Search results for " Reverse Electrodialysi"

A simulation tool for analysis and design of reverse electrodialysis using concentrated brines

2015

Abstract Reverse electrodialysis (SGP-RE or RED) represents a viable technology for the conversion of the salinity gradient power into electric power. A comprehensive model is proposed for the RED process using sea or brackish water and concentrated brine as feed solutions. The goals were (i) reliably describing the physical phenomena involved in the process and (ii) providing information for optimal equipment design. For such purposes, the model has been developed at two different scales of description: a lower scale for the repeating unit of the system (cell pair), and a higher scale for the entire equipment (stack). The model was implemented in a process simulator, validated against orig…

Exergy analysis of reverse electrodialysis

2018

Abstract Reverse electrodialysis in closed loop configurations is a promising membrane technology in the energy conversion and storage fields. One of the main advantages of closed-loop reverse electrodialysis is the possibility of using a wide range of operating concentrations, flow rates and different salts for generating the salinity gradient. In this work, an original exergy analysis of the reverse electrodialysis process was carried out in order to investigate reverse electrodialysis performance in terms of energetic and exergetic efficiency parameters in a wide range of operating conditions. A mono-dimensional model of the reverse electrodialysis process was developed, in which all sou…

Special applications of reverse electrodialysis

2016

Reverse electrodialysis (RED) is a process for direct electricity production from salinity gradients, based on the use of suitable exchange membranes. To develop the RED process on an applicative scale and to add value to the overall process, a key role is entrusted to the selection of electrodic system, redox species, and electrode materials. In particular, it was shown that a proper selection of redox processes allows the use of a RED cell for the wastewater treatment of organic and inorganic pollutants resistant to conventional biological methods and for the synthesis of chemicals without energy supply. The utilization of microbial reverse electrodialysis cells was also proposed to incre…

Cathodic abatement of Cr(VI) in water by microbial reverse-electrodialysis cells

2015

Abstract For the first time a microbial reverse electrodialysis cell (MRC) was used for the treatment of water contaminated by Cr(VI). It has been recently shown that both inorganic and organic pollutants can be removed by reverse electrodialysis processes (RED) using water with different salinity without the supply of electric energy. However, a high number of membrane pairs is usually necessary for the treatment of wastewater by RED. Here, it was showed that a lower number of membranes can be used by the utilization of a MRC (i.e., a RED cell with a biotic anode) for such purposes. Indeed, the abatement of Cr(VI), chosen as model pollutant, was successfully achieved by cathodic reduction …

CFD prediction of concentration polarization phenomena in spacer-filled channels for Reverse Electrodialysis

2014

Abstract Salinity Gradient Power generation through Reverse Electrodialysis (SGP-RE) is a promising technology to convert the chemical potential difference of a salinity gradient into electric energy. In SGP-RE systems, as in most membrane processes, concentration polarization phenomena may affect the theoretical driving force and thus the performance of the process. Operating conditions, including the feed solution flow rate and concentration and the channels׳ geometrical configuration, may greatly influence both the polarization effect and the pumping energy consumption. The present work uses CFD to investigate the dependence of concentration polarization and pressure drop on flow rate, f…

SELECTION OF REDOX SYSTEMS FOR REVERSE ELECTRODIALYSIS PROCESSES

2012

In reverse electrodialysis (RED) processes, electrical energy is directly extracted from chemical potential gradients arising from salinity differences, especially from sea and river water. In RED there are at least four complementary elements: (1) electrodes, where electron transfer reactions occur to allow the transformation of the charge carrier from ion to electron; (2) ion selective exchange membranes, which allow the selective transport of ions; (3) solvents, which make a continuum for ion transport; (4) electrolytes, i.e. the current carriers between cathode and anode. Studies on RED processes were mainly focused on membranes but also on several other aspects including electrolyte co…

Investigation of electrode material - redox couple systems for reverse electrodialysis processes

2012

REVERSE ELECTRODIALYSIS PROCESSES FOR THE PRODUCTION OF CHEMICALS AND THE TREATMENT OF CONTAMINATED WASTEWATER

Investigation of electrode material – redox couple systems for reverse electrodialysis processes. Part II: Experiments in a stack with 10–50 cell pai…

2013

Abstract The performances of reverse electrodialysis depend on several factors, including the nature of the electrode material and of the redox processes adopted to make possible the conversion between chemical potential and electric power. In this paper the possible utilization of various redox processes (reduction/oxidation of iron species, oxidation and reduction of water, oxidation of chlorine and reduction of water) was studied in a stack equipped with 10–50 cell pairs and by focused electrolyses in a three compartment cell. The effect of selected redox processes on power density output and eventual contamination of saline solutions flowing in the stack was evaluated in detail. The eff…

Coupling CFD simulation with a simplified process model for reverse electrodialysis units

2017

Salinity gradient between two solutions is a renewable source of energy. Among the technologies able to exploit the salinity gradient, reverse electrodialysis (RED) is an electrochemical process for electrical power generation through direct conversion. Ion exchange membranes, piled alternately and separated by net spacers or membrane profiles, are the key elements of a RED stack. A multiplex phenomenology occurs in RED units; Ohmic and non-Ohmic (due to concentration changes) voltage losses and pressure drop are the main issues, and the membrane/channel configuration is crucial for the stack performance. In this framework, mathematical modelling can be a powerful tool for predictive purpos…