Effect Of Electrical Double Layer Research Articles

Quantitative Assessment of Molecular Transport through Sub-3 nm Silica Nanochannels by Scanning Electrochemical Microscopy.

Scanning electrochemical microscopy (SECM) has been proved to be a powerful technique to study molecular transport across ionic channels in biomembranes and artificial nanoporous membranes. In this work SECM was used to study the dynamics of molecular transport across the ultrathin silica nanoporous membrane consisting of sub-3 nm diameter perpendicular channels. We focused on the quantitative assessment of permselectivity and permeability of the membrane and the effect of radial electrical double layer (EDL) on them. By SECM imaging, it was phenomenologically observed that the membrane with negatively charged surface exhibited permselectivity to anionic molecule, for instance hexacyanoruthenate(II) (Ru(CN)64-). And the permselective transport of Ru(CN)64- was obviously more favored at a higher concentration of KCl. Precise membrane permeability to Ru(CN)64- was quantitatively determined by overlapping experimental SECM approach curves with the ones generated by finite element simulations. The high permeability up to 35 μm s-1 was ascribed to the straight channel structure and ultrahigh channel density of 4 × 1012 cm-2. Moreover, the permeability was varied from 35 μm s-1 to 2.5 μm s-1 when decreasing the concentration of KCl from 1.0 to 0.01 M, corroborating the electrostatic origin of membrane permselectivity. On the other hand, the simulated concentration profiles at both sides of the membrane suggested that the molecular transport across the membrane was mainly driven by the large transmembrane concentration gradient while the tip-induced transport was relatively negligible. These results help to quantitatively understand the molecular transport selectivity and dynamics across nanoporous membranes and to rationally design artificial molecular sieving membranes.

Mathematical modelling of surface tension of nanoparticles in electrolyte solutions

Nanoparticles (NPs) have been successfully applied to reservoirs for enhanced oil recovery and fines migration mitigation at laboratory scale. Despite the successful implementation at laboratory scale, it is rarely applied at field scale. One of the major reasons for the delay in implementation is the lack of an appropriate model to predict the fluid-particles behaviour in the reservoir. An accurate prediction of the surface tension of the fluid system is particularly important in field design and development in the petroleum sector.The surface tension of NPs in deionized water increases with increase in concentration of NPs. This study exploits the Debye-Hückel constants to calculate the mean activity coefficients of NPs in solution combined with the equation proposed by Li and Lu (2001) for single electrolyte solutions to estimate the change in surface tension.However, NPs behaviour in brine (electrolyte solution) is different from the behaviour of mixture of different electrolytes. In deionized water, the surface tension of the fluid increases with increase in the NPs concentration, but NPs in electrolyte solutions behave as surface active agent decreasing the surface tension with increase in NPs concentration. This work includes the dipole-dipole interaction and structural effects along with the equation developed by Borwankar and Wasan (1988) for surface excess adsorption. This surface excess adsorption is applied to Li and Lu's equation for mixed electrolyte solutions to estimate the change in surface tension.This study is able to model the surface tension of NPs with or without electrolyte. Here, the molecular interaction of NPs in deionized water and electrolyte solutions is considered to predict the fluid-surface tension. The free energy at the interface is affected by the intermolecular interaction of the NPs. This intermolecular interaction includes electrical double layer, dipole-dipole interaction, and structural effects. The proposed model shows a good agreement with the experimental data from previous studies.

Effect of electrical double layer and ion exchange on low salinity EOR in a pH controlled system

Wettability of an oil/brine/sandstone system is an important petro-physical parameter, governing subsurface multi-phase flow and residual oil saturations. While how edge-charged clays (e.g., kaolinite) contribute to low salinity effect has been extensively investigated, few work have been done on basal-charged clays (e.g., illite, smectite, and chlorite), and few have look beyond the application of the low salinity effect in reservoirs bearing basal-charged clays. We thus integrated atomic force microscopy (AFM) (at a given pH = 7), disjoining pressure calculations, together with surface complexation modelling to understand the importance of basal-charged clays during low salinity water flooding in sandstone reservoirs. We found that low salinity effect can take place without pH increase, confirming that electrical double layer is at least one of the mechanisms to yield low salinity effect, which can be interpreted using disjoining pressure isotherm, whereas ion exchange between oil and basal charged clays leads to an opposite effect at a given pH. However, ion exchange likely favors low salinity effect without controlling pH due to the chemical reaction: >Na + H+ = >H + Na+, which in return decreasing the electrostatic bridges between NH+/clays, COOCa+/clays. Knowing the contribution of EDL and ion exchange on oil/brine/basal-charged clays interaction, the potential of low salinity effect in sandstone reservoirs can be quantified.

