Fouling and fouling mitigation of mineral salt using bio-based functionalized graphene nano-plates

Fouling or scaling is the formation of deposits on heat exchanger surfaces which are mostly unwanted compounds formed from the precipitation of the dissolved salts and that retard heat transfer from the surfaces. In many industries, acid is used to dissolve and clean the deposits from the heat transfer surfaces. Nevertheless, the excessive use of acids has caused major safety hazards and created environmental issues to the public. Among the additives used for fouling mitigation, a major share of them is hazardous to the environment and injurious to health, so it was essential to explore eco-friendly additives. The present research investigated the mitigation of calcium carbonate scaling by applying functionalized graphene nano-platelets (FGNP) nanofluids as additives to the fouling liquids on pipe heat exchangers. In addition, the additive used in the present research was functionalized by bio-based method, which was eco-friendly, and unlike most of the available environmental hazardous additives. The deposition of calcium carbonate on the heat exchanger surface and the crystal growth were investigated by the analyses of total deposits, fouling resistance evaluation and conducting crystal characterization by using field emission scanning electron microscope. It was observed that the total deposition, crystal size and compactness of fouling deposition of CaCO₃ were retarded with the increase in FGNP concentration in the fouling liquid. From the results, it was seen that the rate of additive effectiveness gradually diminished with the rate of enhancement of additives in the fouling solution and the total effect was more prominent with the higher percentage of additives in the fouling solution.