Papers by Keyword: Metal Ion Adsorption

Abstract: The potential of rice husk-based activated carbon (RHAC) as an alternative low-cost adsorbent for the removal of Ni²⁺ from aqueous solution was studied. RHAC was prepared via chemical treatment using NaOH followed by the carbonization process. The textural properties of rice husk-based activated carbon, i.e. surface area (253 m²/g) and pore volume (0.17 cm²/g), were determined by N₂ adsorption. The adsorption studies to remove Ni²⁺ from aqueous solution using RHAC were carried out at a fixed initial concentration of Ni²⁺ (150 ppm) with varying RHAC as a function of contact time at room temperature. The concentration of Ni²⁺ was determined by atomic absorption spectrophotometer (AAS). The maximum removal of Ni²⁺ was increased from 40% to 89% when the amount of RHAC was increased from 0.1 g to 0.5 g. The isotherm and kinetic analyses showed that equilibrium data of adsorption studies fitted well Langmuir, Freundlich and second order kinetic models.

Abstract: The potential of rice husk-based activated carbon as an alternative low-cost adsorbent for the removal of Pb (II) ion from aqueous solution was investigated. Rice husk-based activated carbon was prepared via chemical activation process using NaOH followed by the carbonization process at 500°C. Morphological analysis was conducted using field-emission scanning electron microscope /energy dispersive X-ray (FESEM/EDX) on three samples, i.e. raw rice husk, rice husk treated with NaOH and rice husk-based activated carbon. These three samples were also analyzed for their C, H, N, O and Si contents using CHN elemental analyzer and FESEM/EDX. The textural properties of rice husk-based activated carbon, i.e. surface area (253 m²/g) and pore volume (0.17 cm²/g), were determined by N₂ adsorption. The adsorption studies using rice husk-based activated carbon as an adsorbent to remove Pb (II) ion from aqueous solution were carried out at a fixed initial concentration of Pb (II) ion (150 ppm) with varying adsorbent dose as a function of contact time at room temperature. The concentration of Pb (II) ion was determined by atomic absorption spectrophotometer (AAS). The removal of Pb (II) ion from aqueous solution increased from 35 % to 82 % when the amount of rice husk-based activated carbon was increased from 0.05 g to 0.30 g. The equilibrium data obtained from adsorption studies was found to fit both Langmuir and Freundlich adsorption isotherms.

Abstract: A ferritin mutant A1C with 24 free SH groups on its outer surface was prepared, which was successfully cross-linked to hen eggshell membrane outer layer (ESM-OL) by a disulfide linkage as characterized by SEM and TEM. Generally, this ferritin conjugated ESM-OL (Ft-ESM-OL) exhibited a significantly higher activity of heavy metal ion uptake as compared to ESM-OL alone under the same experimental conditions. For example, the adsorption capacity of Ft-ESM-OL for U⁶⁺ and Fe²⁺ were 21.16% and 18.4% higher than that of natural ESM-OL, respectively. On the other hand, the recovery capacity of Fe²⁺ by Ft-ESM-OL was 8.11 mg/g ESM, a value 67.9% higher than that of natural ESM-OL. Thus, this newly ferritin-modified ESM-OL greatly improved the adsorption and recovery efficiency of heavy metal ion as compared to ESM-OL alone.

Abstract: Glutaraldehyde cross-linked Poly (vinyl alcohol)/Polyvinylamine (PVA/PVAm) membranes for removal of metal ions from aqueous solution were prepared by solution casting and solvent evaporation techniques. The membranes were characterized using XRD, Swelling studies and metal ions adsorption experiments. The results show that PVA/PVAm membranes exhibit semi-crystalline natures as PVA macromolecular, however, the degree of crystallinity of membranes decrease as PVAm increased. The membranes were pH-sensitive and the swelling ability of membranes was significantly enhanced. It was found that the change of swelling behavior versus pH was consistent with the change of degree of ionization versus pH. The amount of Cu²⁺ ions adsorbed increased as PVAm increased as well as increasing pH of solution in the range of 2.5~6.0.