Browsing by Author "Díaz de Tuesta, Jose Luis"
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- 17 α-Ethinylestradiol degradation in continuous process by photocatalysis using Ag/Nb2O5 immobilized in biopolymer as catalystPublication . Lenzi, Giane G.; Abreu, Eduardo; Fuziki, Maria Eduarda K.; Fidelis, Michel Zampieri; Brackmann, Rodrigo; Díaz de Tuesta, Jose Luis; Gomes, Helder; Santos, Onélia A.A. dosThis study describes the application of Ag/Nb2O5 catalysts, suspension and spheres alginate immobilized for the degradation of 17α-Ethinylestradiol (EE2). The techniques used to characterize the photocatalysts were as follows: X-ray diffraction (XRD), N2 adsorption–desorption analysis (BET), point charge zero charge (PZC), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Different catalyst calcination temperatures were studied by keeping the silver metal loading at 5%. Among the operational conditions analyzed were pH, catalyst concentration, the emitting source of radiation and the inlet flow rate (in continuous operation). The results of the experiments performed initially with the catalyst in suspension revealed that the highest catalytic activity in the degradation of EE2 was the 5%Ag/Nb2O5 catalyst calcined at 973 K, which removed 77.7% of the initial pollutant concentration in 120 min of reaction. The immobilization of the catalyst in alginate spheres resulted in a degradation reduction, being able to degrade 69.2% of the initial EE2 in a batch system. In the continuous system, the immobilized catalyst obtained a total degraded of 37.3%, with a flow rate of 10 L·h−1. Catalyst reuse was promising, even dropping the removal, degrading around 27% of the initial EE2 concentration in the third cycle of use.
- 3D printed photopolymer derived carbon catalysts for enhanced wet peroxide oxidationPublication . Silva, Adriano S.; Díaz de Tuesta, Jose Luis; Henrique, Adriano; Roman, Fernanda; Omralinov, Daria; Steldinger, Hendryk; Gläsel, Jan; Etzold, Bastian J.M.; Silva, José A.C.; Silva, Adrián; Pereira, Ana I.; Gomes, HelderIn this paper, we explore the application of powdered carbon and 3D-printed carbon monoliths prepared by carbonization of a tailored photopolymer. We demonstrate the efficiency of the developed carbonaceous samples in removing paracetamol (PCM) and sulfamethoxazole (SMX), used as model contaminants. Our results demonstrate that carbon samples are active in CWPO, and their catalytic activity is significantly improved by applying nitric acid and urea functionalization methods. The characterization results showed the pure carbon nature of the material (no ashes), their unique structure defects proven by Raman (D/G > 1.8), textural properties (SBET = 291–884 m2/g) and their surface chemistry, which was addressed by pHPZC (2.5–7.5), acidity (312–2375 μ mol gcat 1) and basicity (117–653 μ mol gcat 1) determination and XPS of highlighted materials (N1s = 0–3.51 at.%, O1s = 7.1–15.3 at.%). Using desorption assays, our study reveals the adsorption role for pollutant degradation by CWPO using carbon monolithic samples. At last, we demonstrated the ability of functionalized 3D-printed carbon monoliths to keep degradation of PCM and total organic carbon (TOC) above 85 % and 80 %, respectively, during 48 h in a continuous flow CWPO system. Sulfamethoxazole degradation in continuous system was also studied to validate the catalyst versatility, achieving 81 % and 79 % pollutant degradation and TOC abatement, respectively, during 48 h on stream. The characterization of the recovered catalyst provides further insights into the absence of structural modifications after the reaction, reinforcing the stability and reusability characteristic of the 3D-printed carbon catalyst.
