Optimization of Binary Adsorption of Metronidazole and Sulfamethoxazole in Aqueous Solution Supported with DFT Calculations

The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/pr11041009/s1Sulfamethoxazole [SMX] and metronidazole [MNZ] are emergent pollutants commonly found in surface water and wastewater, which can cause public health and environmental issues even at trace levels. An efficient alternative for their removal is the application of adsorption technology. The present work evaluated single and binary adsorption processes using granular activated carbon (CAG F400) for SMX and MNZ in an aqueous solution. The binary adsorption process was studied using a Box-Behnken experimental design (RSD), and the results were statistically tested using an analysis of variance. Density functional theory (DFT) modeling was employed to characterize the interactions between the antibiotics and the CAG F400 surface. For the individual adsorption process, adsorption capacities (q(e)) of 1.61 mmol g(-1) for SMX and 1.10 mmol g(-1) for MNZ were obtained. The adsorption isotherm model that best fit experimental data was the Radke-Prausnitz isotherm model. The adsorption mechanism occurs through electrostatic and pi-pi dispersive interactions. For the binary adsorption process, the total binary adsorption capacity achieved was 1.13 mmol g(-1), evidencing competitive adsorption. The significant factors that determine the removal of SMX and MNZ from a binary solution were the solution pH and the initial concentration of antibiotics. From DFT studies, it was found that SMX adsorption on CAG F400 was favored with adsorption energy (E-ads) of -10.36 kcal mol(-1). Finally, the binary adsorption results corroborated that the adsorption process was favorable for both molecules.Consejo Nacional de Ciencia y Tecnologia (CONACyT

Design and fabrication of integral carbon monoliths combining 3D printing and sol-gel polymerization: effect of the channels morphology on the CO-PROX reaction

The authors acknowledge the financial support from the Spanish Ministry of Science and Innovation (PID2019-105960RB-C22), the University of Alicante (Project GRE18-01A), the Generalitat Valenciana (Projects PROMETEO/2018/076 and GV2020-075, PhD grant GRISOLIAP/2017/177 and contract APOSTD/2019/030), the Junta de Andalucia (Project P18-RTJ-2974) and the UE (FEDER funding).A new method to synthesize integral carbon monoliths with a controlled channel morphology has been developed in this work by combining 3D-printing technology and sol–gel polymerization. By this method, robust and consistent carbon monoliths were obtained with a perfect replica of the channel architecture at a microscale range. As a proof of concept, a carbon monolith with tortuous channels that split and join successively along the monolith length has been designed, fabricated and tested as a CuO/CeO2 support for the preferential oxidation of CO in the presence of H2 (CO-PrOx), which is a topic of ongoing research for H2 purification in fuel cells. The behavior of this novel carbon monolith catalyst has been compared with that of a counterpart catalyst prepared with a conventional honeycomb design. Results shown that the wide macroporosity of the carbon network favors the anchoring and dispersion of the active phase both in the channel surface and the carbon network. The channel architecture affects the gas diffusion both through the channel and the carbon network and consequently, affects the active phase accessibility and activity. T50 (the temperature to achieve 50% CO conversion) decreases by almost 13 °C at 240 mL min−1 in the carbon monolith with tortuous channels (T50 = 79.7 °C) compared to the honeycomb monolith (T50 = 93.1 °C). The turbulent path created by the tortuous channels favours the active phase–gas contact and even the gas diffusion inside the macropores of the carbon skeleton improving the catalytic performance of the active phase compared to that by the conventional honeycomb design. Thus, this work demonstrates the potential of 3D printing to improve the catalytic supports currently available.Spanish Government PID2019-105960RB-C22University of Alicante GRE18-01AGeneralitat ValencianaEuropean CommissionGeneral Electric PROMETEO/2018/076 GV2020-075 GRISOLIAP/2017/177 APOSTD/2019/030Junta de Andalucia P18-RTJ-2974UE (FEDER funding

Monitoring intermediate species formation by DRIFT during the simultaneous removal of soot and NOx over LaAgMnO3 catalyst

