4 research outputs found
Opposite Superwetting Nickel Meshes for On-Demand and Continuous Oil/Water Separation
Oil/water separation is widely studied
because of the growing discharge
of industrial and domestic oily water, as well as frequent petroleum
spills; however, on-demand and continuous oil/water separation has
seldom been reported. For this purpose, we prepared opposite wetting
nickel meshes by creating FeNiO<sub><i>x</i></sub>(OH)<sub><i>y</i></sub> micro-/nanostructures on the surface and
further modification. The surface morphology, chemical composition,
and the wetting property were investigated by SEM, EDS, XRD, Raman
spectrum, XPS, and contact angle measurement. The as-prepared superhydrophilic/underwater
superoleophobic and superhydrophobic/superoleophilic meshes could
be used for reusable on-demand oil/water separation with high efficiency.
Additionally, continuous oil/water separation was realized by integrating
the opposite meshes. The current work will be beneficial for the design
and development of materials with special wettabilities and the practical
application of oil/water separation
Matchstick-Like Cu<sub>2</sub>S@Cu<sub><i>x</i></sub>O Nanowire Film: Transition of Superhydrophilicity to Superhydrophobicity
We
fabricated a matchstick-like Cu<sub>2</sub>S@Cu<sub><i>x</i></sub>O nanowire film on copper mesh by applying a CuÂ(OH)<sub>2</sub> nanowires template-sacrificial method, which can transformed
from superhydrophilic to superhydrophobic just after storage in air
for a certain period without any further organic modification. The
surface morphology, chemical composition and the wettability were
investigated by Scanning Electron Microscopy (SEM), X-ray diffractometer
(XRD), Raman, X-ray Photoelectron Microscopy (XPS), and contact angle
measurement. Results showed that the change of surface chemical composition
and the trapped air among the matchstick-like structures were the
decisive factors for the wettability transition. Therefore, on-demand
oil/water separation was achieved, which was performed by using the
superhydrophilic–underwater superoleophobic mesh for separating
light oil/water mixtures and the superhydrophobic one for separating
heavy oil/water mixtures
Dissipative Particle Dynamics Simulation on the Nanocomposite Delivery System of Quantum Dots and Poly(styrene‑<i>b</i>‑ethylene oxide) Copolymer
Dissipative
particle dynamics (DPD) simulation was used to investigate
the self-assembling dynamics process of polyÂ(styrene-<i>b</i>-ethylene oxide) (PS-<i>b</i>-PEO) block copolymer and
quantum dots (QDs) in an aqueous solution. The effects of molecular
weight (MW) and segment construction of a PS–PEO block copolymer
on the structure and size of the self-assembled micelles were discussed.
The structural properties of micelles were characterized by a radial
distribution function. The simulation results are qualitatively consistent
with those of previous experiments and show that there are only small
QD clusters. The hydrophobic PS chains form the micelle core, while
the hydrophilic PEO chains form the shell. The size of the self-assembled
PS–PEO/QDs micelle increases with the MW of PS-<i>b</i>-PEO block copolymer and the lengths of PEO and PS segments. The
simulation results indicate that the assembling process includes four
sequential transient stages: (1) the random distribution of all components
in aqueous solution; (2) formation of small clusters with polymer
chains and QDs; (3) crashing together of small spheres and the formation
of larger aggregates; (4) stabilization of assembled micelles. The
simulation reveals the physical insights of the QD loading mechanism
of the PEG micelle at the mesoscopic scale, indicating the DPD simulation
can be used as an adjunct to provide other valuable information for
experiments
Inspired by Stenocara Beetles: From Water Collection to High-Efficiency Water-in-Oil Emulsion Separation
Inspired by the water-collecting
mechanism of the Stenocara beetle’s
back structure, we prepared
a superhydrophilic bumps–superhydrophobic/superoleophilic stainless
steel mesh (SBS-SSM) filter <i>via</i> a facile and environmentally
friendly method. Specifically, hydrophilic silica microparticles are
assembled on the as-cleaned stainless steel mesh surface, followed
by further spin-coating with a fluoropolymer/SiO<sub>2</sub> nanoparticle
solution. On the special surface of SBS-SSM, attributed to the steep
surface energy gradient, the superhydrophilic bumps (hydrophilic silica
microparticles) are able to capture emulsified water droplets and
collect water from the emulsion even when their size is smaller than
the pore size of the stainless steel mesh. The oil portion of the
water-in-oil emulsion therefore permeates through pores of the superhydrophobic/superoleophilic
mesh coating freely and gets purified. We demonstrated an oil recovery
purity up to 99.95 wt % for surfactant-stabilized water-in-oil emulsions
on the biomimetic SBS-SSM filter, which is superior to that of the
traditional superhydrophobic/superoleophilic stainless steel mesh
(S-SSM) filter lacking the superhydrophilic bump structure. Together
with a facile and environmentally friendly coating strategy, this
tool shows great application potential for water-in-oil emulsion separation
and oil purification