- 3D tuned porous carbon monolith as catalysts in the wet peroxide oxidation of paracetamolPublication . Roman, Fernanda; Steldinger, Hendryk; Díaz de Tuesta, Jose Luis; Henrique, Adriano; Silva, José A.C.; Gläsel, Jan; Etzold, Bastian J.M.; Gomes, HelderIn recent years, many pharmaceuticals have been identified at trace levels worldwide in the aquatic environment [1]. Municipal wastewater treatment plants (WWTPs) are considered the main sources of these pollutants as they are not generally prepared to deal with such complex substances and thus, they are usually ineffective in their removal [1]. Despite the low concentration of drugs contained in those effluents, the presence of pharmaceuticals, even in trace concentrations, affects the quality of water and constitutes a risk of toxicity for the ecosystems and living organisms [1-2]. Consequently, new regulation for micropollutants discharge and monitoring has been issued in Europe (Directive 2013/39/EU). Paracetamol (PCM) deserves particular attention, since it has recently been discovered as a potential pollutant of waters, largely accumulated in the aquatic environment [3]. This work deals with the treatment of PCM, used as a model pharmaceutical contaminant of emerging concern, by catalytic wet peroxide oxidation using carbon-based monoliths (Fig. 1a) as catalysts. Monoliths were prepared by stereolithographic 3D printing of a photoresin, which was later converted into porous carbon by oxidation in air (300 °C, 6 h) and subsequent pyrolysis in N2 (900 °C, 15 min) as described elsewhere [4]. The materials revealed catalytic activity in the CWPO of PCM allowing to reach PCM conversions up to 30% with a residence time of 3.5 min (Fig. 1b).
- 3D-printed activated carbon for post-combustion CO2 capturePublication . Zafanelli, Lucas F.A.S.; Henrique, Adriano; Steldinger, Hendryk; Díaz de Tuesta, Jose Luis; Gläsel, Jan; Rodrigues, Alírio; Gomes, Helder; Etzold, Bastian J.M.; Silva, José A.C.The applicability of 3D-printed activated carbons for their use to CO2 capture in post-combustion streams and the influence of activation conditions on CO2 uptake and CO2 to N2 selectivity were studied. For two monoliths with the same open cellular foam geometry but low and high burnoff during activation, a series of fixed-bed breakthrough adsorption experiments under typical post-combustion conditions, in a wide range of temperature (313 and 373 K), and partial pressure of CO2 up to 120 kPa were carried out. It is shown that the higher burnoff during activation of the 3D printed carbon enhances the adsorption capacity of CO2 and N2 due to the increased specific surface area with sorption uptakes that can reach 3.17 mol/kg at 313 K and 120 kPa. Nevertheless, the lower burnoff time on monolith 1 leads to higher selectivity of CO2 over N2, up to 18 against 10 on monolith 2, considering a binary interaction to a mixture of CO2/N2 (15/85 vol%) at 313 K. The single and multicomponent adsorption equilibrium is conveniently described through the dual-site Langmuir isotherm model, while the breakthrough curves simulated using a dynamic fixed-bed adsorption linear driving force model. Working capacities for the 3D printed carbon with lower burnoff time lead to the best results, varying of 0.15–1.1 mol/kg for the regeneration temperature 300–390 K. Finally, consecutive adsorption-desorption experiments show excellent stability and regenerability for both 3D printed activated carbon monoliths and the whole study underpins the high potential of these materials for CO2 capture in post-combustion streams.
- Activated carbons prepared from a compost obtained in mechanical biological treatment plants for municipal solid waste processingPublication . Díaz de Tuesta, Jose Luis; Masso, Caroline; Pietrobelli, Juliana Martins Teixeira; Silva, Adrián; Faria, Joaquim; Gomes, HelderActivated carbons (ACs) obtained from different organic wastes have been reported in several works, aiming the valorisation of low-cost useful materials [1]. However, organic wastes typically contain inorganic substances, which can be leached away from the prepared ACs when employed in oxidative aqueous conditions. The current study proposes different strategies to produce ACs from a compost obtained (in excess) during the treatment of the organic fraction of municipal solid waste by anaerobic digestion and maturation in waste management sites.
