Removal of Arsenate by Fixed-Bed Columns Using Chitosan-Magnetite Hydrogel Beads and Chitosan Hydrogel Beads: Effect of the Operating Conditions on Column Efficiency

Abstract

Fixed-bed columns packed with chitosan-magnetite (ChM) hydrogel and chitosan (Ch) hydrogel were used for the removal of arsenate ions from aqueous solutions at a pH of 7.0. The effect of flow rate (13, 20, and 25 mL/h), height of the columns (13 and 33 cm), and initial arsenate concentration (2, 5 and 10 mg/L) on the column’s efficiency for the removal of As(V) is reported. The maximum adsorption capacity (qb), obtained before the allowed concentration of contaminant is exceeded, the adsorption capacity (qe) when the column is exhausted, and the mass transfer zone were determined. With this information, the efficiency of the column was calculated, which is given by the HL/HLUB ratio. The higher this ratio, the higher the efficiency of the column. The highest efficiency and the highest uptake capacity value at breakthrough point were obtained when using the lower flow rate, lower initial arsenate concentration, and longer bed length. When 33 cm-high columns were fed with a 10 mg As(V)/L solution at 13 mL/h, the maximum uptake capacity values at exhaustion obtained for Ch and ChM were 1.24 and 3.84 mg/g, respectively. A pH increase of the solution at the column’s exit was observed and is attributed to the proton transfer from the aqueous solution to the amino and hydroxyl groups of chitosan. The incorporation of magnetite into Ch hydrogels significantly increases their capacity to remove As(V) due to the formation of complexes between arsenic and the magnetite surface. Experimental data were fitted to the Thomas model, the Yoon–Nelson model and the Bohart–Adams model using non-linear regression analysis.

Adsorption of Levofloxacin onto Graphene Oxide/Chitosan Composite Aerogel Microspheres

“…Levofloxacin (LOF) is a broad-spectrum antibiotic whose structure contains nitrogen, oxygen, and fluorine atoms, negatively charged groups (-COOH), and aromatic rings (quinolones) [32]. As mentioned in the description of the FTIR analysis, the obtained GO/CS composites can easily form hydrogen bonds, electrostatic attraction, and π-π stacking interactions with LOF [15,33,34]. The fabricated GO/CS aerogel microspheres were used for the removal of LOF with variations in experimental parameters, such as GO content, solution pH value, temperature, initial concentration, and contact time.…”

Efficient Chlorostannate Modification of Magnetite Nanoparticles for Their Biofunctionalization

“…Therefore, non-covalent approaches for binding biomolecules to MNPs are also under consideration. Typically, MNPs are initially modified with polymers or hydrogels to facilitate non-covalent bonds with biomolecules or drugs [23]. In such cases, non-covalent interactions between the capped nanoparticles and biomolecules or drugs are explored [24,25].…”