In this study, MnPc intercalated Zn/Fe layered double hydroxides (MnPc/ZF-LDH) were synthesized by pillared in- tercalation modification with different MnPc intercalation amounts and used for the selective transformation and re- moval of As(III) from the arsenate-phosphate mixed solution. Fe-N bonds were constructed by the complexation of MnPc and iron ions on the Zn/Fe layered double hydroxides (ZF-LDH) interface. The DFT calculation results show that the binding energy of Fe-N bonded to arsenite (-3.75 eV) was higher than that of phosphate (-3.16 eV), result- ing in MnPc/ZnFe-LDH exhibiting high As(III) selective adsorption performance and anchoring it rapidly in the arse- nite-phosphate mixed solution. The maximum adsorption capacity of 1MnPc/ZF-LDH for As(III) could reach 180.7 mg & BULL;g-1 under dark conditions. MnPc also acts as a photosensitizer to provide more active species for the photo - catalytic reaction. A series of experiments demonstrated that MnPc/ZF-LDH exhibits high As(III) selective photocat- alytic performance. A total of 10 mg & BULL;L-1 of As(III) was completely removed in the reaction system within 50 min in a single As(III) environment. In an environment with As(III) and PO43-, it achieved 80.0 % removal efficiency of As(III) and showed a good reuse effect. The introduction of MnPc could improve the utilization of visible light by the MnPc/ ZnFe-LDH. The singlet oxygen generated from photoexciting MnPc leads to abundant ZnFe-LDH interface & BULL;OH. In addition, MnPc/ZnFe-LDH shows good recyclability, making it a promising multifunctional material for the purifica- tion of arsenic-polluted sewage.

The photocatalytic oxidation technology has been verified as an effective method to oxidize As(III) to As(V) with low toxicity and the photocatalyst with perfect performances is still the core factor in the treatment procedure. In this paper, a high property photocatalyst of Sn/N co-doping TiO2 (Sn/N-TiO2) has been synthesized and applied to the photocatalytic oxidation of As(III). Through a series of characterization methods, it is proved that Sn and N atoms have been effectively doped into the crystal structure of TiO2, which makes the optical absorption wavelength of TiO2 extend from ultraviolet light to visible light region. At the same time, the presence of O-Ti-N bonds can offer an efficient electron moving path and further improve the photogenerated electron transfer rate, so as to enhance the photocatalytic oxidation effect. The synthesized Sn/N-TiO2 photocatalyst only takes 21 min to realize complete oxidation of As(III) (10,000 mu g/L, 40 mL) to As(V) under visible light, superior to N-doped TiO2 (27 min) and Sn doped TiO2 (24 min) photocatalysts. The achievements of such efficient photocatalytic oxidation performances result from the synergistic interaction of hydroxyl radicals (center dot OH), superoxide radical (center dot O-2(-)), and hole (h(+)) formed in the photocatalytic oxidation process and the O-Ti-N bond formed by co-doping. This paper provides a new insight for solving arsenic pollution by photocatalytic oxidation technology.y

The interaction process between phosphorus and arsenic is of great significance for controlling arsenic pollution by iron oxide minerals. In this work, the alpha-FeOOH@hydrothermal carbonisation (HTC) composites with abundant oxygen vacancy were synthesized by a hydrothermal method using HTC as a carrier and were used for the removal of arsenic in different phosphate environments. The surface hydroxyls (OHs) in alpha-FeOOH promote the production of OVs on the surface of the composite and improve the adsorption capacity of As(III). The experiment results showed that the maximum adsorption capacity of alpha-FeOOH@HTC on As(III) under the influence of PO43-, HPO42-, and H2PO4- were 8.76 mg center dot g(-1), 10.67 mg center dot g(-1) and 10.21 mg center dot g(-1), respectively. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis showed that after adsorption, a characteristic peak of As(III) was generated on the FeOOH@HTC surface. The possible adsorption mechanism for As (III) by alpha-FeOOH@HTC is the surface complexation and precipitation of M-OH as well as Fe-OH-Fe with As (III). After the application of composite materials in rice seedling hydroponic experiments, it was found that they have a certain degree of biological safety, providing a theoretical basis for reducing arsenic pollution. This work studies the adsorption behavior of OVs on As(III) and provides a new approach to address arsenic contamination in water.

