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Membrane separation is a promising approach for the remediation of oil contamination in water. High-flux separation of membrane relies on the rational design of ultrathin active layer to significantly reduce mass transfer distance for achieving high separation flux, while the ultrathin active layer is usually fragile with poor mechanical strength, which has to be supported on a support. Herein, we employed collagen fiber membrane (CFM) as multi-functional support for the in-situ growth of polyacrylonitrile (PAN) layer by electrospinning to prepare the high-performance PAN/CFM composite membrane. Due to the amphiphilic nature and strong capillary effect, CFM played the role as multi-functional support to provide separation effectiveness and boosted separation flux. The PAN/CFM composite membrane enabled ultrahigh separation flux (e.g., 51751.59 L m -2 h -1 bar -1 ) to a variety of oil-in-water emulsion, which was one order of magnitude higher than that of commercial polyethersulfone membrane and 1.86-fold to that of cellulose acetate membrane. Furthermore, the PAN/CFM composite membrane retained high separation flux (e.g., 11046.97 L m -2 h -1 bar -1 ) during the 5th separation cycle, providing appreciable anti-fouling capability. Therefore, our findings provided a promising way to effectively resolve the problem of oil contamination in water., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Porous structures are essential for some collagen-based biomaterials and can be regulated by crosslinkers. Herein, dialdehyde carboxymethyl cellulose (DCMC) crosslinkers with similar size but different aldehyde group contents were prepared through periodate oxidation of sodium carboxymethyl cellulose with varying degrees of substitution (DS). They can penetrate into the hierarchy of fibril and form inter-molecular and intra-fibril cross-linking within the collagen matrix due to their nanoscale sizes and reactive aldehyde groups. The collagen matrices possessed higher porosity, significantly greater proportion of large pores (Φ > 10 μm), and shorter D -periodicity after cross-linking, showing greater potential for biomedical applications. In addition, the crosslinked collagen matrices showed satisfactory biocompatibility and biodegradation. The decreased DS of carboxymethyl cellulose, which led to the increased aldehyde content of corresponding DCMC, brought about an enhanced cross-linking degree, porosity, and proportion of large pores of the crosslinked collagen matrix. DCMC dosage of 6% was sufficient for cross-linking and pore formation. Excess DCMC would physically deposit in the matrix and decrease the porosity instead. Therefore, the desired pore properties of the collagen matrix could be obtained by regulating the structure of DCMC and thereby achieving the required functions of the biomaterial.

A series of periodate oxidized sodium alginate (OSA) were prepared as green polysaccharide-based crosslinkers. The molecular weight of OSA decreased, while their aldehyde group content increased with increasing dosage of sodium periodate. A typical OSA was further fractionated to four fractions by ethanol with a narrower molecular weight distribution. Then the crosslinking performances of OSAs/fractions on collagen fiber (CF) were investigated. DSC and SEM analyses showed that the thermal stability and dispersion degree of crosslinked CF was considerably enhanced with decreasing molecular weight of OSA. The effect of aldehyde group content of OSA on its crosslinking performance was less obvious than that of molecular weight, probably because the aldehyde group content in each OSA sample was higher than the amino group content of CF involved in the crosslinking reaction. In general, molecular weight of OSA plays a decisive role in improving properties of the crosslinked CF., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Collagen fiber (CF), an abundant natural biopolymer, features many favorable properties that make it a potential carrier for cell immobilization. In the present investigation, CF was grafted with polyethyleneimine (PEI) using glutaraldehyde (GA) as the cross-linking agent, resulting in the formation of a novel CF based carrier (CF-PEI). The properties of CF-PEI as a carrier were evaluated by the immobilization of Microbacterium arborescens (CICC 20196), which has glucose isomerase (EC 5.3.1.5) activity. It was found that M. arborescens cells immobilized on CF-PEI exhibited higher glucose isomerization than those using activated carbon or anion exchange resin as the carriers. The Michaelis constant (K m) of the isomerization reaction for the CF-PEI-immobilized M. arborescens cells was 0.528 mol/L, which was slightly higher than that of free cells (0.473 mol/L). In addition, the apparent activation energies (E a) of free and immobilized cells on CF-PEI were almost the same at 60 kJ/mol. In an isomerization reaction of glucose to fructose in a fixed-bed reactor, CF-PEI-immobilized M. arborescens cells showed appreciable activity and operational stability. The corresponding isomerization ratio was as high as 41 % for 20 days, and the half-life was about 40 days.

In the present investigation, skin collagen fiber (CF) with a well defined hierarchical 3D fibrous structure was employed for the bio-inspired fabrication of high-performance microwave absorption materials. The hierarchical 3D structure of the CF was retained in the CF@Ni-Fe-P composites, and the formation of the Ni-Fe-P coating on the CF surface was identified by XRD and XPS analysis. Based on the electromagnetism parameter measurements, the maximum reflection loss (RL) of the CF@Ni-Fe-P composites reached -31.0 dB, and the width of the absorption band where reflection loss values exceeded -10.0 dB covered the whole Ku-band and some parts of the X-band (9.5-18.0 GHz). The complex permittivity and complex permeability measurements indicated that electronic loss and magnetic loss were involved in the CF@Ni-Fe-P composites for microwave absorption. In addition, due to the magnetic properties of the Ni-Fe-P coating, these CF@Ni-Fe-P composites exhibited excellent magnetic characteristics with high saturation magnetization and low coercivity values. The present investigation indicates a new possibility for the bio-matrix-based fabrication of high-performance microwave absorbing materials with lightweight and efficient absorption properties.

The separation of proteins is a key step in biomedical and pharmaceutical industries. In the present investigation, the collagen fiber adsorbent (CFA) was exploited as column packing material to separate proteins. Bovine serum albumin (BSA), bovine hemoglobin (Hb) and lysozyme (LYS) that have different isoelectric points (pIs) were selected as model proteins to investigate the separation ability of CFA to proteins. In batch adsorption, the adsorption behaviors of these proteins on CFA under different pHs and ionic strengths indicated that the electrostatic interaction plays a predominant role in the adsorption of proteins on CFA. CFA exhibited high adsorption capacity to Hb and LYS. In column separation, the proteins were completely separated by adjusting pH and ionic strength of the eluent. The increase of flow rate could reduce the separation time with no influence on the recovery of protein in the experimental range. The protein recovery was higher than 90% even when the CFA column was re-used for 4 times in separation of BSA and LYS, and the retention time of BSA or LYS was almost constant during the repeated applications. In addition, as a practical application, LYS was successfully separated from chicken egg white powder by CFA column., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: Kaempferol, quercetin and myricetin are typical flavonols that are most concentrated in many medicinal herbs. However, the separation of these flavonols is very challenging due to their similar molecular structures. In the present investigation, the chromatographic separation of the flavonols kaempferol, quercetin and myricetin was performed using glutaraldehyde cross-linked collagen fibre (GCF) as the stationary phase., Results: Kaempferol, quercetin and myricetin could be completely separated from each other by the GCF column by using gradient elution with different solutions of aqueous ethanol (100% to 70%) and 50% acetone. When the chromatographic separation was carried out at a flow rate of 0.75 bed volume h(-1) with a sample loading of 30 mg 7 g(-1) GCF, the purity of kaempferol, quercetin and myricetin was 98.17%, 93.81% and 81.76%, respectively. The separation resolution was influenced by column length, flow rate and sample loading amount. The separation efficiency of GCF was not obviously reduced after applications had been repeated five times. In the fifth repeated application, the purity of the recovered kaempferol, quercetin and myricetin was still higher than 97%, 94% and 78%, respectively., Conclusion: GCF is a promising adsorbent for use as a stationary phase in the chromatographic separation of flavonols from their mixtures., (© 2012 Society of Chemical Industry.)

