C. Laginhas

Phenol removal onto novel activated carbons made from lignocellulosic precursors: influence of surface properties.

The adsorption of phenol from dilute aqueous solutions onto new activated carbons (AC) was studied. The novel activated carbon was produced from lignocellulosic (LC) precursors of rapeseed and kenaf. Samples oxidised with nitric acid in liquid phase were also studied. The results have shown the significant potential of rapeseed and kenaf for the activated carbon production. The activated carbons produced by carbon dioxide activation were mainly microporous with BET apparent surface area up to 1350 m(2)g(-1) and pore volume 0.5 cm(3)g(-1). The effects of concentration (0.1-2 mM) and pH (3-13) were studied. The phenol adsorption isotherms at 25 degrees C followed the Freundlich model with maximum adsorption capacities of approximately 80 and 50 mg g(-1) for the pristine and oxidised activated carbons, respectively. The influence of pH on the adsorption has two trends for pH below and above 10. It was possible to conclude that when phenol is predominantly in the molecular form the most probable mechanism is based on the pi-pi dispersion interaction between the phenol aromatic ring and the delocalised pi electrons present in the activated carbon aromatic structure. When phenolate is the major component the electrostatic repulsion that occurs at high pH values is the most important aspect of the adsorption mechanism.

Removal of Amitriptyline from Aqueous Media Using Activated Carbons

This paper reports the removal of amitriptyline, a widely used tricyclic anti-depressant, from aqueous solutions by six activated carbons produced from cork, coffee endocarp and eucalyptus pulp. The results of this study showed that samples from cork and eucalyptus pulp, activated at 800 °C, exhibited the highest adsorption capacity of 120 mg/g and 110 mg/g, respectively. Samples produced from coffee endocarp showed the lowest capacity. Amitriptyline adsorption was almost independent of the pH of the solution and occurred via three different mechanisms based on the dispersive and chemical interactions between amitriptyline molecules and the carbon surface.

Removal of amitriptyline from simulated gastric and intestinal fluids using activated carbons

In this work, the adsorption behavior of a tricyclic antidepressant, amitriptyline hydrochloride, onto several activated carbons (ACs) is reported. The adsorption was done using in vitro simulated gastric and intestinal fluid at 37°C to test the performance of the carbons as treatment in overdose cases. The tested materials were one commercial AC (carbomix) and two ACs produced in our laboratory. The highest adsorption capacity was achieved by carbomix, followed by the laboratory-made carbons that still have a very good performance with adsorption capacity up to 120 and 100 mg/g for the gastric and intestinal fluids, respectively.

Simulations of Phenol Adsorption onto Activated Carbon and Carbon Black

Grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations have been used to study the adsorption of phenol onto carbon materials. Activated carbon was modelled in terms of its pore-size distribution based on DFT methods, while carbon black was represented by a single carbon slab with varying percentages of surface atoms removed. GCMC results for adsorption from the corresponding gas phase were in reasonable agreement with experimental adsorption results. MD simulations, that studied the influence of the presence of water and surface roughness on the arrangement of the adsorbed phenol molecules, showed that the interaction between the adsorbed molecules was strongly influenced by the presence of water.

Characterization of the surface of activated carbons produced from tire residues

The surface characterisation of new activated carbons produced from tire residues by activation with carbon dioxide was studied. The activated carbons produced were mainly basic with point of zero charge values above 8.8. The main surface functional groups identified by FTIR were ether, quinones, lactones, ketones, hydroxyls (free and phenol) and pyrones. The XRD analysis shows that the materials produced have a microstructural organisation with microcrystallite height around 1.5nm and width from 3 to 5.3nm. This analysis indicates also the possible presence of oxides (single or mixture) of the following heteroatoms: Fe, Al, Ca, Mg, Ti, Si, K, Pb, Cd, Ba, Zn and Sn. The results have shown the significant potential of this type of residues for activated carbon production. Furthermore, the environment friendly use of an industrial residue is also noteworthy.