The microwave-synthesized-LaAgMnO3-catalyst can eliminate soot and NOx simultaneously below 400 °C. To get some insight about the chemical species formed on catalyst and soot surfaces, in situ diffuse reflectanced infrared Fourier transform (DRIFT) spectroscopy under NO, O2, and NO/O2 atmospheres was performed. The DRIFTS results indicated that over 200 °C, at least four types of nitrate-species, mono- and bi-dentate nitrates (bridging and chelating) on the perovskite, as well as Ag-nitrite/nitrate, with different thermos-stabilities were formed. The decomposition of less stable surface nitrates/nitrites accounts for NO2 formation which assisted soot oxidation. The transformation-decomposition of nitrite/nitrate compounds coincided with the appearance of CO2 and carbonate-species coming from re-adsorption of soot combustion products. Monodentate nitrates, which are more stable nitrate-species, were considered NOx storage-species over 400 °C. Chelating- and bi-dentate nitrates formed on perovskite oxygen vacancies appear to be the primary reaction intermediates for the NO oxidation reaction over the Ag-doped perovskite catalyst.The authors want to thank the University of Antioquia for the financial support received through the CODI project No 2015-7828. L.U. thanks the Colombian Administrative Department of Science, Technology and Innovation (COLCIENCIAS), for the Ph.D. Scholarship granted

From CO2 to Value-Added Products: A Review about Carbon-Based Materials for Electro-Chemical CO2 Conversion

This research was funded by Spanish Ministry of Science, Innovation and Universities, grant number RTI2018-099224-B-I00; and Junta de Andalucía, grant numbers P12-RNM-2892, P18- RTJ-2974 and RNM172. L.D.R.V. was funded by MINCIENCIAS.Data sharing not applicable.The authors thank the financial support of the Spanish Ministry of Science, Innovation and Universities (project RTI2018-099224-B-I00) and Junta de Andalucía (Project P12- RNM-2892, P18-RTJ-2974 and RNM172). L.D. Ramírez-Valencia is grateful to the Colombian Ministry of Sciences, Technology and Innovation (MINCIENCIAS) for supporting her PhD studies.The global warming and the dangerous climate change arising from the massive emission of CO2 from the burning of fossil fuels have motivated the search for alternative clean and sustainable energy sources. However, the industrial development and population necessities make the decoupling of economic growth from fossil fuels unimaginable and, consequently, the capture and conversion of CO2 to fuels seems to be, nowadays, one of the most promising and attractive solutions in a world with high energy demand. In this respect, the electrochemical CO2 conversion using renewable electricity provides a promising solution. However, faradaic efficiency of common electro-catalysts is low, and therefore, the design of highly selective, energy-efficient, and cost-effective electrocatalysts is critical. Carbon-based materials present some advantages such as relatively low cost and renewability, excellent electrical conductivity, and tunable textural and chemical surface, which show them as competitive materials for the electro-reduction of CO2. In this review, an overview of the recent progress of carbon-based electro-catalysts in the conversion of CO2 to valuable products is presented, focusing on the role of the different carbon properties, which provides a useful understanding for the materials design progress in this field. Development opportunities and challenges in the field are also summarized.Spanish Ministry of Science, Innovation and Universities RTI2018-099224-B-I00Junta de Andalucia P12-RNM-2892 P18RTJ-2974 RNM17

Effect of Ru loading on Ru/CeO2 catalysts for CO2 methanation

The conversion of CO2 towards added valuable products is considered as a potential alternative to achieve the increase of the petrochemical industry while reducing the CO2 emissions. In the present work, the effect of Ru loading on CeO2 supports has been studied for the CO2 methanation reaction, and catalysts with different Ru loading in the 1–5 wt. % range have been prepared, characterized, and tested. The optimum Ru loading has been found to be 2.5 wt. %. Ruthenium cations are reduced at the lowest temperature for this optimum loading according to H2-TPR experiments (even at room temperature), and the highest proportion of ruthenium cations with strong interaction with ceria is achieved, as deduced from XPS. XRD characterization suggests partial insertion of ruthenium cations into the ceria lattice. In situ DRIFTS experiments evidenced that the balance between formation upon CO2 chemisorption and further hydrogenation of surface carbon intermediates is optimum for 2.5 wt. % Ru/CeO2. For low metal contents, the CO2 chemisorption is limited and no relevant, while as the metal content is increased, the hydrogenation of carbon species is less favourable. The 2.5 wt.% Ru/CeO2 catalyst comprises a balance between surface-carbon groups formation and further hydrogenation.Generalitat Valenciana (PROMETEO/2018/0765); MICINN (PID2019-105960RB-C22); Junta de Andalucía (Project P18-RTJ-2974); European Union's Horizon 2020 research and innovation program (Marie Skłodowska-Curie grant agreement No 713567); Science Foundation Ireland Research Centre (award 12/RC/2278_P2)