Multiscale modeling of ion diffusion in cement paste: electrical double layer effects

Understanding the mechanism of ion diffusion in hardened cement paste is of great importance for predicting long-term durability of concrete structures. Gel pores in calcium silicate hydrate (CSH) phase forms dominant pathway for transport in cement paste with low w/c ratios where the electrical double layer effects play an important role. Experimental results suggest that the effective diffusivity of chloride ions is similar as that of tritiated water (HTO) and higher than the sodium ions. This difference can be attributed to the electrical double layer near the charged CSH surfaces. In order to understand species transport processes in CSH and to quantify its effective diffusivity, a multiscale modeling technique has been proposed to combine atomic-scale and pore-scale modeling. At the pore scale, the lattice Boltzmann method is used to solve a modified Nernst Planck equation to model transport of ions in gel pores. The modified Nernst Planck equation accounts for steric and ion-ion correlation effects by using correction term for excess chemical potential computed through the results from the grand canonical Monte Carlo scheme at atomic scale and in turn bridges atomic scale model with pore scale model. Quantitative analysis of pore size influence on effective diffusivity carried out by this multiscale model shows that the contribution of the Stern layer to ion transport is not negligible for pores with diameter less than 10 nm. The developed model is able to reproduce qualitatively the trends of the diffusivity of different ions reported in literature.

Dispersion of charged solute in charged micro- and nanochannel with reversible sorption.

We study dispersion of a charged solute in a charged micro- and nanochannel with reversible sorption and derive an analytical solution for mass fraction in the fluid, transport velocity and dispersion coefficient. Electrical double layer formed on the charged surface gives rise to a charge-dependent solute transport by modifying the transverse distribution of the solute. We discuss the effect of sorption and electrical double layer on solute transport and show that the coupling between sorption and electrical double layer gives rise to charge-dependent transport even for a thin double layer. However, in this case, it can be reduced to a simple non-charge-dependent case by introducing the intrinsic sorption equilibrium constant.

An analytical model for the transverse permeability of gas diffusion layer with electrical double layer effects in proton exchange membrane fuel cells

An analytical model is presented for the transverse permeability of gas diffusion layer (GDL) based on an ordered array of parallel charged circular cylinders at the steady state. The formula of calculating the permeability of the transverse direction is given by solving the fluid momentum equation in a unit cell. In the present approach, the proposed model is explicitly related to the porosity and fiber radius of fibrous porous media, the zeta potential, and the physical properties of the electrolyte solution. Besides, the effects of these parameters (the porosity, unit cell aspect ratio, fiber radius, and molar concentration) on the transverse permeability are discussed detailedly. The model predictions are compared with the previous studies in the available literature, and good agreement is found.

Electroosmotically induced alterations in peristaltic microflows of power law fluids through physiological vessels

A mathematical model to analyze the effects of electric double layer and applied external electric field on peristaltic transport of non-Newtonian aqueous solution through a microchannel is presented. Ostwald–de Waele power law model is employed to describe the non-Newtonian fluid, in an effort to capture the essential biofluid dynamics. The governing equations of physical problem are simplified using low Reynolds number and long wavelength approximations. Poisson Boltzmann equations are also solved under Debye Huckel linearization. Following non-dimensional transformation of the linearized boundary value problem, closed-form analytical solutions are presented for the velocity components, pressure gradient, average flow rate, and stream function subject to physically appropriate boundary conditions. Validation with existing results is also made. A comparative discussion between shear thinning fluid and shear thickening fluids under the influences of Debye length and Helmholtz–Smoluchowski velocity are presented numerically. Trapping phenomenon for dilatant fluids and pseudoplastic fluids under the electrokinetic phenomenon is also computed. This model can help toward designing artificial biomedical devices based on microfluidic devices which can also be applicable to control the physiological transport.