The reutilization of exhausted biochar is attracting extensive interest among researchers. In this study, the biochar generated from Chinese fir with natural regular porous structure that adsorbed Cd2+/Ni2+ at different concentration levels was used as the precursor, and then combined with simple hydrothermal vulcanization and ion deposition to generate the p-n heterojunction between NiS and CdS compounds (NiS-CdS@C) in situ. The hybrids with 3 cycles of NiS deposition reduced the interfacial transmission resistance from 80 Ω to 40 Ω, and increased photocurrent density by 5 times, thus effectively promoting the separation of photogenerated electrons and holes. The simultaneous removal of As(III) and Cr(VI) was selected to evaluate the oxidation and reduction capacity of the visible light/NiS-CdS@C/oxalate system. The results indicated that 10 mg/L As(III) and Cr(VI) were completely and simultaneously removed with 0.75 mM oxalate addition within 40 min in the system, and the NiS-CdS@C presented good durability and stability for oxalate activation. Electron paramagnetic resonance (EPR) and quenching experiments demonstrated that oxalate was activated by holes under light to produce •CO2- and enhanced the generation of additional •OH and •O2-, further contributing to the oxidation of As(III) and reduction of Cr(VI).

In this study, a carbonized aerogel (CA) decorated with Mn-FeOOH hybrid nanoparticles was prepared and has been used as a better heterogeneous photo-Fenton catalyst. Mn doping accelerated the regeneration of Fe2+ and promoted the decomposition of H(2)O(2 )while producing many hydroxyl radicals (.OH), which solved the mass transfer problem in the traditional heterogeneous Fenton system. The amount of.OH in the Mn-FeOOH@CA/H2O2 system within 40 min was 2.4 times higher than that in the FeOOH@CA/H(2)O(2 )system, which further indicates that.OH was the main active species. High-porosity CA has been designed as an electron transport channel. During photocatalysis, electron transfer occurred between the Mn-FeOOH composite material and CA. The Fe2+ could be used as reaction sites to promote the activation of H(2)O(2 )on the surface of 1-Mn/FeOOH, and achieved 100 % As(III) degradation efficiency within 25 min. The catalyst maintained more than 80 % of its original oxidation capacity after five cycles of experiments, which indicates that it has good durability. This work is expected to provide rational design of heterometallic doped materials with oxygen vacancies to treat arsenic pollution.

The treatment of arsenite pollution in water has always been concerned. Oxidation of high toxic As(III) to relatively low toxic As(V) by efficient photocatalytic oxidation technology is a research hotspot. This paper is focused on the active photocatalyst of TiO2 @Fe3O4 composites synthesized by a simple hydrothermal method for the efficient photocatalytic oxidation of As(III). The successful construction of Ti-O-Fe interface bonds be-tween TiO2 and Fe3O4 significantly promoted the transfer efficiency of photo-generated carriers, and further rapidly improved the photocatalytic oxidation efficiency of As(III). The application results showed that the constructed TiO2 @Fe3O4 photocatalyst with 0.10 g Fe3O4 (TF-0.10) could complete the transformation from As (III) (10,000 mu g/L) to As(V) within 4 min with a high oxidation ratio of 100% and maintained the good properties with unchanged crystal structure after five cycles. Furthermore, the photocatalytic properties of TiO2 @Fe3O4 composites were still stable under different pH values. Electron paramagnetic resonance (EPR) consequence displayed that the superoxide radical (center dot O-2(-)) and hole (h(+)) were the main intermediate product in the arsenic photocatalytic oxidation system, and hydroxyl radical (center dot OH) had little effect on this oxidation system. The possible mechanism of As(III) photocatalytic conversion was further explored based on the results of the data analysis. Furthermore, this work provides a potential new idea for the practicability of efficient photocatalytic arsenic oxidation.

