Harnessing the collagenous structural hierarchy of leather is an intriguing strategy for developing the next-generation skin-friendly e-skins with integrated powerful multifunctional sensory capabilities. The current development of e-skins is significantly hindered by the limited breathability for the long-term wearability and the complexity of integrating multimodal sensors within confined device dimensions. The proteinous composition of leather is capable of providing e-skins with exceptional skin affinity, biocompatibility and water vapor permeability, thus guaranteeing the long-term wearing comfortability. The inherent hierarchical fibrous structure of leather combined with the unique reversible cross-scale deformation behaviors enables the in situ construction of highly sensitive microstructured sensors for realizing the miniaturization and integration of multimodal sensors within the constrained space of leather. As a consequence, the development of leather-based e-skins paves a new way for advancing leather industry from traditional manufacture to cutting-edge innovation.

Spreading is a critical step for emulsion separation. However, the spreading of emulsions on porous size-sieving materials is constrained by their small size-sieving pores formed on rough surface that frequently evolved into lyophobic air-solid-liquid interface to repel emulsions, resulting in poor separation flux. Herein, we demonstrated for the first time that endowing size-sieving materials with amphiphilicity was a promising and universal alternative to manipulate the spreading kinetics of emulsions for accomplishing high-flux separation. A variety of porous materials with varied chemical composition and high porosity, including metal-organic frameworks (ZIF-67, ZIF-8 and HKUST-1), activated carbon and γ-Al2O3, were endowed with amphiphilicity by polyphenolic chemistry-derived noncovalent amphiphilic decoration of polyphenols-iron ions complexes. The endowed amphiphilicity prevented the formation of lyophobic interface on the rough surface of the porous materials, which boosted the emulsion spreading kinetics by up to 11.8-fold, and a significant enhancement (492.3%) on separation flux was achieved by the amphiphilic size-sieving strategy. Our findings exploited a novel strategy for the big family of size-sieving materials to accomplish high-flux separation performances.

Conventional tannin adhesives prepared by the phenol-aldehyde condensation mechanism suffer from the formaldehyde problem. Herein, we developed environmentally benign and formaldehyde-free tannin-derived non-covalent (TNC) adhesives by manipulating the multiple-hydrogen bonding interactions between tannins and poly(vinyl alcohol) (PVA). The as-prepared TNC adhesives featured exceptional interfacial compatibility due to the amphiphilic nature of tannins, which were also capable of providing high-performance non-covalent adhesion to different substrates, including wood, glass and iron. Molecular dynamics simulations combined with the hydrogen-bond breaking experiments manifested that the hydrogen-bonding interactions between tannins and PVA were essential for the TNC adhesives to accomplish high-performance adhesion. The TNC adhesives were further applied in noncovalent adhesion of xylem fibers to prepare high-performance functional materials featured with high static bending strength. Based on this strategy, a series of environmentally benign and formaldehyde-free tannin-derived adhesives were also successfully developed by using larch tannins and black wattle tannins, respectively.

Superwetting aerogel is a promising alternative for the remediation of emulsified oily wastewater for its high porosity combined with extreme wettability enabled high separation performances to emulsion wastewater. However, it remains challenging for superwetting aerogels to accomplish high-performance dual separation to surfactant-stabilized oil-in-water (O/W) and water-in-oil (W/O) emulsions with high stability. Herein, an environmentally benign superamphiphilic composite aerogel was prepared by a green synthesis route that relied on the utilization of natural amphiphilic biomass. Collagen fibers (CFs) were utilized to construct the three-dimensional (3D) supramolecular skeleton of aerogel to provide high storage capacity of water/oil and outstanding capillary effect to boost the mass transfer. The two-dimensional (2D) lamellar structure of gelatin (Gel) was further grown on the skeleton of CFs aerogel to play the role for simultaneously enhanced demulsifying capability and spreading of emulsions. The as-prepared superamphiphilic aerogel enabled the separation of highly stable surfactant-stabilized O/W and W/O emulsions with high separation efficiency and flux. Excellent recycling performances and anti-fouling performance were also confirmed. Our investigations therefore demonstrated that the structural engineering of superamphiphilic aerogel is a promising way to realize high-performance dual separation of surfactant-stabilized O/W and W/O emulsion wastewater.

