This research was aimed to examine the diesel engine’s performance and emission of secondary fuels (SFs), comprising waste plastic oil (WPO) and palm oil biodiesel (POB), and to analyze their tribological properties. Their compositions were analyzed by gas chromatography–mass spectrometry (GC–MS). Five SFs (10–50% POB in WPO) were prepared by mechanical stirring. The results were compared to blank WPO (WPO100) and Malaysian commercial diesel (B10). WPO90 showed the maximum brake power (BP) and brake torque (BT) among the SFs, and their values were 0.52 and 0.59% higher compared to B10, respectively. The increase in POB ratio (20–50%) showed a negligible difference in BP and BT. WPO70 showed the lowest brake-specific fuel consumption among the SFs. The brake thermal efficiency (BTE) increased with POB composition. The maximum reductions in emission of hydrocarbon (HC, 37.21%) and carbon monoxide (CO, 27.10%) were achieved by WPO50 among the SFs. WPO90 showed the maximum reduction in CO 2 emission (6.78%). Increasing the POB composition reduced the CO emissions and increased the CO 2 emissions. All SFs showed a higher coefficient of friction (COF) than WPO100. WPO50 showed the minimal increase in COF of 2.45%. WPO90 showed the maximum reduction in wear scar diameter (WSD), by 10.34%, compared to B10. Among the secondary contaminated samples, SAE40-WPO90 showed the lowest COF, with 5.98% reduction compared to SAE40-WPO100. However, with increasing POB content in the secondary contaminated samples, the COF increased. The same trend was also observed in their WSD. Overall, WPO90 is the optimal SF with excellent potential for diesel engines.

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Purpose The purpose of this paper was to investigate the lubricity of palm biodiesel (PB)–diesel fuel with plastic pyrolysis oil (PPO) and waste cooking biodiesel (WCB). Design/methodology/approach Three quaternary fuels were prepared by mechanical stirring. B10 (10% PB in diesel) fuel was blended with 5%, 10% and 15% of both PPO and WCB. The results were compared to B30 (30% PB in diesel) and B10. The lubricity of fuel samples was determined using high-frequency reciprocating rig in accordance with ASTM D6079. The tribological behavior of all fuels was assessed by using scanning electron microscopy on worn steel plates to determine wear scar diameter (WSD) and surface morphology. The reported WSD is the average of the major and minor axis of the wear scar. Findings The addition of PPO and WCB to B10 had improved its lubricity while lowering wear and friction coefficients. Among the quaternary fuels, B40 showed the greatest reduction in coefficient of friction and WSD, with 7.63% and 44.5%, respectively, when compared to B10. When compared to B30a, the quaternary fuel mixes (B40, B30b and B20) exhibited significant reduction in WSD by 49.66%, 42.84% and 40.24%, respectively. Among the quaternary fuels, B40 exhibited the best overall lubricating performance, which was supported by surface morphology analysis. The evaluation of B40 indicated a reduced adhesive wear and tribo-oxidation, as well as a smoother metal surface, as compared to B20 and B30b. Originality/value Incorporation of PPO and WCB in PB–diesel blend as a quaternary fuel blend in diesel engines has not been reported. Only a few researchers looked into the impact of PPO and WCB on the lubricity of the fuel.

Litsea petiolata Hk. f was included Lauraceae family, and the previous study had been isolated 5 compounds from the Litsea petiolata Hk. f stem bark dichloromethane extract namely harman or aribine, norharman, reticuline, isoboldine, and thalifoline. Antioxidants can prevent tissue damage by free radical. Free radical production continuously in all cells as cellular function usually, but excess production can cause many diseases. The research aimed to assay the activity of antioxidant from the extract and fractions of the Litsea petiolata Hk. f stem bark with DPPH assay and FRAP assay. The extract was obtained by soxhletation used dichloromethane as solvent. The fractions fractionated with column chromatography. The antioxidant test used DPPH assay and FRAP assay. The IC50 values for the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging test of the dichloromethane extract was 27.36 µg/mL, the fraction A was 113.74 µg/mL, fraction B was 60.17 µg/mL, and the control positive (quercetin) was 3.96 µg/ml. The EC50 values for ferric ion reducing antioxidant potential (FRAP) test of the dichloromethane extract was obtained 13.47 µg/mL, the fraction A was 76.49 µg/mL, fraction B was 55.73 µg/mL, and the control positive (quercetin) was 14.01 µg/ml. The extract had higher antioxidant activity than the fractions, and by FRAP test the extract showed better antioxidant activity than the positive control (quercetin).

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