In this study, CdSe cluster-modified biogenic alpha-FeOOH based on macroporous biochar was constructed from rhizosphere iron plaque via pyrolysis. An ultrahigh H2O2 production rate of 655.75 mu mol/L was achieved by the photocatalysis-self-Fenton system within 30 min under visible light irradiation. alpha-FeOOH, with abundant iron ions, can directly activate H2O2 to produce abundant .OH radicals. It was found that As(III) (10 mg/L) could be completely degraded within 20 min. Electron spin resonance spectroscopy (ESR) and density functional theory (DFT) revealed that a suitable energy band structure was achieved by the introduction of CdSe clusters; thus, O-2 was mainly reduced to H2O2 through a two-electron reduction route in the reaction system. The photogenerated electrons promoted the conversion of Fe(III)/Fe(II) by reacting with Fe(III) in alpha-FeOOH. The presence of H2O2 and Fe2+ in this system accelerates the oxidation of As(III) by a Fenton-like reaction.

In this study, a matrix composite material of CdZnS and alpha-FeOOH on carbon cloth (CZS@FeOOH@CC) was prepared by a hydrothermal method, and was used for the degradation of As(III). The composite material has good photocatalytic activity of removing As(III) in the presence of oxalate. CZS@FeOOH@CC can completely degrade 10 mg/L As(III) within 10 min under visible light irradiation. The influence factors of CZS@ FeOOH@CC composite material on catalytic oxidation of As(III) were also studied in the oxalate system. The photocatalytic oxidation efficiency of As(III) is affected by the oxalate concentration in the reaction system, and the atmosphere plays a major role in the degradation of As(III). Under visible light, oxalate first combines with Fe(III) on the surface of iron oxide to form Fe(III)-oxalate complex, and then the Fe(III)oxalate composite is activated to producemiddotC2O4-. In the presence of oxygen, Fe(II) readily reacts with O2 and oxidizes to Fe(III). The introduction of CdZnS promoted the separation of interfacial electron holes, and accelerated the REDOX cycle of Fe(II)/Fe(III). This study provides a feasible and simple method for accelerating the catalytic removal of heavy metals from wastewater by iron-based materials.(c) 2022 Published by Elsevier B.V.

In this study, iron selenide (FeSe2) and ferric oxide (Fe2O3) were constructed through a hydrothermal method on macroporous biochar for enhancing H2O2 adsorption. The mechanism of FeSe2-10/Fe2O3@C adsorption H2O2 to produce hydroxyl radicals (center dot OH) has been explored by density functional theory (DFT) and electron paramagnetic resonance (EPR). Se2- provided electrons for Fe3+ and converted Fe3+ into Fe2+, resulting in the formation of Se vacancies (SVs) on the surface of the original FeSe2 and providing more active sites for H2O2 adsorption. The Bader charge calculations show that the supplied charge for the decomposition of H2O2 is mainly provided by the Fe atom. The whole decomposition of H2O2 reduces the total energy of the system by 0.552 eV. The length of the O-O bond in H2O2 after adsorption on SVs is 0.08 angstrom longer than before. The results of experiments show that As (III) (10 mg/L) was found to be completely degraded within 100 min in the Fenton reaction. The catalyst still maintained 91% degradation rate after 5 cycles and the crystal plane of the catalyst has no changed. This study proposes a kind of theory about H2O2 adsorption by SVs that can be expected to the degradation of As(III) in the environment.

