Chitosan stabilized nanoscale zero-valent iron(CS-NZVI)is a novel composite material with both reducing and adsorption ability,which can be used in the removal of metal ions and arsenates in water and the degradation of aromatic dyes.In this review,the main synthesis methods and characteristics of CS-NZVI were firstly introduced,followed by summarization on the mechanism and application research progress of CS-NZVI in treatment of heavy metal ions,arsenic ions,dye wastewater.Subsequently,the modification methods and application progress of chitosan modified CS-NZVI,metal catalyst modified CS-NZVI and composite modified CS-NZVI were reviewed.Finally,suggestions and prospects for optimizing the preparation process of CS-NZVI,broadening the application conditions and improving the material properties were put forward.
Glycosidically bound volatiles(GBVs)of fermented jujube juice was obtained by adsorption and elution with Amberlite XAD-2 resin.The release principles of GBVs was investigated via three separate treatments:β-D-glucosidase enzymolysis(38℃,48 h),acid hydrolysis(pH 1.0,40℃,4 d)and ultrasound treatment(280 W,20 min,50℃).The GBVs obtained was then identified by electronic nose and headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry(GC-MS),while the valuable aroma components were analyzed for odor activity value(OAV).The results showed that GBVs obtained from the three treatments exhibited significant difference in types and content.In number,a total of 16 aroma compounds were identified from GBVs with ultrasonic treatment,and acids were the most abundant aroma compound.A total of 21 aroma compounds,mainly including acids and other components,were identified from GBVs with acid hydrolysis,while 32 ones were identified with enzymolysis,mainly including esters,alcohols and acids.Damascenone and nonanal played a major role for the aroma of fermented jujube juice.The substances hydrolyzed by ultrasonic treatment and acid hydrolysis treatment were mainly acids of fermented jujube juice,while the esters,alcohols and aldehydes were the main aroma components with enzymolysis.Therefore,β-D-glucosidase enzymolysis treatment was more conducive to the release of many GBVs in fermented jujube juice.
Self-healing hydrogels have been widely used in electronic skin,flexible robots and wearable devices due to their excellent mechanical properties,good biocompatibility and extended material life.The structural adjustability and the diversity of conductive materials also provide the possibility for the synthesis of flexible sensors with different functions.Herein,self-healing hydrogels were classified according to the cross-linking mode,functional type,healing pattern and relative molecular mass of gelatinizer,with a detailed introduction on the formation mechanism and properties of each category self-healing hydrogels.Home and abroad research status of self-healing hydrogels in flexible sensors in terms of mechanics,photoelectricity and biology was reviewed.Finally,the existing problems and the future development directions were discussed.
In order to improve the organic matter degradation in biogas slurry and electricity production of microbial fuel cell(MFC),nano-Fe3O4 was combined with MFC via two different intervention methods by loading nano-Fe3O4 on anode carbon felt(Fe3O4@carbon felt)and loading nano-Fe3O4 on biochar(Fe3O4@biochar)into the anode chamber.The influence of these two intervention methods on the performance of MFCs were investigated.The results showed that MFC could be started by both methods,and exhibited much higher electrogeneration efficiency compared with MFC without nano-Fe3O4 intervention.The MFC treated with Fe3O4 showed maximum voltage of 699 and 707 mV,respectively,with the maximum voltage lasted up to 10 d.The maximum power density was increased by 43%in the Fe3O4@carbon felt(700 mW/m2)and 31%in the Fe3O4@biochar(578 mW/m2)in comparison to that MFC without Fe3O4 nanoparticles.The highest chemical oxygen demand(COD)degradation rate(51.76%)was obtained using Fe3O4@carbon felt as anode electrode.Direct application of Fe3O4@biochar showed the greatest effect on the degradation of NH4+-N,with degradation rate of 89.87%,the NH4+-N decreased from(6800.14±57.86)mg/L to(689.14±37.29)mg/L after the application of Fe3O4@biochar.The microbial community structure of the MFC with the participation of nano-Fe3O4 tended to be rationalized.Both participation methods stimulated the growth of the main hydrolytic bacteria(Clostridia).With the position of nano-Fe3O4 changing,the relative abundance of Clostridia in the MFC with Fe3O4@biochar directly inputting into the anode chamber and the MFC with Fe3O4@carbon felt as anode electrode reached to 61.11%and 50.98%,respectively.Both had the highest content of Betaproteobacteria in electroactivation and denitrifying bacteria Sporosarcina was found on the post-reaction carbon felt.
