Biodiesel production from by extraction of carp fish (Cyprinidae) oil and transesterification using CaO derived from limestone and eggshells as heterogeneous catalysts

The fish market produces a huge amount of fish waste and worsens the ecosystem's condition when dumping into the environment while the treatment to create ecologically and economically acceptable biodiesel is one possible answer. So, this study evaluates the efficiency of three extraction techniques: Wet rendering, Soxhlet, and enzyme hydrolysis in extracting oil from carp fish. The highest yields of oil extraction were 38.61, 36.25, and 22.38% in the Soxhlet extraction, enzyme hydrolysis extraction, and wet rendering respectively. Raw fish oil's physical and chemical characteristics were investigated, and GC-MS was used to determine its free fatty acid profile. This investigation also inquired about the preparation of calcium oxide (CaO) that is efficient in producing biodiesel from waste eggshells and limestone which were calcined at 950 degrees C for 2.5 hr, producing stable and high-purity CaO. XRD and FTIR were used to characterize the prepared catalyst while FESEM analysis of the catalyst's surface structure and EDX spectra analysis of the catalyst's elemental composition were both performed. The highest yields were 91.74 and 89.21% obtained using CaO derived from limestone and eggshells respectively. The optimum transesterification reaction conditions were a methanol to oil molar ratio of 9:1, 3.5 wt% CaO catalyst, 60 degrees C, and 90 min.