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Abstract
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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. Copyright © 2018 John Wiley & Sons, Ltd.
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