The rising levels of chromium (VI) in industrial waste present severe environmental and health hazards, necessitating the development of effective remediation techniques. We have developed polyaniline (PANi)-based composite materials for the selective removal of chromium (VI). Polyaniline noted for its outstanding conductivity and chemical stability, serves as a versatile foundation for composite synthesis, providing enhanced adsorption capabilities specifically designed for chromium (VI) remediation.

This study involves the synthesis, characterization, and optimization of polyaniline-based composite aimed at removing chromium (VI). By systematically varying the composite composition and synthesis parameters, including dopants and morphology, the adsorption efficiency and selectivity for chromium (VI) were finely tuned. Advanced characterization techniques such as X-ray diffraction (XRD), UV-visible spectroscopy for detecting chromium (VI) in solutions, Fourier-transform infrared spectroscopy (FTIR), and FESEM with EDS elucidate the adsorption mechanisms between the polyaniline composite surface and chromium (VI) ions. These insights aid in the rational design of composite materials optimized for improved chromium (VI) adsorption performance.

The practical application of the developed polyaniline-based composite is demonstrated through extensive batch adsorption experiments. The composites’ effectiveness in removing chromium (VI) is assessed under various conditions, including initial chromium (VI) concentrations (up to 2000 ppm), incubation times (up to 24 hours), and different pH levels. Polyaniline based composite proved more effective at lower pH, with a removal capacity of more than 600 mg/g recorded at lower pH for 2000 ppm after 24 hours of incubation. The proposed mechanism for removing negatively charged Cr (VI) ions using the PANi composite includes adsorption and simultaneous reduction to Cr (III), followed by the desorption of Cr (III) from the composite’s surface, as confirmed by ICP-MS. The Freundlich model was found to best describe the adsorption process, indicating a heterogeneous adsorption surface with varying affinities. The adsorption kinetics of Cr (VI) on the polyaniline composite surface followed a pseudo-second-order model.