The number and variety of solid wastes have increased as a result of socioeconomic growth and human activity,and resourcization of solid wastes has become a hot research topic at home and abroad.There is significant room for improvement in waste resourcization in the context of dual carbon,which emphasizes the growth of the circular economy.Treatment of uranium(Ⅵ)-containing radioactive wastewater,produced by the nuclear industry with a rapid advancement of nuclear technology,with adsorbent materials made of solid waste could achieve the goal of"treating waste with waste",alleviate environmental pollution issues and facilitate sustainable development.Herein,main solid waste adsorbents,such as agricultural and forestry solid waste,industrial solid waste and municipal solid waste that can be used for uranium removal were summarized,followed by introduction on the synthesis and modification methods of solid waste adsorbents as well as uranium removal mechanism.Finally,it was pointed out that the uranium adsorption materials should be developed in the direction of high efficiency adsorption,environmental protection and high added value.
Modified biochar(PMBC+PSB)was synthesized from phosphorus solubilizing bacteria(PSB)modification of pig manure biochar(PMBC),and its performance and mechanism on U(Ⅵ)removal from water were analyzed.The samples obtained were characterized by SEM,EDS,TEM,XRD,FTIR,XPS and BET.The results showed that the biochar(PMBC+PSB24),prepared with 24 h of PMBC modification,displayed the best U(Ⅵ)removal effect.Compared with PMBC,biochar(PMBC+PSB24)exhibited significantly increased pore structure in its inner wall and an increment in the specific surface area as well as total pore volume by 88.1%and 40.8%,respectively.Under the conditions of temperature 30℃,pH 4,U(Ⅵ)initial mass concentration 10 mg/L,and dosage of PMBC+PSB24 0.02 g/L,the removal rate of U(Ⅵ)in water by PMBC+PSB24 could reach 99.46%,and the maximum adsorption capacity of PMBC+PSB24 for U(Ⅵ)in water was 533.078 mg/g,26.97%higher than that of PMBC.The adsorption process was in accordance with the Freundlich isothermal model and the proposed secondary kinetic model.Radial crystals,which were metasuranite[K(UO2)(PO4)·3H2O],were found on the surface and inside the bacterium of PMBC+PSB24.The abundance of surface functional group was higher than that of PMBC,and the main groups involved in adsorption were hydroxyl and phosphate groups.The main U(Ⅵ)removal mechanism of modified biochar was surface complexation and mineralization precipitation.After five adsorption-desorption cycles,the adsorption capacity of the modified biochar only decreased by 8.90%,showing good regeneration performance.
Highly active copper-doped manganese dioxide(Cu-MnO2)oxidase-like nanozyme(abbreviated as oxidase-like enzyme)was prepared by one-step hydrothermal method and characterized by XRD,SEM,EDS,N2 adsorption-desorption and XPS.And its catalytic performance on Rhodamine B(RhB)degradation was further investigated.The results showed that the improved catalytic activity of Cu-MnO2 was attributed to the synergistic effect of MnO2 and doped copper.RhB could be fully degraded within 30 min at 30℃under the conditions of solution pH 3.0,initial RhB mass concentration 50 mg/L,and Cu-MnO2-10%(10%is the percentage of amount of substance of CuCl2·2H2O and KMnO4)dosage 0.01 g,while the degradation rate of RhB was still maintained 75%even when the catalyst was recycled 5 times.In addition,the degradation rates of ciprofloxacin,ofloxacin,tetracycline,and hydroquinone were 88.86%,90.47%,92.62%and 90.99%,respectively.The mechanism study of RhB degradation catalyzed by Cu-MnO2 oxidase-like enzyme revealed that there were abundant holes in oxygen vacancy rich Cu-MnO2,which was beneficial for adsorbing and catalyzing dissolved oxygen to produce a large amount of singlet oxygen(1O2)and a small number of superoxide radicals(Oγ2-)and other reactive oxygen species for the rapid degradation of organic pollutants.