Fe (III) modified collagen fibers were used to immobilize catalase through the cross-linking of glutaraldehyde. The loading amount of catalase on the supporting matrix was 16.7 mg/g, and 35% enzymatic activity was remained. A series of experiments were conducted on free and immobilized catalase in order to investigate their optimal pH and temperature, and the thermal, storage and operation stability. Results suggest that the free and immobilized catalase prefer similar pH and temperature condition, which were pH 7.0 and 25 degrees C. It should be noted that the thermal stability of catalase was considerably improved after immobilization owing to the fact that the enzyme kept 30% of relative activity after incubation at 75 degrees C for 5 h. On the contrary, the free catalase was completely inactive. As for the storage stability, the immobilized catalase kept 88% of relative activity after stored at room temperature for 12 days while the free one was completely inactive under the same conditions. Moreover, the immobilized catalase preserved 57% of relative activity after being reused 26 times, exhibiting excellent operation stability. Consequently, this investigation suggests that collagen fiber can be used as excellent supporting matrix for the immobilization of catalase, and it is potential to be used for the immobilization of similar enzymes.

We have investigated the modification of collagen with a natural plant polyphenol, procyanidin under acidic conditions. Fourier transform infrared spectroscopy (FTIR) and Atomic force microscopy (AFM) studies demonstrate that the hydrogen bond interactions between collagen and procyanidin does not destroy the triple helix conformation of collagen, and the fibril aggregation occurs because of the cross-linking with procyanidin. The water contact angle (WCA) tests indicate that the hydrophobicity of the procyanidin modified collagen films can be improved. Whereas, the water vapor permeability (WVP) of the films decrease with the increasing procyanidin content due to the formation of denser structure. Moreover, differential scanning calorimetry (DSC) and thermogravimetric (TG) measurements reveal that the collagen/procyanidin films have improved thermal stability in comparison with pure collagen. The present study reveals that procyanidin stabilizes collagen as a cross-linker and preserves its triple helical structure., (Copyright © 2010 Elsevier B.V. All rights reserved.)

The collagen-tannin resin (CTR), as a novel adsorbent, was prepared via a reaction of collagen with black wattle tannin and aldehyde, and its adsorption properties to Cu(II) were systematically investigated, including pH effect, adsorption equilibrium, adsorption kinetics, and column adsorption. The adsorption capacity of Cu(II) on CTR was pH-dependent, and it increased with the increase of solution pH. The adsorption isotherms were well described by Langmuir isotherm model with correlating constant (R(2)) higher than 0.99. The adsorption capacity determined at 303 K was high up to 0.26 mmol/g, which was close to the value (0.266 mmol/g) estimated from Langmuir equation. The adsorption capacity was increased with the increase of temperature, and thermodynamic calculations suggested that the adsorption of Cu(II) on CTR is an endothermic process. The adsorption kinetics were well fitted by the pseudo-second-order rate model. Further column studies suggested that CTR was effective for the removal of Cu(II) from solutions, and more than 99% of Cu(II) was desorbed from column using 0.1 mol/L HNO(3) solution. The CTR column can be reused to adsorb Cu(II) without any loss of adsorption capacity., (Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.)

Flavonoids and alkaloids are two major classes of plant compounds with biological activities, and they usually coexist in many medicinal herbs. In this study, a novel collagen fiber adsorbent (CFA) was prepared, and its application for adsorption chromatography separation of flavonoids and alkaloids was systematically investigated. The typical flavonoids, rutin and baicalin, and the typical alkaloids, matrine and caffeine, were selected as probe molecules for the investigations. The batch adsorption behaviors of these compounds on CFA in different solvents indicated that hydrogen bond plays a predominant role for the adsorption of flavonoid and alkaloid in pure ethanol, while the hydrophobic interaction plays a predominant role for the adsorption in water. In column chromatography separation, flavonoids were completely separated from alkaloids by a stepwise elution process with pure ethanol followed by aqueous ethanol solution. The two flavonoids, rutin and baicalin, were also well separated although the two alkaloids, matrine and caffeine, were washed out together. The optimal loading volume of sample solution (10 mg/mL) for the separation was determined as 0.66 mL/g CFA. Under these conditions, flavonoid and alkaloid were effectively separated with a recovery higher than 90% in 8 times repeated applications.

Collagen-tannin resin (CTR), as a novel adsorbent, was prepared via reaction of collagen with black wattle tannin and aldehyde, and its adsorption properties to UO(2)(2+) were investigated in detail, including pH effect, adsorption kinetics, adsorption equilibrium and column adsorption kinetics. The adsorption of UO(2)(2+) on CTR was pH-dependent, and the optimal pH range was 5.0-6.0. CTR exhibited excellent adsorption capacity to UO(2)(2+). For instance, the adsorption capacity obtained at 303 K and pH 6.0 was as high as 0.91 mmol UO(2)(2+)/g when the initial concentration of UO(2)(2+) was 1.0 mmol/L. In kinetics studies, the adsorption equilibrium can be reached within 300 min, and the experimental data were well fitted by the pseudo-second-order rate model, and the equilibrium adsorption capacities calculated by the model were almost the same as those determined by experiments. The adsorption isotherms could be well described by the Freundlich equation with the correlation coefficients (R(2)) higher than 0.99, the adsorption behaviors of UO(2)(2+) on CTR column were investigated as well. Present study suggested that the CTR can be used for the adsorptive recovery of UO(2)(2+) from aqueous solutions., (2010 Elsevier B.V. All rights reserved.)

Objective: To investigate the selective removal of tannins from Polygonum cuspidatum extracts by using collagen fiber adsorbent, and to evaluate the adsorption and desorption performances of collagen fiber adsorbent to tannins., Method: The adsorbent was prepared from bovine skin collagen fiber through crosslinking reaction of glutaraldehyde, and then used for the selective removal of tannins from P. cuspidatum extracts. Gelatin-turbidity method, gelatin-ultraviolet spectrometry method and HPLC were used for detection of tannins in the solutions. Ethanol-water solutions with varying concentration were used to test their desorption ability of tannins in order to choose proper desorption solution. On the basis of batch experimental results, the column adsorption and desorption tests were carried out, by using gelatin-turbidity method for detection of tannins., Result: The collagen fiber adsorbent exhibited excellent adsorption selectivity to tannins. It was found that tannins of P. cuspidatum were completely removed, while nearly no adsorption of active components (resveratrol as representative) was found. Moreover, the collagen fiber adsorbent could be regenerated by using 30% ethanol-water solution and then reused., Conclusion: The collagen fiber adsorbent can be considered as a promising material for selective removal of tannins from P. cuspidatum extracts.

