Adsorption Removal of Cationic Dye (Methylene Blue) and Anionic Dye (Congo Red) into Poly(m-aminophenol)/x%SnO2 Nanocomposite (with x = 1, 3, and 10)

Abstract

This study details the synthesis of organic/inorganic hybrid materials by combining the conductive polymer poly(m-aminophenol) (PMAP) with SnO₂ metal oxide. The objective is to broaden the polymer’s environmental applicability and evaluate its adsorption capabilities, focusing on dyes such as Methylene Blue (MB) and Congo Red (CR). The nanocomposite is meticulously formed through in situ polymerization of m-aminophenol in the presence of SnO₂, with varying loading ratios (1, 3, 10%). Extensive characterization, including analytical techniques (IR and XRD), confirms the structural integrity of the synthesized materials. X-ray diffraction (XRD) analyses distinctly show the successful combination of SnO₂ with the polymer matrix. Adsorption kinetics and isotherm were implemented to understand the adsorption mechanism for both dyes. It was found that PMAP/x%SnO₂ nanocomposite materials (with x = 1, 3 and 10) have high adsorption affinity toward MB and low adsorption affinity toward CR. Significantly, the MB removal percentage follows an ascending trend, starting at 85% for pure PMAP and increasing to 89% for PMAP/1%SnO₂, to 92% for PMAP/3%SnO₂, and peaking at 95% for PMAP/10%SnO₂ within 30 minutes. In contrast, CR removal exhibits a lower percentage, with only 54% removal for pure PMAP and a modest increase to 59% for the PMAP/10%SnO₂ nanocomposite, representing a 5% improvement. These outcomes lead to the conclusion that PMAP/x%SnO₂ nanocomposite materials (with x = 1, 3, and 10) exhibit high adsorption affinity for MB and comparatively lower adsorption affinity for CR. The adsorption of MB and CR on the PMAP and on the PMAP/10%SnO₂ nanpcomposite successfully followed the Langmuir adsorption kinetics model, which showed a better fit for the adsorption of MB and CR. The maximum adsorption capacity \({{Q}_{m}}\) of MPAP/10%SnO₂ for MB was 76.99 mg/g, while for CR it was 39.56 mg/g.