Characterization of the Adsorption Mechanism of Cadmium(II) and Methylene Blue upon Corncobs Activated Carbon

GÜNDOĞDU A., Bozbeyoglu P., Imamoglu M., Baltaci C., DURAN C., BULUT V. N.

ANALYTICAL LETTERS, 2022 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2022
  • Doi Number: 10.1080/00032719.2022.2098310
  • Journal Indexes: Science Citation Index Expanded, Scopus, Academic Search Premier, Aerospace Database, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, Biotechnology Research Abstracts, CAB Abstracts, Chemical Abstracts Core, Chimica, Communication Abstracts, Food Science & Technology Abstracts, Metadex, Veterinary Science Database, Civil Engineering Abstracts
  • Keywords: Adsorption mechanism, cadmium(II) (Cd2+), corncob activated carbon, methylene blue, AQUEOUS-SOLUTION, DYE ADSORPTION, METAL-IONS, CHEMICAL ACTIVATION, REMOVAL, CD(II), ACID, EQUILIBRIUM, ADSORBENT, OXIDES


A promising new activated carbon (AC) was produced from corncobs (CCs) by boric acid-based chemical activation to remove methylene blue (MB) as an organic pollutant and cadmium ions (Cd2+) as an inorganic pollutant from aqueous solutions. After the produced activated carbon (CCs-AC) was characterized, the adsorption mechanism of CCs-AC, which is one of the most interesting topics in the literature, was the primarily focus. The possible adsorption mechanisms of Cd2+ and MB on CCs-AC from aqueous solutions are discussed with respect to pH, thermodynamic values, and regeneration parameters. The results show that the adsorption of Cd2+ on CCs-AC was favorable at pH values higher than 4. In contrast, the adsorption process was almost pH-independent for MB. Variation of pH showed that the adsorption of Cd2+ on CCs-AC primarily occurs by electrostatic interaction. However, MB adsorption may also involve pi-pi dispersion forces and partial hydrogen bonding. The Cd2+ adsorbed on CCs-AC was quantitatively desorbed by HCl, whereas MB was not desorbed quantitatively by any solution. While a temperature increase has a positive effect on the adsorption of both methylene blue and Cd2+, the thermodynamic results show that MB adsorption is primarily chemisorption (Delta H of 24.28 kJ/mole), while Cd2+ adsorption is mostly physisorption (Delta H of 7.20 kJ/mole). Using Langmuir adsorption isotherms, the MB adsorption capacity of CCs-AC, which primarily has a microporous structure, was 0.88 mmol/g, while the Cd2+ adsorption capacity was 1.28 mmol/g.