Pau Rodenas

Universitat Jaume I de Castelló, Dept. d’Enginyeria de Sistemes Industrials i Disseny, Post-Doc

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Pau Rodenas holds a Degree in Chemistry (2007) and a Master's Degree in Nanoscience and Molecular Nanotechnology (2012) from Jaume I University and Ph.D. in Bioelectrochemical Systems from Wageningen University (201 7) with long experience in research projects in international research centers (WETSUS from 2012 to 2016) and national (IMDEA Water from 2017 to 2020) (AINIA from 2020 to 2023) in water treatment, desalination and recovery of value-added products. He works in Universitat Jaume I.
Address: Av. Vicent Sos Baynat, s/n

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Papers by Pau Rodenas

Operational Decision-Making on Desalination Plants

International Journal of Decision Support System Technology

This paper describes some of the work carried out within the Horizon 2020 project MIDES (MIcrobia... more This paper describes some of the work carried out within the Horizon 2020 project MIDES (MIcrobial DESalination for low energy drinking water), which is developing the world's largest demonstration of a low-energy sys-tem to produce safe drinking water. The work in focus concerns the support for operational decisions on desalination plants, specifically applied to a mi-crobial-powered approach for water treatment and desalination, starting from the stages of process modelling, process simulation, optimization and lab-validation, through the stages of plant monitoring and automated control. The work is based on the application of the environment IPSEpro for the stage of process modelling and simulation; and on the system DataBridge for auto-mated control, which employs techniques of Machine Learning.

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Algae-assisted Microbial Desalination Cell; A cathode performance and desalination efficiency assessment Cathodic limitations in MDC significant influence on the desalination performance and electricity production

Desalación sin energía, desde el concepto a la realidad

Metals recovery from wastewater by microbial electrochemical technologies

Microbial electrochemical technologies (METs) are novel technologies that enable metal recovery f... more Microbial electrochemical technologies (METs) are novel technologies that enable metal recovery from many different wastewater streams. This chapter describes how microbes can interact with metal ions for both metabolic and recovery purposes. Electroactive bacteria can donate electrons extracellularly to metal ions and electrodes. This ability allows the construction of microbial electrochemical devices to recover metal from polluted wastewaters. These devices can remove organic matter in the anodic compartment while simultaneously reducing metals in the cathodic compartment. This chapter explains the fundamentals of this technology and several factors to take into consideration before designing an experiment. A list of different metal recovery systems targeting metals of industrial and economic relevance are described herein. METs are a real and viable alternative to current technologies, and the field of microbial electrochemical metallurgy (MEM) is continually growing. In compari...

Key elements and materials in microbial desalination cells

Microbial Desalination Cells for Low Energy Drinking Water, 2021

This chapter presents the most relevant advances achieved during the MIDES project in relation to... more This chapter presents the most relevant advances achieved during the MIDES project in relation to material development of key elements for microbial desalination cells. The first section is devoted to electrodes. Providing a general overview of the requirements of carbon-based materials to serve either as anodes or cathodes for microbial desalination cells. Advances achieved during MIDES in the development of materials for anode and cathode application are listed. The second section is focussed on ion-exchange membranes for microbial desalination cells. General considerations for the use of these membranes are reported as well as key parameters. Finally, advances in ion-exchange membrane development, in terms of antifouling and their performance in desalination trials, achieved during the MIDES project, are reported.

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Comparative Performance of Microbial Desalination Cells Using Air Diffusion and Liquid Cathode Reactions: Study of the Salt Removal and Desalination Efficiency

