Biosorption of hexavalent chromium from aqueous solution using raw and acid-treated biosorbent prepared from Lantana camara fruit

Abstract

The aim of the present investigation was to explore the performance of the acid-treated Lantana camara fruit biosorbent in binding hexavalent chromium from aqueous solutions. FTIR studies revealed the contribution of carbohydrates, glycosides, and flavonoids in the biosorbent. EDS analysis exhibited the occurrence of chromium ions after biosorption, whereas SEM image exposed the enhancement of porosity after acid treatment. The isotherm models such as Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin models were studied to depict the mechanism of interaction of the biosorbent with the adsorbate. Besides isotherm models, kinetic studies like pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were also performed to validate the controlling mechanism of biosorption. Langmuir model showed a better fit favoring monolayer adsorption and a high correlation value from the pseudo-second-order model suggests chemisorption. To understand whether the biosorption process releases or absorbs energy, thermodynamic analysis was carried out. The outcome of the findings showed endothermic nature of the process with increased randomness at the solid solution interface. Regeneration studies showed better results with 0.2M NaOH solutions. The obtained maximum uptake capacity of 83 mg/g with a minimal biomass dosage proves the credible potential of the selected biosorbent in removing toxic hexavalent chromium.