalyst.…”

Metal-Organic Framework MIL-53(Fe) as an Adsorbent for Ibuprofen Drug Removal from Aqueous Solutions: Response Surface Modeling and Optimization

“…, k). e parameter β o is the offset coefficient, β i is the linear coefficient, β ii is the second-order coefficient, and β ij is the interaction coefficient [44].…”

Novel NiFe/Si/Au magnetic nanocatalyst: Biogenic synthesis, efficient and reusable catalyst with enhanced visible light photocatalytic degradation and antibacterial activity

“…As seen in Figure a, the peaks at 468 and 582 cm −1 are ascribed to the octahedral (Fe 3+ ‐O) and tetrahedral (Ni 2+ /Fe 3+ ‐O) frameworks of iron or nickel ions, respectively . Because of the previous investigation, FT‐IR spectra show that NiFe 2 O 4 was successfully synthesized . Figure b shows the small adsorption band around 805 cm −1 and a strong peak around 1109 cm −1 that belong to the symmetric and asymmetric vibrations of Si‐O‐Si .…”