New insights on the adsorption of phenol red dyes from synthetic wastewater using activated carbon/Fe2(MoO4)3

Water shortage is considered as one of the main challenges of human life. A practical solution to this problem is the wastewater treatment. The removal of dyes from wastewaters has received considerable critical attention by researchers due to their high volume and toxicity. In the current research, the adsorption of phenol red dyes from synthetic wastewater using the activated carbon produced from Mespilus germanica modified with Fe2(MoO4)3 was studied. The proposed adsorbent was characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX)/Map, Brunauer–Emmett–Teller (BET), and Raman techniques. The optimal adsorption operating parameters including pH, stirring rate, temperature, dosage of adsorbent, dye initial concentration, and contact time were 3, 500 rpm, 25 °C, 1 g/L, 10 mg/L, and 60 min, respectively. Furthermore, the successful regeneration of the adsorbent for 3 times, using methanol solution as a regeneration medium, denoted its capability in performing adsorption and desorption processes. Equilibrium studies showed that the adsorption of phenol red dyes by activated carbon (AC)/Fe2(MoO4)3 was desirable and physical and the experimental data were fitted well by the Freundlich model. In addition, the kinetic behavior of the current adsorption process was well described by the pseudo-second-order kinetic model, while thermodynamic calculations showed that the process was exothermic and spontaneous.