The role of oxygen in a carbon source (castor oil versus paraffin oil) in the synthesis of carbon nano-onions

Abstract

The role of a carbon source containing oxygen groups on the physicochemical properties of carbon nano-onions (CNOs) was investigated. Two oils, castor oil (with O groups) and paraffin oil (without O groups) were converted to CNOs in gram-scale yields using an open flame pyrolysis procedure. The products were heated under argon at 900 °C for varying times (1 h, 2 h, 3 h), to investigate the temperature dependence on their structural properties. TGA studies indicated different decomposition behaviour for the different samples with the annealed paraffinic CNOs (CNOP) having a higher decomposition temperature (>600 °C) than the castor oil derived CNOs (CNOC) (<600 °C). TEM images revealed formation of typical chain-like quasi-spherical nanostructures with particles size distributions for the CNOP (22–32 ± 7.8 nm) and the CNOC (44–51 ± 9.9 nm) materials. A detailed Raman analysis of the CNOs revealed that the graphicity of the CNOs varied with both the carbon oil source and the annealing time. Deconvolution of the first order Raman spectra revealed changes in the parameters of the major Raman bands that were then correlated with defect density ratios. Finally, bandwidth analysis depicted the dependence of the graphicity of the CNOs with heat treatment. The data thus indicate that the presence of oxygen in the carbon source provides a method for producing different CNOs and that simple procedures can be used to produce these different CNOs.

From waste cooking oil to oxygen-rich onion-like nanocarbons for the removal of hexavalent chromium from aqueous solutions

“…34 Overall, the OLNCs synthesised via flame pyrolysis of waste cooking oil showed similar characteristics to those of OLNCs produced from pure oils such as olive oil, castor oil, paraffin oil, and ghee oil. 17,19,21 The results show that the hydrogenation, oxidation and polymerisation reactions that took place during the frying process did not negatively affect the quality of the OLNCs that were synthesised using the waste cooking oil. This finding offers the possibility of using waste oils in place of pure oils for the synthesis of OLNCs.…”

“…The OLNCs showed similar morphological characteristics and diameter with similar materials derived from pure oil. 17 The Brunauer-Emmett-Teller (BET) analysis results indicated that the synthesised material had a surface area of 69 m 2 /g, a pore volume of 0.20 cm 3 /g, and an average pore size of 11 nm. When compared to the BET results of the olive oil synthesised OLNCs, it was found that the olive oil materials had a larger surface area of 81.8 m 2 /g.…”

“…16 The high operational costs, high consumption of energy and the use of a metal catalyst to synthesise such carbons have to date limited their use in water application processes. 17 In the current study, we aimed to simultaneously address the aquatic environmental problem of trace metals (specifically Cr) and oil pollution (specifically cooking oil) in water streams. This was achieved by (1) using waste cooking oil as a precursor for the synthesis of OLNCs and (2) using the OLNCs for the removal of Cr(VI) ions from the aqueous solution.…”

A minireview on the utilization of petroleum coke as a precursor for carbon-based nanomaterials (CNMs): perspectives and potential applications

“…These bonds result in delocalised p electrons in the structure, 130 which confer exemplary electrochemical properties as high-performance materials for energy storage. 136 Moreover, CNOs can be produced from various hydrocarbon sources, which include plant extracts (tomato), 137 castor oil, 138 butter, 139 organic gases, 140 agricultural 141 and plastic 142 wastes, among others. However, petroleum coke is not left out of this list.…”