Highly graphitic Fe-doped carbon xerogels as dual-functional electro-Fenton catalysts for the degradation of tetracycline in wastewater

Fe-doped carbon xerogels with a highly developed graphitic structure were synthesized by a one-step sol-gel polymerization. These highly graphitic Fe-doped carbons are presented as promising dual-functional electro-Fenton catalysts to perform both the electro-reduction of O2 to H2O2 and H2O2 catalytic decomposition (Fenton) for wastewater decontamination. The amount of Fe is key to the development of this electrode material, since affects the textural properties; catalyzes the development of graphitic clusters improving the electrode conductivity; and influences the O2-catalyst interaction controlling the H2O2 selectivity but, at the same time is the catalyst for the decomposition of the electrogenerated H2O2 to OH• radicals for the organic pollutants oxidation. All materials achieve the development of ORR via the 2-electron route. The presence of Fe considerably improves the electro-catalytic activity. However, a mechanism change seems to occur at around −0.5 V in highly Fe-doped samples. At potential lower than −0.5 eV, the present of Feδ+ species or even Fe–O–C active sites favour the selectivity to 2e-pathway, however at higher potentials, Feδ+ species are reduced favoring a O–O strong interaction enhancing the 4e-pathway. The Electro-Fenton degradation of tetracycline was analyzed. The TTC degradation is almost complete (95.13%) after 7 h of reaction without using any external Fenton-catalysts.Grupo RNM-172Universidad de Granada / CBUAMCIN/AEI/10.13039/501100011033/ y "ERDF A way of making Europe” (PID2021-127803OB-I00)Junta de Andalucía (P18-RTJ-2974 y B. RNM.566. UGR20

Key‐lock Ceria Catalysts for the Control of Diesel Engine Soot Particulate Emissions

A new concept, referred to as key‐lock catalyst, is presented in this article. Soot combustion ceria catalysts were prepared combining hard (polymethylmethacrylate colloidal crystals) and soft (Pluronic F127) templates, tuning the porosity of ceria in different size ranges to match the morphology of soot aggregates. The catalysts porosity was characterized in detail by N2 adsorption‐desorption isotherms and Hg‐porosimetry. XRD and H2‐TPR characterization ruled out that differences in activity are related neither with crystallographic nor with redox properties. As a proof of key‐lock catalyst concept, an optimum key‐lock ceria catalyst was synthesized by combining large macropores (100–300 nm) with mesopores (10–30 nm), because they fit to the large soot aggregates and to primary soot particles sizes, respectively. The best soot combustion activity of the optimum key‐lock catalyst is attributed to the optimum transfer of ceria active oxygen from catalyst to soot. The catalytic results confirmed that all ceria catalysts prepared with different porosity oxidize NO to NO2 at the same rate, and the NO2‐assisted soot combustion pathway is not affected by tuning ceria porosity. This double‐templated synthesis and the key‐lock concept opens a new synthesis approach to design noble‐metal free soot combustion catalysts based on the highly effective active oxygen mechanism.The authors thank the financial support of the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R and grant FJCI-2015-23769), the Spanish Ministry of Education, Culture and Sports (grant FPU14/01178), Generalitat Valenciana (Project PROMETEO/2018/076 and APOSTD/2019/030), the Spanish Society of Catalysis (SECAT-“initiation for research in catalysis”) and the UE (FEDER funding)

PrOx catalysts for the combustion of soot generated in diesel engines: effect of CuO and 3DOM structures

