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Alkaline water electrolysis (AWE) holds considerable promise for large-scale hydrogen production. Decreasing energy input and improving efficiency are inevitable in its further commercial development. As one of the critical factors for reducing energy consumption, flow channel design on bipolar plates cannot be ignored. This study utilizes a three-dimensional model for alkaline electrolyzer that couples electrochemical reactions with mass and heat transfer to approximate the real physical process and achieve reliable convergence. Integrating diverse turbulence units tailored to different local flow demands, an advanced Partitioned Point Flow Channel (PPFC) structure is proposed aiming at optimizing electrolyte flow distribution. Results reveal that PPFC's unique combination of turbulence units promotes lateral flow and electrolyte mass transfer rate, increasing electrolyte flow uniformity and hydrogen removal efficiency by 17.5% and 24.4%, respectively. Further comparative analysis with traditional designs shows an average diaphragm temperature drop of 4 K and a current density increase of 10.7% at a cell voltage of 2 V. These results indicate that PPFC offers significant advantages in reducing energy loss in electrolyzer. • 3-D AWE model couples electrochemical reaction with mass and heat transfer is built. • Advanced PPFC integrates different turbulence units for diverse local flow demands. • PPFC improves flow uniformity by 17.5% and hydrogen removal efficiency by 24.4%. • PPFC reduces average temperature by 4 K and increases current density by 10.7%. [ABSTRACT FROM AUTHOR]

The strong oxidation capabilities of Mn sites render Mn-based catalysts showing high activities of selective catalytic reduction (SCR) at temperatures < 250℃, but simultaneously lead to the generation of by-product N 2 O with strong greenhouse effect. The activity-N 2 -selectivity trade-off was a prevalent observation in the development of Mn-based SCR catalysts. Here, a polyoxometallic acid enhancement strategy was devised to simultaneously promote the N 2 selectivity and low-temperature SCR (LT-SCR) activity of Mn-based metal oxide catalysts, where the introduction of uniformly dispersed phosphomolybdic acid (HPMo) tuned the oxidation capabilities and enhanced NH 3 adsorption-storage capability of catalysts. The combination of transient reaction, in-situ DRIFTS analysis and DFT calculations revealed that the main origin of N 2 O on the Mn-based catalysts was the deep oxidation of NH 3 , which was inhibited by the interaction between HPMo and Mn sites. Additional NH 3 molecules adsorbed by the abundant acid sites supplied by HPMo further facilitated the SCR reaction. This strategy could guide the design of high-activity and high-selectivity LT-SCR catalysts for industrial denitration. [Display omitted] • The introduction of HPMo tuned the oxidation abilities and enhanced the acidity. • The loading of HPMo can inhibit the oxidation of NO to NO 2 and deep oxidation of NH 3. • Abundant acid sites supplied by HPMo can accelerate the SCR reaction. • The activity-selectivity trade-off can be broken by the modification of HPMo. [ABSTRACT FROM AUTHOR]

A facile two-step surface modification by aldehydes was proposed to prepare chlorine resistant polyamide (PA) thin film composite (TFC) membranes simultaneously maintaining its high separation performance. Firstly formaldehyde was employed to reduce the chlorine sensitive N-H bonds of amide groups in PA layers into the chlorine resistant N-CH 2 OH bonds. Then glutaraldehyde was introduced to crosslink the newborn N-CH 2 OH groups via the stable ether bonds aimed to tighten the polyamide inter-chains. In the statically accelerating chlorination, the two-step modified PA-TFC membranes exhibited ameliorative chlorine resistance both in the acidic and alkaline aging conditions. More importantly, the sound retention of the typical ridge-valley polyamide structure after modification revealed that it was a mild surface modification solely confined to the outmost surface of the layers and succeeded to maintain the high separation performance. A more hydrophilic surface was also obtained after modification and resulted in a better antifouling performance towards protein. Reagents involved in were all easy-to-get and reacted with each other via chemical covalent bonds, which might open a promising way to commercialize a stable chlorine-resistant polyamide thin film composite membranes simultaneously of high separation performance. [ABSTRACT FROM AUTHOR]

