Multi-ionic effects on energy production based on double layer expansion by salinity exchange Fernández, M. Mar Ahualli Yapur, Silvia Alejandra Iglesias Salto, Guillermo Ramón González Caballero, Fernando Delgado Mora, Ángel Vicente Jiménez Olivares, María Luisa CapMix Electric Double layer expansion Energy extraction from salinity exchange Ionic size effect Multi-ionic solution The edited version of the manuscript can be obtained at: Delgado et al., J. Colloid Interface Science (2014); DOI http://dx.doi.org/10.1016/j.jcis.2014.08.009 It has been recently shown that the free energy change upon salinity mixing in river mouths can be harvested taking advantage of the fact that the capacitance of charged solid/liquid interfaces (electrical double layers, EDLs) depends strongly on the ionic composition of the liquid medium. This has led to a new generation of techniques called Capmix technologies, one of them (CDLE or Capacitive energy extraction based on DL Expansion) based precisely on such dependence. Despite the solution composition playing a crucial role on the whole process, most of the research carried out so far has mainly focused on pure sodium chloride solutions. However, the effect of other species usually present in river and sea waters should be considered both theoretically and experimentally in order to succeed in optimizing a future device. In this paper, we analyse solutions of a more realistic composition from two points of view. Firstly, we find both experimentally and theoretically that the presence of ions other than sodium and chloride, even at low concentrations, may lead to a lower energy extraction in the process. Secondly, we experimentally consider the possible effects of other materials usually dispersed in natural water (mineral particles, microbes, shells, pollutants) by checking their accumulation in the carbon films used, after being exposed for a long period to natural sea water during CDLE cycles. 2014-09-03T12:44:49Z 2014-09-03T12:44:49Z 2014 preprint Fernández, M.M.; et al. Multi-ionic effects on energy production based on double layer expansion by salinity exchange. Journal of Colloid and Interface Science, (2014). [http://hdl.handle.net/10481/32892] 0021-9797 http://hdl.handle.net/10481/32892 10.1016/j.jcis.2014.08.009 eng info:eu-repo/grantAgreement/EC/FP7/256868 open access Elsevier