Removal of phenol from aqueous solution by Mahua seed activated carbon: Kinetic, isotherm, mass transfer and isosteric heat of adsorption studies

Abstract

Article Highlights• Pseudo-second order kinetic model primarily governed the phenol uptake process • The average effective diffusivity (6.4×10 -13 m 2 /s) of phenol was estimated using the Boyd model • The maximum uptake of phenol (54 mg/g) was obtained at 333 K • Overcome the difficulty of recovering the photocatalyst after use • The negative values of ΔG indicate that the sorption of phenol was spontaneous Abstract Mahua (Madhuca longifolia) seed activated carbon (MSAC) has been developed as an effective adsorbent for the removal of phenol from contaminated wastewaters. The prepared MSAC was characterized for various physicochemical properties, by Fourier transform infra-red (FTIR) and scanning electron microscopy (SEM) analysis. Laboratory batch experiments were performed to investigate the effect of MSAC dosage (w), pH, contact time (t), and initial phenol concentration (c o ) on sorption efficiency at optimal conditions. The maximum adsorption capacity of phenol was obtained at pH 6, t = 5 h and MSAC dosage = 1.2 g/l. The kinetics data of phenol adsorption was very well described by the pseudo-second-order kinetic model. The equilibrium adsorption data were best fitted to the Langmuir isotherm. The average effective diffusion coefficient 6.4×10 -13 m 2 /s was calculated from the experimental data. Thermodynamic studies confirmed the sorption process to be spontaneous and exothermic. The isosteric heat of adsorption of phenol was found to increase with an increase in the surface loading indicating that MSAC have more homogeneous surface.