Adsorption Kinetics of Methyl Orange from Model Polluted Water onto N-Doped Activated Carbons Prepared from N-Containing Polymers

Abdel-Basit Al-Odayni; Faisal S Alsubaie; Naaser A Y Abdu; Haifa Masfeer Al-Kahtani; Waseem Sharaf Saeed

doi:10.3390/polym15091983

Adsorption Kinetics of Methyl Orange from Model Polluted Water onto N-Doped Activated Carbons Prepared from N-Containing Polymers

Polymers (Basel). 2023 Apr 22;15(9):1983. doi: 10.3390/polym15091983.

Authors

Abdel-Basit Al-Odayni¹, Faisal S Alsubaie², Naaser A Y Abdu², Haifa Masfeer Al-Kahtani², Waseem Sharaf Saeed¹

Affiliations

¹ Engineer Abdullah Bugshan Research Chair for Dental and Oral Rehabilitation, College of Dentistry, King Saud University, Riyadh 11545, Saudi Arabia.
² Department of Chemistry, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.

Abstract

This study aimed to assess the role of polymeric sources (polypyrrole, polyaniline, and their copolymer) of nitrogen (N)-doped activated carbons (indexed as PAnAC, PPyAC, and PnyAC, respectively) on their adsorption efficiency to remove methyl orange (MO) as a model cationic dye. The adsorbents were characterized using FTIR, SEM, TGA, elemental analysis, and surface area. The kinetic experiments were performed in batches at different MO concentrations (C₀) and adsorbent dosages. The adsorption kinetic profiles of pseudo-first-order, pseudo-second-order (PSO), Elovich, intraparticle diffusion, and liquid film diffusion models were compared. The results showed a better fit to the PSO model, suggesting a chemisorption process. The adsorption capacity (q_e, mg/g) was found to have increased as MO C₀ increased, yet decreased as the adsorbent quantity increased. At the adsorption operating condition, including MO C₀ (200 ppm) and adsorbent dose (40 mg), the calculated q_e values were in the order of PAnAC (405 mg/g) > PPyAC (204 mg/g) > PnyAC (182 mg/g). This trend proved the carbon precursor's importance in the final properties of the intended carbons; elemental analysis confirmed that the more nitrogen atoms are in the activated carbon, the greater the number of active sites in the adsorbent for accommodating adsorbates. The diffusion mechanism also assumed a rate-limiting step controlled by the film and intraparticle diffusion. Therefore, such an efficient performance may support the target route's usefulness in converting nitrogenous-species waste into valuable materials.

Keywords: activated carbon; adsorption kinetic; methyl orange; nitrogen-containing polymers; polyaniline; polypyrrole; water treatment.

Grants and funding

The authors extend their appreciation to the Deputyship for Research and Innovation, Ministry of Education in Saudi Arabia for funding this research work through project no. IFKSURG-2-1468.