Multiscale Modeling of a Proton Exchange Membrane Fuel Cell: Effect of Electric Double Layer in Cathodic Interface at Different O2 Concentrations

Mathematical models have played an important role for the understanding of proton exchange membrane fuel cells (PEMFCs ) (1), (2), (3), (4). Specifically, multiscale models attempt to take into account the physicochemical phenomena from atomistic to macroscopic scales to reliably reproduce the PEMFCs performance and reducing the number of parameters involved in equations. Through the last years multiscale models have employed different approaches: from non equilibrium thermodynamics, electrodynamics, and transport equations in general (5), (6), (7), (8), (9), (10), (11) to statistical mechanics using kinetic monte carlo method (MC) (11), or quantum physics using density functional theory (DFT) (7), (11), (12). In this work a molecular dynamics (MD) simulation of a platinum / oxygen / water interface is employed to describe the formation of the electric double layer (EDL) and also an electric overpotential associated with different operational concentrations of molecular oxygen. Those overpotentials are included in kinetic equations of the oxygen reduction reaction (ORR) mechanism for the cathode. Finally this ORR kinetics is included in a multiscale model of a PEMFC (13). Such multiscale model also utilizes other three approaches: DFT to calculate activation energies (14), a modified transport model for the membrane (15) and also it uses the transition state theory for the catalyst layer. It is expected that this EDL coupling will generate an improvement of the description capacity of the multiscale model in comparison with the experimental data of the electroosmotic drag coefficients vs current density for different relative humidities of the cathode.References D.M. Bernardi, M.W. Verbrugge. J. Electrochem. Soc. 139, 2477–2491 (1992).M. Yoneda, Y Tago, K Suzuki, M. Takimoto, S. Sukemura. ECS Trans. (1) 1149-1158 (2006)K. Takaya and T. Araki, ECS Trans., 75, 563–572 (2016).T. Berning, M. Odgaard, and S. K. Kær, J. Power Sources, 196, 6305–6317 (2011).54. B. Laoun, 14, 441–448 (2011).A. A. Franco, P. Schott, C. Jallut, and B. Maschke, J. Electrochem. Soc., 153, A1053 (2006).P. Rama et al., Energy and Fuels, 24, 3130–3143 (2010).L. F. L. Oliveira, C. Jallut, and A. A. Franco, Electrochim. Acta, 110, 363–374 (2013).S. Strahl, A. Husar, and A. A. Franco, Int. J. Hydrogen Energy, 39, 9752–9767 (2014).L. Chen et al., Int. J. Heat Mass Transf., 63, 268–283 (2013).C. Robin, M. Gerard, A. A. Franco, and P. Schott, Int. J. Hydrogen Energy, 38, 4675–4688 (2013).M. A. Quiroga and A. A. Franco, J. Electrochem. Soc., 162, E73–E83 (2015) http://jes.ecsdl.org/cgi/doi/10.1149/2.1011506jes.R. F. De Morais, P. Sautet, D. Loffreda, and A. A. Franco, Electrochim. Acta, 56, 10842–10856 (2011).S. Castaneda Ramirez, a. E. Perez Mendoza, and R. E. Ribadeneira Paz, ECS Trans., 66, 19–39 (2015).S. Castañeda Ramírez, A. E. Pérez Mendoza and R. E. Ribadeneira Paz, ECS Transactions, 66 (28) 7-18 (2015).A. Z. Weber, J. Newman, J. Electrochem. Soc. 150 (2003) A1008. doi:10.1149/1.1580822.

Junctionless Thin-Film Transistors Gated by an H₃PO₄-Incorporated Chitosan Proton Conductor.

We fabricated an H3PO4-incorporated chitosan proton conductor film that exhibited the electric double layer effect and showed a high specific capacitance of 4.42 μF/cm2. Transparent indium tin oxide thin-film transistors gated by H3PO4-incorporated chitosan films were fabricated by sputtering through a shadow mask. The operating voltage was as low as 1.2 V because of the high specific capacitance of the H3PO4-incorporated chitosan dielectrics. The junctionless transparent indium tin oxide thin film transistors exhibited good performance, including an estimated current on/off ratio and field-effect mobility of 1.2 × 106 and 6.63 cm2V-1s-1, respectively. These low-voltage thin-film electric-double-layer transistors gated by H3PO4-incorporated chitosan are promising for next generation battery-powered "see-through" portable sensors.

Electroclinic effect in the chiral lamellar α phase of a lyotropic liquid crystal.

