Valorization of hazard waste: Efficient utilization of white brick waste powder in the catalytic production of biodiesel from waste cooking oil via RSM optimization process

Abstract

The target of this study is to utilize hazardous white brick waste powder as a heterogeneous catalyst for biodiesel production through the transesterification process of waste cooking oil (WCO) and methanol. Physico-chemical characterization of the processed waste has been carried out using various techniques including TGA, XRD, FT-IR, BET surface area, FE-SEM & mapping EDX, XRF, and CO2-TPD. The influence of calcination temperature on the catalytic activity is studied. The optimization process of variable independent parameters i.e., catalyst loading, reaction temperature and time as well as alcohol:WCO molar ratio is performed via response surface methodology (RSM) through central composite design (CCD). Optimum conditions (biodiesel conversion = 92.7%) are: catalyst loading 1.3%; temperature 64 °C; methanol:WCO molar ratio of 5.5:1; and reaction time 139 min. Kinetic parameters, i.e., rate constant (k), activation energy (Ea = 25.95 kJ/mol) and thermodynamic parameters, i.e., ΔS# and ΔH# of −202.36 J/mol and +23.27 kJ/mol, respectively, are estimated. The reusability of the prepared catalyst is performed up to six consecutives cycles with marginal loss in activity. Physico-chemical properties of the prepared biodiesel are comparable with the ASTM D-6751 and EN-14214 standard ranges.