Collagen fiber-based ultra-porous superamphiphilic aerogel enabled “non-selective permeation and selective capture” separation strategy for accomplishing an ultra-stable continuous separation of water-in-oil emulsion.

Oil contamination has been an increasingly concerned environmental issue due to the large quantity of oily wastewater discharged by the industry. The extreme wettability-enabled single-channel separation strategy guarantees efficient separation of oil pollutant from wastewater. However, the ultra-high selective permeability forces the intercepted oil pollutant to form a blocking layer, which weakens the separation capability and slows the kinetics of permeable phase. As a consequence, the single-channel separation strategy fails to maintain a stable flux for a long-term separation process. Herein, we reported a brand-new water-oil dual-channels strategy for accomplishing an ultra-stable long-term separation of emulsified oil pollutant from oil-in-water nano-emulsion by engineering two drastically opposite extreme wettabilities (i.e. superhydrophilicity and superhydrophobicity) to build the water-oil dual-channels. The strategy established the superwetting transport channels to permit water and oil pollutant to permeate through their own channel. In this way, the generation of intercepted oil pollutant was prevented, which guaranteed an exceptional long-lasting (20 h) anti-fouling performance for successful achievement of an ultra-stable separation of oil contamination from oil-in-water nano-emulsion with high flux retention and high separation efficiency. Therefore, our investigations provided a new route for realizing ultra-stable long-term separation of emulsified oil pollutant from wastewater.

Viscous emulsions with poor fluidity and high adhesion are extremely difficult to separate. Herein, high-flux separation of viscous emulsions is realized by developing structural engineered collagen fibers (CFs)-based composite membrane that featured 3D conductive hierarchical fiber structure with the spaced carbon nanofibers (CNFs) and activated carbon (AC) serving as conductive network and competitive adsorption-based demulsifying sites, respectively. The as-designed membrane structure boosts fast spreading of emulsion droplets on membrane surface aided by the synergistic effect of joule heat in situ generated by the spaced CNFs and the capillary effect derived from CFs, which guarantees the full contact of viscous emulsions with the spaced AC for achieving ultra-efficient demulsifying. The permeation of resultant oily filtrate is accelerated by the capillary effect of hierarchically fibrous structured CFs to exhibit fast transport kinetics, therefore accomplishing high-flux separation. The structural engineered membrane achieves high-performance separation toward different viscous emulsions (55.4-123.7 mPa·s) with separation efficiency >99.9% and flux high up to 259 L m-2 h-1 . The investigations provide a novel structural engineering strategy for realizing high-performance separation of viscous emulsions.

Separation plays a critical role in a broad range of industrial applications. Developing advanced separation materials is of great significance for the future development of separation technology. Collagen fibers (CFs), the typical structural proteins, exhibit unique structural hierarchy, amphiphilic wettability, and versatile chemical reactivity. These distinctive properties provide infinite possibilities for the rational design of advanced separation materials. During the past 2 decades, many progressive achievements in the development of CFs-derived advanced separation materials have been witnessed already. Herein, the CFs-based separation materials are focused on and the recent progresses in this topic are reviewed. CFs widely existing in animal skins display unique hierarchically fibrous structure, amphiphilicity-enabled surface wetting behaviors, multi-functionality guaranteed covalent/non-covalent reaction versatility. These outstanding merits of CFs bring great opportunities for realizing rational design of a variety of advanced separation materials that were capable of achieving high-performance separations to diverse specific targets, including oily pollutants, natural products, metal ions, anionic contaminants and proteins, etc. Besides, the important issues for the further development of CFs-based advanced separation materials are also discussed.

Soft while strong mechanical shock tolerable e-skins relied on non-Newtonian gel embedded within the load-bearing scaffold of conductive collagen fiber sponge spontaneously mimic the protection and sensing functions of natural skin.

