Modified activated carbon as a promising adsorbent for quinoline removal

Activated carbon from coconut shell (Elaeis guineensis), in crude form and as forms chemically modified with concentrated solutions of HNO3 and H2SO4, were initially tested for their ability to remove quinoline from an organic medium. The adsorbents were characterised by techniques such as adsorption/desorption of N-2 at 77 K, the point of zero charge, the Boehm method, infrared spectroscopy, thermogravimetric/differential thermal analysis, X-ray photoelectron spectroscopy and CHNOS elemental analysis. The best results of contaminant removal were achieved using sulfuric acid-treated activated carbon (SAAC). With regard to its potential in quinoline removal, SAAC was evaluated in a closed batch system by a phenomenological investigation of the adsorption process, using experimental data and mathematical modelling of kinetics and equilibrium. The maximum adsorption capacity (q(max)) obtained by the Langmuir model was 56.6 mg g(-1). The kinetic results obtained for different concentrations of quinoline showed that the internal resistance model, with variable mass transfer coefficient, suitably describes the quinoline adsorption process in a batch system. Therefore, such model should be used for the optimisation and design of industrial-scale columns for the investigated, and similar, systems.