ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Comparative evaluation of classical and response surface methodologies approaches for 4-nitroaniline adsorption onto flamboyant seed carbon

Samsudeen Olanrewaju Azeez, Ismaila Olalekan Saheed, Akeem Adebayo Jimoh, Abdullahi Mohammed, and Faiz Bukhari Mohd Suah

Department of Chemistry and Industrial Chemistry, Kwara State University, Ilorin, Nigeria

E-mail: fsuah@usm.my

Received: 5 August 2025  Accepted: 26 September 2025

Abstract:

The flamboyant seed’s activated carbon (FSAC) was carefully studied as a promising adsorbent for removing 4-nitroaniline (4-NA) from an aqueous solution. The comparison between classical methods and response surface methodology (RSM) on operating conditions, including initial 4-NA concentration, pH level, adsorbent dose, and adsorption time, was conducted with great care and attention to detail. In the classical approach, the four operating parameters affected the adsorption capacity of FSAC, which increased with higher initial 4-NA concentrations and longer contact times. Adsorption was enhanced at low pH levels, with equilibrium reached at 120 min. In RSM, the amount of 4-NA adsorbed increased as concentrations rose, pH decreased, and adsorbent dosage was reduced. The quadratic model successfully described the relationship between adsorption and the operating parameters (R² = 0.929). The optimal adsorption capacity of 40.4 mg/g was achieved at 300 mg/L 4-NA concentration, pH 2, 0.1 g of adsorbent, and an adsorption time of 362.5 min. The Freundlich isotherm and pseudo-second-order kinetic models best explain the adsorption process, confirming the thoroughness and reliability of this research.

Keywords: 4-nitroaniline; Adsorption; Isotherm; Kinetics; Activated carbon; Pollutant

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04411-y

Chemical Papers 80 (1) 577–588 (2026)