This study investigated the Fenton-like oxidation of As(III) by three types of iron oxides in oxalate systems. The effects of pH, oxalate concentration and atmosphere on the oxidation of As(III) by iron oxide photocatalyst were studied. Firstly, hydrothermal carbon (HTC) was used as the carrier to load three kinds of iron oxides to prepare new composite materials, including alpha-FeOOH, alpha-Fe2O3 and Fe3O4, which can solve the dispersion problem of iron oxide by using a large number of rich functional groups on the HTC surface. The experiment results showed that under the conditions of O-2, pH = 5.0 and oxalate concentration of 0.5 mmol.L-1, As(III) was completely oxidized by alpha-FeOOH and alpha-Fe(2)O(3 )at 15 min and 20 min, respectively. Density functional theory (DFT) was used to study the surface adsorption energy of iron oxide and oxalate. The calculated results showed that the order of adsorption energy of three iron oxides for the oxalate is alpha-FeOOH > alpha-Fe2O3 > Fe3O4. FeIII(C2O4)(+), a mononuclear bidentate iron oxalate chelate with the strongest photosensitivity, was constructed in the Fe -Oxalate system containing only Fe(III), resulting in the photocatalytic efficiency of alpha-FeOOH and alpha-Fe(2)O(3 )was superior to that of Fe3O4. These findings contribute to arsenic remediation of water bodies by using iron materials and oxalate in the natural environment.

Ethanol has been widely used as a clean fuel, solvent, and hydrogen carrier. Currently, ethanol is generally produced through fermentation of starch- and sugarcane-derived sugars (e.g., glucose and sucrose) or ethylene hydration. Its production from abundant and inexpensive lignocellulosic biomass would facilitate the development of green and sustainable society. Biomass-derived carbohydrates and syngas can serve as important feedstocks for ethanol synthesis via biological and chemical pathways. Nevertheless, the biological pathway for producing ethanol through biomass-derived glucose fermentation has the disadvantages of long production period and carbon loss. These issues can be effectively mitigated by chemocatalytic methods, which can readily convert biomass to ethanol in high yields and high atomic efficiency. In this article, we review the recent advances in chemocatalytic conversion of lignocellulosic biomass to ethanol, with a focus on analyzing the mechanism of chemocatalytic pathways and discussing the issues related to these methods. We hope this mini-review can provide new insights into the development of direct ethanol synthesis from renewable lignocellulosic biomass.

Because of poor water solubility and low thermostability, the application of collagen is limited seriously in fields such as injectable biomaterials and cosmetics. In order to overcome the two drawbacks simultaneously, a novel bifunctional modifier based on the esterification of polyacrylic acid (PAA) with N-hydroxysuccinimide (NHS) was prepared. The esterification degree of PAA-NHS esters was increased upon increasing the NHS dose, which was confirmed by Fourier-transform infrared (FTIR) and nuclear magnetic resonance spectrascopy. FTIR results indicated that the triple helix of the modified collagens remained integrated, whereas the molecular weight became larger, as reflected by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern. The modified collagens displayed excellent water solubility under neutral condition, owing to lower isoelectric point (3.1-4.3) than that of native collagen (7.1). Meanwhile, denaturation temperatures of the modified collagens were increased by 4.8-5.9 °C after modification. The modified collagen displayed hierarchical microstructures, as reflected by field-emission scanning electron microscopy, while atomic force microscopy further revealed a "fishing net-like" network in the nanoscale, reflecting a unique aggregation behavior of collagen macromolecules after modification. As a whole, the PAA-NHS ester as a bifunctional modifier endowed collagen with desired water solubility and thermostability in a conflict-free manner, which was beneficial to the process and application of the water-soluble collagen.

随着胶原/纤维素及其衍生物复合技术进步,其复合体系在各种领域的研究和应用取得了较大的进展.综述了胶原/纤维素及其衍生物复合体系的研究现状,讨论了其在组织工程支架、止血及伤口愈合、水处理材料等领域的应用,针对胶原/纤维素及其衍生物复合体系存在的问题及其未来的发展方向进行了探讨与展望.

