Synthesis of Esters Using Modified Waste Copper Slag: A Sustainable Approach for Waste Valorisation

ABSTRACT The active sites of waste copper slag were moulded using BaO and used as a catalyst for the esterification reaction without solvent. Various concentrations of BaO were doped over the copper slag and investigated for the esterification of various model components of flavour, fragrance and biofuel. The catalyst was characterised by X‐ray photoelectron spectroscopy, attenuated total reflectance‐Fourier transform infrared spectroscopy, surface area analysis and X‐ray diffraction to examine the impact of BaO addition on the structural and morphological characteristics of BaO X /Cp‐Sl. BaO increases the grain size and enhances the BaO X /Cp‐Sl catalyst's activity and selectivity to flavour, fragrance and biofuel. The BaO 2.5% /Cp‐Sl catalyst showed the maximum conversion of oleic acid to the methyl ester. The esterification of various commercially important substrates like geraniol, citronellol, menthol, isoamyl acetate, palmitic acid and waste cooking oil using a catalyst has been explained in detail. The kinetic study of the esterification has been explained with turnover number (TON) and turnover frequency (TOF). The mechanism pathway of the catalyst with various active sites of waste copper slag has been explained using adsorption studies.