Search results for "electrodialysi"

Reverse electrodialysis heat engine for sustainable power production

2017

Abstract Reverse Electrodialysis Heat Engine (REDHE) is a promising technology to convert waste heat at temperatures lower than 100 °C into electric power. In the present work an overview of the possible regeneration methods is presented and the technological challenges for the development of the RED Heat Engine (REDHE) are identified. The potential of this power production cycle was investigated through a simplified mathematical model. In the first part of the work, several salts were singularly modelled as possible solutes in aqueous solutions feeding the RED unit and the corresponding optimal conditions were recognized via an optimization study. In the second part, three different RED He…

Cathodic reduction of hexavalent chromium coupled with electricity generation achieved by reverse-electrodialysis processes using salinity gradients

2014

Abstract A new approach for the simultaneous generation of electric energy and the treatment of waters contaminated by recalcitrant pollutants using salinity gradients was proposed. Reverse electrodialysis allows for the generation of electric energy from salinity gradients. Indeed, the utilization of different salt concentrations gives a potential difference between the electrodes which allows the generation of electric energy by using suitable electrolytes and an external circuit. The simultaneous generation of electric energy and the treatment of waters contaminated by Cr(VI) was successfully achieved for the first time by reverse electrodialysis processes using salinity gradients and pr…

Exergy analysis of electrodialysis for water desalination: Influence of irreversibility sources

2022

The increasing freshwater demand is pushing the development and adoption of desalination technologies. In this framework, electrodialysis has a consolidated role in brackish water desalination, but to make it competitive with other technologies for the desalination of more concentrated solutions (e.g., seawater), the specific energy consumption should be reduced. Exergy analysis provides a useful tool for determining the contribution of each thermodynamic inefficiencies on the process efficiency and the specific energy consumption. In this regard, this paper presents an exergy analysis of the electrodialysis process. A 1-D model is used for evaluating the performance of industrial-scale sys…

Exergy analysis and thermoeconomic cost accounting of a CHP steam cycle integrated with MED-TVC desalination

2016

In this paper exergy analysis and thermoeconomic cost accounting of a CHP steam cycle integrated with MED-TVC plant is performed; the purpose is to show how this methodology provides a rational criterion to allocate production costs on electricity and freshwater. After a brief overview on methodology and a description of reference plant, exergy analysis is carried out in order to calculate exergy flows and plant exergetic performance. A detailed description of the adopted thermoeconomic model is given. Cost accounting is performed considering two scenarios: in the first, the concentrated brine is disposed back to sea, thus being its exergy content definitively wasted; in the second, convers…

Seawater desalination : state of the art on conventional technologies

2009

Desalination of oilfield produced waters via reverse electrodialysis: A techno-economical assessment

2023

Produced waters (PWs) are oilfield waste streams rich in minerals and hydrocarbons whose production rate is largely increased in last decades following the corresponding increase of energy demand. The high salinity level of PWs inhibits the adoption of cheap biological treatments. Also, desalination techniques based on osmotic membranes would require severe pre-treatments. As an alternative, Reverse ElectroDialysis (RED) and Assisted Reverse ElectroDialysis (ARED) are here proposed for the first time to reduce the salinity level of PWs. RED may also guarantee an operation cost reduction thanks to its energy generation. An ad-hoc model for RED and ARED is here developed in order to deal suit…

INVESTIGATION OF ELECTRODE MATERIAL-REDOX COUPLE FOR REVERSE ELECTRODYALISIS PROCESSES. PART I: IRON REDOX COUPLES.

2012

The performances of electrodialysis (ED) and reverse electrodialysis (RED) processes depend on several factors, including the nature of the electrode material and of the redox couple adopted to make possible the conversion between electric power and chemical potential. In this paper, the possible utilization of iron-based redox couples (FeCl3/FeCl2, hexacyanoferrate(III)/hexacyanoferrate(II) and Fe(III)-EDTA/Fe(II)-EDTA) on graphite and DSA electrodes for RED processes was studied by a detailed experimental investigation. The hexacyanoferrate(III)/hexacyanoferrate(II) system was stable for lonf time (more than 12 days) in the absence of light and oxygen at high redox couple concentrations a…

Energy generation and abatement of Acid Orange 7 in reverse electrodialysis cells using salinity gradients

2015

Abstract The simultaneous generation of electric energy and the treatment of wastewaters contaminated by an organic pollutant resistant to conventional biological processes, Acid Orange 7 (AO7), was achieved for the first time using proper redox processes by reverse electrodialysis using salinity gradients. The stack was fed with two aqueous solutions with different concentrations of NaCl and a synthetic wastewater contaminated by AO7. Various electrochemical approaches including electro-Fenton, electrogeneration of active chlorine (IOAC) and coupled process were performed in a stack equipped with 40–60 cell pairs and studied by focused electrolyses. The effect of the number of cell pairs a…

Modelling and characterization of electrodialysis systems for multi-ionic solutions

2019

In this work a simplified approach related to membrane properties is required

Assisted reverse electrodialysis for CO2 electrochemical conversion and treatment of wastewater: A new approach towards more eco-friendly processes u…

2020

Abstract In this paper, the utilization of assisted reverse electrodialysis (A-RED), recently used for pre-desalination, is proposed as a general method to reduce the energy requirements of electrolysis processes and evaluated for two model processes: (i) the cathodic conversion of carbon dioxide to formic acid; (ii) the anodic treatment of water contaminated by organics. In A-RED, two solutions with different salt content and an external potential difference, applied in the direction of the natural salinity gradient, are both used to drive redox processes. It was shown, for the first time, that the cathodic conversion of CO2 to formic acid can be performed by both reverse electrodialysis (…