In thermotropic chiral Sm-A^{*} phases, an electric field along the smectic layers breaks the D_{∞} symmetry of the Sm-A^{*} phase and induces a tilt of the liquid crystal director. This so-called electroclinic effect (ECE) was first reported by Garoff and Meyer in 1977 and attracted substantial scientific and technological interest due to its linear and submicrosecond electro-optic response [S. Garoff and R. B. Meyer, Phys. Rev. A 19, 338 (1979)0556-279110.1103/PhysRevA.19.338]. We now report the observation of an ECE in the pretransitional regime from a lyotropic chiral lamellar L_{α}^{*} phase into a lyo-Sm-C^{*} phase, the lyotropic analog to the thermotropic Sm-C^{*} phase which was recently discovered by Bruckner etal. [Angew. Chem. Int. Ed. 52, 8934 (2013)1433-785110.1002/anie.201303344]. We further show that the observed ECE has all signatures of its thermotropic counterpart, namely (i) the effect is chiral in nature and vanishes in the racemic L_{α} phase, (ii) the effect is essentially linear in the sign and magnitude of the electric field, and (iii) the magnitude of the effect diverges hyperbolically as the temperature approaches the critical temperature of the second order tilting transition. Specific deviations between the ECEs in chiral lamellar and chiral smectic phases are related to the internal field screening effect of electric double layers formed by inevitable ionic impurities in lyotropic phases.

Microwave transparent crosslinked polystyrene nanocomposites with enhanced high voltage resistance via 3D printing bulk polymerization method

Demanded by the application in ultrahigh pulsed power generator as vacuum insulator, the MgO-filled nanocomposites with enhanced high voltage resistance were developed on the basis of microwave transparent crosslinked polystyrene (CPS). Considering the severe thermal runaway problem, a proprietary fabrication method combing the in-situ preparation with 3D printing bulk polymerization technique was also innovated and bulk products with different filler loading were successfully fabricated. The microscope images suggested that the distribution of MgO in the products was uniform, whereat the excellent mechanical properties of CPS were well maintained. Furthermore, owing to the appropriate dielectric characteristics of MgO and tiny filler loading, the relative permittivity of the composites increased very slightly while the loss tangent below 20 GHz was less than 8×10−4, indicating the excellent transparency at the microwave band. Most importantly, the electrical breakdown strength was sharply improved from about 450 to over 600 kV/mm by only 0.1% MgO, as the barrier effect of electric double layer at the tremendous interface had effectively suppressed excessive charge injection and retarded electrical failure. Regarding the high voltage resistance obviously improved and the other properties well maintained, the CPS/MgO nanocomposites designed and developed in this work are applicable for the targeting application.

Effects of Electric Double Layer in Colloidal Hydrodynamics in Electrolyte Solutions

Effects of Electric Double Layer in Colloidal Hydrodynamics in Electrolyte Solutions

Ultralow-voltage albumen-gated electric-double-layer thin film transistors

In recent years, environment-friendly and biocompatible electronics have received extensive attention. As a kind of natural biological material with rich sources, proteins have been widely used in electronic devices. In this work, electric-double-layer (EDL) thin-film transistors (TFTs) gated by natural chicken albumen are fabricated at room temperature. The indium-tin-oxide (ITO) conductive glass is employed as a substrate. The spin coated chicken albumen film is used as the gate dielectric. The indium-zinc-oxide (IZO) is sputtered on an albumen-coated ITO glass as the channel and the source/drain electrodes with only one shadow mask. The capacitance-frequency measurements demonstrate an ultra-large specific capacitance of the albumen film at low frequencies. For the physical understanding of the capacitive coupling within the albumen film, the phase angle is characterized as a function of frequency. The results indicate that such an ultra-large capacitive coupling can be attributed to the proton migration under the electric field, which results in the EDL effect at the interface of the albumen film. By DC sweep measurements, a low leakage current is observed (<3.0 nA at <i>V</i><sub>gs</sub>=1.5 V), which indicates a good isolation of the albumen-based dielectric. By transfer and output measurements, an ultralow operation voltage of 1.5 V, a high field-effect mobility of 38.01 cm<sup>2</sup>/(V·s), a low subthreshold swing of 164 mV/decade, and a large on-off ratio of 2.4×10<sup>6</sup> are obtained for such albumen-gated TFTs. The ultra-large EDL capacitive coupling is responsible for such good electrical characteristics. The dynamic bias stress stability of the albumen-gated TFTs is also investigated. The device exhibits a good reproducibility in response to the repeatedly pulsed gate voltage. A maintainable on-to-off ratio (>10<sup>6</sup>) and no obvious current loss are observed, which suggests that neither chemical doping nor chemical reaction occurs at the albumen-based dielectric/IZO channel interface when the gate potential is biased. After being aged one day in air ambient without surface passivation, the albumen-gated TFTs show a good stability of the electrical properties. Such ultralow-voltage EDL-TFTs gated by albumen electrolyte will be useful for the bioelectronic and low-energy portable electronic products. And our results will also have potential applications in biocompatible artificial neuron networks and brain-inspired neuromorphic systems.

