Abstract
In the following study, green carbon nanotubes and green few-layer reduced graphene oxide (rGO) were synthesized through simple, sustainable, and scalable processes starting from recycled plastic and charcoal, respectively, and with the highest number of steps involving non-harmful substances. After an extensive physicochemical characterization, which evidenced that both nano-carbons exhibit structures comparable with that of materials produced through more traditional methods and from pure sources, the samples were dispersed in two types of conventional base oils, in particular group I and group III, in order to carry out, for the first time on these green nanomaterials, an accurate study on their tribological performance. Tribological tests evidenced a remarkable reduction of coefficient of friction and wear scar diameter, especially for the green rGO dispersed at 0.1 wt% in the group III oil along with SDBS-Tween 80 surfactants mixture: 18% and 15% at ambient temperature, 12% and 13% at 80 °C, respectively. Furthermore, the tribological performance of the synthesized samples in both oils remained high for 160 min of investigation. A comparison with the same material obtained with a traditional synthesis revealed the absence of fouling phenomena in the lubrication chambers in our case, confirming the higher tribological performances of the green rGO sample, probably, as a consequence of its less ordered nature.
Highlights
IntroductionInnovative improvements in the performance of lubricants, which have practically reached their limits, and the replacement of additives with much more environmental friendly and recyclable molecules which interfere as little as possible with other’s functions and base oils properties, would lead to additional consumption reductions, lower emissions, and enhancement of transport environmental sustainability [1,2,3,4,5,6,7,8]
Innovative improvements in the performance of lubricants, which have practically reached their limits, and the replacement of additives with much more environmental friendly and recyclable molecules which interfere as little as possible with other’s functions and base oils properties, would lead to additional consumption reductions, lower emissions, and enhancement of transport environmental sustainability [1,2,3,4,5,6,7,8].In this perspective, control at the nanoscale is undoubtedly an opportunity for the development of new and more efficient additive formulations
5, allow of sheets in the sample. reduced graphene oxide (rGO) is mainly thin with a maximum of 10 layers; a small fraction, as typically occurs starting from other more ordered sources, has a number of layer higher than 12
Summary
Innovative improvements in the performance of lubricants, which have practically reached their limits, and the replacement of additives with much more environmental friendly and recyclable molecules which interfere as little as possible with other’s functions and base oils properties, would lead to additional consumption reductions, lower emissions, and enhancement of transport environmental sustainability [1,2,3,4,5,6,7,8] In this perspective, control at the nanoscale is undoubtedly an opportunity for the development of new and more efficient additive formulations. Two recent papers report some interesting results which can be ascribed to the amorphous nature of the nano-additives or interface [10,11].
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