Synthesis and Characterization of g-C₃N₄/Ag₃PO₄/TiO₂/PVDF Membrane with Remarkable Self-Cleaning Properties for Rhodamine B Removal

g-C3N4/Ag3PO4/TiO2 nanocomposite materials were loaded onto a polyvinylidene fluoride (PVDF) membrane using a phase inversion method to obtain a photocatalytic flat membrane for dye removal. The morphology, structure, and photocatalytic activity of the g-C3N4/Ag3PO4/TiO2 nanoparticles and composite membrane were evaluated. The g-C3N4/Ag3PO4/TiO2/PVDF membrane exhibited superior morphology, hydrophilic properties, and antifouling performance compared with the raw PVDF membrane. Four-stage filtration was performed to evaluate the self-cleaning and antifouling capacity of the g-C3N4/Ag3PO4/TiO2/PVDF membrane. Upon irradiating the composite membrane with visible light for 30 min, its irreversible fouling resistance (Rir) was low (9%), and its flux recovery rate (FRR) was high (71.0%) after five filtration cycles. The removal rate of rhodamine B (RhB) from the composite membrane under visible light irradiation reached 98.1% owing to the high photocatalytic activity of the membrane, which was superior to that of raw PVDF membrane (42.5%). A mechanism of photocatalytic composite membranes for RhB degradation was proposed. Therefore, this study is expected to broaden prospects in the field of membrane filtration technology

Super-hydrophobic PTFE hollow fiber membrane fabricated by electrospinning of Pullulan/PTFE emulsion for membrane deamination

Polytetrafluoroethylene (PTFE) is increasingly used in membrane applications due to its excellent thermal stability, resistance to chemical degradation and strong hydrophobicity. However, it is difficult to prepare high flux membranes by conventional technology due to its high melt viscosity and solvent resistance. Here, a environment-friendly technology is used to fabricate PTFE hollow fiber membrane via emulsion electrospinning. Pullulan is dope into the PTFE emulsion and employ as the binder of PTFE particles to facilitate the formation of the as-spun PTFE-Pullulan hollow fiber membrane. The expected PTFE hollow fiber membrane is obtained after sintering of the as-spun membrane. No organic solvent is used and no pollutant is discharged during the preparation process. The prepared PTFE hollow fiber membrane shows excellent properties such as superhydrophobicity (contact angle > 150 degrees), high porosity (85%) and excellent mechanical properties (Young's modulus of 39 MPa and fracture strain of 245%). In the deamination test, the experimental mass transfer coefficient of the PTFE hollow fiber membrane reaches 2.4*10(-5) m/s when the pH is 11, which is 1.6-2.4 times as that of the commercial membrane. The self-made PTFE hollow fiber membrane shows great potential in the application of membrane deamination

Enhanced desalination performance in asymmetric flow electrode capacitive deionization with nickel hexacyanoferrate and activated carbon electrodes

Flow electrode capacitive deionization (FCDI) has attracted growing attention for the treatment of highconcentration saline water and continuous operation, but the mechanism responsible for the separation of ions has so far received minimal attention. In this study, an asymmetric FCDI (AFCDI) was assembled with nickel hexacyanoferrate (NiHCF) as cathode and activated carbon (AC) as anode. Its desalination performance and distribution of the removed ions were investigated and compared with FCDI using AC as both cathode and anode. Results showed better desalination performance for AFCDI than FCDI at high applied voltages of 2.4 and 2.8 V. The removed ions were adsorbed by active materials (capacitance contribution) and existed in the electrode electrolyte (charge neutralization contribution). However, the contribution of capacitance and charge neutralization was significantly different between NiHCF electrode and AC electrode. When NiHCF was used as electrode, capacitance contribution dominated the removal of sodium and more than 80% sodium was adsorbed by NiHCF at applied voltages of 1.2 & ndash;2.8 V. On the contrary, the removed ions mainly existed in electrode solution when AC was used as electrode and charge neutralization contributed to about 80% of removed ions at 2.8 V. These results clarify the mechanism of ions removal in FCDI

Design of hybrid structure for fast and deep surface plasmon polariton modulation

The electric and optical performance of different surface plasmon polariton (SPP) electric modulation structures have been investigated by comparing the response speed and modulation figures of merit (FoM). To overcome the capacitance limitation and improve the response speed, we proposed a novel silver-graphene-dielectric-graphene-semiconductor vertical structure. Semiconductor nano-waveguide is introduced to help reduce ohmic loss in silver waveguide and reflect the leaked optical field back, enhancing the modulation depth. Through optimization, a device with estimated modulation FoM of more than 70% and hundreds of GHz response speed and 3 dB bandwidth is designed, which may bring great improvement to previous optical modulators