Nanofiltration is a promising technology to recover dye from textile wastewater with highly saline for sustainable resource recovery. However, it is difficult for the conventional piperazine-based nanofiltration membranes, which usually have a tight polyamide matrix structure, to precisely separate dye and salt in wastewater. In this study, 5,5,6',6'-tetrahydroxy-3,3,3',3'-tetramethyl spirobisindane (TTSBI) with rigidly contorted structure has been used instead of piperazine as aqueous-phase monomer to fabricate polyarylate (PAT) nanofiltration membranes with quasi-PIMs structure via interfacial polymerization (IP) with three types of acyl chloride, i.e., rigid trimesoyl chloride (TMC), short-chain glutaryl chloride (GC) and long-chain sebacoyl dichloride (SDC). The contorted structure of TTSBI introduces extra microporosity in nanofiltration membranes, and the differentia of three acyl chlorides in molecular flexibility further endows with tailoring the stacking density of as-formed PAT networks. The PAT NF membranes thereby exhibited high permeability and tunable size-selectivity in desalination from dye effluent. Among these PAT membranes, TTSBI-TMC membranes had the highest water flux of 480.5 LMH, nearly 7-fold increase compared traditional PA NF membranes, whereas TTSBI-SDC membranes had the highest dye rejection of 97.4%, and TTSBI-GC membrane had the relatively balanced dye desalination performance with high rejection 95.4% for Congo Red and 8.3% for NaCl accompanied by high flux of 402.4 LMH. Therefore, this study provides a new prospective for the fabrication of highly permeable nanofiltration membranes for precise separation. [Display omitted] • A quasi-PIMs nanofiltration membrane with TTSBI served as water-phase monomer was developed. • Three types of acyl chlorides with different molecular flexibility were used as oil-phase monomer respectively. • Ultrahigh water permeability was achieved by the introduction of extra microporosity. • Dye/salt selectivity was tailored by the differentia of molecular flexibility. [ABSTRACT FROM AUTHOR]

The separation of Li+ and Mg2+ is a decisive step for achieving high-grade lithium extraction from salt-lake brines to circumvent the lithium supply shortage and sustainability. However, polymer nanofiltration membranes suffer from low lithium selectivity and are hindered by complicated preparation and miniaturized scales. Here, we report a facile surface charge-inversion strategy via a unique secondary non-aqueous medium interfacial reaction of polyethyleneimine to construct a selective positive-nanolayer on nanofiltration membranes surface for selective separation of lithium ions from concentrated magnesium/lithium mixtures. The introduction of amine moieties not only increases the Donnan potential but also improves the compactness of the membrane, which simultaneously enhances the Donnan exclusion and size sieving for the Mg2+ ion with higher valence and larger hydration ion size. The surface interaction theory (DLVO) verified that the high positive-charge density provided an excellent selectivity to allow passage of Li + but reject Mg2+, and the separation factor (S Li/Mg) achieved 12.37 at a high Mg2+/Li+ mass ratio of 150. Such highly positive transmembrane potential barrier simultaneously endowed the membrane surface with the anti-fouling performance against Ca2+. We anticipate that our facile and scalable surface charge-inversion will greatly advance lithium ions permselectivity membranes design and application in lithium extraction. [Display omitted] ● A nanofiltration membrane with a positive-charged blocking layer was developed. ● The surface charge inversion strategy of secondary non-aqueous medium reaction was effective and facile for scalable preparation. ● The constructed positive-charged blocking layer implemented synchronous reinforcement of Donnan exclusion and size sieving conjunct effects. ● Modified membranes exhibited excellent Li+/Mg2+ separation efficiency under high Mg2+/Li+ ratio of 150 and remarkable anti-fouling against Ca2+. [ABSTRACT FROM AUTHOR]