Raul Molina

Raul Molina
King Juan Carlos University | URJC

PhD

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76
Publications
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Introduction
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Publications

Publications (76)
Article
A study of the hydrogen production by thermochemical water splitting with a commercial perovskite La0.8Sr0.2CoO3-δ(denoted as LSC) under different temperature conditions is presented. The experiments revealed that high operational temperatures for the thermal reduction step (>1000 °C) implied a decrease in the hydrogen production with each consecut...
Article
The feasibility of a Fenton-type process for the pretreatment of an oily refinery sludge has been explored taking advantage of the iron contained in the own sludge. This process reduces the content of total petroleum hydrocarbons (TPHs) accompanied by an increase in the total organic carbon concentration in the liquid phase. The effect of the tempe...
Article
Hospital wastewater represents an important source of pharmaceutical active compounds (PhACs) as contaminants of emerging concern for urban wastewater treatment plants. This work evaluates a fungal biological treatment of a hospital effluent before discharging in the municipal sewer system. This treatment was performed in rotating biological contac...
Article
Aluminum based perovskites, La0.8Al0.2MeO3-δ (Me = Co, Ni, Fe, Cu), were synthesized following the Pechini method at different pHs and evaluated for hydrogen production by water splitting in a two-step thermochemical cycle. The pH of the synthesis medium showed a critical influence in the redox properties of the aluminum-based perovskites during th...
Article
Full-text available
Hospitals are one of the key contributors of pharmaceutical contaminants of emerging concern to the sewer systems. Hospitals wastewaters contain concentrations of pharmaceutical compounds between 3 and 150, which are higher than urban wastewater streams. However, dedicated treatments of the hospital effluents before discharge to the sewer system ar...
Article
Full-text available
Bioelectrochemical systems are a promising technology capable of reducing CO2 emissions , a renewable carbon source, using electroactive microorganisms for this purpose. Purple Pho-totrophic Bacteria (PPB) use their versatile metabolism to uptake external electrons from an electrode to fix CO2. In this work, the effect of the voltage (from −0.2 to...
Article
Refinery treatment plants produce large quantities of oily sludge during the petroleum refining processes. The hazardousness associated with the disposal of these wastes, make necessary the development of innovative technologies to handle it adequately, linked to the concepts of circular economy and environmental sustainability. This work provides...
Article
The conventional Fenton process has been evaluated to treat highly furfural-containing wastewater of 76 g/L at an initial pH of 3. Streams of these features can be accidentally generated after solvent extraction operations in petrol refineries, which leads to significant concern for downstream wastewater treatment facilities. The influence of tempe...
Article
Computer-based activities to study chemical kinetic principles have been widely used in engineering education for the last 60 years. These academic tools must be user-friendly for teachers and students and easy to adapt to practical cases. The Chemical and Environmental Engineering Group (GIQA) at University Rey Juan Carlos (URJC) has developed a K...
Article
Full-text available
Domestic wastewater treatment by purple phototrophic bacteria (PPB) is based on the assimilative uptake of organics and nutrients into the bacterial biomass. Thereby, it strongly depends on the carbon/nutrients ratio of the wastewater. The physiological COD/N/P ratio for PPB growth in domestic wastewater makes the addition of an external organic ca...
Article
Full-text available
One of the current challenges in the treatment of wastewater is the recovery and/or transformation of their resources into high value-added products, such as biohydrogen. The aim of the present study was to optimize the production of hydrogen by mixed cultures of purple phototrophic bacteria (PPB), targeting in low CO 2 emission. Batch assays were...
Article
The high temperature required for hydrogen production by solar driven thermochemical cycles is a critical factor hindering full-scale applications. The thermochemical cycle based on Mn3O4/MnO redox pair is one of the most studied despite the high operating temperature required for complete de reduction step (1623–1723 K). The combination of Mn3O4 w...
Article
Powdered LaCu0.5Mn0.5O3 perovskite was successfully conformed in a reticulated macroporous structure to be tested in an up-flow catalytic packed bed reactor as on-site pre-treatment of pharmaceutical micropollutants in a hospital wastewater. Initially, the effect of the pH, the temperature and the hydrogen peroxide were studied using the hospital w...