Frontiers in Energy Research, 2019

Microbial Desalination Cell (MDC) represents an innovative technology which accomplishes simultan... more Microbial Desalination Cell (MDC) represents an innovative technology which accomplishes simultaneous desalination and wastewater treatment without external energy input. MDC technology could be employed to provide freshwater with low-energy input, for example, in remote areas where organic wastes (i.e., urban or industrial) are available. In addition, MDC technology has been proposed as pre-treatment in conventional reverse osmosis plants, with the aim of saving energy and avoiding greenhouse gases related to conventional desalination processes. The use of oxygen reduction (i.e. O 2 + 2H 2 O + 4e − → 4 OH − , E 0 ′ = 0.815 V, pH = 7) was usually implemented as cathodic reaction in most of the MDCs reported in literature, whereas other strategies based on liquid catholytes have been also proposed, for example, ferroferricyanide redox couple (i.e. Fe(CN) 3− 6 + 1e − → Fe(CN) 4− 6 , E 0 = 0.37 V). As the MDC designs in the literature and operation modes (i.e., batch, continuous, semi-continuous, etc.) are quite different, the available MDC studies are not directly comparable. For this reason, the main objective of this work was to have a proper comparison of two similar MDCs operating with two different catholyte strategies, and compare performance and desalination efficiencies. In this sense, this study compares the desalination performance of two laboratory-scale MDCs located in two different locations for brackish water and sea water using two different strategies. The first strategy consisted of an air cathode for efficient oxygen reduction, while the second strategy was based on a liquid catholyte with Fe 3+ /Fe 2+ solution (i.e., ferro-ferricyanide complex). Both strategies achieved desalination efficiency above 90% for brackish water. Nominal desalination rates (NDR) were in the range of 0.17-0.14 L•m −2 •h −1 for brackish and seawater with air diffusion cathode MDC, respectively, and 1.5-0.7 L•m −2 •h −1 when using ferro-ferricyanide redox MDC. Organic matter present in wastewater was effectively removed at 0.9 and 1.1 kg COD•m −3 •day −1 using the air diffusion cathode MDC for brackish and Ramírez-Moreno et al. Comparative Performance of Microbial Desalination Cells sea water, respectively, and 7.1 and 19.7 kg COD•m −3 •day −1 with a ferro-ferricyanide redox MDC. Both approaches used a laboratory MDC prototype without any energy supply (excluding pumping energy). Pros and cons of both strategies are discussed for subsequent upscaling of MDC technology.

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Gas diffusion electrodes improve hydrogen gas mass transfer for a hydrogen oxidizing bioanode

Journal of Chemical Technology & Biotechnology, 2017

BACKGROUND: Bioelectrochemical systems (BESs) are capable of recovery of metals at a cathode thro... more BACKGROUND: Bioelectrochemical systems (BESs) are capable of recovery of metals at a cathode through oxidation of organic substrate at an anode. Recently, also hydrogen gas was used as an electron donor for recovery of copper in BESs. Oxidation of hydrogen gas produced a current density of 0.8 A m-2 and combined with Cu 2+ reduction at the cathode, produced 0.25 W m-2. The main factor limiting current production was the mass transfer of hydrogen to the biofilm due to the low solubility of hydrogen in the anolyte. Here, the mass transfer of hydrogen gas to the bioanode was improved by use of a gas diffusion electrode (GDE). RESULTS: With the GDE, hydrogen was oxidized to produce a current density of 2.9 A m-2 at an anode potential of-0.2 V. Addition of bicarbonate to the influent led to production of acetate, in addition to current. At a bicarbonate concentration of 50 mmol L-1 , current density increased to 10.7 A m-2 at an anode potential of-0.2 V. This increase in current density could be due to oxidation of formed acetate in addition to oxidation of hydrogen, or enhanced growth of hydrogen oxidizing bacteria due to the availability of acetate as carbon source. The effect of mass transfer was further assessed through enhanced mixing and in combination with the addition of bicarbonate (50 mmol L-1) current density increased further to 17.1 A m-2. CONCLUSION: Hydrogen gas may offer opportunities as electron donor for bioanodes, with acetate as potential intermediate, at locations where excess hydrogen and no organics are available.

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Hydrogen as electron donor for copper removal in bioelectrochemical systems

International Journal of Hydrogen Energy, 2016

Hydrogen gas is an attractive alternative electron donor since it is produced in large quantities... more Hydrogen gas is an attractive alternative electron donor since it is produced in large quantities as a side product in the metallurgical industry. Aim of this study was to demonstrate that microbial anodic hydrogen oxidation on a non-catalyzed graphite electrode can be coupled with cathodic copper reduction in a BES to simultaneously recover copper and produce power. The strategy was first to grow an anodic biofilm on acetate, then replace the acetate with hydrogen as electron donor, and finally combine hydrogen oxidation with copper reduction in the cathode. The maximum current density was 1.8 A/m2 at-250 mV anode potential vs Ag/AgCl. When coupled with Cu2+ reduction, the maximum power density was 0.25 W/m2 at a current density of 0.48 A/m2. Anode overpotentials were higher compared to acetate oxidation, probably a result of limited hydrogen solubility and transfer.

