Converting polyethylene terephthalate(PET)wastes to its monomer and valuable chemicals via ecofriendly chemical method is still a challenge task.Previously,phase transfer catalysts used for alkaline hydrolysis were so...Converting polyethylene terephthalate(PET)wastes to its monomer and valuable chemicals via ecofriendly chemical method is still a challenge task.Previously,phase transfer catalysts used for alkaline hydrolysis were soluble in reaction media and hardly separated after reaction.Here,we reported several pH-responsive catalysts combined alkyl quaternary ammonium units with heteropolyacid anion for achieving stepwise product/catalyst separation and catalyst recycling.The properties of homogeneous/heterogeneous transfer behavior allow catalyst to be easily separated from reaction media by adjusting of pH value.Among them,[C_(16)H_(33)N(CH_(3))_(3)]_(3)PW_(12)O_(40)(abbreviated as[CTA]_(3)PW)exhibits the highest activity and the most suitable pH responsive values.Such a pH triggered switchable catalytic system not only shows good performance for depolymerization of pure PET,but also some real PET wastes such as coloured trays and PE/PET complex films could be completely degraded into terephthalic acid.Additionally,the reaction kinetics and activation energy of PET alkaline hydrolysis also studied with and without pH-responsive[CTA]_(3)PW.展开更多
Terephthalic acid,2,5-furandicarboxylic acid and 1,8-octanediol were adopted as monomers and antimony trioxide as catalyst,and poly(terephthalic acid-2,5-furandicarboxylic acid-1,8-octanediol) copolyesters identified ...Terephthalic acid,2,5-furandicarboxylic acid and 1,8-octanediol were adopted as monomers and antimony trioxide as catalyst,and poly(terephthalic acid-2,5-furandicarboxylic acid-1,8-octanediol) copolyesters identified as PEOT-x,where x is the mole fraction of furandicarboxylic acid in the samples,were synthesized by direct esterification.The molecular structure of the copolyesters was characterized by FTIR and 1H NMR spectroscopy.Gel permeation chromatography (GPC),differential scanning calorimetry (DSC),and thermogravimetric analysis (TGA) were used to characterize the molecular weight,molar mass dispersity,glass transition temperature,and thermal stability of the copolyesters,respectively.The mechanical properties of the samples were also investigated.The number-average molecular weight (M_(n)) of the samples varies from 9 700-18 800 g/mol,and molar mass dispersity (■=M_(w)/M_(n)) from 2.15-3.34.The initial decomposition temperature of the copolyesters is in the 332-356 ℃ range,with maximum decomposition rates at 390-410 ℃,while the glass transition temperature (Tg) varies from 0-33 ℃.Mechanical test shows that PEOT-10 has the highest tensile strength,while PEOT-90 has the largest tensile modulus and elongation at break.The experimental results show that these copolyesters can be synthesized with relatively high molecular weights,good thermal stability,and fair mechanical properties,which makes them excellent replacements for commercial polyesters,such as PET,and these properties can be tuned through the relative amounts of biomass monomer 2,5-furandicarboxylic acid used in the reactions.展开更多
The fungi Phanerochaete chrysosporium (PC) and Saccharomyces cerevisiae Y99 and the native bacterium YZ1 were the three parental strains for construction of hybrid cells through protoplast fusion to degrade terephthal...The fungi Phanerochaete chrysosporium (PC) and Saccharomyces cerevisiae Y99 and the native bacterium YZ1 were the three parental strains for construction of hybrid cells through protoplast fusion to degrade terephthalic acid (TPA) wastewater. The results showed that the native bacterium YZ1 protoplasm could integrate with that of PC to form the hybrid cell Fhh and the fungus Y99 protoplasm also could integrate with that of Fhh to form the hybrid cell Fhhh. The protoplasts of YZ1 and Y99 could change the morphology of PC spore and mycelium for two times. The hybrid cell Fhhh got the best growth and degradation abilities in the wastewater. It suggested that the hybrid strains obtained from the inter\|kingdom protoplast fusion of the three parental strains could create potential for the purification of TPA wastewater.展开更多