Article
In this work, we present for the first time the preparation and evaluation of Ceria-based mixed oxides reticulated porous ceramic (RPC) structures for H2 production by thermochemical water splitting. After appropriate screening of the powder materials, ceria-based materials modified with Co, Mn and Zr were discarded due to their low cyclability and...
Article
A great challenge in electro-Fenton processes is the development of active heterogeneous catalysts at circumneutral or even basic pH in order to avoid the acidification of the wastewater effluents and the generation of an undesirable metallic sludge after the treatment. In this work, LaCu0.5Mn0.5O3 perovskite has been assessed as heterogeneous elec...
Article
Propagation of emerging pollutants (EPs) in wastewater treatment plants has become a warning sign, especially for novel resource-recovery concepts. The fate of EPs on purple phototrophic bacteria (PPB)-based systems has not yet been determined. This work analyzes the performance of a photo-anaerobic membrane bioreactor treating a low-N wastewater c...
Article
White rot fungi have been studied for the removal of micropollutants of emerging concern from wastewater during the last decade. However, several issues need to be overcome for its plausible implementation at full-scale installations such as the addition of supplementary substrates, the partial re-inoculation of fresh fungi or the use of extended h...
Article
Full-text available
Conventional wastewater treatment plants (WWTPs) are not able to remove completely some emerging contaminants, such as residual pharmaceutical compounds (PCs) with potential ecotoxicity to water bodies. An advanced bio-oxidation process (ABOP) using white-rot fungi (WRF) has been proposed as alternative biological treatment for degradation of non-b...
Article
Τhe coupling of biological with advanced oxidation processes for the removal of 13 pharmaceuticals is reported in this study. The efficiency of this system was examined by using two ligninolytic fungi, Trametes versicolor and Ganoderma lucidum. Pharmaceuticals’ removal was examined by using four different quinone substances (1,4-benzoquinone, 2,6-d...
Article
Full-text available
The simulation of chemical kinetic models is necessary in order to analyze comprehensive chemical reaction mechanisms and perform the estimation of the kinetic parameters. In many cases, a chemical process can be composed of several series and/or independent reactions that requires a complex set of kinetic equations to be solved. Computer-based too...
Article
The cyclability of Mn2O3/MnO thermochemical cycle for solar hydrogen production has been experimentally evaluated. The results of three consecutive cycles show a stable hydrogen production per mass of initial solid that is in agreement with the maximum expected amount according to the stoichiometry of the process. The characterization of the materi...
Article
Micropollutants of emerging concern such as pharmaceuticals can significantly affect the performance of secondary biological processes in wastewater treatment plants. The present study is aimed to evaluate the toxicity and inhibition of three pharmaceutical compounds (caffeine, sulfamethoxazole and carbamazepine) on two cultures of microbial consor...
Article
A wastewater coming from a pharmaceutical plant of chemical organic synthesis with a TOC of ca 1.4 g/L and low biodegradability has been treated by coupling of advanced Fenton oxidation process and subsequent biological treatment. The influence of the reaction temperature, the hydrogen peroxide concentration and the iron/copper loadings as catalyst...
Article
Full-text available
The influence of Zero Valent Iron (ZVI) addition on the potential resource recovery during the anaerobic digestion (AD) of domestic waste sludge is assessed. Potentially recoverable resources analyzed were nutrients such as struvite to recover P, and energy as biogas to recover C. Short term (biochemical methane potential tests, BMP) and long term...
Article
The chrome plating industry originates wastewater containing hazardous pollutants as hexavalent chromium. In this work, two alternatives for the treatment of the wastewater streams generated in a Spanish chrome-plating plant are studied from environmental and techno-economic perspectives. Both scenarios include the operations needed to obtain a chr...
Chapter
This chapter reviews briefly the principles of anaerobic digestion with special interest in innovative technologies to enhance the methane production. Biogas production from anaerobic digestion has been widely described in literature but this chapter wants to give a step forward focusing on two topics recently reported in literature and with specia...
Conference Paper
The objective of this study is to show the preliminary results of a (dynamic) mathematical model describing the effects of zero valent iron (ZVI) addition during the anaerobic digestion of waste activated sludge from wastewater treatment systems. A modified version of the Anaerobic Digestion Model No. 1 (ADM1) upgraded with an improved physico-chem...
