Competitive Adsorption of Neutral Red and Cu2+ onto Pyrolytic Char: Isotherm and Kinetic Study

Pyrolytic char treated with muffle furnace (TPC) was used as an adsorbent for the removal of neutral red (NR) and Cu2+ from aqueous solutions in a batch system. The adsorption behavior of NR and Cu2+ in single and binary systems on the TPC was studied. For a single system, the NR and Cu2+ adsorption isotherm followed Langmuir and Redlich-Peterson models with a maximum adsorption capacity of (0.216 and 0.261) mmol.g(-1), respectively. The adsorption kinetics of NR and Cu2+ followed both the pseudosecond-order and Elovich equations. The diffusion process with two stages for NR and Cu2+ can describe the adsorption process. For a binary system, NR and Cu2+ showed competitive adsorption on the TPC. The adsorption isotherm of NR and Cu2+ still followed the Langmuir model, and the adsorption kinetic models of NR and Cu2+ still followed the pseudosecond-order kinetic model, while the diffusion process of NR was single-stage and two-stage for Cu2+. The adsorption capacity of NR and Cu2+ is reduced compared with that in a single system, but the total adsorption capacity is higher. TPC has a higher affinity toward Cu2+ over NR