- Adsorption of Sudan IV from oily wastewater by using modified activated carbon materialsPublication . Díaz de Tuesta, Jose Luis; Guliyeva, Rima; Martin-Martinez, Maria; Silva, Adrián; Faria, Joaquim; Gomes, HelderA commercial activated carbon (AC: Norit ROX 0.8, D = 0.8 mm) was modified by chemical and thermal processes, following the procedures described elsewhere [1]. The materials were tested as adsorbents for the removal of a lipophilic pollutant, Sudan IV (S-IV), using a biphasic medium (water/cyclohexane) in order to simulate contaminated petroleum mixtures with water [2]. The AC was modified in successive steps considering: (1) grinding and sieving (< 250 μm) and (2) treatment with nitric acid, followed by hydrotreatment with urea and thermal treatment at 800 ºC under inert atmosphere, resulting in the adsorbents PAC and PACNAUT, respectively. Adsorption experiments were performed in a 500 mL batch glass reactor, using 2.5 g of adsorbent per litre of organic phase, 2.5 g/LOP. Fig.1A shows results with different particle size (ps), initial S-IV concentration (CS-IV,0) and AC modifications. As expected, it can be observed that adsorption is faster when ps is smaller. However, the powdered activated carbon (PAC) is not able to adsorb all S-IV in high initial concentration (500 mg/L). This target was achieved with PACNAUT (adsorption of S-IV was 90 % at 1 h and 2.5 g/LOP of adsorbent, higher than the removal observed by other authors [2] at the same time and 4 g/LOP of material). The adsorption kinetics was fitted by a pseudo-second-order model to the data obtained with 500 mg/L of CS-IV,0 (Fig. 1B). PACNAUT has higher adsorption capacity (qe) and rate constant (kS).
- Adsorption of Sudan-IV contained in oily wastewater on lipophilic activated carbons: kinetic and isotherm modellingPublication . Díaz de Tuesta, Jose Luis; Silva, Adrián; Faria, Joaquim; Gomes, HelderUp to nine kinetic and fourteen isotherm adsorption models are employed to model the adsorption of Sudan IV, a lipophilic model pollutant present in a biphasic mixture of cyclohexane-water system to simulate oily wastewater. Six different modified activated carbons were used as adsorbents. The highest amount adsorbed of Sudan IV was found in the material prepared by successive treatments of the parent commercial activated carbon Norit ROX 0.8 with nitric acid and urea, followed by thermal treatment at 800 °C under continuous flow of nitrogen. Kinetic and isotherm adsorption models can be employed to simulate the process, since the effect of the presence of water in the adsorption of Sudan IV from the cyclohexane phase was found to be negligible, owing to the high lipophilic character of both adsorbent and adsorbate. All kinetic and isotherm coefficients, coupling with statistical parameters (r2, adjusted r2 and sum of squared errors), are determined by non-linear regression fitting and compared to literature data. The model of Avrami is found to be the most appropriate model to represent the adsorption of the pollutant in any of the six modified carbons tested, the highest value of the kinetic constant being 0.055 min−1. The isotherm adsorption is wellmodelled by using the general isotherm equation of Tóth and the multilayer Jovanović expression for the adsorption of Sudan-IV on that material, resulting in a high monolayer uptake capacity (qm = 193.6 mg g−1).
- Águas oleosas contaminadas: ameaças, tratamentos e desafiosPublication . Roman, Fernanda; Díaz de Tuesta, Jose Luis; Silva, Adrián; Faria, Joaquim; Gomes, HelderAs águas oleosas contaminadas são uma fonte de poluição gerada por várias indústrias. São constituídas por uma fase aquosa e uma oleosa, contendo ainda outros poluentes provenientes tanto dos processos produtivos, como naturalmente associados aos óleos constituintes. Esses efluentes têm um elevado impacto sobre a qualidade dos recursos hídricos, da vida aquática, do ar, do solo e da saúde humana. É por isso essencial o seu devido tratamento. Os estudos de investigação focam-se normalmente na recuperação da fase aquosa, embora a fase oleosa possua, não raras vezes, um elevado valor acrescentado que justifica o seu tratamento e recuperação. Os tratamentos tradicionais, como os processos físico-químicos ou biológicos, são normalmente ineficientes para o seu tratamento. Os processos avançados de oxidação (Advanced Oxidation Processes, AOPs) são uma alternativa viável para o tratamento adequado de águas e eliminar poluentes das fases orgânicas de interesse com o objetivo da sua recuperação.
