Adsorption of ammonium from aqueous solutions on environmentally friendly barbecue bamboo charcoal: Characteristics and kinetic and thermodynamic studies

Abstract

Environmentally friendly barbecue bamboo charcoal (EFBBC), an inexpensive biosorbent, was successfully used to remove ammonium (NH4+) from aqueous solutions. The effects of contact time, pH, initial concentration, average particle size, biosorbent dosage, and temperature on NH4+ removal were investigated. Biosorption conditions were as follows: contact time, 80 min; pH, 6.0–10; initial concentration, 60 mg/L; optimum particle size, 0.075–0.180 mm; biosorbent dosage, 4.0 g/L; temperature, 30°C. To investigate adsorption mechanisms, pseudo‐first‐order, pseudo‐second‐order, Elovich, and intraparticle diffusion models were fit to experimental results. Results indicated that kinetic data for NH4+ adsorption were better described by the pseudo‐second‐order model. Also, the Langmuir, Freundlich, and Temkin models were employed to analyze equilibrium data. Results indicated that the Freundlich isotherm best represented the data for NH4+ adsorption. Changes in the standard free energy, enthalpy, and entropy were also evaluated: the reaction was spontaneous and endothermic. The EFBBC surface was analyzed by X‐ray diffraction, scanning electron microscopy, X‐ray energy dispersive spectrometry, and Fourier transform infrared spectrometry. From the results, it was proposed that the adsorption behavior of NH4+ on the EFBBC surface depends on the internal structure and chemical composition, and the results highlight the need to understand specific surface characteristics. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 655–662, 2015