Redox cycling in nanogap electrochemical cells

Summary The repeated oxidation and reduction of a redox species (redox cycling) in a gap between two working electrodes has primarily been used to study the kinetics of electrochemical reactions. New fabrication methods have allowed the gap between the two working electrodes to be reduced to 10′s of nanometers in size. This reduced nanogap width has allowed recent innovations such as single molecule electrochemistry and probing the effect of electrical double layer on molecular transport at electrode/electrolyte interfaces.

Carbon Textile Decorated with Pseudocapacitive VC/Vx Oy for High-Performance Flexible Supercapacitors.

It is demonstrated that, via V2 O5 coating by low temperature atomic layer deposition and subsequent pyrolysis, ubiquitous cotton textile can readily turn into high-surface-area carbon textile fully decorated with pseudocapacitive Vx Oy /VC widely usable as electrodes of high-performance supercapacitor. It is found that carbothermic reduction of V2 O5 (C + V2 O5 → C' + VC + CO/CO2 (g)) leads to chemical/mechanical activation of carbon textile, thereby producing high-surface-area conductive carbon textile. In addition, sequential phase transformation and carbide formation (V2 O5 → Vx Oy → VC) occurred by carbothermic reduction trigger decoration of the carbon textile with redox-active Vx Oy /VC. Thanks to the synergistic effect of electrical double layer and pseudocapacitance, the supercapacitors made of the hybrid carbon textile exhibit far better energy density (over 30-fold increase) with excellent cycling stability than the carbon textile simply undergone pyrolysis. The method can open up a promising and facile way to synthesize hybrid electrode materials for electrochemical energy storages possessing advantages of both electrical double layer and pseudocapacitive material.

Modelling of diffusion behavior of ions in low-density and high-density calcium silicate hydrate

To investigate the relationship between morphology and specific ion transport properties in low-density (LD) and high-density (HD) calcium-silicate-hydrate (C-S-H), a numerical method of directly achieving diffusivities is developed. Firstly, a multiscale structural model is proposed to reconstruct C-S-Hs in which self-similarity and quantitative physical properties are compared to experimental results. Subsequently, electrical double layer (EDL) theory is introduced into analysis of ion transport in pore solution. The quantitative analysis of various influence factors of EDL on ion diffusivities in pore solution is carried out and average diffusivity in pore solution is also obtained. Moreover, a numerical method for solving Fick’s first law equation is performed on the simulated C-S-H structures to obtain numerous diffusivities of common ions in C-S-H. Finally, the significant parameter for durability in reinforcement concrete, chloride diffusivity in hardened cement paste, is predicted using simulated diffusivities in C-S-Hs, based on a multiscale method. It is found that compared to the atomic force microscope image and surface area of C-S-H, this self-similar model can well reconstruct real C-S-H structures. In addition, the influence factors of EDL including overlapping diffuse layer, relative potential, cation/anion, valence, zeta potential and bulk solution have great effects on ion diffusivities, which demonstrates EDL effects cannot be ignored when investigating ion transport behavior in C-S-H. Furthermore, using an appropriate case of pore solution with diffusivities of 8.2×10−12m2/s in LD C-S-H and 2.0×10−13m2/s in HD C-S-H, estimated chloride diffusivities in cement pastes agree well with measured values, which can indirectly indicate this modelling work is reasonable.

Upscaling scheme for long-term ion diffusion in charged porous media.