Polydopamine(PDA)nanosheets were prepared from in-situ liquid phase deposition of PDA onto Mg(OH)2 nanosheets.PDA nanosheets composite filter membrane(referred to as composite filter membrane)was then synthesized via coating the PDA nanosheets onto hydrophobic cotton cloth,characterized by SEM,TEM,BET,FTIR,XPS,XRD and contact angle tester,and evaluated on its separation performance for oil-water mixture and emulsified oil,recycling performance as well as anti-pollution performance.The results showed that the introduction of PDA nanosheets significantly increased the surface roughness of the composite filter membrane.The permeation fluxes of the composite filter membrane for oil-water mixture and emulsified oil driving by self-gravity(both with cyclohexane as oil phase)were 2866.24 and 1015.13 L/(m2·h),respectively,with separation efficiency of 99.5%.The permeation flux of the composite filter membrane,which was recycled 10 times,for emulsified oil was 798.11 L/(m2·h)and the separation efficiency was 98.1%.In addition,PDA nanosheets also exhibited universality and could coat onto different substrates for emulsified oil separation,showing good application prospects.
The synthesis of Ru59063 was improved.Here,intermediate 4-isothiocyanato-2-(trifluoromethyl)benzonitrile(Ⅳ)was firstly prepared from 4-amino-2-(trifluoromethyl)benzonitrile(Ⅲ)and thiophosgene,which further reacted with methyl 2-aminoisobutyrate hydrochloride via[3+2]cycloaddition to obtain 4-[2-thio-4,4-dimethyl-5-oxomidazolidine-1-yl]-2-trifluoromethylbenzonitrile(Ⅶ).Then,4-{3-[4-(tert-butyldimethylsilane)-hydroxybutyl]-4,4-dimethyl-5-oxo-2-thiomidazole-1-yl}-2-(trifluoromethyl)benzonitrile(Ⅷ)was synthesized from Ullmann C—N coupling reaction of intermediate Ⅶ and tert-butyl(4-chlorobutoxy)dimethylsilane.Finally,target product Ru59063 was obtained by hydroxy-deprotection of intermediate Ⅷ.The total yield and HPLC purity of 4-step reaction were 61.6%and 98.2%.An improvement of 4.7 times compared with conventional method.This method for Ru59063 preparation was easier and safer without use of cyanide.The total yield of Ru59063 was 60.7%in the scaled-up production using 2 kg 4-amino-2-(trifluoromethyl)benzonitrile as starting material.
A multifunctional sodium alginate(SA)crosslinked polyethyleneimine(PEI)water-based adhesive binder SAPEI with cross-linked network structure for lithium sulfide battery cathode was prepared from SA and PEI and characterized by FTIR.The adhesion and polysulfide adsorption of SAPEI binder as well as its influence on the structure and electrochemical performance of the lithium sulfur battery cathode were further investigated.The results demonstrated that the SAPEI binder displayed a stronger binding capacity than conventional commercial polyvinylidene difluoride(PVDF)binder with the amide bond produced during the reaction showing an adsorption effect on polysulfide ions.After cycling,the lithium-sulfur battery with SAPEI binder had a more consistent microstructure and improved electrochemical performance.The specific discharge capacity was still 620 mA·h/g after 200 cycles of charging and discharging at a rate of 0.2 C,and the capacity retention rate could reach 72.6%,which was higher than that of a lithium-sulfur battery with PVDF binder.
