Keywords: bovine bone, bone char, 2,4–dinitrophenol, 2,4–DNP, Langmuir isotherm, Freundlich isotherm, Redlich–Paterson isotherm, Toth isotherm, adsorption kinetics, nitrogen adsorption isotherms, modelling
Study of 2,4–dinitrophenol adsorption from aqueous solution on bovine bone char
A sample of bovine bone, an industrial by–product, was submitted to carbonisation at 800°C for 2 h at a heating rate of 3°C min−1 and a N2 flow of 80 cm3 min−1. The char obtained was characterised by nitrogen adsorption isotherms at 77 K using scanning electron microscopy, X–ray diffraction and Fourier transform infrared spectroscopy. The textural parameters showed a surface area of 171 m2 g−1, pore volume of 0.07 cm3 g−1 and morphological characteristics of meso– and macroporous material. Additionally, adsorption isotherms of 2,4–dinitrophenol (2,4–DNP) were made on the char obtained, and the adsorption behaviour was studied using the models of Langmuir, Freundlich, Redlich–Paterson and Toth. Of these, the one that best describes the adsorption system was the Toth model, which indicates a multilayer adsorption. The adsorption capacity of 2,4–DNP was 41.3 mg L−1, from a model solution of 100 mg L−1. Finally, we evaluated the adsorption kinetics, correlating the experimental data with pseudo–first–order and pseudo–second–order models. It was found that the chemical kinetics of the removal of 2,4–DNP in the bovine char was described by the pseudo–second–order equation, which represented the chemisorption between the adsorbate and adsorbent in a monolayer on the surface.