BACKGROUND: Oil pollution has drawn a great deal of attention due to the large quantity of oily wastewater generated from various industries. Some industrial processes discharge corrosive oily wastewater that is difficult to be separated by conventional approaches. Moreover, the co-existence of oil pollution with other pollutants further increases the separation difficulty of oily wastewater. RESULTS: Herein, distillers' grains (DG) were utilized as raw materials to prepare mesoporous biochars and further tuned their structure and surface wetting behaviors by steam activation, which improved the contacts between the DG biochars and the oil-in-water (O/W) emulsion droplets for demulsification as well as the volumetric capacity for oil capture. The as-prepared DG biochars realized a highly efficient separation of corrosive O/W nanoemulsions with the separation efficiency high up to 99.9996%. Moreover, the DG biochars separated dye-containing corrosive O/W emulsions with similar to 100% removal of dyes and obtained a separation efficiency of corrosive O/W emulsions high up to 99.9981%. CONCLUSION: We have explored an effective approach for developing mesoporous DG biochars, with tunable pore structure and surface wetting properties, that are highly efficient for separating corrosive O/W emulsions. The present investigation not only provides a useful approach for remedying the contamination caused by corrosive oily wastewater but it also develops a new route for realizing value-added utilization of solid wastes generated by the distilled liquor industry. (c) 2022 Society of Chemical Industry (SCI).

Recently, fluoride (F-) pollution in groundwater and surface water is widespread all around the world. Although adsorption is regarded as one of the simplest and cost-effective processes for removing F-, the removal efficiency of F- has always been restricted by the low adsorption ability and poor stability of adsorbent. In this study, zirconium (Zr(IV)) loaded on tannin foam (TF) was synthesized and utilized as adsorption material for efficient removal of F-. It was found that the amount of Zr loaded on TF affected the adsorption of F- and the optimal mass ratio of Zr/TF was 0.25. Through static adsorption experiments, the optimal material exhibited highly efficient adsorption performance for different concentrations of F- (2.0-20 mg L-1), with the removal efficiency as high as around 80% in a wide pH range of 3.0-10.0. Co-existing ions could reduce the adsorption of F(- )on TF-Zr, especially CO32- with the F(- )removal efficiency of only 38.4%. Moreover, the adsorption data were highly adjacent with the Langmuir adsorption model with monolayer coverage and pseudo-second-order kinetic model. The calculated maximum adsorption was 10.2 mg g(-1) at 25 degrees C, which was higher than most of the other forms of materials. The thermodynamics of F- adsorption was found to be a spontaneous and exothermic process. It was identified that the highly effective adsorption performance was ascribed to the powerful complex adsorption between Zr(IV) and F-, porous properties of tannin foam matrix, and exceptional stability of Zr(IV) as well. Finally, dynamic adsorption experiment revealed that 3.8 g Zr-TF material could continuously remove 11.02 L water contaminated by low concentration (2.0 mg L-1) of F with adsorption capacity of 5.8 mg g(-1). The present work could provide an alternative material for effective removal of fluoride in aqueous solution.

Cross-scale deformable piezoresistive sensors with a pillar-supported directional multi-layer structure were prepared by using tannery solid wastes, which were highly efficient for monitoring human body motions.

Manufacture of eco-friendly chrome-free leather is of great significance for realizing sustainable development of leather industry. Conventional tanning theory believes that it is impossible to convert raw hide to leather without the utilization of cross-linking agent (e.g., chrome salts) among collagen fibers in raw hide. Here, we developed a brand-new leather manufacture strategy that relied on the composite dehydration media enabled self-driven directional dehydration mechanism to accomplish chrome-free leather manufacture for the first time, rather than followed the classic cross-linking mechanism that has been obeyed for more than one century in leather industry. We demonstrated that the essence of leather making is to regulate the water content in raw hide rather than to form cross-linkage among collagen fibers. The composite dehydration media comprised of anhydrous ethanol and molecular sieves (3A activated zeolite powder) successfully guaranteed continuous self-driven directional dehydration of raw hide by establishing stable water concentration gradient between raw hide and ethanol, which significantly increased the dispersity of collagen fibers in raw hide (with the water content reduced from 56.07% to 5.20%), thus obtaining chrome-free leather that is more ecological than chrome-tanned leather due to the elimination of any tanning agent. The as-prepared chrome-free leather exhibited outstanding tear force (174.86 N), tensile strength (24.56 N mm −2 ), elongation at break (53.28%) and dry-thermal stability, superior to chrome-tanned leather. Notably, the used composite dehydration media was recyclable for chrome-free leather manufacture, therefore facilitating an environmentally benign leather manufacture process. Our investigations are expected to open up a new conceptual leather making strategy that is applicable for realizing substantial manufacture of eco-friendly leather. Graphical abstract

