Development of novel and green NiFe2O4/geopolymer nanocatalyst based on bentonite for synthesis of imidazole heterocycles by ultrasonic irradiations

Abstract

Geopolymers as aluminosilicate inorganic polymers and eco-friendly building materials which can be used as substrate for different kinds of composite. In this research, according to the fabrication of geopolymer based on bentonite as a substrate and embedment of nife 2 o 4 nanoparticles in the construction of this polymer, the synthesis of a new magnetic nanocomposite (nife 2 o 4 /geopolymer) was investigated for the first time. In order to describe its chemistry and morphology features, different analyses such as Fourier transform infrared spectroscopy, field-emission scanning electron microscopy and transmission electron microscopy images, Brunauer-emmet-teller adsorptiondesorption isotherm, X-ray diffraction pattern, energy-dispersive X-ray analysis, thermogravimetric analysis, and vibrating-sample magnetometer analysis were used. The application of this novel nanocatalyst was studied for one-pot three-component condensation reaction of substituted imidazole derivatives by accelerated ultrasonic irradiations. Compared to the other conventional catalysts which were used for the synthesis of imidazole derivatives, the green synthesis method for fabrication of this heterogeneous and magnetic nanocatalyst, its high thermal stability, being ecofriendly, noticeable efficiency and easy reusability have become privileges to be superior. Geopolymeric compounds as amorphous, three-dimensional alkali aluminosilicate binder materials were first introduced by Davidovits in 1978. In recent years, the perusal of geopolymeric materials has been increased due to their specific properties such as compliance with green chemistry, high mechanical performance as building materials, having micro or nano-porosity, thermal stability, high surface hardness, and acid and fire resistance 1. These kind of materials can be fabricated by alkaline activation of various aluminosilicate materials including natural minerals such as kaolin 2 and montmorillonite 3 , mineral resources like bentonite 4 , and also, industrial wastes such as fly ash 1,5. Among them, natural bentonite is one of the most multifunctional mineral clays with low cost, abundant accessibility, superb swelling capability, viscoelastic property at low concentration, superb absorption capacity and eco-friendly properties 1. This phyllosilicate clay primarily consists of montmorillonite. Two main contributions to the surface charges of montmorillonite are the constant negative charges on the basal planes; which are related to the isomorphic substitutions and the pH-dependent charges developed on the hydroxyl groups at broken edges 6. A localized charge distribution can be generated by a negative charge associated with a cation replacement (e.g., Al +3 for Si +4) in the tetrahedral sheet; while, a diffused negative charge can be achieved by the cation replacement (e.g., Mg +2 for Al +3) in the octahedral sheet 6. This natural clay can be utilized as superb absorbent in various fields such as water purification and absorption of heavy metals 7 due to its specific structure. The ...

HETEROGENEOUS CATALYSIS USING BENTONITE-SUPPORTED Fe-Co-Ni TRIMETALLIC NANOPARTICLES

“…Further weight loss of 5 % (w/w) was also observed in the temperature range of 120-700 ℃ which can be attributed to the removal of water from the dihydroxylation process [23]. It can also be attributed to the destruction of carbonate which existed in the structure of iron that is present in the nanoparticle [24]. The temperature above 700 ℃ reveals a more stable sample which indicates that the bentonite-supported Fe-Co-Ni trimetallic nanoparticles are a high-temperature-stable catalyst.…”

Ultrasound irradiation in heterocycle synthesis: An overview

“…Hajizadeh et al reported the preparation of NiFe 2 O 4 /geopolymer nanocatalyst for the synthesis of imidazole derivatives [22]. The three‐component reaction of benzil, benzaldehyde, and ammonium acetate under ultrasound irradiation in the presence of 0.03 g catalyst ensued the anticipated product in 91% yield when ethanol was used as the solvent (Scheme 6).…”

Novel Magnetic Inorganic Composites: Synthesis and Characterization

“…Geopolymers and magnetic geopolymers have also been proposed as low-cost, effective catalysts for environment governance by “end-of-pipe” treatments, such as photocatalytic degradation of dye wastewater or gas purification and have been employed for hydrogen and biodiesel production as well as in green heterogeneous catalytic processes [ 25 , 26 ].…”