The antifouling process of the membrane is very vital for the highly efficient treatment of industrial wastewater, especially high salinity wastewater containing oil and other pollutants. In the present work, the dynamical antifouling mechanism is explored via molecular dynamics simulations, while the corresponding experiments about surface properties of the zwitterionic monomer-grafted polyvinylidene difluoride membrane are designed to verify the simulated mechanism. Water can form a stable hydration layer at the grafted membrane surface, where all the simulated radial distribution function of water/membrane, hydrogen bond number, water diffusivity, and experimental oil contact angles are stable. However, the water flux across the membrane will increase first and then decrease as the grafting ratio increases, which not only depends on the reduced pore size of the zwitterionic monomergrafted membrane but also results from water diffusion. Furthermore, the dynamical fouling processes of pollutants (taking sodium alginate as an example) on the grafted membrane in water and brine solution are investigated, where both the high grafting ratio and electrolyte CaCl 2 can enhance the fouling energy barrier of the pollutant. The results show that both the enhanced hydrophilic property and the electrostatic repulsion can affect the antifouling capability of the grafted membrane. Finally, the ternary synergistic antifouling mechanisms among the zwitterionic membrane, electrolyte, and pollutant sodium alginates are discussed, which could be helpful for the rational design and preparation of new and highly efficient zwitterionic antifouling membranes.
Membrane
separation has been considered as one of the most revolutionary
technologies for the removal of oils, dyes, or other pollutants from
wastewater. However, most membranes still face great challenges in
water permeability, antifouling property, and even antibiotic ability.
Possessing a pathogen-repellent surface is of great significance as
it can enable membranes to minimize the presence of active viral pathogens.
Herein, we demonstrate a distinct design with a molecular dynamics
simulation-guided experiment for the surface domination of antibiotic
zwitterionic nanogel membranes. The zwitterionic nanoparticle gel
(ZNG)/Cu2+/glutaraldehyde
(GA) synergy system is first simulated by introducing a ZNG into a
preset CuCl2 brine solution and into a GA ethanol solution,
in which the nanogel is observed to initially swell and subsequently
shrink with the increase of GA concentration, leading to the membrane
surface structure transition. Then, the corresponding experiments
are performed under strict conditions, and the results suggest the
surface structure transition from nanoparticles to network nanoflowers,
which are consistent with the simulated results. The obtained network
structure membrane with superhydrophilic and underwater superoleophobic
abilities can significantly enhance the water permeability as high
as almost 40% with its original rejection rate in comparison with
unoptimizable ZNG-PVDF (polyvinylidene difluoride) membranes. Moreover,
the obtained membrane achieves additional excellent antibiofouling
capacity with the antibiotic efficiency exceeding 99.3%, manifesting
remarkable potential for disinfection applications. By comparison,
the conventional antibiotic methods generally improve the membrane’s
antibiotic property solely but can hardly improve the other properties
of the membrane. That is to say, our simulation combined with the
experimental strategy significantly improved the zwitterionic membrane
property in this work, which provides a new perspective on the design
of high-performance functional materials.
To date, there has been extensive research conducted
on Li-ion
batteries to address the challenge of achieving both safety and high
energy density. This paper describes the successful synthesis of an
anode material for lithium storage with exceptional performance by
utilizing cobalt nitrate as a Co3O4 precursor
and dates as a carbon source. The carbon derived from the dates possesses
several desirable properties, including a high specific surface area,
hierarchical arrangement, satisfactory electronic conductivity, and
remarkable mechanical flexibility. This carbon effectively maintains
the stability of large-capacity Co3O4 particles.
The electrochemical behavior of lithium cells containing the fabricated
carbon electrodes was analyzed using various electrochemical techniques.
As a result, the carbon–metal oxide composite electrodes in
lithium-ion batteries exhibit satisfactory reversible capacity, cycling
stability, Coulombic efficiency, and comparatively high-rate capability,
which can be attributed to their unique structure that facilitates
the rapid transport of Li+ ions.
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