Synergistic effect of silica/polypyrrole nanocomposites synthesized by hydrothermal method using rice husk as a silica source for corrosion protection

Abstract

Rice husk, a plentiful agricultural waste, is a natural and environmentally friendly silica reservoir. In this study, a hydrothermal synthesis was employed to produce silica/polypyrrole nanocomposites, with the primary objective of developing corrosion-resistant materials. The nanocomposites are comprehensively characterized using XRD, FTIR, FESEM, and electrochemical studies. The results confirmed the successful formation of a silica/polypyrrole nanocomposite and revealed that the adsorption of polypyrrole molecules onto silica clusters controls the formation of larger silica nanoparticles. Pure silica exhibits spherical particles ranging from 500 to 1 μm. A low concentration of polypyrrole results in nanoparticles with dimensions ranging from 100 to 200 nm, while a higher concentration leads to reduced silica nanoparticles with sizes 10–20 nm. Aggregation of spherical nanoparticles is more prominent in silica/polypyrrole nanocomposites than pure silica nanoparticles. The nanocomposites of silica/polypyrrole, namely SP-1, SP-2, and SP-3, demonstrated significantly higher corrosion resistance (Rct) values of 36613 Ω, 44536 Ω, and 49060 Ω, respectively, in comparison to the pure silica (19540 Ω). The corrosion rates of pure silica, SP-1, SP-2, and SP-3 were determined to be 1.2687 mm/yr, 0.4715 mm/yr, 0.4681 mm/yr, and 0.3042 mm/yr, respectively. Silica exhibits remarkable chemical stability and exceptional corrosion resistance, whereas polypyrrole is a conducting polymer endowed with distinctive electrical characteristics. These constituents can be synergistically combined within a nanocomposite matrix, enhancing corrosion resistance. The synthesized nanocomposite exhibits considerable promise as a corrosion-resistant coating agent, presenting a sustainable remedy for corrosion mitigation in different industrial contexts.