A heterogeneous catalyst for Fenton reaction was prepared by immobilizing Fe(III) onto collagen fiber and its catalytic activity for the photo-assisted decomposition of Malachite Green (MG) was investigated. The results indicated that this Fe(III)-immobilized collagen fiber (Fe-CF) can effectively catalyse the decoloration and decomposition/mineralization of MG in aqueous solution. Catalysed by Fe-CF, MG solution was completely decolorized in 30 min, while 55.0% of TOC was removed from the dye solution within 120 min in the presence of H(2)O(2) and UVA irradiation (365 nm, 10 W). Fe-CF was recycled for seven times with certain activity loss (32.6% in decoloration, 18.5% in TOC removal), and its catalytic activity can be easily recovered by re-immobilization of Fe(III). Therefore, Fe-CF could act as an efficient and cost-effective catalyst for the photo-assisted decomposition of MG, and shows potential applications in practice.

A novel adsorbent was prepared by immobilizing barberry tannin (BT) onto collagen fiber, which was found effective to remove Hg(II) from aqueous solution. The bayberry tannin-immobilized collagen fiber (BTICF) shows high adsorption capacity to Hg(II) in a wide pH range of 4.0-9.0, and a maximum adsorption capacity (198.49 mg/g) was reached at pH 7.0 and 303 K when the initial concentration of Hg(II) was 200.0 mg/L. The adsorption isothermal and kinetic data were well fitted by the Langmuir equation and the pseudo-first-order rate equation, respectively. The adsorption mechanism of BTICF to Hg(II) was proved to follow a chelating reaction. The BTICF can be easily regenerated with 0.1M lactic acid after adsorption process and recycled at least 4 times without the loss of adsorption capacity. These facts indicate that BTICF can be used as a low-cost adsorbent for effective removal of Hg(II) from aqueous solutions.

Hierarchical mesoporous alumina fiber was synthesized by using collagen fiber as the template, and characterized by means of scanning electron microscopy, transmission electron microscopy, N2 adsorption techniques, X-ray photoelectron spectroscopy, and X-ray diffraction. The alumina fiber obtained is approximately 1-4 microm in outer diameter and 0.5-1 mm in length. The pore size distribution of the alumina fiber is narrow (2-20 nm), and its pore size is controllable by varying preparation methods. This study indicates that collagen fiber, which has hierarchical supermolecular structure, could be used as an ideal template to prepare well-defined porous metal oxide fibers.

A novel catalyst for the Fenton reaction was prepared by immobilizing Fe(III) onto collagen fiber and its high activity as a catalyst for degradation of dyes under irradiation of UVC was proved.

A novel adsorbent, zirconium(IV)-impregnated collagen fiber, was prepared. Zr(IV) was uniformly dispersed in collagen fiber, mainly through chemical bonds, and was able to withstand the extraction of water. This adsorbent is effective for the removal of fluoride from aqueous solutions. The adsorption capacity was 2.29 mmol/g at pH = 5.5 when 5.00 mmol/L fluoride solution was adsorbed by use of 0.100 g of adsorbent, and the extent of removal was 97.4% when the adsorbent dose was 0.300 g. The adsorption isotherms were well fitted by the Langmuir equation, and the maximum adsorption capacities calculated by the Langmuir equation were close to those determined by experiment. The adsorption capacity increased with rising temperature. These facts imply that the mechanism of chemical adsorption might be involved in the adsorption process of fluoride on the absorbent and that fluorides are adsorbed in the form of monolayer coverage on the surface of the adsorbent. The adsorption kinetics of fluoride onto Zr(IV)-impregnated collagen fiber could be described by Lagergren's pseudo-first-order rate mode. The investigation on desorption indicated that this adsorbent is easily regenerated by use of dilute NaOH solution.

The extracellular matrix, which includes collagens, laminin, or fibronectin, plays an important role in peripheral nerve regeneration. Recently, a Schwann cell-derived extracellular matrix with classical biomaterial was used to mimic the neural niche. However, extensive clinical use of Schwann cells remains limited because of the limited origin, loss of an autologous nerve, and extended in vitro culture times. In the present study, human umbilical cord-derived mesenchymal stem cells (hUCMSCs), which are easily accessible and more proliferative than Schwann cells, were used to prepare an extracellular matrix. We identified the morphology and function of hUCMSCs and investigated their effect on peripheral nerve regeneration. Compared with a non-coated dish tissue culture, the hUCMSC-derived extracellular matrix enhanced Schwann cell proliferation, upregulated gene and protein expression levels of brain-derived neurotrophic factor, glial cell-derived neurotrophic factor, and vascular endothelial growth factor in Schwann cells, and enhanced neurite outgrowth from dorsal root ganglion neurons. These findings suggest that the hUCMSC-derived extracellular matrix promotes peripheral nerve repair and can be used as a basis for the rational design of engineered neural niches.

The effect of hydrophobic modification on the performances of collagen fibers (CFs) was investigated by using silane coupling agents with different alkyl chains as hydrophobic modifiers. It was found silane could be easily grafted onto CF surface through covalent bonds under 5% water content. This modification led to the transformation of surface wettability of CF from hydrophilic to hydrophobic. Interestingly, the change of surface wettability resulted in substantial improvement of the modified CF properties, presenting well dispersity of collagen fibers, higher thermal stability and enhanced mechanical properties in comparison with natural CF. The degree of improvement mainly depended on the length of alkyl chain in silane. Longer alkyl chain produced strong hydrophobicity and subsequently more superior performances of the modified CF. When the length of alkyl chain increased to 18 carbon atoms, the modified CF possessed durable superhydrophobicity even exposed to aqueous solutions of different pH, UV, and organic solvents, and had excellent thermal and mechanical properties like leather fibers. In general, this work clearly revealed that the properties of CF are closely and positively related to the hydrophobicity, which is suggestive in developing new leather making technology. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study demonstrated the interaction mechanism of collagen peptides (CPs) with 4-ethylphenol (4-EP), phenol, guaiacol, and 4-ethylguaiacol (4-EG) in the ethanol-water solution. The ultraviolet visible spectroscopy, zeta potential tests and hydrogen nuclear magnetic spectroscopy manifested that CPs interacted with the phenolic compounds. Meanwhile, Isothermal titration calorimetry determination indicated that the CPs was hydrogen bonded with 4-EP in 52 %(v/v) ethanol-water solution, while the hydrophobic forces played a major role in the interaction of CPs with guaiacol and 4-EG, respectively. Moreover, hydrogen and hydrophobic bonds were involved in the interaction between CPs and phenol. Finally, Head Space-solid Phase Microextraction Gas Chromatography Mass Spectrometry analysis indicated that the content of phenolic compounds in model solution efficiently decreased with the presence of CPs. In the real liquor, it was found that the content of volatile compounds (including phenolic compounds) was obviously decreased after CPs added. [ABSTRACT FROM AUTHOR]

