a comparative study on the performance of polyaniline-silica and reduced graphene oxide-silica nanocomposites to oil-water emulsion separation

Oily water is one of the most common issues, which is attributed to the petroleum industry in the form of oil-water (o-w) emulsion. therefore, it is necessary to treat it before being released into the environment. in this study, the possibility of two different nanocomposites has been investigated in the demulsification of o-w emulsions. first, silica (sio2) nanoparticles and graphene oxide (go) nanosheets were synthesized using the sol-gel process and the hummers’ method, respectively. next, polyaniline (pani)-silica and reduced graphene oxide (rgo)-silica nanocomposites were synthesized by applying in situ chemical oxidative polymerization and sol-gel processes, respectively. edx analysis showed the proper reduction of go to rgo nanosheets. in addition, sem results revealed that the pani-silica nanocomposite was more functional compared to rgo-silica due to its higher specific surface area and higher demulsification efficiency. accordingly, bottle tests and optical microscopy images proved that the adsorption capacity of pani-silica nanocomposite is greater than that of rgo-silica nanocomposite. furthermore, the demulsification results indicated that the optimum adsorption percentage of oil from the o-w emulsion corresponded to the oil content in the emulsion and was not correlated to the nanocomposite type. it was figured out that the performance of nanocomposites was better when using less oil in the o-w emulsion. bet analysis also showed that the surface area of pani-silica was two times greater than that of ego-silica, which caused better o-w emulsion separation. the hydrophobicity observations confirmed that the surface of pani-sio2 can absorb more oil droplets compared to rgo-sio2. last, the possible mechanism of demulsification by applying nanocomposite as an adsorbent was also explained.