WORCESTER BOSCH SET OF ELECTRODES 87186643010

Product Information

P. Ratajczak, M. E. Suss, F. Kaasik and F. Béguin, Energy Storage Mater., 2019, 16, 126–145 CrossRef. For the case where all ions are monovalent, or all ions are divalent, the resulting equation for σ 0 versus ϕ D has been often presented, see ref. 156. A. Hassanvand, G. Q. Chen, P. A. Webley and S. E. Kentish, Water Res., 2018, 131, 100–109 CrossRef CAS.

Formation of an electrical double-layer (EDL) is a fundamental feature of many topics in physics and chemistry, and is also exploited in CDI. The first EDL model, the Helmholtz model, was proposed by Hermann Helmholtz in 1879. This model was later revised by Louis Gouy and David Chapman in 1910 and in 1913, respectively. The Helmholtz model and the Gouy–Chapman model were combined into the widely utilized Gouy–Chapman–Stern (GCS) model by Otto Stern in 1924. 35 Broader context Increasing demand of non-renewables and dwindling resources require robust solutions to establish secure supply lines in the immediate future. The ability of capacitive deionization (CDI) to tune the system selectivity towards a particular ion of interest reveals tremendous potential in this endeavor. CDI has exhibited promising and exponential growth in the last two decades. This progress has been inspired by a multitude of motives including new electrodes, membranes, and their surface functionalization, CDI cell architectures, novel applications, and a better understanding of theory and practice. Particularly considering novel applications, CDI has recently deepened its roots in the field of selective ion separation. Ion selectivity is a crucial component in resource recovery, wastewater treatment, as well as ion sensing. Therefore, this work is intended to thoroughly examine the rapid growth of CDI in the field of ion selectivity until the state-of-the-art, and consequently, initiate new research dimensions by bringing forth a new theory of selective ion separation with intercalation materials. Ren et al. employed a flow MCDI (FCDI) cell to remove phosphate and ammonium from an aqueous solution. 133 Although it was found to be possible to remove large amounts of phosphate, the selectivity using this cell design was not explored. Further insight about selectivity using FCDI was reported by Bian et al. who studied the best operational conditions for the removal of phosphate and nitrate. 134 They observed a strong increase in the phosphate removal by increasing the carbon loading of the anode. This increase was steeper than that for nitrate (and ammonia), and was ascribed to the physical adsorption of phosphate in addition to electrosorption ( Fig. 6E), similar to the results obtained by Ge et al. On the other hand, for low carbon loadings, FCDI was found to be much more selective towards nitrate (1.1 at 15 wt% carbon loading to 1.7 at 5 wt%). Another recent approach that has provided viable results for selectivity between mono/divalent ions is the use of monovalent ion-selective membranes. Pan et al. investigated the use of such membranes to separate fluoride and nitrite from sulfate. 137 Using an equimolar solution, the authors observed a selectivity ( ρ) of ≈1.4 for fluoride ions over sulfate ions. Furthermore, it was found that the pH of the feed solution was an important parameter to control and improve the ion selectivity. Higher pH values increased the selectivity towards fluoride, while for acidic solutions the selectivity was lost due to an interaction between protons and the surface of the membrane. The effect of the feed concentration was also explored, keeping the concentration ratio between the two anions constant. An increasing fluoride selectivity was observed upon increasing the concentration of both F − and SO 4 2−. When the cell voltage was increased, the selectivity was reduced towards F − demonstrating that high cell voltages cannot attain high selectivity. This result is in line with other works that show lower selectivity at higher cell voltages. 41,77

Article Menu

S. Buczek, M. L. Barsoum, S. Uzun, N. Kurra, R. Andris, E. Pomerantseva, K. A. Mahmoud and Y. Gogotsi, Energy Environ. Mater., 2020, 3, 398–404 CrossRef CAS. P. Srimuk, J. Lee, A. Tolosa, C. Kim, M. Aslan and V. Presser, Chem. Mater., 2017, 29, 9964–9973 CrossRef CAS. K. Zuo, J. Kim, A. Jain, T. Wang, R. Verduzco, M. Long and Q. Li, Environ. Sci. Technol., 2018, 52, 9486–9494 CrossRef CAS. S. Choi, B. Chang, S. Kim, J. Lee, J. Yoon and J. W. Choi, Adv. Funct. Mater., 2018, 28, 1–9 Search PubMed. Moving forward, research into new electrode materials and chemistries, modification and optimization of existing materials, investigation of parameters in selectivity operation, modeling of selectivity at the system and molecular level, and finally, techno-economic analysis into the viability of selective ion separation via CDI will be crucial for fully realizing the potential of ion-selectivity via CDI.