Industrial manufacture generates a huge quantity of emulsion wastewater, which causes serious threats to the aquatic ecosystems. Water-in-oil (W/O) and oil-in-water (O/W) emulsions are two major types of emulsions discharged by industries. However, dual separation of W/O and O/W emulsions remains a challenging issue due to the contradictory permselectivity for separating the two emulsions. In the present investigation, the amphiphilicity-derived regional wetting mechanism of water and oil on the amphiphilic collagen fibers was revealed based on the combination of numerous experiments and molecular dynamics (MD) simulations. Electrostatic interactions and van der Waals force were manifested to be the driving forces of regional wetting in the hydrophilic and hydrophobic regions, respectively. The regional wetting endowed amphiphilic collagen fibers with underwater oleophobicity and underoil hydrophilicity, which enabled dual separation of emulsions by selectively retaining the dispersed water phase of W/O emulsions in the hydrophilic regions while the dispersed oil phase of O/W emulsions in the hydrophobic regions. The achieved separation efficiency was higher than 99.98%, and the flux reached 3337.6 L m-2 h-1. Initial wetting status significantly affects the regional wetting-enabled dual separation. Based on the MD simulations, amphiphilic intramolecular conformations of tropocollagen were suggested to be the origins of regional wetting on collagen fibers. Our findings may pave the way for developing high-performance dual separation materials that are promising to be utilized for the practical treatment of emulsion wastewater.

Developing high-performance separation membrane with good durability is a highly desired while challenging issue. Herein, we reported the successful fabrication of chemically and mechanically durable superhydrophobic membrane that was prepared by embedding UiO-66 as size-sieving sites within the supramolecular fiber structure of collagen fiber membrane (CFM), followed by the polydimethylsiloxane (PDMS) coating. The as-prepared CFM/UiO-66(12)/PDMS membrane featured capillary effect-enhanced separation flux and homogeneous porous channels guaranteed high separation efficiency. When utilized as double-layer separation membranes, this new type of composite membranes separated various surfactant stabilized water-in-oil microemulsions and nanoemulsions, with the separation efficiency high up to 99.993 % and the flux as high as 973.3 L m − 2 h − 1 . Compared with commercial polytetrafluoro ethylene (PTFE) membrane, the advantage of the double-layer CFM/UiO-66(12)/PDMS membranes in separation flux was evident, which exhibited one order of magnitude higher than that of commercial PTFE membrane. The CFM/UiO-66(12)/PDMS membrane was acid-alkali tolerant, UV-aging resistant and reusable for emulsion separation. Notably, the CFM/UiO-66(12)/PDMS membrane was mechanically durable against strong mechanical abrasion, which was still capable of separating diverse water-in-oil emulsions after the abrasion with sandpaper and assembled as double-layer separation membranes. We anticipate that the combination of CFM and metal organic frameworks (MOFs) is an effective strategy for fabricating high-performance separation membrane with high mechanical and chemical durability. Graphical Abstract

