This study investigates the corrosion resistance of chitosan and its crosslinked form coatings applied on stainless steel as substrate using various analytical techniques. Fourier transform infrared spectroscopy (FTIR-ATR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were employed for surface characterization. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques were used to analyze the electrochemical behavior. Four coatings were evaluated along with naked stainless steel (ss): chitosan (Chi), chitosan crosslinked with ammonium paratungstate (Chi/PTA), chitosan crosslinked with polyethylene glycol (Chi/PEG), and chitosan crosslinked with polyvinylpyrrolidone (Chi/PVP). Electrochemical measurement parameters analysis assessed the coating corrosion resistance, such as impedance modulus (|Z|) and corrosion potential (Ecorr). Results indicate varying degrees of corrosion resistance among the coatings. Chi/PTA exhibited notable characteristics in the electrochemical tests, showing promising polarization resistance (Rp) and impedance behavior trends. Conversely, Chi/PEG showed differing electrochemical responses, suggesting higher susceptibility to corrosion under the study conditions. These findings contribute to understanding the electrochemical performance of chitosan-based coatings on stainless steel, highlighting their potential in corrosion protection applications.

Metals are widely used in various industrial applications due to their advantageous properties, but they often exhibit signs of degradation over time because of prolonged exposure to environmental conditions. To prevent corrosion, coatings have gained popularity owing to their practicality in maintaining the original shape and dimensions of the object being protected. Nevertheless, traditional coatings may pose significant toxicological and environmental concerns, leading researchers to explore eco-friendly alternatives such as chitosan-based coatings. Chitosan, a biopolymer derived from chitin, is abundant in nature and has been extensively studied for its physicochemical properties, including its potential in the development of new materials. Chitosan-based coatings have shown promise as effective corrosion inhibitors, and this study aims to develop a crosslinked chitosan-based coating from shrimp waste as an alternative to expensive, commercial coatings. Chitosan, and chemically modified polyethylene glycol, polyvinylpyrrolidone, and ammonium paratungstate chitosan coatings of high- and medium molecular weight prepared by the sol-gel technique, were used for the study of corrosion protection of aluminum in 3.5% synthetic seawater. The molecular interactions and structural alterations following cross-linking of chitosan-based coatings was supported by FTIR-ATR. Surface morphology analysis by AFM indicated good coating adsorption on aluminum surfaces. Contact angle measurements showed hydrophilic properties with contact angles >62° and <90°. Physicochemical characterization (molecular weight (kDa), deacetylation (%), humidity (%), and ash (%)) was also carried out. The corrosion inhibition effectiveness was assessed by gravimetric tests after immersion studies, and the results highlighted the MMW-Chi-based coating’s performance.

Polymeric membranes based on chitosan (Cs) were extracted from shrimp shells and evaluated. These membranes were modified using polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and glycerol (Gly) and crosslinked with glutaraldehyde (GA) to examine their suitability for water filtration processes. The Cs exhibited high purity, a total nitrogen content of 6.49%, and an average molecular weight of 456 kDa, all of which are suitable for membrane formation. Four membranes (Cs-GA, B2: Cs-PEG, B5: Cs-PEG-PVP, and B7: Cs-Gly) were characterized by means of FTIR, SEM, AFM, thickness, contact angle, tensile testing, TGA, DSC, and filtration with distilled water at 4.83 bar. B2 and B5 showed thicknesses of 207 and 190 μm and contact angles of 56.7° and 58.9°, lower than that of Cs-GA (89.4°). In filtration, B2 achieved a flux of 2222.70 LMH, a permeance of 460.19 LMH·bar⁻¹, and a hydraulic resistance of 8.79 × 10¹¹ m⁻¹, while Cs-GA, B5, and B7 exhibited fluxes of 24.10, 40.43, and 24.77 LMH, respectively, permeances of 9.75, 8.37, and 5.13 LMH·bar⁻¹, and hydraulic resistances of 4.15 × 10¹³, 4.83 × 10¹³, and 7.89 × 10¹³ m⁻¹, in the same order. Overall, membranes B2 and B5 are recognized as the most promising for water filtration under pressured operating conditions.