The paper provides a critical comparison between mesophilic and thermophilic anaerobic treatment of PTA wastewater through diagnosis of a case study. Aspects covered are bioavailability, biodegradability, microbial po...The paper provides a critical comparison between mesophilic and thermophilic anaerobic treatment of PTA wastewater through diagnosis of a case study. Aspects covered are bioavailability, biodegradability, microbial population, thermodynamics, kinetics involved and bio-reactor design for PTA wastewater treatment. The results of the case study suggests that one- stage thermophilic anaerobic reactor coupled with coagulation-flocculation pre-treatment unit and an aerobic post treatment unit could be techno-economically viable for PTA wastewater treatment to ensure that the final effluent quality conforms to the international standard. The in-formation emanated from this study could be useful and thought provoking to the professionals and academia in the area of PTA wastewater treatment and can serve as impetus toward the development of research lines in similar problems like the treatment of other petrochemical wastewater such as phenol-con- taining wastewater, benzene/benzoic acid-con- taining wastewater or wastewater from other similar industrial settings.展开更多
A series of complexes of europium (III)/gadolinium (III) with 2-thienyltrifluoroacetonate (HTTA), terephthalic acid (TPA) and phenanthroline (Phen) were synthesized by coprecipitation. The resulting complexes includin...A series of complexes of europium (III)/gadolinium (III) with 2-thienyltrifluoroacetonate (HTTA), terephthalic acid (TPA) and phenanthroline (Phen) were synthesized by coprecipitation. The resulting complexes including Eu2(TPA)(TTA)4Phen2, Eu1.4Gd0.6(TPA)(TTA)4Phen2, Eu1.0Gd1.0(TPA)(TTA)4Phen2 and Eu0.8Gd1.2(TPA)(TTA)4Phen2 were characterized by elemental analysis, IR spectroscopy and thermal stability analysis. The results of analysis indicate that the complexes obtained have similar binuclear structure with each other. The thermal stability analysis indicates that the complexes Eu2(TPA)(TTA)4Phen2and Eu1.0Gd1.0(TPA)(TTA)4Phen2 possess good thermal stability, which melt at ~241°C and decompose at ~370°C - 430°C corresponding to the formation of the complexes. The fluorescence spectra of Eu2(1-x)Gd2x(TPA)(TTA)4Phen2 (x = 0 - 1) complex powders and their doped silica gels were studied. The co-fluorescence effect of Gd3+ ions in complex powders is different from that of their doped silica gels. The optimum concentration of Gd3+ for complex powders and their doped silica gels is 0.5 and 0.3 (molar fraction), respectively. The co-fluorescence distinction of Gd3+ ions for complex powders and their doped silica gels is preferably interpreted from the proposed binuclear structure together with monomolecular compositions of the complexes for the first time. Both intermolecular energy transfer and intra molecular energy transfer in cross binuclear monomolecular EuGd(TPA)(TTA)4Phen2 are thought to be responsible for the co-fluorescence effect of the complex powders;yet only the latter is thought to be responsible for the co-fluorescence effect in silica gels, for the complex molecules in this case are isolated from each other.展开更多
Plastic waste puts a huge burden on the ecosystem due to the current lack of mature recycling technology.Poly(ethylene terephthalate)(PET)is one of the most produced plastics in the world.Enzymatic decomposition holds...Plastic waste puts a huge burden on the ecosystem due to the current lack of mature recycling technology.Poly(ethylene terephthalate)(PET)is one of the most produced plastics in the world.Enzymatic decomposition holds the promise of recovering monomers from PET plastic,and the monomers can be used to regenerate new PET products.However,there are still limitations in the activity and thermal stability of the existing PET hydrolases.The recent study by Lu et al.introduced a novel PET hydrolase via machine learning-aided engineering.The obtained PET hydrolase showed excellent activity and thermal stability in the hydrolysis of PET and is capable of directly degrading large amounts of postconsumer PET products.This approach provides an effective method for recycling PET waste and is expected to improve the current state of plastic pollution worldwide.展开更多
