Hierarchical Porous Fibers for Intrinsically Thermally Insulated and Self-Sensing Integrated Smart Textile.

Here, stretchable hierarchical porous polyurethane fibers were designed, fabricated, and employed as a three-dimensional hierarchical interconnected framework for conductive networks interwoven with silver nanoparticles and carbon nanotubes. The fiber possessed favorable thermal insulation, strain sensing, and electric heating properties. The core-shell layered porous structure of fiber made the fiber have high heat insulation performance (the difference value of temperature |ΔT| = 3.54, 8.9, and 12.7 °C at heating stage temperatures of 35, 50, and 65 °C) and ultrahigh elongation at break (813%). Importantly, after conductive filler decoration, the fiber could exhibit real-time strain-sensing capacities with a high gauge factor. In addition, the fibers could be heated at low voltage, like an electrical heater. The development of flexible, stretchable, and multifunctional porous fibers had great potential applications in intelligent wearable devices for integrated thermal management, strain sensing, and intrinsic self-warming capability.

Electronic structure modulation of iron sites with fluorine coordination enables ultra-effective H2O2 activation.

Electronic structure modulation of active sites is critical important in Fenton catalysis as it offers a promising strategy for boosting H2O2 activation. However, efficient generation of hydroxyl radicals (•OH) is often limited to the unoptimized coordination environment of active sites. Herein, we report the rational design and synthesis of iron oxyfluoride (FeOF), whose iron sites strongly coordinate with the most electronegative fluorine atoms in a characteristic moiety of F-(Fe(III)O3)-F, for effective H2O2 activation with potent •OH generation. Results demonstrate that the fluorine coordination plays a pivotal role in lowering the local electron density and optimizing the electronic structures of iron sites, thus facilitating the rate-limiting H2O2 adsorption and subsequent peroxyl bond cleavage reactions. Consequently, FeOF exhibits a significant and pH-adaptive •OH yield (~450 µM) with high selectivity, which is 1 ~ 3 orders of magnitude higher than the state-of-the-art iron-based catalysts, leading to excellent degradation activities against various organic pollutants at neutral condition. This work provides fundamental insights into the function of fluorine coordination in boosting Fenton catalysis at atomic level, which may inspire the design of efficient active sites for sustainable environmental remediation.

Effective Detergency Determination for Single Polymeric Fibers Using Confocal Microscopy.

Detergency determination for single polymeric fibers is of significant importance to screening effective detergents for laundry, but remains challenging. Herein, we demonstrate a novel and effective method to quantify the detergency for single polymeric fibers using a confocal laser scanning microscope (CLSM). It was applied to visualize the oil-removing process of single polymeric fibers and thus assess the detergency of various detergents. Four typical surfactants were selected for comparison, and a compounded detergent containing multiple components (e.g., anionic and nonionic surfactants, enzymes) was demonstrated to be the most effective and powerful soil-removing detergent because more than 50% of oil on the cotton fiber could be easily removed. Moreover, the oil removal process of three kinds of fibers (i.e., cotton, viscose, and polyester) was imaged and monitored by confocal microscopy. It was found that the percentage of the detergency of a single polyester fiber exceeded 70%, which is much higher than that of cotton and viscose fibers (~50%), which may be due to its relatively smooth surface. Compared to traditional methods, the CLSM imaging method is more feasible and effective to determine the detergency of detergents for single polymeric fibers.

Radix Astragali residue-derived porous amino-laced double-network hydrogel for efficient Pb(II) removal: Performance and modeling.