Description of long-term (over years) ion diffusion at the pore scale is a huge challenge since the characteristic time of diffusion in a typical representative elementary volume is around microseconds, generally ten orders of magnitude lower than the time we were concerned with. This paper presents a numerical upscaling scheme for ion diffusion with electrical double-layer effects (electrodiffusion) considered in charged porous media. After a scaling analysis for the nondimensional governing equations of ion transport at the pore scale, we identify the conditions for decoupling of electrical effect and diffusion, and therefore are able to choose apposite temporal and spatial scales for corresponding directions of the electrodiffusion process. The upscaling scheme is therefore proposed based on a numerical framework for governing equations using a lattice Boltzmann method. The electrical potential or concentration profiles from steady- or unsteady-state electrodiffusion in the long, straight channel, calculated by this upscaling scheme, are compared with the well-meshed full-sized simulations with good agreement. Furthermore, this scheme is used to predict tracer-ion throughdiffusion and outdiffusion in hardened cement pastes. All numerical results show good agreement with the full-sized simulations or experiment data without any fitting parameters. This upscaling scheme bridges the ion diffusion behaviors in different time scales, and may help to improve the understanding of long-term ion transport mechanisms in charged porous media.

Rotational electrohydrodynamics of a non-Newtonian fluid under electrical double-layer phenomenon: the role of lateral confinement

We investigate the transient analysis of the transport features of a non-Newtonian fluid in a rotating microfluidic channel as modulated by the electrical double-layer effect. We use the power-law model to describe rheology of the non-Newtonian fluid in this study. We bring out the rotational force-induced development of the secondary flows inside the channel, taking the effects of the lateral confinement into account. We show that the consideration of lateral confinement into the analysis gives rise to a complex flow dynamics, allowing the formation of double-vortex structures as well as the sister vortexes in the flow field. In particular, we show that the sister vortexes formed in the flow field exhibit different senses of rotations under the influence of the electrical forcing, leading to a potential enhancement in mixing in microfluidic channel. Also, we show the variation of the volume flow rate through the channel for different cases and unveil the secondary flow-induced alteration in the device throughput. We believe that the inferences obtained from this analysis may improve the design of miniaturized systems/devices, typically used for the transportation of bio-fluids, which are largely non-Newtonian in nature, in a rotating platform.

Electroosmotic flow and ionic conductance in a pH-regulated rectangular nanochannel

Infinite series solutions are obtained for electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties of long pH-regulated rectangular nanochannels of low surface potential utilizing the double finite Fourier transform method. Closed form expressions are also obtained for channels of large height to width ratio for which the depthwise variations vanish. Neglecting the Stern layer impact, the effects of EDL (Electric Double Layer) overlap, multiple ionic species, and association/dissociation reactions on the surface are all taken into account. Moreover, finite-element-based numerical simulations are conducted to account for the end effects as well as to validate the analytical solutions. We show that, with the exception of the migratory ionic conductivity, all the physicochemical parameters are strong functions of the channel aspect ratio. Accordingly, a slit geometry is not a good representative of a rectangular channel when the width is comparable to the height. It is also observed that the distribution of the electrical potential is not uniform over the surface of a charge-regulated channel. In addition, unlike ordinary channels for which an increase in the background salt concentration is always accompanied by higher flow rates, quite the opposite may be true for a pH-regulated duct at higher salt concentrations.

Impact of reverse nutrient diffusion on membrane biofouling in fertilizer-drawn forward osmosis

Biofouling in fertilizer-drawn forward osmosis (FDFO) for water reuse was investigated by spiking pure bacteria species Pseudomonas aeruginosa PAO1+GFP and using three different fertilizers KNO3, KCl and KH2PO4 as draw solutions. The performance of FO process for treating synthetic wastewater was assessed and their influence on the membrane fouling and in particular biofouling was evaluated relative to the type of different fertilizers used and their rates of reverse diffusion. FO performances using KNO3 as draw solute exhibited severer flux decline (63%) than when using KCl (45%) and KH2PO4 (30%). Membrane autopsy indicated that the mass of organic foulants and biomass on fouled membrane surface using KNO3 as draw solute (947.5mg/m2 biopolymers, 72µm biofilm thickness and 53.3mg/m2 adenosine triphosphate) were significantly higher than that using KCl (450mg/m2 biopolymers, 33µm biofilm thickness and 28.2mg/m2 ATP) and KH2PO4 (440mg/m2 biopolymers, 35µm biofilm thickness and 33.5mg/m2 ATP). This higher flux decline is likely related to the higher reverse diffusion of KNO3 (19.8g/m2/h) than KCl (5.1g/m2/h) and KH2PO4 (3.7g/m2/h). The reverse diffused potassium could promote the organics and bacterial adhesion on FO membrane via charge screening effect and compression of electrical double layer. Moreover, reverse diffused nitrate provided increased N:P nutrient ratio was favorable for the bacteria to grow on the feed side of the FO membrane.