Removal of noxious dye—Acid Orange 7 from aqueous solution using natural pumice and Fe-coated pumice stone

•Pumice, is a type of volcanic rock with high porosity, and Fe-coated pumice were used as adsorbents.•The qmax of the NP and Fe-CP were found to be 15.56 and 27.68mg/g, respectively.•The use of such adsorbents is very promising since they are cheap and readily available. Rapid removal of the Acid Orange 7 (AO7) from aqueous solutions using natural pumice (NP) and Fe-coated pumice (Fe-CP) as low-cost adsorbents was well investigated and elucidated. The impact of several influential parameters such as initial pH, initial AO7 concentration and contact time on the adsorption of AO7 removal was studied and optimized. The good agreement of adsorption equilibrium data and analysis of isotherms with the Freundlich isotherm proved that it is the best fitted adsorption isotherm model for the depicting the AO7 adsorption on both the developed adsorbents, which clearly indicates the heterogeneity of the adsorbent surface. The maximum adsorption capacities for the NP and Fe-CP were found to be 15.56 and 27.68mg/g, respectively. The rate of adsorption followed the pseudo-second-order kinetic model.