Pecan shell based activated carbon for removal of iron(II) from fracking wastewater: Adsorption kinetics, isotherm and thermodynamic studies

Pecan shell based activated carbon (PSBAC) developed in this work had a high specific surface area (1500 m2/g) and pore volume (0.7 cm3/g). The maximum adsorption capacity of the PSBAC was found to be 41.66 mg/g at 55 mg/L iron(II), pH = 3, 3 g/L adsorbent dose, at 90 min and at 30 °C. Iron(II) adsorption can be best described by the pseudo second order model. The adsorption system was thermodynamically favorable, endothermic and increase in entropy. The experimental data were fitted against common adsorption isotherms and yielded excellent fits in the following order: Temkin > Freundlich > Sips > Halsey Dubinin-Radushkevich > Langmuir > Harkins-Jura > Redlich-Peterson > Elovich.