A sustainable and strong superhydrophobic photothermal self-healing cotton fabric (SPS cotton fabric) was prepared by the simple one-pot method using nano-titanium nitride (TiN), hydroxyl-terminated polydimethylsiloxane (HPDMS), and tetraethyl orthosilicate (TEOS). After nano-TiN is adsorbed to the cotton fabric by hydrogen bonding, HPDMS and TEOS are catalyzed by ammonia to form a PDMS-SiO 2 hybrid on the cotton fabric, and finally the SPS cotton fabric is obtained. After plasma etching, cotton fabric can quickly restore superhydrophobicity by light irradiation. The micro−nanocoating on the SPS cotton fabric can resist at least 10 sandpaper abrasion cycles and etching of acid and alkali solutions without losing its superhydrophobicity. Owing to the good water repellency, the separation efficiency of the SPS cotton fabric can reach more than 98.00% for various oil−water mixtures. Even after 10 separation cycles, the separation efficiency only decreased by 0.20%, showing potential applications for waste oil treatment.
Although the photocatalytic reduction
of Cr(VI) to Cr(III)
by traditional
powder photocatalysts is a promising method, the difficulty and poor
recovery of photocatalysts from water hinder their wide practical
applications. Herein, we present that FeC2O4/Bi2.15WO6 (FeC2O4/BWO)
composites were tightly bonded to modified polyvinylidene fluoride
(PVDF) membranes by chemical grafting with the aid of polyvinyl alcohol
(PVA) to form photocatalytic composite membranes (PVDF@PVA–FeC2O4/BWO). The contact angle of PVDF@PVA–FeC2O4/BWO (0.06 wt % of FeC2O4/BWO) is 48.0°, which is much lower than that of the pure PVDF
membrane (80.5°). Meanwhile, the permeate flux of 61.43 g m–2 h–1 and water flux of 250.60 L
m–2 h–1 were observed for PVDF@PVA–FeC2O4/BWO composite membranes. The tensile strength
of composite membranes reached 48.84 MPa, which was 9.8 times higher
than that of PVDF membrane. It was found that the PVDF@PVA–FeC2O4/BWO membrane exhibited excellent photocatalytic
Cr(VI) reduction performance under both simulated and real sunlight
irradiation. The adsorption for Cr(VI) by PVDF@PVA–FeC2O4/BWO can reach 47.6% in the dark process within
30 min, and the removal percentage of Cr(VI) could reach 100% with
a rate constant k value of 0.2651 min–1 after 10 min of light exposure, indicating a synergistic effect
of adsorption and photoreduction for Cr(VI) removal by the composite
membrane. The PVDF@PVA–FeC2O4/BWO membrane
had good stability and reusability after seven consecutive cycles.
Most importantly, the influences of foreign ions on Cr(VI) reduction
were investigated to mimic real sewage, which revealed that no obvious
adverse effects can be found with the presence of common foreign ions
in sewage. The photocatalytic membrane material developed in this
study provides a new idea for treating Cr(VI)-containing wastewater
and has a more significant application prospect.
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