The effect of head group of surfactant on the adsorption of methyl red onto modified coffee residues

•The effect of the head group of a zwitterionic and a cationic surfactant on the methyl red dye adsorption onto modified coffee residues was evaluated.•Macroscopic data fit better with a pseudo second order kinetic and equilibrium data agreed better with Langmuir isotherm model.•Adsorption capacity of methyl red was enhanced with the zwitterionic loading coffee residues.•Adsorption mechanisms involve hydrogen bonds, electrostatic and hydrophobic interactions.