Polyaniline-Modified Fibrous Nanosilica: a Thermally Stable and Highly Effective Adsorbent Towards Simulated and Real Water Samples

In this work, polyaniline (PANI) functionalized fibrous porous silica nanoparticles (KCC-1 NPs) namely KCC-1/PANI nanocomposite with good surface area (391 m² g⁻¹) and adsorption capacities have been successfully developed by the hydrothermal method followed by in-situ polymerization technique. The KCC-1/PANI was characterized using various techniques, including FE-SEM, FT-IR, XRD, TGA-DTA, BET, and Zeta potential analyses. The adsorption mechanism and kinetics were investigated, and thermodynamic studies were conducted to understand the nature of the adsorption process. The morphological characterization shows wrinkle shaped, fibrous type KCC-1 NPs. According to the TGA results, KCC-1/PANI withstands the temperature upto 470 ℃ with weight loss of only 35%. The maximum adsorption capacity (q_max) of KCC-1/PANI against Crystal violet (CV) was 456.62 mg g⁻¹ (obtained from Langmuir model). Adsorption mechanism investigation disclosed that the sorption of CV dye onto KCC-1/PANI was ascribed because of π-π and electrostatic interactions, and hydrogen bonding (dipole-dipole interaction and Yoshida bonding) between hydrogen containing functional groups (hydroxyl and amine) of the KCC-1/PANI and CV molecules. Adsorption process strictly fulfilled pseudo-second-order kinetic model. Thermodynamic studies revealed that the CV adsorption on KCC-1/PANI is endothermic process with ΔH° = 9.11 kJ mol⁻¹ and spontaneous as value of ΔG° is negative at all temperatures (ΔG° = -9.29 to -11.15 kJ mol⁻¹). In conclusion, KCC-1/PANI is a highly effective material for the removal of cationic dye pollutants, specifically CV dye, from aqueous solutions. Batch adsorption tests confirmed the KCC-1/PANI efficacy in treating real wastewater samples also. This research highlights the potential of KCC-1/PANI as an exquisite material for environmental remediation applications.