Valorizing solid waste for heavy metal adsorption is highly desirable to avoid global natural resources depletion. In this study, we developed a new protocol to valorize Radix Astragali residue (one of the Chinese medicine residues) into a low-cost, chemically robust, and highly permeable (ca. 90%) amino-laced porous double-network hydrogel (NH2-CNFs/PAA) for efficient Pb(II) adsorption. The NH2-CNFs/PAA showed (i) excellent Pb(II) adsorption capacity (i.e., 994.5 mg g-1, ~4.8 mmol g-1), (ii) fast adsorption kinetics (kf = 2.01 ×10-5 m s-1), (iii) broad working pH range (2.0-6.0), and (iv) excellent regeneration capability (~15 cycles). (v) excellent performance in various real water matrices on Pb(II) removal. Moreover, its high selectivity (distribution coefficient Kd ~2.4 ×106 mL g-1) toward Pb(II) was owing to the present of abundant amino groups (-NH2). Furthermore, the fix-bed column test indicated the NH2-CNFs/PAA can effectively remove 114.6 bed volumes (influent concentration ~5000 µg L-1) with an enrichment factor 10.9. The full-scale system modeling (i.e., pore surface diffusion model (PSDM)) has been applied to predict the NH2-CNFs/PAA performance on Pb(II) removal. Overall, we have provided an alternative "win-win" scenario that can resolve the Chinese medicine residues disposal issue by valorizing it into high performance gel-based adsorbents for efficient heavy metal removal.

Unraveling timescale-dependent Fe-MOFs crystal evolution for catalytic ozonation reactivity modulation.

Iron-based metal-organic frameworks (Fe-MOFs) have been considered competitive catalyst candidates for the effective degradation of organic pollutants via advanced oxidation processes (AOPs) due to their unique porous architecture and tunable active site structure. However, little is known about the role of synergetic relationship between porous architecture and active site exposure of Fe-MOFs on catalysis for AOPs yet. Here, we demonstrated an overlooked compromise over these two features on modulating the catalytic ozonation reactivity of MIL-53(Fe) through a timescale-dependent crystal evolution. Enabled by intramolecular hydrogen bonds, the MIL-53(Fe) was subjected to six evolution steps in terms of crystal morphology, leading to a volcano plot of catalytic ozonation reactivity for Rhodamine B (RhB) degradation versus the crystallization time. Evidence suggested that the surface area of MIL-53(Fe) decreased dramatically, while the density of accessible active site increased when prolonging crystallization time, allowing for the facile modulation of catalytic ozonation reactivity of MIL-53(Fe). Electron paramagnetic resonance and fluorescence quantification tests verified that the screened MIL-53(Fe)s had a much better capacity for ∙OH generation than benchmark ozonation catalyst α-MnO2 and α-FeOOH. Moreover, the MIL-53(Fe) with the highest reactivity (i.e., MIL-53(Fe)-18H) could effectively destruct a broad spectrum of emerging and refractory organic pollutants and allow the thorough purification of secondary effluents discharged from textile dyeing & finishing industry for in situ reuse. Therefore, our study advances the understanding of the compromise effect between porous architecture and active site on catalysis reactivity of Fe-MOFs and promotes the rational design of more effective Fe-MOFs as well as their derivatives for environmental applications.

Critical Review of Advances in Engineering Nanomaterial Adsorbents for Metal Removal and Recovery from Water: Mechanism Identification and Engineering Design.

Nanomaterial adsorbents (NAs) have shown promise to efficiently remove toxic metals from water, yet their practical use remains challenging. Limited understanding of adsorption mechanisms and scaling up evaluation are the two main obstacles. To fully realize the practical use of NAs for metal removal, we review the advanced tools and chemical principles to identify mechanisms, highlight the importance of adsorption capacity and kinetics on engineering design, and propose a systematic engineering scenario for full-scale NA implementation. Specifically, we provide in-depth insight for using density functional theory (DFT) and/or X-ray absorption fine structure (XAFS) to elucidate adsorption mechanisms in terms of active site verification and molecular interaction configuration. Furthermore, we discuss engineering issues for designing, scaling, and operating NA systems, including adsorption modeling, reactor selection, and NA regeneration, recovery, and disposal. This review also prioritizes research needs for (i) determining NA microstructure properties using DFT, XAFS, and machine learning and (ii) recovering NAs from treated water. Our critical review is expected to guide and advance the development of highly efficient NAs for engineering applications.

Rational tailoring of the electronic structure for the SrxNaTayO3 semiconductor: Insights into its enhanced photoactivity and optical property.