The presence of ciprofloxacin (CIP) in natural water may cause potential threats to the environment. Adsorption is a convenient and efficient method to remove CIP from aqueous solution. Bayberry tannin (BT), a natural polyphenol, has been utilized in the synthesis of tannin foam (TF) due to its abundant polyphenolic hydroxyls to chelate with metal ions. The obtained TF was subsequently immobilized with Fe3+ via a facile chelative adsorption to fabricate functional tannin foam (TF-Fe), which was highly porous, with a porosity of 78.93%. The Fe species in the TF-Fe featured good dispersity, which were active for chelative adsorption of CIP. The adsorption of CIP on the TF-Fe was a pH-dependent process. At the optimized pH of 7.0, the TF-Fe provided the adsorption capacity of 91.8 mg g-1. When applied in removal of CIP at the low concentration of 2.0 µg mL-1, a high removal efficiency of 96.60% was still obtained, which was superior to commercial activated carbon (28.78%). The adsorption kinetics were well fitted by the pseudo-second-order rate model while the adsorption isotherms were well described by the Langmuir model. The TF-Fe was capable of recycling, which still maintained a high removal efficiency of 92.25% in the 5th cycle.

Herein, a heterogeneous Pd catalyst was prepared by embedding Pd nanoparticles in a highly porous nitrogen-doped mesoporous carbon (NMCs) synthesized by the ZIF-8 template. The as-prepared Pd/NMC catalyst was efficient and recyclable in mild catalytic hydrodechlorination of 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol, showing superior performances to those of the activated carbon-supported Pd commercial catalysts.

Heterogeneous Pd catalysts were developed by immobilizing Pd nanoparticles (Pd NPs) onto plant polyphenol (bayberry tannin, BT) decorated γ-Al 2 O 3 . The abundant hydroxyls of plant polyphenols were capable of stabilizing the Pd NPs. Transmission electron microscopy observation confirmed that the Pd NPs with the diameter of 3.75 ± 0.5 nm were highly dispersed in the catalyst. The as-prepared Al 2 O 3 –BT–Pd catalysts were found to be highly active in mild hydrodechlorination (HDC) of 2,4-dichlorophenols (DCPs) using formic acid as a hydrogen source. The 2,4-DCPs were completely dechlorinated in 4 h at 30°C and under atmospheric pressure. During the catalytic HDC, the stabilizing capability of BT successfully prevented the leakage and aggregation of Pd NPs, thus ensuring a high cycling stability with stable and high catalytic activity. The Al 2 O 3 –BT–Pd catalysts were recycled six times, without obvious loss of activity. In the sixth cycle, the catalytic HDC yield still reached 98.29% under the same reaction conditions, superior to the control catalysts, including γ-Al 2 O 3 supported Pd NPs (Al 2 O 3 –Pd) and powdered activated carbon supported Pd NPs (AC–Pd). Furthermore, the Al 2 O 3 –BT–Pd also showed high activity in the mild catalytic HDC of 2,4,6-trichlorophenols and chlorobenzene derivatives. Our results demonstrated efficient catalysts to address the environmental issue of chlorophenol pollution.

Simultaneous high activity and selectivity are highly desired in heterogeneous catalysis of various important organic intermediate compounds. In the present investigation, we realized ultra-high selective hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline (py-THQ) under atmospheric conditions by encapsulating 7 +/- 2 nm Pd nanoparticles (PdNPs) inside the 10 +/- 2 nm nanochannels of carbon nanotubes (CNTs). For the prepared Pd@CNTs catalysts, the encapsulated PdNPs was found to selectively absorb the nitrogen heterocyclic ring of quinoline, which led to the increase of average length of C-C bonds in the heterocyclic ring, further resulting in selective activation of the heterocyclic ring and similar to 100% selectivity to py-THQ. The DFT calculations confirmed the selective hydrogenation feature of Pd@CNTs. In contrast, the Pd-CNTs catalyst with PdNPs supported on the outer surface of CNTs is incapable of selectively activate the heterocyclic ring of quinoline, showing poor selectivity and catalytic activity. The Pd@CNTs catalysts also exhibited universal ultra-high selectivity to other quinoline derivatives (7-Methylquinoline, quinaldine and quinoxaline) and oxygen heterocyclic compounds (2,3-benzofuran). Due to the confined effect, the Pd@CNTs catalysts presented superior cycling stability to the Pd-CNTs and activated carbon (AC) impregnated with Pd (Pd-AC) catalysts. The Pd@CNTs catalyst was also found to highly stable in air storage for months, without loss of activity.