Chrome(VI) ion biosorption modelling in a fixed bed column on Dioscorea rotundata hull

Abstract

This work aimed to evaluate the yam peel in a bed column packaged as a chromium(VI) ion adsorbent in an aqueous solution. Yam peel was used as adsorbent, prior washing, drying, size reduction, and selection. The experimental work consisted in determining the effect of bed depth, particle size, and temperature, keeping inlet flow = 0.75 cm 3∙s –1, pH = 2 and initial concentration of 100 mg∙dm –3. The Adsorption Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDS) analysis on yam ( Dioscorea rotundata) peel showed a heterogeneous, porous structure, with functional groups characteristic in lignocellulosic materials. It was analysed regarding the influence of temperature, bed height, and adsorbent particle size on the removal efficiency; it was found that the decrease of particle size and the increase of the bed height favour the elimination of the metallic ion, with removal rates between 92.4 and 98.3%. The bed maximum adsorption capacity was 61.75 mg∙g –1, and break time of 360 min. The break curve’s adjustment to the Thomas, Yoon–Nelson, Dose–Response and Adams–Bohart models was evaluated, concluding that the Yoon–Nelson and Dose–Response models best described the behaviour of the break curve with a coefficient of determination ( R2) of 0.95 and 0.96, respectively. The results show that the bio-adsorbent studied can be used to eliminate Cr(VI) in a continuous system.