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Using N,N-bis(1-methylheptyl)acetamide (N503) synergized with TBP-NaFeCl 4 (T Fe), a ternary composite extraction membrane known as T Fe N-PIM was created. Under optimum membrane phase conditions, the mass transfer properties of T Fe N-PIM-Li(Ⅰ) and its Li/Mg selective separation performance by electric field augmentation were examined, and confirmed the mechanism of T Fe N-PIM-Li(Ⅰ) electric field enhanced mass transfer. The findings demonstrate a homogeneous distribution of [FeCl 4 -] in the T Fe N-PIM membrane phase and a decrease in the water contact angle as the T Fe content increases. In the T Fe N-PIM membrane, the cation binding order of the composite carrier was H+>Li+>Na+>Mg2+, and the mass transfer was carried out at the interface of the two phases of the membrane through the mechanism of "cation exchange-neutralization", in which Li(Ⅰ) was bonded with the carrier in the form of 2N503-LiFeCl 4 -2TBP, and showed a fixed-site "hopping" mass transfer characteristics under the reinforcement of electric field. The mass transfer process of the T Fe N-PIM- Li(Ⅰ) system under electric field enhancement conforms to the first-order kinetic rate equation, and the voltage (5–45 V) is positively correlated with the permeability coefficient P Li(Ⅰ) but decreases the Li/Mg selectivity of T Fe N-PIM. The S Li(Ⅰ)/Mg(Ⅱ) of T Fe N-PIM was 9.18 at 3 V. After three cycles of 72 h cycling at 40 V, the decrease rate of P Li(Ⅰ) was <7.42 %, which showed good stability. [Display omitted] • A ternary composite extraction membrane (T Fe N-PIM) of N503 synergy with TBP-NaFeCl 4 (T Fe) was prepared. • The increase in permeability coefficient stabilization after T Fe /N503 > 2/1 (w/w) in T Fe N-PIM. • Voltage accelerates the "ion hopping" rate of Li(Ⅰ) in T Fe N-PIM. • Voltage positively correlates with permeability coefficient but reduces Li/Mg selectivity of T Fe N-PIM. • The separation factor of T Fe N-PIM for Li/Mg at 3 V was 9.18. [ABSTRACT FROM AUTHOR]

Heavy metal pollution can significantly harm water systems and human health. Combining photoelectrocatalytic (PEC) and nanofiltration (NF) membrane separation technologies can effectively remove heavy metal ions from wastewater. In this study, a water bath method was used to form SrF 2 /Ti 3 C 2 T x (ST) nanoparticles on the surface of polyvinylidene fluoride (PVDF) membranes and an additional polyamide (PA) functional layer was formed at the interface by crosslinking. ST@PA composite NF membranes (STPP) with good photocatalytic performance were obtained. The separation and catalytic properties of the STPP membranes were controlled by the ST content, which modifies the surface structure and properties of the membranes. The membrane with optimal ST crosslinking exhibited a water contact angle of 50.8°, pure water flux of 24.6 L·m−2·h−1·bar−1, and rejection rates of Mn2+, Ni2+, Cu2+, and Zn2+ of 98.8%, 95.3%, 95.7%, and 97.3%, respectively, under PEC-assisted separation with visible light illumination from a Xe lamp (300 W) and an applied voltage (2 V). The STPP membranes showed improved rejection rates of heavy metal ions under PEC-assisted operation. The mechanism for the improved membrane performance under PEC conditions was preliminarily clarified considering the relationship between the photocatalytic and filtration properties of STPP membranes along with the influence of light irradiation and an external voltage on the heavy metal ions. The generation of electrons, holes, superoxide radicals, and hydroxyl radicals during membrane operation enhances the rejection rates of heavy metal ions. Based on these results, STPP membranes are considered a promising technology for industrial applications in heavy metal removal. [Display omitted] • Photoelectrocatalytic (PEC) SrF 2 /Ti 3 C 2 T x synergistically removes heavy metals. • Under PEC conditions internal/external electric fields promote carrier separation. • PEC-assisted membranes exhibit high water flux and efficient heavy metals removal. • The Mn2+ removal mechanism of the membranes in aqueous solutions is proposed. [ABSTRACT FROM AUTHOR]