Conference Paper
This work investigates the biological treatment of synthetic wastewater contaminated with emerging pollutants (EPs) by anaerobic purple phototrophic bacteria (PPB) in a continuous photo-anaerobic membrane bioreactor. The effect of the hydraulic retention time (HRT) on the reactor performance has been analysed. Results indicate that the reactor perf...
Article
Full-text available
Mn and Co spinels (Mn3-xCoxO4) were thermally reduced and subsequently oxidized showing successful hydrogen production from water splitting by a three-step thermochemical cycle involving sodium hydroxide (NaOH). The spinel materials overcome the main limitation of the Mn2O3/MnO redox cycle, reducing the required temperatures from 1300–1400 °C to 85...
Article
Full-text available
The performance of perovskites as redox materials for solar thermochemical hydrogen production and energy storage have been studied theoretically by several authors but there are only a few experimental studies about them. In this work, an evaluation of commercial perovskite materials La1−xSrxMeO3 (Me = Mn, Co and Fe) for thermochemical water split...
Article
Fe2O3/SiO2 materials were prepared using a simple sol-gel method and subsequent agglomeration to yield macroscopic particles of catalyst. The influence of silica source as well as the iron content in their physicochemical properties were studied and related with the catalytic performance and stability in a continuous intensified Fenton process. Lik...
Article
The efficiency of two white-rot fungi (WRF), Trametes versicolor and Ganoderma lucidum, to eliminate thirteen pharmaceutical pollutants with concomitant biodiesel production from the accumulating lipid content after treatment, was examined. The removal efficiency was studied using both individual and combined strains. The results of individual and...
Article
An integrated system based on a heterogeneous catalytic wet hydrogen peroxide oxidation (CWHPO) and subsequent rotating biological contactors (RBCs) has been modeled for the treatment of agrochemical wastewater. One dimensional pseudo-homogeneous model was proposed for the CWHPO step. The reaction rate for TOC removal (k1) was 0.087 1/min. In the c...
Article
The applicability of any wastewater technology should be related not only to its degradation, mineralization or detoxification efficiency, but also to its environmental impacts. This could be particularly relevant in case of Advanced Oxidation Processes (AOPs), which are usually highly demanding on chemicals, energy, and generating residual fluxes...
Article
Two different approaches have been investigated for the production of biodiesel from glycerides and free fatty acids (FFAs) extracted from sewage sludge. The first one is a two-step process consisting of organic solvent extraction followed by acid-catalyzed esterification/transesterification of the isolated oil fraction. The second one is a one-ste...
Article
An intensified-Fenton process for the treatment of phenol aqueous solutions has been studied as a continuous catalytic wet hydrogen peroxide oxidation system. This process consists of coupling the catalytic activity of a heterogeneous Fenton-like catalyst with the homogeneous contribution of its dissolved iron species. Agglomerated mesoporous SBA-1...
Article
The performance of biological reactors longer times than those usually devoted to regular laboratory demonstrations. Biological wastewater treatments are inherently dynamic systems and any change in the operation conditions would take several weeks for stabilization. In order to overcome this lack, computer simulations are useful tools to describe...
Article
Background Activated carbons (AC) can be used as catalyst in advanced oxidation processes due to the potential activity for hydrogen peroxide decomposition to hydroxyl radicals. Chemical surface groups and textural properties can play a crucial role in its catalytic behaviour. The pH of the reaction medium can also affect the adsorption properties...
Article
Background Growing environmental concern about the presence of pesticides in water demands their removal, particularly in industrial wastewater effluents. These streams are characterized by high content of organic colloidal matter. Physicochemical treatments based on the combination of coagulation-flocculation processes have been deeply studied. An...
Article
In this work, a complete study of the second step of the Mn2O3/MnO thermochemical cycle for solar hydrogen production has been performed. It includes a complete thermodynamic calculation of the equilibrium phases between MnO, NaOH and H-2, which shows that the reaction takes place theoretically at temperatures above 75 degrees C. However, the exper...
Article
The performance of a mixed-culture on the removal of caffeine (CFN), sulfamethoxazole (SMX), ranitidine (RNT), carbamazepine (CZP) and ibuprofen (IBP) in a suspended growth reactor has been studied. The sorption and biodegradation of these compounds were examined when they were individually or simultaneously tested. The sorption of individual compo...
