Finite Ion Size Effects on Electrolyte Transport in Nanofiltration Membranes

Abstract

The pressure-driven electrolyte transport through nanofiltration membrane pores with specified wall potential is investigated theoretically.

Theoretical Study of Electrolyte Diffusion through Polarizable Nanopores

“…The transport of electrolyte through the pore is characterized by the solution velocity U = (U, V ), pressure P , cation C + and anion C − concentrations (mol/m 3 ), and electric poten-tial Φ. These quantities satisfy the system of two-dimensional Navier-Stokes, Nernst-Planck, and Poisson equations [13,14,17]. In this work, we consider three types of pores with different boundary conditions on the walls: (1) constant surface charge density σ; (2) constant surface potential Φ s ; (3) constant total surface charge Q.…”

“…Then the ratio of fluxes f = v/j is found numerically from (12), and the ion flux j is obtained from (13). The potential difference between reservoirs ∆φ = ϕ v (c R ) is determined from (14), while the virtual variables are found by integration of (10), (11).…”

“…Here problem (3), (4), (6) is solved for each c vk at fixed φ s and j. Note that ,k−1 ) and repeating the solution of (3), (4), (6) followed by application of (14). The calculation is performed iteratively to find the fluxes ratio f from (12).…”

“…Using membrane potential measurement at zero current, it was shown that their selectivity can be reversible switched from anion to cation by changing the potential applied to the conductive membrane surface. Theoretical studies of electrolyte transport in nanofiltration membranes with conductive surface were performed in [13,14]. To correctly describe the ion transfer in conductive nanopores, the fixed surface potential should be assumed [15].…”

Performance and properties of coking nanofiltration concentrate treatment and membrane fouling mitigation by an Fe(ii)/persulfate-coagulation-ultrafiltration process

“…2 To date, "near-zero emission" processes have been developed to reduce wastewater emissions and control the use of fresh water based on the characteristics of the intercepting screening effect and chargeability of NF. 3 However, the secondarily generated NF concentrates with high salinity and resistant pollutants still need further handling, 4,5 and the problem of membrane fouling also needs to be addressed. 6 The control of membrane fouling basically includes three approaches, i.e.…”