Taguchi optimisation studies for removal of hexavalent chromium using magnetic chitosan crosslinked tripolyphosphate/TiO₂ hybrid nanocomposite

ABSTRACT

Chromium contamination has been a concern over decades owing to its carcinogenic and determinantal impact on human health. The study aims to develop an easy to synthesise environment-friendly material capable of removing Cr(VI) from phenolic wastewater. To this end, a novel hybrid composite in the form of magnetic chitosan crosslinked tripolyphosphate functionalised with titanium dioxide (CFTPP/TiO₂) was prepared using a simple reduction-precipitation technique. Taguchi optimisation study showed that maximum Cr(VI) adsorption could be achieved at optimum synthesis conditions of 90% CFTPP concentration, duration 60 min at room temperature. Similarly, the taguchi optimised adsorption process yielded maximum Cr(VI) removal of 94.36% at pH (2), composite dose (0.8 g), and initial chromium (20 mg L⁻¹) in an equilibrium time of 270 min. Successful formation of composite having a rough surface with broad pore size distribution was further verified using characterisation techniques like FTIR, FESEM-EDX, BET and XRD. Adsorption studies showed that process is mostly chemisorption aligning best with Freundlich isotherm and pseudo second-order kinetics having the maximum adsorption capacity of 82.89 mg g⁻¹. The composite showed good reuse potential and maintained removal efficiencies around 80% even after five cycles. It was observed that %CFTPP concentration in the composite played a significant role in the behaviour of the composite as a photocatalyst in which 35% CFTPP demonstrated higher photocatalytic performance. Higher Cr(VI) removal efficiencies of 70.88% and 98.74% were attained under both visible and UV light respectively on treating 50 mg L⁻¹ Cr(VI) in an irradiation time of 420 min. The research findings demonstrate that CsFe@TPP/TiO₂ composite as an environment-friendly material is capable of providing synergistic effect in adsorption and oxidation of chromium contaminated wastewaters.

KEYWORDS:

• Taguchi
• adsorption
• chitosan
• titanium dioxide
• Cr(VI)
• photocatalysis

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data will be made available on request.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03067319.2023.2277332.

Additional information

Funding

This research was financially supported by National Institute of Technology, Rourkela.