Polyaniline-based filtration assembly for efficient recovery and recycling of used lubricant oil: a sustainable approach for environmental remediation

In the current study, polyaniline (PANI) for the first time has been employed to purify ULO. Conducting polymer, polyaniline, was effectively synthesized via the <i>in-situ</i> oxidative polymerization process. The physiochemical properties of recovered oil were analyzed, and the results were compared with fresh oil samples. The viscosity and density of the recovered oil sample were significantly decreased from 105.6 cP to 59.04 cP and from 869.54 kg/m³ to 858.17 kg/m³, respectively, indicating significant removal of impurities. The flash point of the used oil sample was observed at 180°C, and the recovered oil was found to be 220°C, which indicates the substantial elimination of volatile impurities from the ULO. Thus, the properties of the recovered oil sample demonstrated that the PANI effectively decontaminated ULO without generating secondary contaminants. The efficiency of oil purification was measured using FT-IR, UV, and ICP-OES. The concentration level of Fe, Zn, and Pb in the recovered oil sample has been decreased to a greater extent. To conclude, a polyaniline-based filtration assembly was employed to recycle ULO and remove contaminants effectively.