Article
The coupling of membrane separation and photocatalytic oxidation has been studied for the removal of pharmaceutical pollutants. The retention properties of two different membranes (nanofiltration and reverse osmosis) were assessed. Comparable selectivity on the separation of pharmaceuticals were observed for both membranes, obtaining a permeate str...
Article
The treatment of a non-biodegradable agrochemical wastewater has been studied by coupling of heterogeneous catalytic wet hydrogen peroxide oxidation (CWHPO) and rotating biological contactors (RBCs). The influence of the hydrogen peroxide dosage and the organic content of the wastewater (dilution degree) were studied. The CWHPO of the raw wastewate...
Article
The application of Fenton chemistry has emerged as potential alternative for the remediation of organic pollution in wastewaters. The effective role of Fenton reagent (FeII/H2O2) is based on the generation of oxidizing hydroxyl radicals from the catalytic decomposition of hydrogen peroxide. This technology is nowadays implemented on industrial scal...
Article
This work reports the kinetic study of the first step of the Mn2O3/MnO thermochemical cycle for hydrogen production by water splitting. The reaction kinetics of Mn (III) oxide thermal reduction has been evaluated using dynamic thermogravimetric analysis at constant heating rate under nitrogen flow. This way the reaction rate can be described as a f...
Article
The immobilization of active photo-Fenton heterogeneous catalysts over different materials, mainly polymers, has been studied in the literature to avoid their separation from the reaction solution. However, those materials exhibited a high preparation cost and low stability in the process, being difficult their application in an industrial wastewat...
Article
This work investigates for the first time the occurrence of drugs of abuse and metabolites in surface waters from the Tagus River on its way through the province of Toledo (downstream Madrid metropolitan area) and in drinking waters in two nearby cities. Some of the studied drugs are used for therapeutic purposes but they can also be consumed as il...
Article
In this work, a complete thermodynamic study of the first step of the Mn2O3/MnO thermochemical cycle for solar hydrogen production has been performed. The thermal reduction of Mn2O3 takes place through a sequential mechanism of two reaction steps. The first step (reduction of Mn2O3 to Mn3O4) takes place at temperatures above 700 °C, whereas the sec...
Article
In this study, a successful mineralization of phenol was achieved by means of coupling zero-valent iron (ZVI) particles, hydrogen peroxide and a short input of ultrasonic irradiation. This short sono-advanced Fenton process (AFP) provided a better performance of ZVI in a subsequent silent degradation stage, which involves neither extra cost of ener...
Chapter
The application of ultrasound (US) irradiation for the degradation of organic pollutants in water has been broadly described in literature in the past. The thermal decomposition of pollutants by direct pyrolysis and/or oxidation by means of the reactive radicals coming from water and oxygen dissociation in the presence of US irradiation have been p...
Article
An investigation into the use of activated carbon cloth (ACC) as a potential adsorbent and/or catalyst for oxidation processes is reported. The extent of increase/decrease of oxidation/adsorption of phenol, as measured by total organic carbon content (%), is explained by considering the effects of the oxidants such as ozone and hydrogen peroxide on...
Article
Fifty-six pharmaceuticals of various chemical groups, such as anti-inflammatory, antibacterial and cardiovascular drugs, were detected in four selected river waters receiving sewage effluents in the Community of Madrid (Spain). A promising approach for the degradation of those residues is the application of a photo-Fenton treatment. Several new bio...
Article
The aim of this work is to establish the influence of different ultrasonic frequencies ranging from 20 to 1142kHz on the efficiency of the US/Fe2O3/SBA-15/H2O2 (sono-Fenton) system. The frequency of 584kHz has been established as the optimum ultrasonic irradiation for the degradation of aqueous phenol solutions by the sono-Fenton system and the eff...
Article
The aim of this work was to assess the treatment of wastewater coming from a pharmaceutical plant through a continuous heterogeneous catalytic wet peroxide oxidation (CWPO) process using an Fe(2)O(3)/SBA-15 nanocomposite catalyst. This catalyst was preliminary tested in a batch stirred tank reactor (STR), to elucidate the influence of significant p...
Article
Full-text available
The removal of organic compounds from aqueous solutions has been tackled by a novel integrated heterogeneous system. The efficacy of the different systems has been assessed using Fenton-like processes (H2O2/Fe2O3-SBA-15) and phenol as model pollutant. Sono- and photo-Fenton processes separately applied as well as combined systems were studied in or...
