The objective of this research was to evaluate the adsorption capacity of the shell biomass ( Dioscorea rotundata), taking into account the impact of temperature, bed height, and particle size on the removal of nickel(II) ions in aqueous solution in a continuous fixed-bed column system; performing the modelling of the break curve. The biomass was characterised by SEM-EDS analysis. The analysis found that it represents a rough, heterogeneous structure, rich in carbon and oxygen, with mesopores, and is suitable for removing heavy metals. It also determined the optimum parameters of the bed height, particle size, and temperature, keeping the pH and the initial concentration of the solution constant. The results revealed that the bed height and the particle size are the two most influential variables in the process. Ni(II) removal efficiencies range between 85.8 and 98.43%. It was found that the optimal conditions to maximise the efficiency of the process are temperature of 70°C, 1.22 mm particle size, and 124 mm bed height. The break curve was evaluated by fitting the experimental data to the Thomas, Adams–Bohart, Dose–Response, and Yoon– Nelson models, with the Dose–Response model showing the best affinity with a coefficient of determination R2 of 0.9996. The results obtained in this research showed that yam shell could be suggested as an alternative for use in the removal of Ni(II) ions present in an aqueous solution in a continuous system.

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.

In the present study, the removal capacity of Pb(II) ions was investigated using the biomass of dried cattle manure in an aqueous solution. The biomaterials were characterized using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) techniques. The results reveal that the adsorption mechanism may be associated with the interaction between Pb(II) ions and functional groups through aggregation, coordination, ion exchange, microprecipitation, oxidation, and hydrophobicity. The bio-adsorption of the metal was analysed in discontinuous tests; the effect of temperature, pH, agitation, and adsorbent dose was evaluated. The maximum adsorption capacity was determined at pH 7.5, 18°C and 200 rpm. The bio-adsorption of Pb(II) was best fitted to the pseudo-second order model. The experimental data of the isotherm were adjusted to the models of Langmuir, Freundlich and Dubinin–Radushkevich; while Langmuir’s model related better to the experimental data forming a single layer at saturation. The rate of adsorption was rapid, reaching equilibrium after 25 min and removal of 96.8%. Thermodynamic parameters determined that the process was viable, spontaneous, and exothermic. The present study contributes mainly to demonstrating that a biomaterial prepared from bovine manure is a promising adsorbent for heavy metals such as Pb(II). It also reduces the environmental impact of this waste through the generation of greenhouse gases in countries that maintain intensive livestock. Another important aspect is the reduction of the micro- and macronutrients accumulation in soil and contamination of surface waters and aquifers by runoff and seepage during rainy periods.