High-capacity adsorption of hexavalent chromium by a polyaniline-Ni(0) nanocomposite adsorbent: Expanding the Langmuir-Hinshelwood kinetic model

• Published in: Journal of molecular liquids 2023-11, Vol.389, p.122931, Article 122931
• Main Authors: Lohrentz, Luca, Bhaumik, Madhumita, Brink, Hendrik G.
• Format: Article
• Language: English
• Subjects: Adsorption-coupled reduction; Langmuir kinetics; Nanocomposite; Polyaniline nanotubes; Zero-valent nickel nanoparticles
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2023.122931

•The zero-valent metal nanocomposite PANI-NSA@Ni0 exhibits high Cr(VI) removal capacity of 820.5 mg/g.•PANI-NSA@Ni0 was highly selective towards the target ionic pollutants Cr(VI).•PANI-NSA@Ni0′s affinity towards to Cr(VI) is not significantly affected by common competing ions.•The adsorption-coupled reduction process responsible for Cr(VI) removal by PANI-NSA@Ni0 is best described by a transient Langmuir-Hinshelwood type model.•Mechanistic models such as the transient Langmuir-Hinshelwood kinetic model provide the compartment-independence required for continuous-flow adsorption system design.•Cr(VI) adsorption onto PANI-NSA@Ni0 significantly reduces the crystallinity of the highly-crystalline Ni0 nanoparticles during adsorption. A nanocomposite of 2-napthalenesulfonic acid doped-polyaniline decorated with zero valent nickel nanoparticles (PANI-NSA@Ni0), was considered for the removal of hexavalent chromium from synthetic effluent. Adsorption conditions (pH, dose) were optimised, and parameters necessary for the design of PANI-NSA@Ni0-based adsorption equipment (adsorbent capacity, kinetic constants, etc.) were estimated from batch adsorption experiments. PANI-NSA@Ni0 successfully achieves total hexavalent chromium removal at a dose of 0.6 g/L, corresponding to a Cr(VI) loading of 333.3 mg/g, and when 2