Biodiesel Production from Waste Cooking Oil using Macroalgae-Derived Biochar Catalyst

Abstract

This study presents the synthesis, characterization, and utilization of marine macroalgae-derived biochar catalysts (BC and KOH-AC) for the production of biodiesel from waste cooking oil (WCO). The biochar catalyst (BC) was produced via slow pyrolysis of marine macroalgae biomass, which was subsequently activated with potassium hydroxide (KOH) to produce a KOH-modified activated carbon catalyst (KOH-AC). Advanced characterization techniques such as SEM, EDX, XRD, FTIR, and TGA were used to examine the physicochemical and structural properties of the synthesized catalysts. To evaluate the catalytic performance of marine macroalgaederived biochar catalysts, the impact of various transesterification variables such as temperature, M/O ratio, time, and catalyst loading on the yield of biodiesel was examined. It was found that the maximum biodiesel yields of 98.96% and 47.54% were obtained using KOH-AC and BC, respectively, under optimal reaction conditions of 65 °C of temperature, 12:1 of M/O molar ratio, 120 min of time, and 3 wt. % of catalyst loading. The KOH-AC catalyst was recycled up to five times, with the fifth cycle producing a significant biodiesel yield of 80.37%. Biodiesel characterization using GC-MS confirmed the existence of 97.34% FAME compounds in the produced biodiesel. The fuel characteristics of the produced biodiesel were analyzed, and the results were compared to those of the ASTM Standard (D6751) and the EN Standard (14214), which ensured that the produced biodiesel possesses excellent fuel properties and can be used as a substitute for traditional fossil fuels.