This research focuses on the enhancement of the biosorption process via apple waste (a cheap adsorbent) for the treatment of heavy metals (including Cu2+, Cd2+, Zn2+ and Pb2+). The apple pomace modified by potassium permanganate (ACAPMP), apple pomace modified by sodium hydroxide (APMSH) and activated carbon apple pomace (ACAP) were synthesized as adsorbents for the removal of heavy metals. The prepared biomass adsorbents were analyzed by FTIR, BET, EDS and FE-SEM. The Box-Behnken design was applied to optimize the process. The influence of pH, the time of removal, the type of adsorbent and concentration of heavy metal on the adsorption performance were investigated by batch experiments. The results revealed that ACAP, APMS and ACAP adsorbents were able to remove approximately 95% of zinc, cadmium, lead and copper from wastewater. The ACAPMP indicated the best performance compared to other adsorbents in optimal condition. Also, the results exhibited excellent removal performance for Pb2+, Zn2+, Cu2+ and Cd2+ with maximum adsorption percent 99.72%, 99.28%, 99.18% and 96.45%, respectively. To define the best correlation, the equilibrium data for adsorption were studied by using Langmuir and Freundlich isotherm models. The FTIR, BET and EDS characterization of functional groups and morphology confirm the suitable preparation of ACAPMP, ACAP and APMSH. The adsorption results indicate that apple waste as low-cost and high surface capacity adsorbents can be used
