Adsorptive Detoxification of m-Cresol from Wastewater using nano La₂NiMnO₆ Double Perovskites

Abstract

A simple sol-gel method was developed to synthesize La₂NiMnO₆ (LNMO) double perovskite in nano dimensions, which was evaluated for the effective adsorptive removal of m-cresol from aqueous solutions. The structural and chemical properties of the synthesized LNMO were characterized using X-ray Diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The LNMO material possessed a hexagonal crystal structure and an average particle size of approximately 50 nm, which contributed to improving adsorptive properties. Furthermore, adsorption studies revealed that m-Cresol removal is significantly pH dependent, as maximum adsorption was found at pH 2. As a weak acid, m-cresol exists in its neutral form in acidic conditions and promotes interaction through hydrogen bonding and Lewis acid-base interactions with LNMO's surface. Moreover, adsorption isotherms were analyzed using Langmuir, Freundlich, and Temkin model where the Langmuir model fitted the best, indicating a maximum adsorption capacity of 204 mg/g while the values of Langmuir equilibrium constant (K_L) of 0.1158 L/mg, and a dimensionless constant (R_L) of 0.256, suggesting a favorable adsorption process. Thermodynamic parameters like Gibbs free energy (ΔG^o), enthalpy (ΔH^o), and entropy change (ΔS^o) were analyzed, and it revealed that the adsorption process is spontaneous, heat-releasing, and leads to reduced randomness at the solid-liquid interface. Hence, this study demonstrates the exceptional potential of LNMO as an efficient, cost-effective adsorbent for m-cresol removal, offering valuable insights for the development of novel material for wastewater treatment.

Dhaka Univ. J. Sci. 74(1): 17-26, 2026 (January)