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High performance configuration on MFC for copper recovery

Heavy metals are a serious problem for the environment and for industry. Copper and other metals ... more Heavy metals are a serious problem for the environment and for industry. Copper and other metals are getting scarcer on new mining ores, but everyday more present in water and soils. MfC’s have been used to remove copper from waste streams, but to achieve an efficient process high current and power densities are required. We report high currents and high power densities with a Microbial Fuel Cell (MFC) for copper recovery using acetate as electron donor and copper sulphate solution as electron acceptor. The cell was constructed using an Anion Exchange Membrane (AEM), carbon felt and a flat copper electrode all of them with a surface of 100 cm2 . Current density of 23.2 Am-2 and a power output of 5.5 Wm-2 is produced. A stable current of 19 Am-2 was achieved and maintained for days with a power output of 3.9 Wm-2. The recovery efficiency of copper was 90.6% with a coulombic efficiency of 70%. In this presentation we will show that the membrane and the efficiency of the anode are the ...

High rate copper and energy recovery in microbial fuel cells

Frontiers in Microbiology, 2015

Bioelectrochemical systems (BESs) are a novel, promising technology for the recovery of metals. T... more Bioelectrochemical systems (BESs) are a novel, promising technology for the recovery of metals. The prerequisite for upscaling from laboratory to industrial size is that high current and high power densities can be produced. In this study we report the recovery of copper from a copper sulfate stream (2 g L −1 Cu 2+) using a laboratory scale BES at high rate. To achieve this, we used a novel cell configuration to reduce the internal voltage losses of the system. At the anode, electroactive microorganisms produce electrons at the surface of an electrode, which generates a stable cell voltage of 485 mV when combined with a cathode where copper is reduced. In this system, a maximum current density of 23 A m −2 in combination with a power density of 5.5 W m −2 was produced. XRD analysis confirmed 99% purity in copper of copper deposited onto cathode surface. Analysis of voltage losses showed that at the highest current, most voltage losses occurred at the cathode, and membrane, while anode losses had the lowest contribution to the total voltage loss. These results encourage further development of BESs for bioelectrochemical metal recovery.

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Bioelectrochemical systems for metal recovery

ABSTRACT BioelectroMET is a collaborative research project between Magneto special anodes (NL), M... more ABSTRACT BioelectroMET is a collaborative research project between Magneto special anodes (NL), MAST Carbon International ltd (UK), Centre de Recherche Public Henri Tudor (Lux), Universitat Jaume I (ES), Linnaeus University (SE), Tampere University of Technology (FI) and Wetsus, centre of excellence for sustainable water technology (NL). The project is funded by Europe’s 7th Framework Programme and is coordinated by Wetsus. BioelectroMET will investigate, develop and demonstrate a bioelectrochemical system capable of recovering metals from metallurgical waste and process streams with no or limited energy input.

Quantum Dot Based Heterostructures for Unassisted Photoelectrochemical Hydrogen Generation

Advanced Energy Materials, 2012

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Water Oxidation at Hematite Photoelectrodes with an Iridium-Based Catalyst

The Journal of Physical Chemistry C, 2013

The iridium complex [Cp*Ir(H 2 O) 3 ](SO 4) was used as an organometallic source for the electrod... more The iridium complex [Cp*Ir(H 2 O) 3 ](SO 4) was used as an organometallic source for the electrodeposition of iridium oxide onto Fe 2 O 3. The new iridium-containing electrode allowed us to study the coupling between the photocatalytic properties of hematite with the electrocatalytic properties of the iridium-based material. A cathodic shift of the photocurrent for water oxidation upon electrodeposition of the iridium complex was observed, which increased with increasing surface concentration of IrO x on Fe 2 O 3. The shift for the highest surface concentration of iridium tested amounts to 300 mV at 200 A•cm-2 current density. The catalytic mechanism of the IrO x layer was unveiled by impedance spectroscopy measurements fitted to a physical model, and can be explained on the basis of a highly capacitive layer, which enhances charge separation and stores photogenerated holes at Fe 2 O 3 , subsequently oxidizing water. These findings improve our understanding of the mechanism of water oxidation by heterogenous Ir-based catalysts coupled to semiconductor electrodes.

