Exploring the activity of chemical-activated carbons synthesized from peach stones as metal-free catalysts for wet peroxide oxidation

Peach stones were used as raw material for the synthesis of activated carbons with different properties. Firstly, peach stones were chemically activated using a 12M H3PO4 solution and carbonized under flowing air (400 °C). The obtained activated carbon, named as PS, is characterized by a high surface development (SBET=1262m2 g−1) and acidic character (pHPZC=4.2). A fraction of PS was further carbonized under N2 atmosphere at 800 °C to remove surface functionalities and to increase its basicity (PS-800). In addition, a Pt catalyst supported on PS (3% w/w Pt/PS) was synthesized by incipient wetness impregnation, resulting in a considerable hydrophilicity increasing. The synthesized materials were tested in the catalytic wet peroxide oxidation (CWPO) of highly concentrated solutions of 4-nitrophenol (4-NP, 5 g L−1) during 24 h experiments, conducted at relatively mild operating conditions (T=50–110 °C, pH=3, catalyst load=2.5 g L−1 and [H2O2]0=17.8 g L−1, corresponding to the stoichiometric amount of H2O2 needed for the complete mineralization of 4-NP). It was observed that the increase of electron-donating functionalities in PS-800 promotes the generation of reactive HO% radicals, being the activity towards CWPO twice higher than that obtained with the pristine PS. Besides, increasing operating temperature substantially enhances CWPO, finding a 80% of 4-NP removal at 110 °C. On the other hand, despite the sharp increment in H2O2 decomposition due to the presence of Pt particles in Pt/PS catalyst, this decomposition is inefficient in all cases, with a consequent poor pollutant removal. This can be attributed to the recombination of HO% radicals into non-reactive species −scavenging effects, promoted by the hydrophilicity of the catalyst.This work is a result of project “AIProcMat@N2020 − Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”, with the reference NORTE-01-0145-FEDER-000006, supported by NORTE 2020, under the Portugal 2020 Partnership Agreement, through the ERDF and of Project POCI-01-0145-FEDER- 006984–Associate Laboratory LSRE-LCM funded by ERDF through COMPETE2020 − POCI − and by national funds through FCT. M. Martín Martínez and A.M.T. Silva acknowledge the FCT Postdoc grant SFRH/BPD/108510/2015 and FCT Investigator 2013 Programme IF/ 01501/2013, respectively.info:eu-repo/semantics/publishedVersio

Synthesis of glycerol-based carbon materials as environmental application

Crude glycerol, obtained from the biodiesel production, is actually an abundant and low-cost feedstock, making the preparation of carbonaceous materials by partial carbonization and sulfonation of this by-product an interesting research focus. Bearing this in mind, the aim of this study is to explore several types of glycerol-based carbon materials synthesized by partial carbonization of glycerol in concentrated sulphuric acid solution for the removal of flumequine and tetracycline from aqueous solutions. This study is focused on the synthesis and application of glycerol-based carbon materials as adsorbents for the removal of the antibiotic compounds flumequine and tetracycline from aqueous solution. The different synthesized materials were labelled as GBCM followed by a subscript number corresponding to the activation temperature in oC (i.e., GBCM200, GBCM300, and GBCM350

Adsorption of bentazon on CAT and CARBOPAL activated carbon: experimental and computational study

Removal of the bentazon by adsorption on two different types of activated carbon was investigated under various experimental conditions.Kinetics of adsorption is followed and the adsorption isotherms of the pesticide are determined. The effects of the changes in pH, ionic strength and temperature are analyzed. Computational simulation was employed to analyze the geometry and the energy of pesticide absorption on activated carbon. Concentration of bentazon decreases while increase all the variables, from the same initial concentration. Experimental data for equilibrium was analyzed by three models: Langmuir, Freundlich and Guggenheim–Anderson–de Boer isotherms. Pseudo-first and pseudo-second-order kinetics are tested with the experimental data, and pseudo-second-order kinetics was the best for the adsorption of bentazon by CAT and CARBOPAL with coefficients of correlation R 2 = 0.9996 and R 2 = 0.9993, respectively. The results indicated that both CAT and CARBOPAL are very effective for the adsorption of bentazon from aqueous solutions, but CAT carbon has the greater capacity.Laboratorio de Estudio de Compuestos Orgánico

Adsorption of bentazon on CAT and CARBOPAL activated carbon: experimental and computational study

Removal of the bentazon by adsorption on two different types of activated carbon was investigated under various experimental conditions.Kinetics of adsorption is followed and the adsorption isotherms of the pesticide are determined. The effects of the changes in pH, ionic strength and temperature are analyzed. Computational simulation was employed to analyze the geometry and the energy of pesticide absorption on activated carbon. Concentration of bentazon decreases while increase all the variables, from the same initial concentration. Experimental data for equilibrium was analyzed by three models: Langmuir, Freundlich and Guggenheim–Anderson–de Boer isotherms. Pseudo-first and pseudo-second-order kinetics are tested with the experimental data, and pseudo-second-order kinetics was the best for the adsorption of bentazon by CAT and CARBOPAL with coefficients of correlation R 2 = 0.9996 and R 2 = 0.9993, respectively. The results indicated that both CAT and CARBOPAL are very effective for the adsorption of bentazon from aqueous solutions, but CAT carbon has the greater capacity.Laboratorio de Estudio de Compuestos Orgánico