Q. Dong, X. Guo, X. Huang, L. Liu, R. Tallon, B. Taylor and J. Chen, Chem. Eng. J., 2019, 361, 1535–1542 CrossRef CAS. R i and R j are calculated by dividing the effluent concentration by feed concentration of each ion. Mrs Sevil Sahin received her BSc degree from the Department of Chemistry at Istanbul Technical University, and her MSc degree from the Department of Pharmaceutical Chemistry at Istanbul University, Turkey. During her MSc research, she synthesized porphyrin derivatives for photodynamic therapy. Since 2017, she is a PhD candidate in the Department of Organic Chemistry at Wageningen University, The Netherlands. Her doctoral research includes, among others, the use of polyelectrolyte multilayers for tuning ion selectivity in capacitive deionization.In CDI experiments using a CMX membrane, selectivity towards divalent over monovalent cations was reported. 119,120 Although the CMX membrane was not designed to differentiate between different cations, its negatively charged outermost layer attracts divalent more than the monovalent cations. 121 Hassanvand et al. stated that the implementation of CMX in CDI leads to sharper desorption peaks of divalent cations since larger amounts of di-over monovalent cations are temporarily stored within the CMX membrane. 53 On the other hand, the CIMS membrane resulted in preferential transport of monovalent over divalent cations. 122 Similarly, Choi et al. used a CIMS membrane and obtained monovalent cation selectivity ( R) of 1.8 for sodium over calcium ions. 121 By selectively removing Na +, a Ca 2+-rich solution was obtained. In addition, the selectivity attained its maximum value at higher cell voltages, pH, and lower TDS (total dissolved solids) concentration. For the term, γα′, γ is a constant, namely γ = 0.0725, while α′ = d i/ h p. Here, d i is the (hydrated) ion size and h p is the ratio of pore volume over pore wall area. For a slit-shaped pore, h p is equal to the pore width divided by 2, and for a cylindrical pore it is equal to pore size ( i.e., pore diameter) divided by 4. Thus h p is a characteristic pore size, but because we typically do not know these values exactly, neither the ion size in the pore, nor the factor h p, α′ is typically an empirical factor. Mr Jayaruwan Gunathilake Gamaethiralalage is currently a PhD candidate in the Department of Organic Chemistry at Wageningen University & Research, The Netherlands. He received his BSc in chemistry from Kutztown University of Pennsylvania in the United States of America, joint MSc degrees in analytical chemistry from University of Tartu in Estonia, and Åbo Akademi University in Finland. His research interests include development of new material for ion separation and sensing, wastewater treatment, and electrodriven systems for circular water economy. The most accurate approach in describing the ion transport in combination with adsorption has been the porous electrode theory, put forward in 2010. 140 It was further developed by Biesheuvel and co-workers when they used this framework in a model that combined faradaic reactions and capacitive electrode charging for a mixture of a monovalent anion, a monovalent cation, and divalent cations, making use of the mD model to describe ion adsorption ( μ att = 0). 141 The same porous electrode theory was also used by Zhao et al. for a purely capacitive electrode, and extended by Dykstra et al. 48 for a solution with two types of monovalent cations and a monovalent anion. Here for the first time, a full cell with two electrodes is considered. Furthermore, the simple mD model with μ att = 0 is replaced by the improved mD model which considers a salt-concentration dependent ion adsorption energy. In Dykstra et al., the only mechanism causing a difference in adsorption between different monovalent cations was the diffusion coefficient of the ions leading to a selectivity for K + over Na + of up to S ≈ 1.4, in close agreement with detailed experiments. Theoretical calculations predict this selectivity to be at a maximum at intermediate cycle times, a result that was not fully corroborated by the experiments. Recently, Guyes et al. presented a theory which predicted an enhancement of size-based selectivity towards K + over Li + and Na +, with increasing chemical charges in the micropore added by surface modification. 142 S. J. Seo, H. Jeon, J. K. Lee, G. Y. Kim, D. Park, H. Nojima, J. Lee and S. H. Moon, Water Res., 2010, 44, 2267–2275 CrossRef CAS.