ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Biomass extract waste plants as a green inhibitor for carbon steel in hydrochloric acid: integrated experimental, computational analysis, and design‑expert optimization study

H. S. Gadow, A. A. Zaatout, H. A. Farag, and R. O. Abo Raza

Chemical Engineering Department, Higher Institute for Engineering and Technology, New Damietta, Egypt

E-mail: hendgadow@gmail.com

Abstract:

This research compares waste green bean peel extract as a waste-based green inhibitor for carbon steel corrosion in 1 M HCl and thus produces a high-value corrosion-control agent from a plentiful agricultural by-product. The influence of inhibitor concentration, temperature, and immersion time was determined using a combined approach of weight-loss measurements, electrochemical methods (open circuit potential, PDP, EIS), surface analysis (AFM, XPS), and quantum chemical/molecular dynamics calculations. The inhibition efficiency increased with increasing extract concentration and temperature, reaching the highest efficacy of 84.88% at 250 ppm and 55 °C, at which the lowest corrosion rate was obtained. The activation parameters and adsorption isotherms (Langmuir, Temkin, Henry, kinetic-thermodynamic) demonstrated spontaneous adsorption with a major chemisorptive contribution, resulting in the formation of a stable protective film on the steel surface. AFM and XPS verified smooth surfaces and a layer with a high concentration of inhibitors on protected samples. The quantum chemical descriptors and adsorption energies of the key phytochemicals (pyrogallol, gallic acid, ellagic acid, catechin, caffeine) exhibited a high affinity for the Fe(110) surface, which agrees with the experimental trends of inhibition. Reduced quadratic models were developed using response surface methodology, and conditions were identified where corrosion rate and inhibition efficiency can be minimized and maximized, respectively. Altogether, the paper illustrates the novelty and usefulness of green bean peel waste as a very effective acid-corrosion inhibitor and offers a predictive model to design and optimize biomass-based inhibitors for use in industries.

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-05062-3

Chemical Papers 80 (9) 11055–11084 (2026)