Effective and ecofriendly converting biomass to chemicals is important for sustainable engineering based on the foreseeable shortage of fossil resources. Undecylprodigiosin (UP) is a promising antibiotic, but the direct feeding of pure precursor amino acids makes it costly for large-scale production. Here, collagen peptide (CP), a renewable animal-derived biomass contains abundant precursor amino acids of UP. CP can act as carbon and nitrogen source for the growth of Streptomyces coelicolor CGMCC 4.7172. The plant biomasses including soybean meal, wheat bran, and malt extract were unsuitable for UP prodution. However, 365.40 µg/L UP was detected after 24 h in the media containing CP, and its highest concentration reached 1198.01 µg/L. UP was also detected in the media containing meat hydrolysates of domestic animals, but its initial production time was delayed, and final concentration was lower than that in the medium containing CP only. Compared the fermentation performances of CP and other proteins, CP has a special superiority for UP production. These results revealed that UP biosynthesis may be dependent on amino acid availability of substrates and CP is beneficial for UP production because of its specific amino acid composition. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Conventionally, the manufacture of leather relies on the utilization of tanning agents that are capable of forming cross-linkages among collagen fibers, thus realizing the transformation of rawhide into leather. This theory has been followed for more than a hundred years. Herein, we realized tanning agent free leather making, which was achieved by controlled dehydration of pelt with ethanol, followed by a superhydrophobic coating. The controlled dehydration of the pelt guaranteed high dispersity of collagen fibers with substantially enhanced porosity, and the dehydrated pelt with the water content of ≤8.90% exhibited leather-like properties. The superhydrophobic coating improved the water repellency of dehydrated pelt significantly, which prevented the re-absorption of water by dehydrated pelt, thus allowing for the as-prepared leather to stably present leather-like properties. Notably, tanning agent free leather exhibited comparable physical properties to those of conventional chrome tanned leather, including the tensile strength (19.24 N mm−2), tear force (94.27 N), elongation at break (49.57%) and fullness. The tanning agent free leather making strategy developed by us might open up a new way for realizing environmentally benign leather manufacture. [ABSTRACT FROM AUTHOR]

Collagen fiber (CF) and silane coupling agent-modified collagen fiber (MCF) were used as flame retardant filler for natural rubber (NR) modification. The combustion phenomena and properties of composites blended with different dosages of CF or MCF were compared to elucidate the flame retardant mechanism of the composites. The flame retardancy of NR can be enhanced effectively by increasing nitrogen content (the nitrogen content of CF is about 18%), creating air pockets, and structuring the flame retardant network in the composites. MCF failed to structure a flame retardant network in the composite, indicating that its modification effects of MCF are weaker than those of CF. When CF dosage was 30 wt%, the composite can achieve the best flame retardancy, with limited oxygen index of 29.4% and without smoke and dripping during burning. This study demonstrated a new method for the flame retardant modification of NR. [ABSTRACT FROM AUTHOR]

Superhydrophobicity is vital to natural rubber‐based materials and can endow materials with intriguing features, such as self‐cleaning. Normally, low surface energy and surfacial micro/nanostructure are the two premises of superhydrophobicity. However, the fragility of micro/nanostructures in natural rubber (NR) composite surfaces makes the maintenance of durable superhydrophobicity under external forces difficult. Thus, the application of NR composite elastomers is limited in industrial fields. In this work, a novel NR‐based elastomer is prepared by uniquely dispersing perfluorooctytriethoxysilane‐modified leather collagen fibers (M‐LCF) with multiscale structures into rubber matrix. The as‐prepared NR composite with 40% M‐LCF content displays excellent superhydrophobicity with a water contact angle of 156°, and the endowed superhydrophobicity is ultradurable and can be retained after 2000 cycles of mechanical abrasion under a pressure of 100 kPa. Moreover, the prepared material features superior self‐cleaning performance and mechanical properties. The reported work may serve as a basic for fabricating materials with durable superhydrophobicity. [ABSTRACT FROM AUTHOR]

Developing dual separation materials that exhibit high-flux separation capabilities towards oil-in-water (O/W) and water-in-oil (W/O) emulsions provides a promising and facile remediation strategy for the contamination caused by emulsified oily wastewater. Herein, environmentally benign amphiphilic composite fibers (ACFs) were facilely prepared by a green synthesis approach that relied on the non-covalent decoration of tannic acid (TA), the natural amphiphilic phenolic compound, onto collagen fibers (CFs) with inherent amphiphilicity and structural hierarchy. Hydrophobic interactions and multi-hydrogen bonding interactions between the amphiphilic TA and CFs brought the enhancement of amphiphilicity-enabled wetting behaviors as well as the structural stability of CFs. The green synthesized ACFs exhibited hydrophilicity, underwater superoleophobicity and underoil hydrophilicity. The as-prepared ACFs were directly utilized for the dual separation of O/W and W/O emulsions with high separation efficiency (> 99.99%) and high flux (e.g. 2471 L m−2 h−1) by selectively permeating the continuous water phase of O/W emulsions and the continuous oil phase of W/O emulsions, respectively. Compared with CFs, the structural stability of ACFs was improved significantly, which therefore provided appreciable reusability and long-term separation stability. Our findings demonstrated the essential role of amphiphilicity played in the dual separation of O/W and W/O emulsions, which also provided a new solution for the remediation of emulsified oily wastewater by developing biomaterials-based amphiphilic separation materials. [Display omitted] • Collagen fibers-derived amphiphilic composite fibers were fabricated. • Amphiphilicity and structural stability of collagen fibers were enhanced. • Non-covalent decoration with tannin acid enabled a green synthesis process. • A high-flux dual separation to O/W and W/O emulsions were achieved. [ABSTRACT FROM AUTHOR]