It is difficult to prepare homogeneous concentrated collagen with concentration >40 mg/mL due to its extremely high viscosity. Herein, cooled (-12 degrees C) urea/HAc solutions was employed as novel solvent to prepare collagen samples with concentrations varied from 40 to 120 mg/mL Fourier transform infrared spectroscopy and sodium dodecyl sulfonate-polyacrylamide gel electrophoresis demonstrated that the concentrated collagen maintained the intact triple-helical structure. As reflected by differential scanning calorimetry, collagen with acetic acid as solvent displayed two thermal transition peaks when concentration >= 60 mg/mL., which could be attributed to the denaturation of dissolved collagen and un-dissolved collagen. Whereas, collagen prepared in cooled urea/HAc just exhibited one thermal denaturation peak other than samples with concentration >= 100 mg/mL Images from polarizing optical microscopy displayed that the cholesteric band grew more pronounced upon increasing collagen concentration. Field-emission scanning electron microscopy exhibited more aligned topographical features of the collagen sponges when increasing concentration from 10 to 100 mg/mL, nevertheless both of the aligned structure and anomalous structure could be captured when collagen concentration further reached 120 mg/mL Rheological properties were found to be dependent on the collagen concentration, additionally, compared with collagen in acetic acid, a weaker entanglement network and lower viscosity for collagen with the same concentration using cooled urea/HAc as solvent could be reflected by the rheological measurements. Overall, this method presents a simple mean for generating homogeneous concentrated collagens, which can be applied to wider fields such as wet spin and biomimetic mineralization. (C) 2019 Elsevier B.V. All rights reserved.

The rheological behaviors of a polyanionic collagen, fabricated using poly(γ‐glutamic acid)‐N‐hydroxysuccinimide (γ‐PGA‐NHS) as a novel modifier, were investigated in this study. It was found that both of the native and modified collagen solutions were pseudoplastic fluids, as shown from the steady‐shear tests. While the storage modulus and loss modulus of collagen increased with increasing the amount of γ‐PGA‐NHS, or with increasing the degree of esterification of γ‐PGA‐NHS; meanwhile, the dynamic denaturation temperature determined by dynamic temperature sweep was also increased, indicating an improved thermal stability of collagen solution modified by γ‐PGA‐NHS. The creep–recovery measurements showed that the resistance to deformation was enhanced for modified collagen, probably due to the cross‐linking occurred between the ε‐amino groups of collagen molecules and α‐COOH groups of γ‐PGA‐NHS, as well as the electrostatic interaction and hydrogen‐bond interactions between the two molecules. Furthermore, the aggregation of collagen fibers was promoted due to these interactions between collagen and γ‐PGA‐NHS as observed by atomic force morphology. In addition, the modified collagen exhibited good cytocompatibility as demonstrated by cell growth culturing. The obtained information was expected to give valuable clues to the design and fabrication of controlled stable collagen‐based products for applications in various biomedical fields.

Hyaluronic acid (HA) is a natural polysaccharide possesses outstanding physiological activities. In this work, HA was activated as a novel collagen modifier via the esterification reaction between N-hydroxysuccinimide (NHS) and the carboxyl groups of HA. Both of Fourier transform infrared spectroscopy (FTIR) and 1H- nuclear magnetic resonance (NMR) spectra indicated the successful synthesis of HA-NHS esters. As reflected by FTIR, circular dichroism (CD) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), collagens modified with HA-NHS ester maintained its intact triplex structure with larger molecular weight. The resultant polyanionic collagen displayed an excellent dissolubility in the neutral water to form a clear solution, due to the significantly lower isoelectric point values (3.8-4.4) compared with that of the native collagen (7.1). In addition, the thermal transition temperature of collagen was significantly increased (16 °C) after modifying with HA-NHS esters. Both of the aggregation morphology and rheological property exhibited high dependence on the NHS/COOH ratio of HA-NHS esters, as reflected by field-emission scanning electron microscopy (FESEM) and rheological test, respectively. The present study offered a novel dual-functional modifier based on the design of HA-NHS ester to obtain water-soluble collagen with desired thermal stability and rheological property, which will significantly widen the application range of collagen, especially in the fields of injectable biodegradable materials and cosmetics.