Extraction of neonicotinoid pesticides from aquatic environmental matrices with sustainable terpenoids and eutectic solvents

The potential environmental impact and adverse effects of the occurrence of pesticides in the aquatic environment have raised great social and political concern, leading to their control by means of several regulations, such as the European Directive 98/83/EC. In this regard, the three neonicotinoid pesticides analyzed in this work (acetamiprid, imidacloprid, and thiamethoxam) have been included in the surface water European Watch Lists under the Water Framework Directive. This research proposes the use of terpenoid-based solvents for the extraction of the three emerging contaminants previously mentioned. An initial screening of the extraction solvents was carried out through the COSMO-RS methodology, selecting the most favourable pure terpenes, eutectic terpenoid-based and conventional solvents. Furthermore, relevant issues were experimentally analyzed, such as extraction in more realistic multicomponent mixtures together with key parametric studies covering operating temperature and matrix influence. Carvacrol, a pure terpenoid not applied before as an extraction solvent of pesticides, has been revealed as an effective and sustainable substitute for conventional solvents for the first time to the best of our knowledge. Specifically, carvacrol exhibited overall extraction yields of around 97.5 % from a river water matrix at a volumetric S/F ratio of 0.1 and 303.2 K. High extraction yields from river water matrices regardless of temperature pointed to the potential of this solvent for a wide range of industrial application

Magnetite-Based Catalyst in the Catalytic Wet Peroxide Oxidation for Different Aqueous Matrices Spiked with Naproxen–Diclofenac Mixture

Magnetite supported on multiwalled carbon nanotubes catalysts were synthesized by co-precipitation and hydrothermal treatment. The magnetic catalysts were characterized by X-ray diffraction, Fourier-transform infrared spectrometry, thermogravimetric analysis and N2 physisorption. The catalysts were then tested for their ability to remove diclofenac (DCF) and naproxen (NAP) from an aqueous solution at different conditions (pH, temperature, and hydrogen peroxide) to determine the optimum conditions for chemical oxidation. The optimization of the process parameters was conducted using response surface methodology (RSM) coupled with Box–Behnken design (BBD). By RSM–BBD methodology, the optimal parameters (1.75 mM H2O2 dosage, 70 °C and pH 6.5) were determined, and the removal percentages of NAP and DCF were 19 and 54%, respectively. The NAP–DCF degradation by catalytic wet peroxide oxidation (CWPO) was caused by •OH radicals. In CWPO of mixed drug solutions, DCF and NAP showed competitive oxidation. Hydrophobic interactions played an important role during the CWPO process. On the other hand, the magnetic catalyst reduced its activity after the second cycle of reuse. In addition, proof of concept and disinfection tests performed at the operating conditions showed results following the complexity of the water matrices. In this sense, the magnetic catalyst in CWPO has adequate potential to treat water contaminated with NAP–DCF mixtures.Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasTRUEComunidad de Madridpu

Extraction of pharmaceuticals from hospital wastewater with eutectic solvents and terpenoids: Computational, experimental, and simulation studies

The presence of pharmaceuticals in wastewater, mainly in hospital wastewater, is a serious environmental concern, as they are not removed by conventional processes in wastewater treatment plants and are discharged into the natural environment. This work proposes extracting drugs from hospital wastewater using natural, renewable, and non-toxic solvents such as terpenes and eutectic solvents. First, molecular simulation has been used with the COSMO-RS method performing a massive screening of 43 terpenes, 11 eutectic solvents, and 5 conventional solvents with 31 common pharmaceuticals. The most promising solvents in the screening have been chosen to extract 11 pharmaceuticals simultaneously. Experimental tests with ultrapure water and real hospital wastewater matrices showed a strong influence of pH and matrix on extraction. Under the optimal conditions, global pharmaceutical extraction yields with carvacrol of 94.16 % and the eutectic solvent thymol + dodecanoic acid of 96.86 % were obtained. The regeneration and reuse of both solvents were studied in 5 consecutive stages, showing the carvacrol's high stability and regenerability. Using carvacrol, countercurrent extraction tests showed a fast mass transfer of pharmaceuticals and high extraction yields using low solvent-to-feed (S/F) ratios. The predictions obtained with COSMO-RS were similar to the experimental results, confirming the reliability of this method for selecting alternative solvents for the extraction of pharmaceuticals. Finally, the drug removal process was simulated in a countercurrent extraction. The complete removal of pharmaceuticals from hospital wastewater could be achieved using carvacrol with an S/F of 2.00 at pH 4.00 in an extractor with six equilibrium stagesP2018/EMT-4341, PR65/19-22441, CTM2017-84033-

Carbon-encapsulated iron nanoparticles as reusable adsorbents for micropollutants removal from water