Bifunctional photocatalytic nanofiltration (NF) membranes are becoming increasingly popular because of their ability to separate and degrade azo compounds (azos) in water. However, several serious drawbacks limit their practical implementation. In this study, a polyamide (PA) layer formed by interfacial polymerization on the polyvinylidene fluoride membrane surface and polydopamine (PDA) were combined with BaTiO 3 /Ti 3 C 2 T x (BT) nanoparticles to prepare photocatalytic BT@PDA (BTPP) membranes, which integrated physical separation and photocatalytic degradation into a single process. By optimizing synthesis conditions, a BTPP membrane with high water permeability (34.0 L·m–2·h–1·bar–1) and Na 2 SO 4 rejection rate (94.7%) was produced. The photocatalytic activity of this membrane was examined by studying the photocatalytic degradation efficiency of several azos. After 180 min of irradiation with a 300 W Xe lamp (λ ≥ 420 nm), the degradation rate of methyl orange (MO) reached 95.3%, while the degradation rates of alizarin yellow GG and methyl red were 92.7% and 83.5%, respectively. The photocatalytic performance of the BTPP membranes for azos degradation was verified by studying the charge transfer process and generation of reactive radical species (·OH and·O 2 –), and possible structures of the main intermediates formed during MO degradation were identified. This work provides new insights into the synthesis and degradation properties of bifunctional photocatalytic NF membranes. [Display omitted] • BaTiO 3 /Ti 3 C2T x (BT) structure with good photocatalytic properties. • Bifunctional photocatalytic BT@dopamine (BTPP) membranes with excellent performance is proposed. • BTPP membranes promote the simultaneous separation and photodegradation of azo compounds. • The degradation of azo compounds by BTPP membranes include ·OH and ·O 2 – active radicals. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-flux PEI-TDI PUNF membrane doped with TA-MoS 2 nanosheets was prepared. • MoS 2 nanosheets were uniformly dispersed in membrane by TA. • TSPU is positively charged and retains magnesium salts higher than sodium salts. • TSPU has good retention behavior for heavy metal ions. Heavy metal pollution poses a serious threat to human health. Positively charged nanofiltration membranes show excellent application prospects in the field of heavy metal removal due to the combined effect of electrostatic repulsion and size sieving. Here, molybdenum disulfide (MoS 2) nanosheets were dispersed in aqueous solution polyethyleneimine (PEI) by virtue of the adhesion effect of tannic acid (TA). Positively charged polyurea NF membranes (TSPU) were prepared by interfacial polymerization of aqueous phase PEI/TA-MoS 2 and organic phase 2,4-toluene diisocyanate (TDI). The surface of the optimized membrane TSPU-0.015 showed better hydrophilicity, the water contact angle was 74.53°, and the functional layer thickness of TSPU-0.015 was 114.8 nm. TSPU-0.015 interface was positively charged (IEP TSPU - 0.015 = 5.62), so the rejection of magnesium salts is significantly higher than that of sodium salts. It shows a retention performance of more than 99% for high-valent heavy metal ions such as Fe3+ and Cu2+, and the retention for Cd2+ is as high as 92.53%. The permeation flux of TSPU-0.015 is 2.88 times higher than that of undoped MoS 2 (TSPU-0), and the flux to MgSO 4 solution reaches 34.5 L/m2·h (6 bar, R (MgSO4) = 93.18%). TSPU has long-term stable operation and excellent anti-pollution properties, showing wide application potential in the fields of inorganic salt separation and heavy metal pollution. [ABSTRACT FROM AUTHOR]

Ag 3 PO 4 and AgBr–Ag 3 PO 4 were deposited on the surface of nanofiltration membrane (FT) with tannic acid (TA) and toluene-2,4 diisocyanate (TDI) as functional layers by alternate impregnation method to obtain composite NF membranes (FTA and FTAB) with visible catalytic activity. Under optimal conditions, the catalyst loads on the surfaces of FTA and FTAB were uniform, the initial water contact angle was lower than 28°, the zeta potential was close to −17 mV, the fluxes with FTA and FTAB were respectively 16 and 17.5 L m−2 h−1 (0.4 MPa), and the rejection of Na 2 SO 4 and sulfamethoxazole (SMZ) were more than 75% and 90%, respectively. FTA and FTAB had good photochemical properties, strong absorption of visible light, low electrochemical impedance and sensitive transient photocurrent response. FTA and FTAB with an effective area of 16 cm2 had a static degradation rate of over 90% for 100 mL of 10 mg L−1 SMZ and ciprofloxacin and can achieve dynamic degradation in NF within 300 min under visible light. FTAB effectively alleviated the photo-corrosion behaviour of FTA, maintained the degradation rate of Congo red above 85% after four cycles and had good stability and anti-pollution self-cleaning performances. [Display omitted] • Stable AgBr–Ag 3 PO 4 visible-light catalytic composite NF membrane (FTAB) was prepared. • The nanofiltration functional layer of FTAB was constructed by TA and TDI monomers. • FTAB was prepared by alternate impregnation on the nanofiltration functional layer. • The stability of photocatalytic layer was from the chelation of Ag+ with –OH of TA. • FTAB can achieve high-efficiency interception and the synchronous degradation of PPCPs. [ABSTRACT FROM AUTHOR]