Fabrication of network nanocomposite of polyaniline coating chitosan-graphene oxide-functionalized carbon nanotube and its efficacy in removing dyes from aqueous solution

In this investigation, we employed chemical oxidative copolymerization techniques to produce cross-linked polyaniline/chitosan-graphene oxide-oxidized single-wall carbon nanotubes (Cross PANI/Chito-GO-OXS NCs) as a network to increase the surface area, as well as the active centers to enhance the efficiency of the adsorption of anionic and cationic dyes. This novel material was utilized as an adsorbent for decontaminating water by eliminating acid red dye (AR1) and brilliant green dye (BG). Several analytical techniques were employed to assess the composition and structure of the synthesized adsorbent, including scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and Raman spectroscopy. To assess the efficacy of Cross PANI/Chito-GO-OXS NCs in dye removal, batch experiments were carried out under diverse conditions, such as varying pH, adsorbent quantity, agitation duration, ionic strength, and temperature. The results indicated that the optimum conditions for AR1 removal were achieved at pH 2, using 5 mg of Cross PANI/Chito-GO-OXS NCs at a concentration of 20 mg/L for 120 min. Conversely, for BG removal, the most favorable outcomes were observed at pH 6, with the use of 5 mg of Cross PANI/Chito-GO-OXS NCs at a concentration of 5 mg/L for 120 min. Under these operating conditions, the maximum removal efficiency for actual wastewater was determined to be 96.73% for AR1 dye and 95.55% for BG dye. Additionally, we analyzed the adsorption isotherm data utilizing various models. The adsorption kinetics were elucidated through a pseudo-second-order model, supported by regression data, which yielded R2 values of 0.9839 for AR1 and 0.9928 for BG, respectively, describing the adsorption of both dyes onto Cross PANI/Chito-GO-OXS NCs. Furthermore, the thermodynamic analysis revealed that the removal of AR1 dye is an endothermic process, while BG dye removal is exothermic, and both removal of AR1 and BG dyes are spontaneous and chemisorption processes.