Equilibrio y cinética de adsorción de compuestos farmacéuticos sobre carbón activado granular en solución acuosa

The aim of this study was to investigate the adsorption equilibrium and kinetics of several pharmaceutical compounds (Ronidazole, Metronidazole, Dimetridazole, Diclofenac, Sulfamethoxazole and Carbamazepine) onto granular activated carbon (GAC) from aqueous phase. The adsorption mechanism of the six compounds was dominated by π-π dispersive interactions between the aromatic ring of pharmaceutical compound and the aromatic rings of the graphene layers of GAC. Furthermore, the adsorption capacity of GAC can be enhanced by attractive electrostatic interactions. The overall rate of adsorption of the nitroimidazoles was interpreted using diffusional models and the intraparticle diffusion of the nitroimidazoles was the controlling mechanism of overall adsorption rate. Besides, the surface diffusion contributed from 68 to 98 % of total intraparticle diffusion.El objetivo del presente trabajo fue investigar el equilibrio y velocidad de adsorción de seis compuestos farmacéuticos (Ronidazol, Metronidazol, Dimetridazol, Diclofenaco, Sulfametoxazol y Carbamazepina) en solución acuosa sobre carbón activado granular (CAG). Los resultados mostraron que el mecanismo de adsorción de los seis fármacos se debe principalmente a las interacciones dispersivas π-π entre el anillo aromático del compuesto farmacéutico y los anillos aromáticos de los planos grafénicos del CAG. Además, la capacidad de adsorción del CAG se incrementa debido a las interacciones electrostáticas atractivas. La velocidad global de adsorción se interpretó usando modelos difusionales, y el mecanismo controlante de la velocidad global fue la difusión intraparticular. Asimismo, la contribución de la difusión superficial varió entre 68 y 98 % de la difusión intraparticular total

Effect of surface area and physical–chemical properties of graphite and graphene-based materials on their adsorption capacity towards metronidazole and trimethoprim antibiotics in aqueous solution

[EN] The adsorption of metronidazole (MNZ) and trimethoprim (TMP) antibiotics from water on nanomaterials synthesized from graphene oxide and graphite, was examined thoroughly. The effect of the physicochemical properties and surface area onto the adsorption capacity of the nanomaterials was studied in detail. The nanocarbon materials used were graphene oxide (GO), and GO reduced in inert medium (rGO) or ammonia (N-rGO), and four high surface area graphites (HSAG100, HSAG300, HSAG400, HSAG500). The nanomaterials characterization was performed by transmission and scanning electron microscopy, N physisorption, TG-profiles and X-ray diffraction. The increasing order of the nanomaterial adsorption capacity toward MNZ was: HSAG100 < HSAG300 < N-rGO < HSAG400 < HSAG500 < GO < rGO and toward TMP was: HSAG100 < N-rGO ≈ HSAG300 < HSAG400 < HSAG500 ≈ rGO < GO; and except for GO, the adsorption capacity of the nanomaterials increased almost linearly with the surface area. At T = 25 °C, the maximum mass adsorbed of MNZ and TMP on GO were 190 and 218 mg/g, at pH 7 and pH 10, respectively. The adsorption of TMP and MNZ on GO corroborated the presence of different adsorption mechanisms dependent on antibiotic speciation and pH. The adsorption of both antibiotics on the materials based on graphite and reduced graphene oxide was predominantly due to π-π dispersive interactions.This work was supported by the Consejo Nacional de Ciencia y Tecnologia, CONACyT, Mexico [grant numbers CB-2012-02-182779, INFR-2012-01-188381].Supplementary data to this article can be found online at https://doi.org/10.1016/j.cej.2020.126155

Effect of N-doping and carbon nanostructures on NiCu particles for hydrogen production from formic acid

