Waste to wealth: conversion of nano‐magnetic eggshell (Fe₃O₄@Eggshell) to Fe₃O₄@Ca(HSO₄)₂: cheap, green and environment‐friendly solid acid catalyst

Abstract

Eggshell is a hazardous waste by European Union regulations, so that discarded thousands of tons per year. To convert waste (eggshell) to wealth (catalyst), nano‐magnetic eggshell was prepared based on the nano‐Fe3O4, and then the eggshell was converted to Ca(HSO4)2 with organic acid, namely, chlorosulfonic acid. Based on the back titration, 5.18 mmol SO4H group was loaded per gram of the nano‐structure. Using this method eggshell was converted to cheap, green and environment‐friendly solid acid catalyst. The prepared catalyst (nano‐ Fe3O4@Ca(HSO4)2) was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), energy dispersive X‐ray spectroscopy (EDX), field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and thermal gravimetric analysis (TGA). The activity of eggshell waste‐derived catalysts was successfully evaluated in the synthesis of value‐added products, namely indazolo[1,2‐b]‐phthalazinetrione derivatives as a benchmark multicomponent reaction. In addition, design of experiments shows that increase in amount of catalyst (and temperature), boost the reaction yield, especially with steeper slope at higher temperature.

Synthesis of 1‐aminoalkyl‐2‐naphthols derivatives using an engineered copper‐based nanomagnetic catalyst (Fe3O4@CQD@Si (OEt)(CH2)3NH@CC@N3@phenylacetylene@Cu)

“…[24,25] MNPs have a high affinity to agglomeration, and therefore, suitable protective materials have been investigated for their stabilization. [26][27][28][29][30][31][32][33][34] Surfactant/polymer, silica, and carboncoating or embedding them in a matrix/support are some of the critical approaches adopted to stabilize nanostructured particles. [35,36] It is noteworthy to note that the outer protective shells created as a result of the coating not only stabilize nanoparticles but also provide interaction sites with other synthetic atoms, nanoparticles, and organic groups suitable for their intended applications.…”

Zn (II)‐Schiff base covalently anchored to CaO@SiO2: A hybrid nanocatalyst for green synthesis of 4H‐pyrans

“…These reactions have many useful advantages over traditional multistep processes including short reaction times, low costs, high efficiency, atom economy, and environmentally friendliness. [2][3][4][5] Furthermore, one of the most critical developments in green chemistry is the widespread application of heterogeneous nanocatalysts in MCRs [6][7][8][9] because homogeneous catalysts suffer from separation difficulty over reaction mixture. Heterogeneous catalysts compared to homogeneous ones have several advantages like milder experimental conditions, simple separation, easy recycling, and recovery of catalyst.…”