Table 1 Overview of a variety of nano additives and their influence on characteristics of engine.

Sivakumar et al.⁶⁸

Al₂O₃ (50–100 ppm), Cetyltrimethylammonium bromide

Palm oil methyl ester

Single cylinder, 4 S, Kirloskar AV1, 210 bar IP and 23degbTDC IT, 16.5:1 CR, 1500 rpm

7% high BTE, lowered BSFC, HC, CO, higher NOx emissions

Ranjan et al.⁶⁹

MgO (30 ppm), 4-Chlorobenzoyl chloride

Waste cooking oil biodiesel

Single cylinder, Kirloskar TV1, vertical, 1500 rpm, 17:1 CR, load (4.7–18.11 kg)

Higher BP, BSFC and BTE, CO₂,Lowered HC, CO and NOx, Improved combustion

Mehregan et al.⁷⁰

Manganese oxide and cobalt oxide (25 ppm and 50 ppm), no surfactant

B20 waste frying oil

4 Cylinder, 4Stroke Urea-SCR Direct Injection, CR 17.9: 1, IP210 bar, IT 23 deg bTDC

Lowered SFC at part and full load, higher thermal η, drastic reduction of NOx and CO

El-Seesy et al.⁷¹

Al₂O₃ (50–100 ppm), 20 mg per lit., no surfactant

Jojoba oil methyl ester

Deutz F1l511, 1 cyl, 4 S, DI, 1500 rpm, IP175 bar, IT 24 deg bTDC

NOx 70%↓, CO 80%↓, HC 60%↓, and Smoke 35%↓, 12% drop in BSFC

Hoseini et al.⁷²

Graphene oxide (30,60 and 90ppm), no surfactant

Ailanthus altissima biodiesel

LombardiniDiesel3LD510, 1800 rpm, 17.9:1 CR, 1 cyl, non-turbocharged, 32.8Nm torque

↓HC, ↓CO, ↓BSFC, ↑NO_x and ↑CO

Kumar et al.⁷³

Ferrous oxide and ferrofluid (0.5%, 1% and 1.5%), surfactant: 2 mol of NaOH

B20 palm oil methyl ester

Single cylinder, 4 S, Kirloskar TV1, 210 bar IP and 23degbTDC IT, 16.5:1 CR, 1500 rpm

↑ BTE (by 16.6%), ↓BSFC (by 11.1%), other emissions reduced simultaneously

Ashok et al.⁷⁴

Zinc oxide (50 and 100ppm), Ethanox (200 and 500 ppm) Surfactant: Alcohol

CalophyllumInophyllum methyl ester

Simpson S217, Two cyl 4 S, DI, Vertical, IT 23 deg bTDC, IP 200 bar 18.5:1 CR

High BTE for ZnO (29.5%) than Ethanox (26.8%), lowest BSFC for ZnO50 ppm, 18.4% and 13% less CO and HC for ZnO 50 ppm, 17.8% less NOx for Ethanox (500 ppm), 12.6% less NOx for ZnO100 ppm.

Leo et al.⁷⁵

Al₂O₃and FeCl₃ (50 and 100 ppm), no surfactant

Waste cooking oil biodiesel (WCOB)

Homogeneous CCI-DI , 210 bar IP and 23degbTDC IT, 17.5:1 CR, 1500 rpm, 4.4 kW

HC reduced by 54.17%, NOx reduced by 4.3%, 100ppm additive lowers 30.4% smoke in diesel, 23.65% in WCOP

Mohanraju et al.⁷⁶

Aluminium nitrate (Al (NO₃)₃) nanoparticles and graphene oxide nanoplates (GONP_S)  50 ppm, no surfactant

Industrial leather waste fat biodiesel

Single cylinder, Kirloskar TV1, vertical, 1500 rpm, 17:1 CR, load (4.7–18.11 kg)

CO₂↓6.84%, HC↓13.11%,, and smoke ↓5.75 emissions for Al (NO₃)₃) nano particles

Jayabal et al.⁷⁷

Bio-silica (Bio-Si) 50-100 ppm, no surfactant

Leather waste fat biodiesel

Kirloskar TV1, vertical, 1500 rpm, 17:1 CR, 210 bar IP and 23degbTDC IT

Higher BTE and lowered NOx for 50 ppm additive fuel. For 100ppm additive, HC and CO reduced by 31.87% and 34.14%, but NOx increased by 4.45%.