The role of formaldehyde (HCHO) in vegetable-aldehyde-collagen cross-linking reaction was investigated at the B3LYP/6-31+G(d) level, where lysine (LYS) was used as model of collagen and catechin (EC) as model of condensed vegetable tannin. Atomic charge and Frontier molecular orbital analysis show that intermediates formed by HCHO reacting with LYS or EC, that is, MLYS, MEC-6, and MEC-8, still have both nucleophilic and electrophilic sites, which are elements to form ternary cross-linking in vegetable-aldehyde-collagen system. The analysis of energy gap between HOMO (highest occupied molecular orbit) and LUMO (lowest unoccupied molecular orbit) indicate that the intermediate of HCHO-LYS residues (MLYS) can further react with free HCHO to form product P-N(CH2OH)2 (P-N-represents amino acid residue; N represents nitrogen atom on side chain), but the reaction of intermediate MLYS with free EC is difficult to take place. So, the probability of forming ternary cross-linking structure of amino acid residue-HCHO-EC is small, if HCHO is added before vegetable tannin in vegetable-aldehyde-collagen system. However, the reactions of EC-HCHO intermediates (MEC-6 and MEC-8) with free amino acids, HCHO-amino acid residue intermediate (MLYS), as well as with other EC-HCHO intermediates (MEC-6 and MEC-8), are very easy to take place. The reaction enthalpy also shows that the cross-linking tendency is favorable in thermodynamics. So, it can be deduced that covalent cross-linking among amino side chain of collagen and vegetable tannin may take place when aldehyde is added after vegetable tannin. In this way, a multiple point cross-linking reaction occurs to create a high stabilization of collagen. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A facile method for one-step synthesis of size-controlled gold nanoparticles (AuNPs) supported on collagen fiber (CF) at room temperature was proposed. Epigallocatechin-3-gallate (EGCG), a typical plant polyphenol, was grafted onto CF surface to serve as reducing/stabilizing agent, so that the AuNPs were generated on CF surface without introduction of extra chemical reagents or physical treatments. The prepared AuNPs were fully characterized, and the results showed that the dispersed AuNPs were successfully produced and the mean particle size of AuNPs could be effectively controlled in range of 18 to 5 nm simply by varying the grafting degree of EGCG on CF surface. These stabilized AuNPs were found to be active heterogeneous catalysts for the reduction of 4-nitrophenol to 4-aminophenol in aqueous phase. The catalytic behaviors of AuNPs depended on the particle size and the grafting degree of EGCG. A distinct advantage of these catalysts is that they can be easily recovered and reused at least twenty times, because of the high stability of the AuNPs supported by EGCG-grafted CF. [ABSTRACT FROM AUTHOR]

By using skin collagen fiber (CF) as raw material, Schiff base structure containing CF (Sa-CF) was synthesized through CF-salicylaldehyde reaction. Then a novel radar absorbing material (Fe-Sa-CF) was prepared by chelating reaction between Sa-CF and Fe3+. The coaxial transmission and reflection method was used to analyze the complex permittivity and complex magnetic permeability of these CF-based materials, and the radar cross section (RCS) method was used to investigate their radar absorbing properties in the frequency range of 1.0-18.0 GHz. Experimental results indicated that the conductivity of CF increased from initial 1.08 x 10-11 to 2.86 x 10-6 S/cm after being transferred into Fe-Sa-CF, and its dielectric loss tangent (tan δ) in the frequency range of 1.0-17.0 GHz also increased. These facts suggest that the Fe-Sa-CF is electric-loss type radar absorbing material. In the frequency range of 3.0-18.0 GHz, Sa-CF (1.0 mm in thickness) exhibited somewhat radar absorbing property with maximum radar reflection loss (RL) of -4.73 dB. As for Fe-Sa-CF, the absorbing bandwidth was broadened, and the absorbing intensity significantly increased in the frequency range of 1.0-18.0 GHz where a maximum radar RL of -9.23 dB was observed. In addition, the radar absorbing intensity of Fe-Sa-CF can be further improved by increasing membrane thickness. When the thickness reached to 2.0 mm, the RL values of Fe-Sa-CF were -15.0- -18.0 dB in the frequency range of 7.0-18.0 GHz. Consequently, a kind of novel radar absorbing material can be prepared by chemical modification of collagen fiber, which is characterized by thin thickness, low density, broad absorption bandwidth and high absorption intensity. [ABSTRACT FROM AUTHOR]

A novel adsorbent, collagen immobilized tannin adsorbent (CITA), was prepared and its adsorption behaviors to Th(IV) were investigated. CITA was in fibrous state due to the reassembly of collagen molecules by the inducement of tannin. This adsorbent loaded a greater amount of tannin and exhibited higher adsorption capacity to Th(IV) than the tannin immobilized adsorbent prepared from collagen fiber. The adsorption of CITA to Th(IV) is mainly attributed to surface complexation, which is a pH- rather than an ionic strength-dependent process. The adsorption kinetics and isotherms were described by pseudo-second-order rate model and Freundlich equation, respectively. Column adsorption studies indicated that CITA is available for effectively recovering Th(IV) from aqueous solution. [ABSTRACT FROM AUTHOR]

Novel adsorbents which can concentrate Th(IV) in aqueous solution were prepared by immobilizing Myrica rubra tannin and larch tannin onto collagen fibre matrices. The adsorption capacities of the immobilized tannins to Th(IV) are related to temperature and pH value of the adsorption process. For example, when the initial concentration of Th(IV) was 116.0 mg.l-1 and the immobilized tannin was 100 mg, the adsorption capacities of immobilized Myrica rubra tannin and larch tannin were 55.98 mg Th(IV).g-1 and 13.19 mg Th(IV).g-1, respectively at 303 K, and 73.67 mg Th(IV).g-1 and 18.19 mg Th(IV).g-1 at 323 K. It was also found that the higher adsorption capacity was obtained at higher pH value. The adsorption equilibrium data of the immobilized tannins for Th(IV) can be well fitted by the Langmuir model and the mechanism of the adsorption was found to be a chemical adsorption. In general, the adsorption capacity of immobilized Myrica rubra tannin to Th(IV) is significantly higher than that of immobilized larch tannin, probably due to the fact that the B ring of Myrica rubra tannin has a pyrogallol structure which has higher reaction activity with metal ions. The breakthrough point of the adsorption column of immobilized Myrica rubra tannin was at 33 bed volumes for the experimental system. The mass transfer coefficient of adsorption column determined by Adams-Bohart equation was 1.61.10-4 l.mg-1.min-1. The adsorption column can be easily regenerated by 0.1 mol.l-1 HNO3 solution, showing outstanding ability of concentrating Th(IV). [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is a typical bio-based polymer derived from crops. Its widespread application has been limited due to stress relaxation and brittleness. Here, a sustainable strategy to simultaneously improve the anti-stress relaxation and toughness of PLA biocomposites was proposed by blending PLA with epoxidized soybean oil (ESO)-modified collagen fiber (CF, ESO-CF). ESO enhanced the interfacial interaction between ESO-CF and PLA by constructing cross-linked networks in ESO-CF/PLA. Comparative analyses of stress relaxation and fracture behaviors were conducted between ESO-CF/PLA and pure PLA. The stress–strain curves of ESO-CF/PLA showed lower peak stress reduction rate (1% strain; 27.1%) and irrecoverable strain (zero stress; 0.3%) after 10 cycles compared with those of pure PLA, indicating that the introduction of ESO-CF greatly improved the anti-stress relaxation of PLA. Moreover, the elongation at break and the impact strength of ESO-CF/PLA were 301.6% and 78.9% higher than those of pure PLA, respectively, indicating that ESO-CF improved the toughness of PLA. The enhancements were mainly attributed to the naturally multidirectional and hierarchical structure of ESO-CF and the effective interfacial interaction between ESO-CF and PLA. This work provides insights into the development of PLA biocomposites with enhanced mechanical properties by blending with vegetable oil-modified natural fibers. [Display omitted] • PLA biocomposites with excellent mechanical properties were prepared. • A multifunctional natural filler (ESO-CF) was prepared. • ESO enhanced the interfacial interaction between ESO-CF and PLA. • Crosslinked networks were successfully constructed in ESO-CF/PLA. • The anti-stress relaxation and toughness of PLA were simultaneously improved. [ABSTRACT FROM AUTHOR]