Adsorption represents the most plausible technology for micropollutants removal from water nowadays. Nevertheless, the regeneration of the saturated carbon materials is still an important challenge, being these solids in practice commonly disposed. This work aims at overcoming this issue by using innovative carbonencapsulated iron nanoparticles (CE-nFe). This material was synthesized by a low-cost and green method viz. hydrothermal carbonization (HTC), using olive mill wastewater as carbonaceous source. The solid was fully characterized by different techniques (magnetic properties, elemental analyses, N2-sorption isotherms, pHPZC, ICP, XRD and TEM). It showed a clear core-shell structure of around 40 nm in diameter. The core was mainly formed by zero-valent iron and the shell by graphitized carbon. Accordingly, it showed an essentially mesoporous structure, with a specific surface area of 169 m2 g−1 , and a clear hydrophobic character (pHPZC = 10). Its adsorption performance was investigated using three relevant micropollutants (diclofenac (DCF), sulfamethoxazole (SMX) and metronidazole (MNZ)). A very fast removal of the micropollutants was achieved (30 min at the most, with rate constants in the range of 0.11–0.41 g mg−1 min−1 ). The adsorption isotherms revealed the vertical packing of the adsorbate molecules onto the adsorbent active centers, being the data successfully described by the GAB model. The saturated adsorbents were effectively regenerated by heterogeneous Fenton oxidation, taking advantage of the iron core of CE-nFe and the opened mesoporous carbon shell. The regeneration efficiency increased with increasing the operating temperature (25–75 ◦C) and contact time (1–4 h), as well as the H2O2 dose up to 6 g L-1. The micropollutant nature affected the adsorbent regeneration yield in the order: SMX > DCF > MNZ, consistent with their reactivity towards Fenton oxidationThis research has been supported by the Spanish MINECO through the project CTM-2016-76454-R and by the CM through the project P2018/EMT-4341. M. Munoz and J. Nieto-Sandoval thank the Spanish MINECO for the Ramón y Cajal postdoctoral contract (RYC-2016-20648) and the FPI predoctoral grant (BES-2017-081346), respectivel

Extraction of antibiotics identified in the EU Watch List 2020 from hospital wastewater using hydrophobic eutectic solvents and terpenoids

The increasing consumption of pharmaceuticals, along with the ineffectiveness of conventional wastewater treatment, has resulted in an increased presence of these pollutants in both drinking water supplies and aquatic environments. The potential adverse health effects and environmental impact of these chemicals are drawing the attention of several bodies around the world. For instance, some antibiotics such as ciprofloxacin, trimethoprim, and sulfamethoxazole have been included in the most recent European Surface Water Watch List under the EU Water Framework Directive (Decision 2020/1161). The present work proposes the use of terpenoids and eutectic solvents, as effective and green solvents with low toxicity, for multicomponent liquid-liquid extraction of ciprofloxacin, trimethoprim, and sulfamethoxazole from ultrapure water and hospital wastewater. The COSMO-RS method was used for a predictive initial solvent screening. Thymol, carvacrol, eutectic solvents (thymol + fatty acids), and conventional solvents (methyl isobutyl ketone and ethyl acetate) were selected to be used in the experiments. The influence of the volume S/F ratio, aqueous matrix, and pH was analysed. Conventional solvents show significantly lower overall extraction yields than those observed for eutectic solvents and terpenoids at any pH and matrix. Carvacrol presented the most favourable conditions, reaching overall extraction yields above 98.0% (98.9% for trimethoprim, 99.5% for ciprofloxacin, and 97.0% for sulfamethoxazole) with hospital wastewater at pH 5.0 and S/F ratio of 1.00. Carvacrol showed a feasible operating in a continuous extraction column at room temperature, providing effective reuse and regeneration processes in this study.The increasing consumption of pharmaceuticals, along with the ineffectiveness of conventional wastewater treatment, has resulted in an increased presence of these pollutants in both drinking water supplies and aquatic environments. The potential adverse health effects and environmental impact of these chemicals are drawing the attention of several bodies around the world. For instance, some antibiotics such as ciprofloxacin, trimethoprim, and sulfamethoxazole have been included in the most recent European Surface Water Watch List under the EU Water Framework Directive (Decision 2020/1161). The present work proposes the use of terpenoids and eutectic solvents, as effective and green solvents with low toxicity, for multicomponent liquid-liquid extraction of ciprofloxacin, trimethoprim, and sulfamethoxazole from ultrapure water and hospital wastewater. The COSMO-RS method was used for a predictive initial solvent screening. Thymol, carvacrol, eutectic solvents (thymol + fatty acids), and conventional solvents (methyl isobutyl ketone and ethyl acetate) were selected to be used in the experiments. The influence of the volume S/F ratio, aqueous matrix, and pH was analysed. Conventional solvents show significantly lower overall extraction yields than those observed for eutectic solvents and terpenoids at any pH and matrix. Carvacrol presented the most favourable conditions, reaching overall extraction yields above 98.0% (98.9% for trimethoprim, 99.5% for ciprofloxacin, and 97.0% for sulfamethoxazole) with hospital wastewater at pH 5.0 and S/F ratio of 1.00. Carvacrol showed a feasible operating in a continuous extraction column at room temperature, providing effective reuse and regeneration processes in this study