Native collagen cannot be dissolved in neutral pH buffer, limiting its application in many fields. The traditional method to prepare water-soluble collagen is succinylation modification, which causes the decrease in the thermal stability. Therefore, poly(γ-glutamic acid)-N-hydroxysuccinimide (γ-PGA-NHS) esters were used as a novel modifying agent of collagen. FTIR results indicated the intact retention of native triple-helix structure after modification. Isoelectric point of the modified collagens shifted continuously to lower values with increasing the γ-PGA-NHS/collagen ratios (w/w). Consequently, the modified collagen can form a clear solution in neutral pH buffer. Furthermore, the denaturation temperature (Td) of the modified collagens reached 44.8–49.9°C, which were 6.0–11.1°C higher than that of native collagen. However, it should be noted that gelation occurred when modifier/collagen ratio (w/w)=50% as γ-PGA-NHS with a relatively high esterification degree was used. As a whole, these results indicated that dual-functional modification in regards to both of water solubility and thermal stability on collagen can be achieved using γ-PGA-NHS esters with a relatively low esterification degree. In addition, the proliferation of fibroblasts could be promoted as reflected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and 4′,6-diamidino-2-phenylindole (DAPI) method, suggesting the excellent cytocompatibility of the modified collagens. The present study provided useful information to the design of novel water-soluble collagen, which could be applied in the fields including biomaterials, cosmetics etc.

A hydrophilic bamboo cellulose nanofiltration membrane (IP-NF-BCM) was prepared through interfacial polymerization (IP) of amino-functional piperazine (PIP) and 1,3,5-trimesoyl chloride (TMC) on a cellulose surface. The in situ formation of polyamide into the mesoporous structure of the regenerated cellulose film created a uniform microporous membrane, which can be used for water softening by nanofiltration. The interfacial polymerization reaction conditions were optimized in terms of the performance of resultant nanofiltration membranes. The chemical structure, morphology, and surface charge of the composite membranes were characterized based on thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), nuclear magnetic resonance (NMR), and Brunauer-Emmett-Teller (BET) nitrogen absorption. The water permeation and salt rejection capability of the bamboo cellulose thin-film-composite nanofiltration membranes were evaluated using 500 ppm salt solutions at 0.5 MPa pressure. Results show that the rejection rate for NaCl reached 40% and water flux reached 15.64 L/(m(2).h). The average pore size of the bamboo cellulose thin-film-composite membranes was 1.0 nm.

The poly(γ-glutamic acid)-NHS (γ-PGA-NHS) esters were used to endow collagen with both of excellent water-solubility and thermal stability via cross-linking reaction between γ-PGA-NHS and collagen. In the present work, the effect of γ-PGA-NHS on the aggregation of collagen molecules was studied by fluorescence techniques. The fluorescence emission spectra of pyrene in collagen solutions and the intrinsic fluorescence emission spectra of collagen suggested different effects of γ-PGA-NHS on collagen molecules: inhibiting aggregation below critical aggregation concentration (CAC) and promoting aggregation above CAC. The two-dimensional (2D) fluorescence correlation spectra indicated that the intermolecular hydrogen bonding and cross-linking between γ-PGA-NHS and collagen would influence the aggregation of collagen molecules. By the ultra-sensitive differential scanning calorimeter (VP-DSC), it was found that the main denaturational transition temperature (Tm2) of modified collagen increased, while its calorimetric enthalpy changes (ΔH2) decreased compared to those of native collagen, further indicating that the modification of γ-PGA-NHS influenced the aggregation of collagen molecules. The study provide useful information for the utilizing and or the processing of water-soluble collagen in aqueous solution in the fields such as cosmetics, health care products, tissue engineering and biomedical materials, etc.

Regenerated leather billet (semi-finished product) was prepared via hot pressing with chrome shaving and environment-friendly polymer waterborne polyurethanes (WPU) as the materials. The influence of WPU/chrome shaving ratios (w/w) on the performance of the billet was investigated by mechanical property test, dynamic thermal mechanical analysis, thermogravimetric analysis, differential scanning calorimetry and field-emission scanning electron microscopy. Furthermore, the ability of heat storage and temperature regulation was endowed for the regenerated leather by the addition of paraffin micro capsules. The results showed that a strong interface interaction could be achieved for the regenerated leather billet, which could be due to the formation of hydrogen bonds and the entanglement between WPU and leather shavings. In this way, WPU/leather shaving composites with favorable mechanical properties, thermal stability, ability of heat storage and temperature regulation were obtained.