- Amphiphilic carbon nanotubes for catalytic wet peroxide oxidation of 4-nitrophenolPublication . Roman, Fernanda; Sanches, Flávia Kim; Díaz de Tuesta, Jose Luis; Marin, Pricila; Machado, Bruno; Serp, Philippe; Silva, Adrián; Faria, Joaquim; Gomes, HelderCarbon nanotubes (CNTs) were synthesized via chemical vapor deposition (CVD) over an AlCoFeO4 catalyst by a sequential feed of ethylene (E, as carbon source) and acetonitrile (A, as nitrogen source). The resulting samples were noted E20 (hydrophobic), E10A10 (amphiphilic), and A20 (hydrophilic), the number referring to the feed time (minutes) of each precursor, as reported elsewhere1. These materials were tested in the catalytic wet peroxide oxidation (CWPO) of 4-nitrophenol (4-NP). The reaction was monitored by HPLC (to determine the concentration of 4-NP and respective intermediates), TOC analyzer, and UV-vis spectrophotometry (to quantify H2O2) (Figure 1). After 8 h of reaction, A20 led to the highest consumption of H2O2 (90%), followed by E10A10 (61%) and E20 (52%). On the other hand, the highest degradation of 4-NP was observed with the amphiphilic E10A10 material (98%) followed by E20 (95%), whereas A20 only led to a removal of 69%. Similar behavior was found when analyzing the formation of reaction intermediates (data not shown), i.e., while A20 resulted in the accumulation of 4-nitrocatechol (4-NTC) and hydroquinone (HQ) E10A10 and E20 led to the total conversion of formed 4-NTC and HQ. This resulted in a lower TOC removal for A20 (37%) than to E10A10 and E20 (53%). Therefore, the amphiphilic E10A10 material is a promising catalyst for the CWPO of 4-NP.
- Aplicación del proceso Fenton al tratamiento de aguas oleosasPublication . Munoz, Macarena; Domínguez, Carmen M.; Díaz de Tuesta, Jose Luis; Gomes, Helder; Casas, Jose A.En este trabajo se explora la viabilidad de procesos tipo Fenton, homogéneo y heterogéneo, para el tratamiento de contaminantes lipofílicos contenidos en aguas oleosas. Se ha seleccionado el colorante Sudán IV como contaminante modelo y el ciclohexano como fase oleosa. Atendiendo al distinto coeficiente de reparto en el sistema bifásico agua-ciclohexano, se han seleccionado cuatro catalizadores basados en hierro; dos compuestos de hierro homogéneos: una sal soluble en la fase acuosa y un complejo soluble en la fase orgánica, y dos catalizadores heterogéneos: hierro soportado en carbón activo (localizado preferentemente en la fase orgánica) y magnetita natural (con afinidad por ambas fases y principalmente concentrado en la interfase). El estudio preliminar de los cuatro catalizadores en la descomposición de H2O2 (en ausencia de contaminante) reveló que los catalizadores homogéneos son más activos y, por tanto, presentan mayor potencial para ser utilizados en sistemas bifásicos. En presencia de estos materiales (10 mg L-1) se consiguen conversiones de contaminante superiores al 50% a las 24 h de reacción, trabajando con la cantidad estequiométrica de oxidante. Los resultados obtenidos son prometedores y abren la puerta a la síntesis y aplicación de nuevos catalizadores homogéneos adecuados para este tipo de sistemas.