Bating animal hides with trypsin is an essential step for making leathers. But the mechanism why the calcium in the hide influences the bating performance remains unclear. Here, the enzyme activity of trypsin was determined using N-alpha-benzoyl-L-arginine ethyl ester, bovine albumin (BSA) and collagen fibres as substrates in the presence and absence of calcium salts. The interactions of calcium with trypsin, BSA and collagen were analysed by fluorescence spectroscopy and molecular docking. Data reveal that calcium which binds to BSA and collagen improves the structural stability and enzyme resistance of hide proteins. As a result, a high calcium content of delimed hide is useful to obtain an intact surface of bated hide. However, a low calcium content of hide for pickling is necessary for producing leathers with high physical properties and uniform colour. According to these results, a novel bating system involving deliming, bating and redeliming operations was developed. This system provides a high calcium content of hide for bating and a low calcium content of hide for subsequent pickling and tanning, which effectively reduces the risk of hide damage and improves the physical properties and colour uniformity of leather. [Display omitted] • How calcium salts affect hydrolysis of hide proteins with trypsin in bating was revealed. • A high calcium content of delimed hide protects the grain surface of hide. • A low calcium content of hide is necessary for high physical properties of leather. • A novel system involving deliming, bating, and redeliming operations was designed. • This system effectively reduces the risk of hide damage and can ensure leather quality. [ABSTRACT FROM AUTHOR]

Bating pelt with protease is an important process, which removes unwanted non-collagenous proteins from the pelt and moderately disperse hide collagen network. However, the grain surface, may be excessively hydrolyzed during bating due to the longer retention time of protease in the grain than in the middle layer caused by the low mass transfer rate of protease in pelt. Here, the effects of protease dosage, common auxiliaries and molecular weight of protease on protease transfer during bating were investigated so that we can find the key points to avoid excessive collagen damage, particularly in the grain. Observably, increasing protease dosage led to faster protease transfer and softer leather, but along with more considerable grain damage. Using penetrating agent JFC (fatty alcohol-polyoxyethylene ether) and ammonium sulfate enhanced protease transfer and simultaneously alleviated collagen damage due to the decrease in interfacial tension and electrostatic attraction between protease and pelt, respectively. Additionally, proteases with lower molecular weight transferred faster in pelt, which suggests that a potential strategy to solve the conflict between the mass transfer and the reaction of protease in pelt might be to produce/employ smaller bating proteases. [ABSTRACT FROM AUTHOR]

The fabrication of nanostructure can alleviate the problem of electrode pulverization so as to exhibit high cycling stability with large gravimetric energy density. However, the high volumetric fraction of voids in nanomaterials inevitably results in low tap density and poor volumetric energy density. Herein, we prepared micron-sized hierarchical fibrous bundle that is composed of C@Sn@C nanofibers with close-packing arrangement. The C@Sn@C primary nanofiber provided efficient structural accommodation to the huge volumetric change, showing high cycling stability with large gravimetric energy density. The close-packing of constituent C@Sn@C nanofibers minimizes the voids and porosity of formed micron-sized fibrous bundle, exhibiting an extremely high tap density of 1.31 g cm −3 , superior to the sandwiched CNTs@Sn@C nanofiber (0.53 g cm −3 ) and MicroC@Sn@C microfiber (0.94 g cm −3 ) without close-packing arrangement. At the current density of 0.5 A g −1 , the gravimetric energy density of C@Sn@C nanofiber bundle still reached ∼ 580 mAh g −1 , with corresponding volumetric energy density of ∼ 760 mAh cm −3 , higher than those of CNTs@Sn@C and MicroC@Sn@C by ∼ 437 and ∼ 210 mAh cm −3 , respectively. Notably, the gravimetric energy density of C@Sn@C nanofiber bundle is superior to most transition-metal oxides, and the volumetric energy density is comparable to high-performance Si anodes. [ABSTRACT FROM AUTHOR]

Natural fiber-based foams demonstrate outstanding potential for energy-efficient building and personal protective equipment applications due to their lightweight, high porosity, and sustainability. However, the weak interfacial interaction among fibers, functional additives, and the matrix hampers effective stress dissipation, largely affecting the material performance. Herein, this paper demonstrates a facile strategy for fabricating high-performance collagen fiber-based foams by constructing efficient energy dissipation networks using tannin-modified leather collagen fibers (T-LCF) and waterborne polyurethane (WPU). Tannin acts as a coupling bridge, linking the fiber and polyurethane to create a hydrogen-bonded network, enhancing energy dissipation and imparting excellent mechanical properties. Compared to WPU foam (WPUF), the T-LCF-based foam (WPUF/T-LCF) showed 65%, 34 times, and 35% improvements in tensile strength, compressive strength, and ultimate oxygen index, respectively. This study provides new insights into the cleaner production of high-performance natural fiber-based foam composites and a new way for the high-value utilization of collagen solid waste. [Display omitted] • Innovatively produces high-performance collagen fiber foam with tannin-modified fibers and polyurethane. • Tannin acts as a bridging agent, enhancing mechanical properties and flame resistance. • Foam exhibits significant improvements in mechanical and thermal insulation behaviors. • This innovative approach contributes to the sustainable utilization of collagen solid waste. [ABSTRACT FROM AUTHOR]

Conventional methods of enhancing the creep resistance of polyvinyl chloride (PVC) often compromise its resilience. This study proposes a novel strategy to achieve a balance between creep resistance and resilience in PVC-matrix composites by incorporating epoxidised soybean oil-modified collagen fibres (MCFs). A comparative analysis of creep and recovery behaviour was conducted among MCF/PVC, pure PVC, and other conventional modified systems. Results revealed that MCF/PVC exhibited a lower total creep strain (12.82%) than pure PVC and a higher recoverable deformation (10.80%) than the other conventional modified systems. Moreover, MCF/PVC had the longest predicted creep lifetime among all the modification systems, which was 103 times longer than that of pure PVC. These improvements were attributed to the natural multidirectional and hierarchical structure of MCF, which hindered the movement of PVC chains and provided sufficient gaps for recoverable deformation. This work provides a new perspective on developing resilient creep-resistant modifications of polymers by leveraging the structural advantages of natural products. [Display omitted] • The balance between creep resistance and resilience in composites was achieved. • Collagen fibres (CFs) with a multidirectional and hierarchical structure were prepared. • MCF/PVC was successfully prepared by blending PVC with modified CF (MCF). • The mechanism of resilient creep-resistant modification of PVC was revealed. • MCF/PVC exhibited good comprehensive performance and promising application prospects. [ABSTRACT FROM AUTHOR]