Liquorice residue was pretreated with two dilute basic solutions(Na2CO3 aqueous solution and NaOH aqueous solution)and the mixtures of the above dilute basic solution and ethanolamine acetate,respectively.The effects of different base concentrations and pretreatment temperature on the composition and enzymatic hydrolysis of liquorice residue were studied.The results showed that the removal rate of lignin and cellulose recovery rate reached 54.1%and 77.2%,respectively,under the conditions of 2%(mass fraction)NaOH aqueous solution as solvent,solid-liquid ratio(g∶mL,the same below)1∶10,time 1.5 h and temperature 100℃.The glucose yield was 53.5%after 24 h enzymatic digestion,which was 4.0 times higher than that without pretreatment(10.6%).When the pretreated liquorice residue was subjected to high solid enzymatic digestion at a solid-liquid ratio of 3∶10 with an enzyme dosage of 45 FPU/gliquorice residue for 72 h,the yield of glucose and xylose reached 86.2 and 18.9 g/L,respectively.This hydrolysate was used as carbon source for fermentation,the production of 2,3-butanediol and acetoin was 43.9 g/L after 64 h,and the conversion rate of reducing sugar was 0.42 g/g.Compared with control group,the hydrolysate was more favorable to the growth of bacteria,while the productivity of 2,3-butanediol and acetoin was increased and the conversion rate was slightly lower.
Fifteen 2-(2-cyanophenoxy)-2-fluoroacetamides were designed,synthesized from salicylonitrile,ethyl bromofluoroacetate and amines,and characterized by 1HNMR,13CNMR and MS.The antibacterial performance of these compounds against Penicillium italicum and Penicillium digitatum was then evaluated by mycelial growth rate method.The results showed that these compounds exhibited certain antibacterial activity against the tested strains.Among them,2-(2-cyanophenoxy)-2-fluoro-N-phenylacetamide(Ⅱa),2-(2-cyanophenoxy)-2-fluoro-N-(thiazol-2-yl)acetamide(Ⅱf),N-(4-bromothiazol-2-yl)-2-(2-cyanophenoxy)-2-fluoroacetamide(Ⅱh),2-(2-cyanophenoxy)-2-fluoro-N-(4-methylthiazol-2-yl)acetamide(Ⅱi),2-(2-cyanophenoxy)-2,2-difluoro-N-(thiazol-2-yl)acetamide(Ⅳc)displayed more than 87.41%inhibition rate against the two bacteria at a mass concentration of 200 mg/L.Compound Ⅱh showed the best antibacterial activity among all compounds.Its inhibition rates on Penicillium italicum and Penicillium digitatum were 60.96%and 53.95%,respectively,at a mass concentration of 50 mg/L,and>30%at a mass concentration of 25 mg/L.2-(2-Cyanophenoxy)-2-fluoroacetamides exhibited better antibacterial activity against the tested strains than 2,4-dichlorophenoxyacetic acid.
Vegetable oil-based plasticizers are regarded as the most promising bio-based environmentally friendly plasticizers owing to their wide resources,adjustable structure,excellent plasticity,non-toxicity and biodegradability.However,the high proportion of long chain alkyl groups in the structure of vegetable oil-based plasticizers results in their poor compatibility with polyvinyl chloride(PVC),which makes the plasticizers usually used as auxiliary plasticizer and their application value not fully demonstrated.In recent years,domestic and foreign scholars have chemically modified the vegetable oil-based plasticizer'structures and developed a series of multifunctional vegetable oil-based plasticizers(such as compatibilization,heat tolerance,flame retardant,suppressed migration,etc.)to achieve the"quality and efficiency improvement"for vegetable oil-based plasticizers.Herein,starting with the molecular structure design of vegetable oil,the modification research on vegetable oil-based plasticizers was summarized,analyzed and discussed via molecular simulation as well as combination of micro and macro analysis.Meanwhile,the"structure-activity"relationship between the structure of plasticizer and the performance of plasticized PVC products was also established,aiming to provide a theoretical basis for the structural design and industrial production of high-performance and multi-functional vegetable oil-based plasticizers.
Polyurethane emulsions have been widely used in painting and protection in construction,leather,metal anti-corrosion and other fields due to their excellent performances.Most of the existing polyurethane emulsions are petroleum-based products.With the need for sustainable development as well as the rapid development and large-scale commercialization of bio-based raw materials,bio-based polyurethane emulsions have achieved rapid development.Herein,bio-based raw materials and additives for the synthesis of polyurethane emulsions,including bio-based isocyanates,polyols,chain extenders acrylic acid(acrylate)monomers and other modified raw materials were reviewed.Recent progress on lignin-based,vegetable oil-based,unnatural monomer bio-based and other bio-based polyurethane emulsions was analyzed.Main problems faced by bio-based polyurethane emulsions,including insufficient raw material supply,high cost and poor product performance were discussed.Development directions of bio-based polyurethane emulsions in solvent-free,high bio-based content and multi-functional products were prospected.
