This study investigates the use of waste fat biodiesel (WFB) from the leather industry as a substitute for diesel fuel.Specifically,it examines the diesel engine performance of WFB,a blend of WFB and diesel (B50),and different blends of WFB and silicon dioxide (SiO2) nanoparticles (B50SiO240,B50SiO280,and B50SiO2120μg/g).The results indicate that the B50SiO2120 blend increases brake thermal efficiency by 10.03%compared to pure biodiesel but falls 1.93%short of neat diesel.Furthermore,the B50SiO2120 mixture reduces smoke,hydrocarbon,and carbon monoxide emissions by31.87%,34.14%,and 43.97%respectively,compared to diesel.However,the B50SiO2120 blend shows a 4.91%increase in nitrogen oxide emissions compared to diesel.