Leather shavings are generated as solid waste in the leather industry and may cause environmental pollution if not disposed judiciously. These solid wastes, primarily composed of collagen fibers (CFs), can be recycled as biomass composites. However, CFs are incompatible with natural rubber (NR) due to its hydrophilicity. Conventionally, the compatibility has been improved by utilizing silane coupling agents (SCAs) along with a large number of organic solvents, which further contribute to environmental pollution. In this study, we developed a novel complex coupling agent (CCA) to enhance the compatibility between CF and NR. The CCA was synthesized through a coordination reaction between Cr(III) and α-methacrylic acid (MAA). Cr(III) in the coupling agent coordinates with the active groups in CFs, while the unsaturated double bonds in MAA facilitate covalent crosslinking between the CCA and NR, improving compatibility. The coordination bonding between CF and NR exhibits strong interfacial interaction, endowing the composites with desirable mechanical properties. Moreover, the proposed method is an economical and green approach that can be used to synthesize CF-based composites without requiring organic solvents. Herein, a strategy promoted sustainable development in the leather industry has been established. [Display omitted] • Collagen fiber and natural rubber were blended to prepare the biomass composite. • A complex coupling agent named CCA was synthesized and added into the composite. • The compatibility between collagen fiber and natural rubber was improved by CCA. • The reinforcing mechanism of CCA in the biomass composite was determined. • A promising strategy for solid waste recycling in leather industry was established. [ABSTRACT FROM AUTHOR]

Producing metal-free leather is an effective approach to eliminate Cr pollution and achieve sustainable development of the leather industry. However, the high water sorption of the metal-free leather and the mismatching of the charge properties between the metal-free tanned leather and anionic post-tanning chemicals result in the unsatisfactory properties of the leather products, thereby restricting the industrial application of metal-free tanning technologies. Herein, a series of cationic amphiphilic acrylic copolymers (PSD) with different molar ratios of hydrophobic monomer to cationic hydrophilic monomer were synthesized and applied in the retanning of a metal-free tanned leather. PSD can effectively penetrate to the hierarchy of collagen fibril of leather and firmly bind to collagen carboxyls to form a thin hydrophobic coating on the fibril surface due to their small particle size (< 70 nm), excellent surface activity and cationic amine groups (3–27 μmol/g). Molecular dynamics (MD) simulations confirm that the primary driving force between PSD and collagen is electrostatic interaction. MD simulations and water resistance tests demonstrate that the amphiphilic PSD provides the metal-free leather with moderate hydrophobicity, which indicates the upgrade of the comprehensive properties of leather. PSD retanning enhances the uptake rate of anionic dyes and fatliquors (> 90 %) and endows the metal-free leather with excellent filling effect and bright color. The molar ratio of hydrophilic monomer and hydrophobic monomer plays an important role in the performance of PSD. The hydrophobic segments contribute to the hydrophobicity enhancement of leather, and the cationic hydrophilic segments in PSD contribute to the charge regulation of leather and robust binding of post-tanning chemicals. Hence, the multifunctional PSD retanning agents can fulfill the demands for versatile metal-free leather types and promise to boost the sustainable development of the leather industry. [Display omitted] • Multifunctional cationic amphiphilic acrylic copolymer (PSD) was synthesized. • The primary driving force between PSD and collagen is electrostatic interaction. • PSD coating on fibrils improves the hydrophobicity of metal-free leather. • PSD shows robust binding and excellent filling performance on metal-free leather. • PSD retanning endows metal-free leather with vibrant color. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrophobic collagen fiber (HCF) with alkyl chains was successfully prepared. • The hydrogen bond interaction between HCF and catechins was largely weakened. • The recovery rates of catechins from HCF column were significantly improved. • The separation of HCF to caffeine and catechins was superior to Sephadex LH-20. Previous research had proved that collagen fiber can be used as separation material for removing caffeine from tea polyphenol extract effectively. But the recovery rate of catechin compounds from collagen fiber column was quite low by using water and ethanol as eluent because of excessively strong hydrogen bond interaction between collagen fiber and polyphenols. To solve the problem, collagen fiber was hydrophobically modified in this work by using silane coupling agents with alkyl chains (butyl, octyl, dodecyl and octadecyl). FT-IR, DSC, SEM and EDS Mapping proved the successful grafting of alkyl chains on collagen fiber, leading to the significantly enhanced hydrophobicity of collagen fiber. Static adsorption showed that the adsorption capacity of EGCG decreased when the grafted alkyl chain length increased mainly relying on the weakened hydrogen bond interaction. Dynamic adsorption and elution behavior also indicated less retention capacity of EGCG on collagen fiber with higher hydrophobicity. In column separation of simulated tea polyphenol extract containing caffeine and catechin compounds, the collagen fiber grafted with octadecyls (CF(C18)) presented excellent separation efficiency for caffeine and catechin compounds, and simultaneously the catechin compounds were highly recovered. The recovery rates of EGC and EGCG were 2–7 times higher than those separated by pristine collagen fiber column and glutaradehyde crosslinked collagen fiber column developed in our previous work. In the reusing round of CF(C18) column, the chromatogram was almost the same as the first round, showing excellent reusability. In fact, the separation performance of CF(C18) to caffeine and catechin compounds was comprehensively superior to Sephadex LH-20, presenting great practical application potential in effectively removing caffeine from tea polyphenol extract and recovering catechin compounds. [ABSTRACT FROM AUTHOR]

The removal and separate recovery of radioactive Cs+ and Sr2+ remains a challenge for the sustainable development of nuclear energy. A novel adsorbent (ZMPP-CFs) was prepared by in-situ synthesis of zirconium molybdopyrophosphate on collagen fibers to co-adsorb and recover Cs+ and Sr2+ from radioactive wastewater with good thermal stability and radiation resistance stability. ZMPP-CFs showed high adsorption capacities of 1.125 mmol g−1 for Cs+ and 0.445 mmol g−1 for Sr2+ in a wide pH range of 4–11. Furthermore, ZMPP-CFs column exhibited excellent simultaneous removal of Cs+ and Sr2+ with efficiency over 95%, followed by their perfect separation through gradient elution. Significantly, after four cycles of adsorption-desorption-regeneration experiments, ZMPP-CFs column still maintained superior removal rates and excellent separation performance, indicating high application potential. This work provides an effective method for the removal and recovery of radionuclides, which not only purifies nuclear wastewater, realizes the separation and recovery of Cs+ and Sr2+ for resource utilization, but also develops the application of renewable biomass of collagen fibers to reduce waste accumulation in various aspects. [Display omitted] • Removal and separative recovery of radioactive 137Cs and 90Sr remain a challenge. • ZMPP-CFs were prepared by immobilizing zirconyl molybdopyrophosphate on CFs. • ZMPP-CFs column could efficiently co-sorb and perfectly separate Cs+ and Sr2+. • ZMPP-CFs column had good reusability always maintaining a removal rate of over 93%. • ZMPP-CFs facilitate the recycling of radionuclides and reduce waste accumulation. [ABSTRACT FROM AUTHOR]

