Innovative dual-functional, green and biodegradable dicarboxylated inulin as scale and corrosion inhibitors for sustainable oil and gas operations.

The oil and gas industry urgently needs greener, smarter solutions to combat the dual challenges of inorganic scale formation and corrosion of metallic infrastructure. In this work, we introduce a novel, dual-functional, phosphorus-free corrosion and scale inhibitor derived from the in situ dicarboxylation of inulin through an environmentally benign two-step oxidation strategy. Inulin was efficiently converted into a highly functionalized dicarboxylated biopolymer through a selective sodium periodate oxidation followed by Pinnick oxidation, while maintaining the integrity of its backbone structure, as confirmed by FT-IR and 1H NMR spectroscopy. The dicarboxylated inulin formed a resilient, protective film on carbon steel surfaces, as revealed by electrochemical impedance spectroscopy (EIS), with adsorption behavior fitting the Langmuir isotherm and a ΔG°ads of -39.32 kJ·mol-1, highlighting a strong chemisorption process supplemented by physisorption with corrosion inhibition efficiency of 94.5 % at 100 ppm. Interestingly, the resulting dicarboxylated inulin exhibited excellent inhibition performance against gypsum scale at low inhibitor concentrations, following the NACE Standard TM0374-2007 protocol. Additionally, it demonstrated a remarkable 90 % inhibition efficiency against calcite scaling, outperforming commercially available carboxymethyl inulin at the same tested concentration. The dicarboxylated inulin also showcased outstanding compatibility under high‑calcium brine conditions, maintaining performance even at inhibitor dosages up to 10,000 ppm.