PrOx and CuO/PrOx catalysts have been prepared with conventional (Ref) and three dimensionally ordered macroporous (3DOM) structures, and the effect of the structure on soot combustion has been studied. It has been demonstrated that the 3DOM structure significantly improves the catalytic combustion of soot with O2. The activity follows the trend PrOx-3DOM > CuO/PrOx-3DOM ∼ CuO/PrOx-Ref ≫ PrOx-Ref, which is explained considering two aspects: the production of active oxygen and its transfer from catalyst to soot. FESEM microscopy, N2 adsorption, Hg porosimetry and He density show that the 3DOM catalysts have ordered macroporosity with pores of 80 nm in diameter, which favors the carbon–catalyst contact. In addition, the 3DOM catalysts present higher surface density of active oxygen (Oads), which follows the trend CuO/PrOx-3DOM > PrOx-3DOM ∼ CuO/PrOx-Ref > PrOx-Ref. Consequently, the PrOx-3DOM catalyst combines a good production of active oxygen and an efficient transfer to soot, making it the most active catalyst to accelerate soot combustion. In contrast, PrOx-Ref is the least active since it is the least efficient in producing and transferring active oxygen. The impregnation of copper with the conventional support (CuO/PrOx-Ref) enhances the production and transfer of active oxygen, improving the activity with respect to PrOx-Ref. However, CuO blocks the porosity of the 3DOM support, hindering the contact with soot. Soot combustion is accelerated in the presence of NOx due to the production of NO2. This NO2, once produced, is mostly readsorbed on the surface of the catalysts producing active oxygen that must be transferred to soot. For this reason, the porosity of the catalysts also plays a relevant role during combustion with NOx/O2 because it affects the transfer of active oxygen produced by NO2 to soot.The authors thank the financial support of the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R and grant FJCI-2015-23769), the Spanish Ministry of Education, Culture and Sports (grant FPU14/01178) and the UE (FEDER funding)

Mineral Manganese Oxides as Oxidation Catalysts: Capabilities in the CO-PROX Reaction

Cryptomelane is an abundant mineral manganese oxide with unique physicochemical features. This work investigates the real capabilities of cryptomelane as an oxidation catalyst. In particular, the preferential CO oxidation (CO-PROX), has been studied as a simple reaction model. When doped with copper, the cryptomelane-based material has revealed a great potential, displaying a comparable activity to the high-performance CuO/CeO2. Despite stability concerns that compromise the primary catalyst reusability, CuO/cryptomelane is particularly robust in the presence of CO2 and H2O, typical components of realistic CO-PROX streams. The CO-PROX reaction mechanism has been assessed by means of isotopic oxygen pulse experiments. Altogether, CuO/CeO2 shows a greater oxygen lability, which facilitates lattice oxygen enrolment in the CO-PROX mechanism. In the case of CuO/cryptomelane, in spite of its lower oxygen mobility, the intrinsic structural water co-assists as active oxygen species involved in CO-PROX. Thus, the presence of moisture in the reaction stream turns out to be beneficial for the stability of the cryptomelane structure, besides aiding into the active oxygen restitution in the catalyst. Overall, this study proves that CuO/cryptomelane is a promising competitor to CuO/CeO2 in CO-PROX technology, whose implementation can bring the CO-PROX technology and H2 purification processes a more sustainable nature.The authors thank the financial support of the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-67597-C2-2-R and grant FJCI-2015-23769), the Spanish Ministry of Science and Innovation (PID2019-105960RB-C22), Spanish Ministry of Education (FPU14/01178), Generalitat Valenciana (Project PROMETEO/2018/076), and the EU (FEDER funding)

From Fenton and ORR 2e−-Type Catalysts to Bifunctional Electrodes for Environmental Remediation Using the Electro-Fenton Process

Currently, the presence of emerging contaminants in water sources has raised concerns worldwide due to low rates of mineralization, and in some cases, zero levels of degradation through conventional treatment methods. For these reasons, researchers in the field are focused on the use of advanced oxidation processes (AOPs) as a powerful tool for the degradation of persistent pollutants. These AOPs are based mainly on the in-situ production of hydroxyl radicals (OH center dot) generated from an oxidizing agent (H2O2 or O-2) in the presence of a catalyst. Among the most studied AOPs, the Fenton reaction stands out due to its operational simplicity and good levels of degradation for a wide range of emerging contaminants. However, it has some limitations such as the storage and handling of H2O2. Therefore, the use of the electro-Fenton (EF) process has been proposed in which H2O2 is generated in situ by the action of the oxygen reduction reaction (ORR). However, it is important to mention that the ORR is given by two routes, by two or four electrons, which results in the products of H2O2 and H2O, respectively. For this reason, current efforts seek to increase the selectivity of ORR catalysts toward the 2e(-) route and thus improve the performance of the EF process. This work reviews catalysts for the Fenton reaction, ORR 2e(-) catalysts, and presents a short review of some proposed catalysts with bifunctional activity for ORR 2e(-) and Fenton processes. Finally, the most important factors for electro-Fenton dual catalysts to obtain high catalytic activity in both Fenton and ORR 2e(-) processes are summarized.Ministry of Science and Innovation, Spain (MICINN) Spanish Government PID2021-127803OB-I00Junta de Andalucia B.RNM.566.UGR2