Effective and sustainable methylene blue removal from wastewater using palm kernel cake

= 0.999) best described the adsorption rate, indicating intraparticle diffusion controlled physical adsorption confirmed by an activation energy of 37.8 kJ/mol. Thermodynamic analysis revealed a spontaneous (ΔG° = - 3.98 to - 4.25 kJ/mol), endothermic (ΔH° = 1.47 kJ/mol) process. The adsorption process is mainly physical, which depends on the electrostatic attraction, hydrogen bonding, π-π stacking, and intraparticle diffusion as shown in the Weber-Morris, Boyd, FTIR, and SEM analyses. PKC maintained a high adsorption efficiency of 96.5% even after four regeneration cycles, which showed great reusability and high potential of sustainable treatment of textile wastewater.