This study explored the possible application of collagen hydrolysate (CH) in the fermentation process using Bacillus pumilus as probe bacterial strain. When CH acted as an only source of carbon and nitrogen in the culture medium, B. pumilus was observed to show normal characterizations during its growing process. Meanwhile, the utilization degree of CH by B. pumilus could be enhanced when wheat bran was added (used as carbon source) in the fermentation process. It was found that the highest alkaline protease activity was 325 U/mL when only CH was used, while it was increased to 620 U/mL with the addition of wheat bran. Besides, with different combination of soybean meal and CH, it was found that the ability using CH to produce alkaline protease is comparable to that of soybean meal in the presence of wheat bran. Moreover, the growth behaviors of the strain were not affected by inoculation concentrations, but the time of producing alkaline protease was greatly saved as reducing loading volume. Present investigation suggested that CH can be used as carbon and nitrogen sources in the fermentation process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel absorbent PBA-CFs were fabricated by anchoring Prussian blue analog on CFs. • PBA-CFs showed high thermal stability and excellent radiation tolerance. • PBA-CFs displayed low pH sensitivity, high rate, and selectivity for Cs+ removal. • PBA-CFs could efficiently adsorb Cs+ from various actual water environments. • PBA-CFs were suitable for continuous column adsorption and easily regenerated. Removing radioactive cesium from wastewaters is necessary for sustainable development of nuclear energy. In this study, a novel adsorbent (PBA-CFs) was successfully fabricated by securely anchoring Prussian blue analog on porous collagen fibers (CFs) crosslinked with Zr4+. PBA-CFs showed low pH sensitivity and high adsorption capacity (q e) for cesium, with an optimal adsorption pH range of 2–10 and a maximum of 1.32 mmol g−1. The novel adsorbent also displayed high selectivity for Cs+ in the presence of competing ions (K+, Na+, Ca2+, Mg2+, Sr2+, or Co2+). They could effectively remove above 98 % Cs+ from tap water, lake water, and mineral water and more than 75 % of Cs+ in seawater at the Cs+ concentration of 10–60 mg/L. The adsorption process could rapidly reach equilibrium within 30 min and satisfy the pseudo-second-order kinetics model. Adsorption thermodynamics further indicated the process was exothermic, feasible, and spontaneous. Significantly, PBA-CFs exhibited superior adsorption performance in the continuous column process, with q o of 1.53 mmol g−1. One gram of PBA-CFs could effectively treat 4.03 L (666 BV) of water at a flow rate of 0.3 mL min−1, with a removal rate beyond 95 %, superior to other common adsorbents. Moreover, 0.1 mol/L NH 4 Cl solution with pH 2 could rapidly regenerate the saturated PBA-CF column. PBA-CFs demonstrated notable irradiation stability after exposure to 10–350 kGy of 60Co γ-ray. These results demonstrate PBA-CFs are a highly effective and promising adsorbent for the removal of radioactive 137Cs from wastewater. This work not only provides a feasible method for Cs+ removal to facilitate the environmental protection and sustainable development of nuclear energy but also extends the effective application and circular development of CFs as a reproducible biomass resource. [ABSTRACT FROM AUTHOR]

[Display omitted] • The AO-CF adsorbent is fabricated via in situ oxidative grafting. • The AO-CF is capable of selectively adsorbing uranium with exceptional capacity. • COOH and/or –NH 2 groups in CF participate in the interaction of UO 2 2+ with AO groups. • AO-CF could be used for selective enrichment of radionuclides at low content in wastewater. The development of an amidoxime (AO)-based biomass adsorbent offers a solution for uranium extraction from radioactive wastewater and seawater. It also provides a strategy for realizing environmental safety and resource sustainability. Here, an AO-based collagen fiber (CF) adsorbent (AO-CF) was fabricated via in situ oxidative grafting. The fibrous morphology enables AO-CF to realize faster adsorption rate and higher adsorption capacity. During batch adsorption, the adsorption capacity of AO-CF was 0.877 mmol g−1 (234.16 mg g−1) at 318 K and pH 5.0 when the initial concentration of UO 2 2+ was 2.5 mmol/L, while the adsorption capacity of AO-CF at pH 8.2 was 1.128 mmol g−1 (301.18 mg g−1). Moreover, AO-CF exhibited high selectivity for UO 2 2+ in bilateral mixed solutions, including NH 4 +, Zn2+, Cr3+, Mg2+, Al3+, Ca2+, Ni2+, Ba2+, and Sr2+. Furthermore, AO-CF demonstrated higher adsorption capacity of UO 2 2+ than its major competing element, namely, VO2+, in seawater. The adsorption behavior of UO 2 2+ in the nuclear fuel preparation wastewater on the AO-CF column showed that the breakthrough point was approximately 175.0 bed volume (BV), and the AO-CF column could be rapidly regenerated by using only 3.0 BV of 0.1 mol/L HCl solution, indicating excellent reapplication ability. This work presents a new technology for the synthesis of highly efficient adsorbents for the recovery of UO 2 2+ from radioactive wastewater. [ABSTRACT FROM AUTHOR]

A series of collagen hydrolysate-basedsurfactants (CHBS) wereprepared by grafting different amount of oleoyl group onto collagenhydrolysate (CH). Their physicochemical properties and surface activitieswere investigated, and their emulsifying ability on rapeseed oil–wateremulsion was evaluated. The results showed that, as increasing graftingdegree of oleoyl group, the free amino content and isoelectric pointof CHBSs and the size of CHBS particles formed in aqueous solutiondeclined, while their molecular weight and surface hydrophobicityincreased. The CHBSs with high grafting degree, such as CHBS-30, CHBS-40,and CHBS-50 (postfix datum represents mmol amount of oleic acid chlorideto react with 10 g collagen hydrolysate), exhibited satisfactory wettingcapacity and foaming capacity, and the CHBSs with low grafting degree,such as CHBS-10 and CHBS-20, presented good emulsifying capacity.The surface activity of CHBSs was closely correlated with the hydrophobicityof their molecules, as well as their capacity to reduce the surfacetension of air–water interface. In addition, CHBS-20 showedgood emulsifying ability on rapeseed oil–water emulsion inneutral and alkaline pH, even in the condition of low salt concentration. [ABSTRACT FROM AUTHOR]

The separation of baicalein and baicalin, two major flavonoidsin Scutellaria, by using collagen fiber adsorbent(CFA), was investigated. Static adsorption and adsorption kineticsindicated that baicalin had stronger hydrogen-bond interaction withCFA in high ethanol concentration solution, while baicalein presentedstronger hydrophobic interaction with CFA in low ethanol concentrationsolution. In CFA column chromatography separation, baicalein and baicalincould be well separated by stepwise elution of 90% and 70% aqueousethanol solutions, and their recoveries were 83.42% and 94.31%, respectively.The maximum loading mass for separating baicalein and baicalin ona CFA column was higher than 90 mg/g CFA, which is much more thanthe loading mass on a D101 macroporous resin column. Applicationsrepeated 10 times indicated that the CFA column has satisfactory reusability.Furthermore, the separation of baicalein and baicalin from Scutellariaextracts using CFA was investigated. The purityof baicalein and baicalin obtained was both higher than 98%. [ABSTRACT FROM AUTHOR]