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Harnessing Infrared Photons for Photoelectrochemical Hydrogen Generation. A PbS Quantum Dot Based “Quasi-Artificial Leaf”

The Journal of Physical Chemistry Letters, 2013

Hydrogen generation by using quantum dot based heterostructures has emerged as a promising strate... more Hydrogen generation by using quantum dot based heterostructures has emerged as a promising strategy to develop artificial photosynthesis devices. In the present study, we sensitize mesoporous TiO 2 electrodes with in-situ deposited PbS/CdS quantum dots (QDs), aiming at harvesting light in both the visible and the near infrared for hydrogen generation. This heterostructure exhibits a remarkable photocurrent of 6 mA•cm-2 leading to 60 ml•cm-2 •day-1 hydrogen generation. Most importantly, confirmation of the contribution of infrared photons to H 2 generation was provided by the incident-photon-to-current-efficiency (IPCE), and the integrated current was in excellent agreement with that obtained through cyclic voltammetry. The main electronic processes (accumulation, transport and recombination) were identified by impedance spectroscopy, which appears as a simple and reliable methodology to evaluate the limiting factors of these photoelectrodes. Based on this TiO 2 /PbS/CdS heterostructrure, a "quasiartificial leaf" has been developed, which has proven to produce hydrogen under simulated solar illumination at (4.30 ± 0.25) ml•cm-2 •day-1 .

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Carrier density and interfacial kinetics of mesoporous TiO2 in aqueous electrolyte determined by impedance spectroscopy

Journal of Electroanalytical Chemistry, 2012

Water splitting at a semiconductor/solution interface with the only input of sunlight to generate... more Water splitting at a semiconductor/solution interface with the only input of sunlight to generate hydrogen is one of the most attractive strategies to produce and store chemical energy. In the present study we have investigated carrier dynamics and interfacial kinetics of mesoporous TiO 2 in an aqueous solution. The applicability of the transmission line model for mesoporous semiconductors has been validated to identify chemical capacitance, transport resistance and charge transfer resistance in this system by testing samples of different thicknesses in the dark and under illumination. We found that both transport resistance and chemical capacitance scale well with sample thickness, while charge transfer resistance scales with thickness when the FTO substrate is not exposed to the solution. Otherwise, there is a competition between charge transfer through TiO 2 and through the FTO substrate. Under illumination, the electron density is dominated by photogenerated carriers at biases below the open circuit potential, whereas at higher bias, the applied potential determines the electron density. Evidence of charge transfer via surface states has been experimentally observed and corroborated with a physical model, which explicitly includes charge transfer through a monoenergetic trap for electron and holes. This study may lay the basis for understanding more complex processes at anodic potentials on the TiO 2 /solution interface where water splitting reactions take place.

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Algae-Assisted Microbial Desalination Cell: Analysis of Cathode Performance and Desalination Efficiency Assessment

Processes, 2021

Algae-assisted microbial desalination cells represent a sustainable technology for low-energy fre... more Algae-assisted microbial desalination cells represent a sustainable technology for low-energy fresh water production in which microalgae culture is integrated into the system to enhance oxygen reduction reaction in the cathode chamber. However, the water production (desalination rate) is low compared to conventional technologies (i.e., reverse osmosis and/or electrodialysis), as biocathodes provide low current generation to sustain the desalination process. In this sense, more research efforts on this topic are necessary to address this bottleneck. Thus, this study provides analysis, from the electrochemical point of view, on the cathode performance of an algae-assisted microbial desalination cell (MDC) using Chlorella vulgaris. Firstly, the system was run with a pure culture of Chlorella vulgaris suspension in the cathode under conditions of an abiotic anode to assess the cathodic behavior (i.e., cathode polarization curves in light-dark conditions and oxygen depletion). Secondly, ...

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Microbial desalination cell design bioengineering assays: Main concepts

Microbial Desalination Cells for Low Energy Drinking Water

The main goal of this chapter is to present the main concepts and principles for the microbial de... more The main goal of this chapter is to present the main concepts and principles for the microbial desalination process. Also, a rational explanation of the electrochemical behaviour of the microbial desalination cell (MDC) setup under different experimental conditions is presented. The final section of the chapter shows the design and construction of an MDC pre-pilot unit, as well as the main results of desalination and water treatment capacity for the scaled-up device.

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