NaTaO3 (NTO), as a popular photocatalyst with the prominent redox ability, largely straddles across the conduction band minimum (CBM) and valence band maximum (VBM) edge over Fermi level. Pristine NTO exhibits the poor light-harvesting ability and the rapid recombination of electron-hole pairs. We proposed an effective method to improve the photocatalytic property of NTO (ABO3-type) by substituting B site with Sr. The SrxNaTayO3 (SNTO) exhibited the boosted photocatalytic activity toward tetracycline oxidation under solar light irradiation. The rate constant for S0.5NTO (molar ratio of Sr: Ta = 1 : 2) was 5.1 times higher than the pure NTO. DFT results indicated that the Sr 3d orbital combining the O 2p and Ta 5d hybrid orbitals, widened the VB of SNTO. The band gap was narrowed from 3.86 to 2.82 eV after Sr substitution, which enhanced its light-harvesting ability. The VBM moved upward for 1.42 V and the CBM moved upward for 0.38 V. The shifts of the CBM and VBM, together with the more stretched Ta-O-Ta configuration, highly facilitated the electron-hole pair separation in SNTO. These electronic structure changes accounted for the significant photocatalytic performance enhancement of NaTaO3 via Sr substitution for B-site-Ta.

Highly efficient heterogeneous photo-Fenton BiOCl/MIL-100(Fe) nanoscaled hybrid catalysts prepared by green one-step coprecipitation for degradation of organic contaminants.

An excellent heterojunction structure is vital for the improvement of photocatalytic performance. In this study, BiOCl/MIL-100(Fe) hybrid composites were prepared via a one-pot coprecipitation method for the first time. The prepared materials were characterized and then used as a photo-Fenton catalyst for the removal of organic pollutants in wastewater. The BiOCl/MIL-100(Fe) hybrid exhibited better photo-Fenton activity than MIL-100(Fe) and BiOCl for RhB degradation; in particular, the hybrid with 50% Bi molar concentration showed the highest efficiency. The excellent performance can be ascribed to the presence of coordinatively unsaturated iron centers, abundant Lewis acid sites, fast H2O2 activation, and efficient carrier separation on BiOCl nanosheets due to the high charge carrier mobility of the nanosheets. The photo-Fenton mechanism was studied, and the results indicated that ˙OH and h+ were the main active species for organic pollutant degradation. The coprecipitation-based hybridization approach presented in this paper opens up an avenue for the sustainable fabrication of photo-Fenton catalysts with abundant coordinatively unsaturated metal centers and efficient electron-hole separation capacity.

Highly Efficient and Selective Hg(II) Removal from Water Using Multilayered Ti3C2Ox MXene via Adsorption Coupled with Catalytic Reduction Mechanism.

Mercury (Hg) removal is crucial to the safety of water resources, yet it lacks an effective removal technology, especially for emergency on-site remediation. Herein, multilayered oxygen-functionalized Ti3C2 (Ti3C2Ox) (abbreviated as M-Ti3C2) nanosheets were prepared to remove Hg(II) from water. The M-Ti3C2 has demonstrated ultrafast adsorption kinetics (the concentration decreased from 10 400 to 33 µg L-1 in 10 s), impressively high capacity (4806 mg g-1), high selectivity, and broad working pH range (3-12). The density functional theory (DFT) calculations and experimental characterizations unveil that this exceptional Hg(II) removal is owing to the distinct interaction (e.g., adsorption coupled with catalytic reduction). Specifically, Ti atoms on the {001} facets of M-Ti3C2 prefer to adsorb Hg(II) in the form of HgClOH, which subsequently undergoes homolytic cleavage to form radical species (e.g., •OH and •HgCl). Immediately, the •HgCl radicals dimerize and form crystalline Hg2Cl2 on the edges of M-Ti3C2. Up to ∼95% of dimeric Hg2Cl2 can be efficiently recovered via facile thermal treatment. Notably, owing to the adsorbed •OH and energy released during the distinct interaction, M-Ti3C2 has been oxidized to TiO2/C nanocomposites. And the TiO2/C nanocomposites have shown to have better performance on the photocatalytic degradation of organic pollutants than Degussa P25. These exceptional features coupled with mercuric recyclable nature make M-Ti3C2 an outstanding candidate for rapid/urgent Hg(II) removal and recovery.

