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The adsorption mechanisms of methylene blue (MB) onto olive waste (residue) treated with KOH (OR-KOH) and onto an OR-KOH and PEG–silica gel composite (OR-KOH/PEG-SG) at various temperatures were investigated using a combination of experimental analysis and Monte Carlo ab-initio simulations. The effects of adsorption process variables such as pH, temperature, and starting adsorbate concentration were investigated. The experimental data were fitted to Langmuir and Freundlich models. The maximum adsorption capacities of MB onto OR-KOH and OR-KOH/PEG-SG adsorbents reached values of 504.9 mg/g and 161.44 mg/g, respectively. The experimental FT-IR spectra indicated that electrostatic attraction and hydrogen bond formation were critical for MB adsorption onto the adsorbents generated from olive waste. The energetic analyses performed using Monte Carlo atomistic simulations explained the experimental results of a differential affinity for the investigated adsorbents and confirmed the nature of the interactions between methylene blue and the adsorbents to be van der Waals electrostatic forces.

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International audienceThe present work aimed to investigate the removal feasibility of organic micropollutants (o-nitrophenol (o-NP) and p-nitrotoluene (p-NT)) from aqueous solutions using an original activated carbon prepared from chicken bones (CAB). The activated carbon is treated with 30% H2O2 and carbonised at 800 degrees C for 3h. Thus, the obtained CAB is characterised by the way of different physico-analytical methods as X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and the method of Boehm titration. The kinetic experimental data were fitted according to theoretical models: pseudo-first-order, pseudo-second-order, intraparticle diffusion models and the Elovich and Avrami models. The maximum removal obtained for o-NP and p-NT is around similar to 80% at 5-20mg/L respectively. The required time for the adsorption equilibrium is between 70 and 145min. The adsorption kinetics of o-NP and p-NT is tested according to the intraparticle diffusion equations. The results obtained in the present study indicate that the bioadsorbent material CAB is a promising adsorbent for the removal of organic micropollutants from wastewater