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Sol–gel-assisted synthesis of ultra-fine porous SiO2 nanoparticles for investigation of lubricity and rheological properties of eco-friendly bio-lubricant oil

Meghana K. Navada, Ranjitha Rai, Akshatha R. Shetty, Girish Hariharan, Nitesh Kumar, Shiva Kumar, Gurumurthy Sangam Chandrashekar, and Ganesha Aroor

Department of Chemistry, Manipal Institute of Technology, Manipal Academy of Higher Education (MAHE), Manipal, India



Received: 26 October 2023  Accepted: 30 November 2023


The smooth functioning of the machinery demands good lubricants. Today mineral oils are extensively used to lubricate machine parts, which are not environmentally friendly. The increased environmental pollution and depletion of crude oil reserves triggered the search for eco-friendly alternate sources of lubricating oils. The bio-lubricants derived from plants and vegetable sources are renewable and environmentally friendly. An in-depth exploration of their potential to replace petroleum-based lubricants is essential. In the present work, the tribological characteristics of Pongamia oil blended with neem oil and enriched with SiO2 nanoparticles (NPs) are investigated. The SiO2 NPs are fabricated via sol–gel methodology and characterized by numerous analytical techniques. A ring-on-block concept is used to measure the lubricity of the oils and to understand the influence of SiO2 NPs on the lubricating regimes, which underlines the novelty of this research work. The rheological properties are studied under rotational shear mode. The results show that the SiO2 NPs extend the mixed lubrication regime of the Pongamia oil by reducing 8.69% of the average coefficient of friction. The antioxidant property was carried out using DPPH analysis and found a maximum of 74.38% at the highest concentration (700 µg/mL).

Graphical abstract

Keywords: Bio-lubricant; Lubricity; Rheology; SiO2 nanoparticles; Coefficient of friction

Full paper is available at

DOI: 10.1007/s11696-023-03250-z


Chemical Papers 78 (4) 2437–2450 (2024)

Thursday, June 20, 2024

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