Porous Film Coating Enabled by Polyvinyl Pyrrolidone (PVP) for Enhanced Air Permeability of Fabrics: The Effect of PVP Molecule Weight and Dosage.

This study developed a versatile and facile method for creating pores and tuning the porous structure in the polymer latex films by selectively etching the added functional polyvinyl pyrrolidone (PVP) molecules. The pore formed in the latex films had a similar morphology to that of PVP aggregation before etching. This observation promotes us to regulate the pore morphology that determines the film's property, such as air permeability through varying the PVP molecule weight and dosage. To this end, the effects of PVP molecule weight and dosage on the pore formation were systematically studied. The results showed that the average pore size of porous film decreased from >10 µm to sub-micron (about 0.4 µm) as the molecular weight or the dosage of PVP increased. This was ascribed to the strong adsorption affinity of PVP molecule onto the latex particle surface, which further hindered the diffusion and self-assembly of PVP molecule. In addition, this interaction became much stronger when the higher molecule weight of PVP or the higher dosage of PVP was employed, leading to the decreased size of PVP aggregation, as well as the formed pores in the latex films. Furthermore, the addition of PVP had little effect on the color of coated fabric based on the results of CIE L*a*b* measurement. The proposed facile method can be used to improve the air permeability of coated fabrics.

Hyperbranched polyamide-functionalized sodium alginate microsphere as a novel adsorbent for the removal of antimony(III) in wastewater.

In order to enhance the removal of Sb(III) in wastewater, hyperbranched polyamide-functionalized sodium alginate (HA@SA) microsphere was prepared by grafting of hyperbranched polyamide (HA) on the surface of sodium alginate (SA) microsphere. Adsorption properties of Sb(III) were investigated via static and dynamic adsorption tests. The cycling reusability of HA@SA microspheres was explored through adsorption-desorption tests. The changes of HA@SA microspheres before and after adsorption were characterized by FT-IR, SEM-EDS, and XPS. Results showed that the maximum Sb(III) adsorption capacity of HA@SA microspheres reached up to 195.7 mg/g, improved by 1.16 times in comparison with SA microspheres. The Sb(III) adsorption processes of HA@SA microspheres were depicted by pseudo-second-order kinetics and the Langmuir isotherm models with accuracy. It covered a homogeneous single-layer adsorption controlled by chemisorption along with exotherm spontaneously. After recycling for 8 times, the adsorption capacity of HA@SA microspheres still retained higher than 90% of the original value.

Iron-based metal-organic frameworks as novel platforms for catalytic ozonation of organic pollutant: Efficiency and mechanism.

Developing new heterogeneous catalysts has attracted much attention and is of significant importance for the efficient catalytic ozonation of organic pollutant. Herein, for the first time, we explored four environmental-benign iron-based MOFs (Fe-MOFs) for the catalytic ozonation reaction. These Fe-MOFs were characterized by PXRD, FT-IR, SEM, XPS, N2 sorption-desorption isotherms and chemisorbed-pyridine IR. All Fe-MOFs show high catalytic performances with their intrinsic Lewis acid sites (LAS). Furthermore, MIL-53(Fe) demonstrates the highest catalytic activity because of its largest amount of LAS and suitable porosity-derived attractive mass-transfer property. The Rhodamine B (RhB) degradation kinetic rate is calculated to be 5.76 min-1 with MIL-53(Fe), while 1.82 min-1 with MIL-88B(Fe), 1.40 min-1 with MIL-101(Fe), 0.87 min-1 with MIL-100(Fe) and 0.43 min-1 of ozonation alone. The TOC removal in MIL-53(Fe)/O3 system is 4 times higher than that of ozonation alone. MIL-53(Fe) displays acceptable reusability and stability after 5 cycles. Surface LAS of MIL-53(Fe) are the active sites for the ozone decomposition. Moreover, surface-adsorbed hydroxyl radical, superoxide radical and singlet oxygen are confirmed as the reactive oxygen species from ozone decomposition in MIL-53(Fe) suspension. This work offers new platforms for catalytic ozonation and may drive the development of MOFs-based catalytic ozonation for effective water treatment.