[EN] A series of NiCu based catalysts were prepared using different carbon nanostructure as support and loading 2.5 wt% of each metal. The studied nanocarbon materials were: reduced graphene oxide (rGO), N-doped reduced graphene oxide (NrGO), high surface area graphite (HSAG), single and multiwalled carbon nanotubes (SWCNT and MWCNT), N-doped carbon nanotubes (NCNT), spheres of xerogel carbons (SXC) and N-doped SXC (NSXC). The effect of N-doping, electronic properties and morphology of the carbon nanostructures on the metallic particle size was studied as well as their capacity to produce high purity hydrogen from formic acid decomposition at low temperature. The NiCu based catalysts tested are highly selective to H (98−94 % at conversions above 95 %). The site time yield (STY) of the catalysts follows the order: NCNT > SXC > SWCNT∼HSAG∼rGO>rGO>MWCNT∼NSXC > NrGO>NrGO, indicating that N-doped catalysts are less active, except in the case of NCNT which is ascribed to the N-pyrrolic heteroatoms of this material.This work was supported by the Spanish Agencia Estatal de Investigación (AEI) and EU (FEDER) (projects CTQ2017-89443-C3-1-R and CTQ2017-89443-C3-3-R). ABD acknowledges financial support from Fundación General CSIC (ComFuturo).Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.apcatb.2021.12060

Guaiacol hydrodeoxygenation in hydrothermal conditions using N-doped reduced graphene oxide (RGO) supported Pt and Ni catalysts: Seeking for economically viable biomass upgrading alternatives

Herein we present an innovative route for model biomass compounds upgrading via “H2-free” hydrodeoxygenation (HDO) reactions. The underlaying idea is to implement a multifunctional catalyst able to activate water and subsequently use in-situ generated hydrogen for the HDO process. In this sense we have developed a series of effective Ni and Pt based catalysts supported on N-promoted graphene decorated with ceria. The catalyst reached commendable conversion levels and selectivity to mono-oxygenated compounds considering the very challenging reaction conditions. Pt outperforms Ni when the samples are tested as-prepared. However, Ni performance is remarkably boosted upon applying a pre-conditioning reductive treatment. Indeed, our NiCeO2/GOr- N present the best activity/selectivity balance and it is deemed as a promising catalyst to conduct the H2-free HDO reaction. Overall, this “proof-concept” showcases an economically appealing route for bio-compounds upgrading evidencing the key role of advanced catalysts for a low carbon future.Peer reviewe

Tailoring the textural properties of an activated carbon for enhancing its adsorption capacity towards diclofenac from aqueous solution

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Tailoring the textural properties of an activated carbon for enhancing its adsorption capacity towards diclofenac from aqueous solution

A series of activated carbons (ACs) were prepared by modifying a commercial AC by physical activation using CO2 during different activation times. The ACs were designated as F, F12, F24, and F40 corresponding to the activation times of 0, 12, 24, and 40 h, respectively. The surface area, total pore volume, micropore volume, and mean micropore width were determined for all the ACs. The textural properties of the modified ACs increased substantially with the activation time, and the capacity of the ACs for adsorbing diclofenac (DCF) was almost linearly dependent upon the surface area of the ACS. The maximum adsorption capacities of F, F12, F24, and F40 carbons towards diclofenac (DCF) from aqueous solution were 271, 522, 821, and 1033 mg/g, respectively. Hence, the adsorption capacities of ACs were considerably enhanced with the activation time, and F12, F24, and F40 carbons presented the highest adsorption capacities towards DCF reported in the technical literature. The F40 adsorption capacity was at least twice those of other carbon materials. The adsorption capacities decreased by raising the pH from 7 to 11 due to electrostatic repulsion between the ACs surface and anionic DCF in solution. The removal of DCF from a wastewater treatment plant (WWTP) effluent was effectively carried out by adsorption on F40. Hence, the capacity of ACs for adsorbing DCF can be optimized by tailoring the porous structure of ACs.This work was supported by Consejo Nacional de Ciencia y Tecnologia, CONACyT, Mexico (grants numbers INFR-2012-01-188381 and CB-2012-02-182779). COA and JBP thank the support of the Spanish MINECO (grant number CTM2014/56770-R)