Conductive polymer composites(CPCs)based on graphene/polymers with three-dimensional porous structures have been the optimal choice for the wearable and flexible strain sensors due to the advantages of lightweight,high sensitivity,wide pressure range,low cost and scalability.Herein,the sensing mechanisms such as crack propagation,overlapping-disconnection and tunneling effect of flexible strain sensors were summarized,followed by introduction on the three kinds of construction processes of CPCs with porous structures,including polymer based foam,graphene/polymer mixed dispersion and graphene foam.Then,the sensing performances of flexible strain sensors with porous structures prepared by the above-mentioned three techniques were reviewed,and the relevant examples of flexible strain sensors with porous structures in human motion monitoring fields were presented.Finally,the challenges and development prospects of porous and flexible strain sensors based on graphene/polymers were discussed.
Effective dispersion of hydroxylated multi-walled carbon nanotubes(MWCNT for short)in water was achieved utilizing the amphiphilic molecular structure and nano-size effect of bacterial cellulose(BC).BC/MWCNT composite films were then constructed by vacuum filtration assisted self-assembly based on three-dimensional porous and flexible scaffold structure of BC and excellent conductivity of MWCNT.Finally,novel BC/MWCNT/MnO2 composite film electrodes were constructed by electrodeposition of MnO2 on the BC/MWCNT composite films.BC/MWCNT composite film and BC/MWCNT/MnO2 composite film electrodes were characterized by SEM,TEM,XRD,Raman spectrum and XPS,and evaluated for their mechanical and electrochemical properties.The results showed that BC and MWCNT were closely bonded through hydrogen bonds to confer excellent electrical conductivity and mechanical properties.The porous structure of BC/MWCNT composite film,the electrolyte absorption characteristics and the bridge structure of honeycomb active MnO2 nanosheets endowed it excellent electrochemical performance and remarkable cycling stability.At a current density of 1 mA/cm2,the area specific capacitance and mass specific capacitances of BC/MWCNT/MnO2-20(electrodeposition time of 20 min)reached 1.17 F/cm2 and 200 F/g,respectively.And the specific capacitance retention was stable at 96%after 10000 cycles at a current density of 20 mA/cm2.The BC/MWCNT/MnO2 composite film electrode was facile and inexpensive to prepare and showed great potential in the development of flexible energy storage devices.
Compared with the traditional process,the preparation of caprolactam by butadiene has the characteristics of green,economical and environmentally friendly,in which the partial hydrogenation of adiponitrile(ADN)to produce 6-aminohexonitrile(ACN)is the core step of the process.Ni/CaO and Ni-Fe/CaO catalysts were synthesized via deposition-precipitation method using urea as precipitant and CaO as support,characterized by TEM,XRD,N2 physical adsorption and desorption,XPS and H2-TPR,and then applied to catalyze the partial hydrogenation of ADN to obtain ACN.The effects of reaction temperature,pressure and time on the hydrogenation performance of ADN were investigated.The results showed that FeNi3 alloy phase was formed in the catalyst after Fe doping,and Fe doping made metal Ni become more dispersed.ADN conversion rate and ACN selectivity reached 87.5%and 74.4%,respectively,under mild conditions of 80℃,4 MPa,Ni-Fe/CaO catalyst dosage of 0.1 g,and reaction time of 2 h.In addition,the deactivated catalyst could be regenerated after H2 reduction.