Article
Full-text available
The effect of the presence and absence of the chloroalkanes, dichloromethane (CH(2)Cl(2)), chloroform (CHCl(3)) and carbon tetrachloride (CCl(4)) on the extent of oxidation of aqueous I(-) to I(3)(-) has been investigated in (a) a liquid whistle reactor (LWR) generating hydrodynamic cavitation and (b) an ultrasonic probe, which produces acoustic ca...
Article
The objective of this research is to assess the effect of ultrasonic irradiation (20 KHz) on the catalytic activity and catalyst particle size of different iron-containing solids (hematite/SBA-15 nanocomposite; hematite; goethite). The catalytic activities of the different catalysts were investigated in the sono-Fenton degradation of a phenolic aqu...
Article
In this work, the catalytic wet peroxide oxidation of phenolic aqueous solutions over a novel Fe2O3/SBA-15 nanocomposite material was deeply studied. The catalytic performance was monitored in terms of aromatics and total organic carbon (TOC) removals. In order to reduce the major operation cost, significant operating reactions parameters that affe...
Article
Iron oxide supported over mesostructured SBA-15 material (Fe2O3/SBA-15) has been used in a fixed-bed reactor (FBR) for the catalytic wet hydrogen peroxide oxidation (CWHPO) of phenolic aqueous solutions. This catalyst is agglomerated by extrusion with different particle sizes (0.35−2 mm) using bentonite mineral clay and methyl cellulose as inorgani...
Article
Iron-containing catalysts have been prepared following different synthesis routes and silica supports (amorphous, zeolitic and mesostructured materials). Activity and stability of these materials were assessed on the photo-Fenton degradation of phenolic aqueous solutions using near UV irradiation (higher than 313 nm) at room temperature and initial...
Article
A novel heterogeneous catalyst has been used for the oxidation of aqueous solutions of phenol by catalytic wet peroxide oxidation assisted by ultrasound irradiation. This composite catalyst material that contains crystalline hematite particles embedded into a mesostructured SBA-15 matrix was used successfully in the oxidation of phenol by heterogen...
Article
Crystalline Fe2O3 and CuO particles have been incorporated into surfactant-templated SBA-15 materials by direct synthesis. Activity and stability of this material were evaluated on the wet peroxide oxidation of phenol under mild reaction conditions. Its catalytic performance was monitored in terms of total organic carbon (TOC) conversion. The stabi...
Article
Iron containing micro-and mesoporous substances were exposed to various treatments and changes in coordination and oxidation states of iron are analysed. ZSM-5 (Si/Fe = 200) and MCM-22 (Si/Fe = 13.5) are applied as microporous hosts. Most of iron is stabilized in tetrahedral framework positions in the first structure, whereas profound rearrangement...
Article
A novel iron-containing mesostructured material has been successfully tested for the heterogeneous photo-Fenton degradation of phenolic aqueous solutions using near UV–vis irradiation (higher than 313 nm) at room temperature and close to neutral pH. This catalyst is a composite material that contains crystalline hematite particles embedded into the...
Article
Iron-containing materials have been prepared following several strategies of synthesis and using different silica supports (amorphous, zeolitic and mesostructured materials). Activity and stability of these materials was evaluated on the wet peroxide oxidation of phenol under mild reaction conditions (100 degrees C, air pressure of 1MPa and stoichi...
Article
Four different iron-containing SBA-15 based mesoporous materials have been prepared. The first three (DS-1, DS-2 and DS-3) are synthesised directly from the same synthesis gel containing iron—just modifying the second ageing step at different pH values (<1, 3.5, and 7 respectively). The fourth substance (PS sample) is a grafted material, with iron...
Article
The crystallization mechanism of Fe-MFI zeolite synthesized from amorphous Fe2O3–SiO2 xerogels wetness impregnated with aqueous TPAOH solutions has been studied. Samples with different degrees of crystallinity were prepared and characterized by means of conventional techniques. Activity and stability of these iron-containing samples has been tested...
Article
Full-text available
ABS TRA CT Several wastewaters coming from petrochemical, pharmaceutical, agrochemical and printing industries have been treated by application of heterogeneous catalytic wet hydrogen peroxide oxidation (CWHPO). A home-made catalyst based on the immobilization of iron oxide over a mesostructured silica support has been used as heterogeneous catalys...