Pengxiao Liu,Xinzhang Yu,Yang Liu,Rong Han,Houfen Li
This study established a novel three-dimensional electrochemical oxidation coupled with forward osmosis and reverse osmosis (3DEO-FO-RO) system with the purpose to achieve simultaneous degradation and rejection of pharmaceuticals and personal care products (PPCPs) in wastewater. 18 frequently detected PPCPs were selected as the target pollutants to prepare the synthetic wastewater with a concentration of 200 μg/L for each pollutant. Ti/IrO 2 –Ta 2 O 5 –SnO 2 mesh anode, titanium mesh cathode and Sn–Sb–Bi/γ-Al 2 O 3 particles electrodes were integrated in the 3DEO-FO reactor. Experimental results demonstrated that degradation efficiency exceeding 98.5 % and rejection exceeding 99.4 % for each PPCP were achieved simultaneously in the 3DEO-FO-RO processes at a current density of 1 mA/cm 2 after 8 h treatment. Despite variations in applied current density, the 3DEO-FO-RO processes exhibited superior PPCPs removal efficiencies, particularly for refractory compounds, compared to the 2DEO-FO-RO processes. Increased hydroxyl radical (·OH) generation in the 3D reactor was considered to be responsible for the excellent performance. Furthermore, results derived from ultraviolet (UV) absorption spectra and fluorescence excitation-emission matrix (EEM) spectra provided additional validation for the effective removal of PPCPs in the 3DEO-FO-RO processes, along with evidence indicating the decomposition of PPCPs into smaller constituents. Ultimately, the 3DEO-FO-RO process demonstrated its capacity in removing PPCPs from actual secondary effluent from a wastewater treatment plant. This integrated system coupling 3D EO with FO-RO membranes can provide an efficient approach for simultaneous degradation and rejection of trace contaminants for wastewater reuse.
Introduction of nanomaterials into thin–film nanocomposite (TFN) membranes can improve the solvent permeance for organic solvent reverse (OSRO) and forward osmosis (OSFO) processes. However, the severe nanomaterials aggregation and the formation of defects in membrane rejection layer, which decreased the rejection of membrane against various solutes. Herein, we proposed a novel strategy of thin–film nanocomposite (TFNi) membrane featuring an interlayer of metal–organic framework (MOF, ZIF–8) by one–step fabrication in the simultaneous phase–inversion and crosslinking process. This strategy integrates the precipitation of polyimide (PI) substrates, crosslinking between the PI and hexanediamine, and generated ZIF–8 nanocrystals through the interfacial diffusion. Furthermore, one–step strategy of ZIF–8 effectively mitigate its agglomeration in the surface of support layers by SEM characterization. A prepared polyamide (PA) rejection layer with high crosslinking and low thickness was characterized by XPS and TEM. The resulting TFNi membranes with ZIF–8 interlayer (OSFO ISG –2.5) showed a molecular weight cut–off of ~500 Da, the remarkable DI water and THF permeances (9.73 and 1.62 L m–2 h–1 bar–1 under RO mode), and the higher ethanol fluxes (2.10 ± 0.11 LMH under FO mode and 2.97 ± 0.31 LMH under PRO mode). In addition, the solvents permeance of the OSFO ISG –2.5 membrane was furtherly improved by 10 h DMF activation without loss of the polystyrene rejection in RO mode. This study also provides insight for the preparation of ZIF–8 on the polymer's matrix for large–scale production.
A large dielectric constant and high breakdown strength in a flexible energy storage capacitor would allow for increased energy storage capacity and higher durability, making it a more efficient and reliable option for various electronic devices. This work presented a continuous three-dimensional barium titanate (3DBT) skeleton, which was facilely synthesized by the sol–gel method and subsequent high-temperature calcination process using a cleanroom wiper as a template. Flexible 3DBT/PVDF-BNNS dielectric materials were then prepared by reversely infiltrating poly(vinylidene fluoride)–boron nitride nanosheet (PVDF-BNNS) solutions into the above 3DBT network. The obtained 3DBT/PVDF-BNNS composites were dense with a saturated 3DBT concentration of ∼18 wt % (6.1 vol %). The 3DBT enabled successive polarization, while the BNNS inhibited charge carrier transition, thereby enhancing the dielectric constant, breakdown strength, and energy storage density of 3DBT/PVDF-BNNS composites simultaneously. The 3DBT/PVDF-0.75BNNS composite reached a comprehensive large dielectric constant of 18.2@1 kHz, high breakdown strength of 120.9 kV·mm–1, and accordingly an enhanced energy density of 1.16 J·cm–3, overperforming that of neat PVDF and 3DBT/EP systems. The synergistic effect of 3DBT and wide bandgap BNNS is distinct, indicating potential applications in embedded capacitor related applications.
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