TA-CNTs/SiO2 black transparent coated slides with self-cleaning and anti-fogging effects were obtained from slides sprayed with the dispersion of tannic acid modified carbon nanotubes(TA-CNTs),dendritic nano SiO2 sol and ethyl orthosilicate(TEOS)hydrolysates and cured at room temperature.The carbon nanotubes before and after modification were characterized by FTIR,TEM and TG,the morphology and elemental composition of the coating were analyzed by SEM,AFM and XPS.The influence of mass of TA-CNTs and TEOS hydrolysate on the contact angle(CA)of the coating as well as the mass of TA-CNTs in the coating with a unit area on the light transmittance of the coating were explored via the contact angle measuring instrument and UV-Vis spectrophotometer,and the anti-fogging performance,self-cleaning property and wear resistance of the coating were evaluated.The results showed that,when the mass of TEOS hydrolysate and TA-CNTs was 6.00 g and 0.16 g respectively,the coating displayed super-hydrophilicity(CA was 2.5°)and excellent self-cleaning and anti-fogging effects.After 120 times of friction experiments,the coating still maintained super-hydrophilicity and showed certain wear resistance.The addition of TA-CNTs made the coating surface rougher,which was conducive to reduction of light reflection and pollution.Moreover,when the mass of TA-CNTs in the coating per unit area was 2.0×10-3 g/cm2,the light transmittance of the coating decreased to 60%,and the coating could keep privacy while maintaining certain transparency.
A carbamate organocatalyst(TEPA-EC)for the synthesis of methyl ethyl carbonate(EMC)was synthesized from addition reaction of tetraethylenepentamine(TEPA)and ethylene carbonate(EC),then characterized by FTIR and NMR,and further analyzed for its catalytic mechanism.The influence of synthesis and application conditions on the catalytic activity and transesterification efficiency of TEPA-EC were investigated,followed by assessment on its stability and water resistance.The results showed that the hydroxyethyl tert-aminoformate group in TEPA-EC could facilitate the transesterification between dimethyl carbonate(DMC)and ethyl alcohol(EtOH)via synergistic hydrogen bonds.The TEPA-EC with high catalytic activity could be obtained under reaction conditions of n(EC)∶n(TEPA)=5∶1,temperature 140℃and reaction time 2 h.The conversion of EtOH and selectivity of EMC reached 59.50%and 83.77%,respectively,when DMC reacted with EtOH(4.60 g)by a molar ratio of 2∶1 at 78℃for 7 h with 1%(based on the total mass of raw materials,the same below)TEPA-EC.The TEPA-EC displayed comparable catalytic efficiency to that of sodium ethoxide used in industrial application.When 3%TEPA-EC was recycled 8 times alone and 14 times with water,the conversion of EtOH and the selectivity of EMC fluctuated around 62.35%,86.03%and 57.33%,87.91%,respectively,demonstrating much better stability and water resistance than sodium ethoxide.
In order to determine the optimal extraction process of Osmanthus fragrans flavonoids and their antibacterial effect on Candida albicans(C.albicans),three methods,ultrasonic extraction,ultrasonic-assisted enzyme extraction and ultrasonic-assisted double aqueous phase extraction,were compared for their extraction rates of Osmanthus fragrans flavonoids.The method with the highest extraction rate was selected for process optimization by single factor and response surface experiments.The components of four kinds of Osmanthus fragrans flavonoids were identified by liquid chromatography-mass spectrometry(UPLC-MS/MS).The inhibition effects of the four Osmanthus fragrans flavonoids on C.albicans in terms of minimum inhibitory concentration(MIC),cell membrane integrity and biofilm formation were analyzed.The results showed that,under the optimal extraction process of temperature 50℃,liquid-solid ratio 17∶1(mL∶g),and ethanol volume fraction 52%,the extraction rates of Thunbergii group,Latifolius group,Aurantiacus group,and Semperflorens group were 13.88%±0.29%,8.79%±0.56%,13.16%±0.33%,and 10.28%±0.41%,respectively.The four Osmanthus fragrans flavonoids displayed different antibacterial effect on C.albicans,among which,Osmanthus fragrans var.thunbergii exhibited the best antifungal effect with MIC of 1.50 g/L,significantly improved the C.albicans cell membrane permeability,led to the efflux of cell contents,and inhibited the biofilm formation with the inhibition rate of flavonoid of Aurantiacus group reaching up to 46.59%.
