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Modified three-compartment electrodialysis (MTED), a novel process containing intermediate compartment with fluorinated ion exchange membrane, has been applied to the recovery of petroleum sulfonate from petrochemical dispersion. The fluorinated ion exchange membrane has higher degree of crosslinking than heterogeneous ion exchange membrane. The petroleum sulfonate is separated from the petrochemical dispersion during anion migration by the different steric effect of ion exchange membranes. In order to reduce the membrane fouling and increase the current efficiency, the 50 nm ceramic membrane was utilized as the pretreatment of MTED. The result indicated that in total of 99.4 wt% of petroleum sulfonate in the petrochemical dispersion could be recovered at the applied voltage 25 V, flux rate 30 L/h, temperature 40 °C and initial concentration 7.5 wt% (NH 4 ) 2 SO 4 . Simultaneously, the (NH 4 ) 2 SO 4 solution without petroleum sulfonate was received in concentrate compartment of MTED. The results verified the feasibility of MTED on separating the petroleum sulfonate and inorganic salt in petrochemical dispersion, and provided important technical basis for a large-scale procedure of MTED in petrochemical dispersion treatment. [ABSTRACT FROM AUTHOR]

Highlights: [•] The voltage drop follows the orders: U BP-A-C-BP > U BP-A-BP > U BP-C-BP. [•] Concentration follows the orders: C BP-C-BP > C BP-A-C-BP > C BP-A-BP. [•] Current efficiency follows the orders: ŋ BP-A-C-BP > ŋ BP-C-BP > ŋ BP-A-BP. [•] Energy consumption follows the orders: E BP-A-BP > E BP-A-C-BP > E BP-C-BP. [•] It is wise to choose BP-A-C-BP configuration for preparation the succinic acid. [Copyright &y& Elsevier]

Highlights: [•] Regenerating spent acid produced by HZSM-5 zeolite preparation is proved feasible by BMED. [•] The pure sodium hydroxide in the base chamber can be recycled. [•] The recycled acid solution can replace the pure acid solution completely. [Copyright &y& Elsevier]

[Display omitted] • Monovalent cation permselective membranes were prepared by the combination of surface-crosslink and inorganic nanomaterial doping. • Two-dimensional MOFs were introduced into the monovalent cation permselective membranes for the first time. • 2D MOF, Zn-TCPP, effectively enhanced the ion transport. • Tremendous permselectivity and permeability were obtained simultaneously. Monovalent cation permselective membranes (MCPMs) manifest remarkable effectiveness and potential in lithium extraction whereas facing the challenge to achieve high permselectivity and high Li+ permeability simultaneously. In this work, Zn-TCPP, a kind of two-dimensional nanosheet with abundant negative charges, was successfully synthesized via surfactant-assisted method and introduced into surface cross-linked SPES membrane to fabricate MCPMs. The physicochemical properties, electrochemical properties and Li+/Mg2+ separation performance of resulted MCPMs were systematically estimated. As ions passing through the membrane, dense PVA/GA crosslinked layer separated Li+ and Mg2+ by pore-size sieving effect. Afterwards, uniformly distributed Zn-TCPP nanosheets with rich negative charges and physically adsorbed water molecules elevated the charge density and water content in the membrane and thus expedited Li+ transporting. Therefore, high Li+/Mg2+ permselectivity (P Mg 2 + Li + = 8.99) and Li+ permeation flux (J Li + = 9.12 × 10−9 mol cm−2∙s−1) were obtained. Furthermore, membrane surface resistance was reduced from 108.99 Ω cm2 to 24.12 Ω∙cm2. This study points out the feasibility of the new method for accelerating monovalent ion transport and alleviating the restriction between ion permeation and permselectivity in selective ion exchange membranes. [ABSTRACT FROM AUTHOR]

The spacer geometries have a crucial effect on the hydrodynamics of spacer-filled channels in electrodialysis (ED) process, which are beneficial to mass transfer enhancement. Herein, a three-dimensional, isothermal, and steady flow model was developed by computational fluid dynamics (CFD) to illuminate the impacts of the spacer geometrical configurations on hydrodynamic behaviors in the spacer-filled channel for ED applications. Simultaneously, the finite element analysis method was employed to investigate the effects of spacer geometries on the velocity and pressure profiles. Furthermore, the normalized expenditure (NEXP) was introduced to acquire one comparable cost estimation index, which determined the optimal spacer geometries subserving the efficiency and economic competitiveness of ED process. Theoretical and techno-economic analysis validated that the optimal mesh parameters within the range of the test parameters were a cylindrical mesh, a filament diameter of 0.8 mm, a filament interval of 1.0 mm, a flow attack angle of 30°. Therefore, this work can provide a feasible strategy to visualize and quantitate the hydrodynamics in the spacer-filled channel and insight into the optimization of ED stack, potentially reducing the expenditure related to materials usage, energy consumption and test time. [ABSTRACT FROM AUTHOR]