One new Mn(Ⅱ)coordination polymer,[Mn(Htia)_(2)(H_(2)O)_(2)]_(n)·2nH_(2)O(1,H_(2)tia=4-(1,2,4-triazol-1-yl)isophthalic acid)has been synthesized in mixed solvents under solvothermal conditions.Further characteri...One new Mn(Ⅱ)coordination polymer,[Mn(Htia)_(2)(H_(2)O)_(2)]_(n)·2nH_(2)O(1,H_(2)tia=4-(1,2,4-triazol-1-yl)isophthalic acid)has been synthesized in mixed solvents under solvothermal conditions.Further characterizations including single-crystal XRD,elemental analysis,IR spectroscopy,thermogravimetric analysis and powder XRD were performed to verify the structure.Complex 1 displays a one-dimensional(1D)chain and is similar to a reported Mn(II)complex 2{[Mn(Htta)_(2)(H_(2)O)_(2)]·2H_(2)O}_(n).It crystallizes in triclinic P1 space group,with a=7.5557(3),b=7.5974(3),c=11.8448(4)Å,α=90.088(1)°,β=95.863(1)°,γ=113.668(1)°,V=618.81(4)Å^(3),Z=1,M_(r)=591.36 g/mol,D_(c)=1.587 mg/m^(3),μ=0.609 mm^(-1),F(000)=303,GOOF=1.062,the final R=0.0359and w R=0.0818 for 4272 observed reflections with I>2σ(I).Based on two similar structures,Hirshfeld surface analysis confirmed both structures are mainly stabilized by O···H/H···O and C···H/H···C hydrogen bonds.Further,weak ferromagnetic behaviors between adjacent Mn(II)ions in 1D chain are obtained.展开更多
Several works have been based on the study of thermal variations in biomass to derive more valuable products such as fuels capable of replacing oil in the event of a crisis or activated carbon used as an adsorbent mat...Several works have been based on the study of thermal variations in biomass to derive more valuable products such as fuels capable of replacing oil in the event of a crisis or activated carbon used as an adsorbent material, widely used in industry for the elimination of unwanted materials, both in liquid and gaseous environments. A study of thermal parameters such as: heating speed, retention time, drying temperature, carbonization temperature, particle size, was carried out with the aim of determining the characteristic factors of the carbonization of Polyethylene terephthalate (PET), sawdust (SC) and sawdust/polyethylene terephthalate (CPS) mixture. The results of the immediate analysis revealed a very low level of ash in PET (0.013%) compared to the level of ash in sawdust (2.9%), as well as a high level of fixed carbon (82.960%), which suggests the presence of mineral oxides and a significant carbon matrix unlike PET, which indicates a very significant organic matrix (essentially made up of organic matter) with the absence of mineral oxides. The study of thermal parameters showed the water loss from Sawdust (SC) and the Sawdust/Polyethylene terephthalate (CPS) mixture, an increase with temperature, unlike that of PET whose variation is essentially zero. Without heat treatment, sawdust alone contains approximately 7% water. The optimal drying temperature for this study is 110˚C for a stay of 24 hours. It appears that the largest mass losses for the PET samples are between 87.19% and 96.05%, followed by that of the mixture, between 47.33% and 64.37%. And the lowest are observed, those of sawdust (from 24.02% to 62.6%). However, here we can say that the influence of the mass is not great, given the slight difference between the losses by temperature. The results of the study of the influence of grain size showed that the differences are insignificant, even if we vary the diameter of the grains from simple to triple. To better minimize physical constraints such as the intragranular diffusibility of the volatile matter and the homogeneity of the temperature in the grains, 75 μm particles are found to be optimal for our study. It can be noted when studying the heating rate that the mass loss at the end of the reaction is approximately the same depending on each precursor material. However, it has been demonstrated that the heating rate strongly influences the nature of the reaction products both for volatile materials and for the solid residue as well as on the kinetic parameters of the chemical reaction. Furthermore, the variation in apparent density shows a decrease as a function of the increase in the residence time of the materials in the reactor. As the carbonization time increases, the apparent density decreases. We note, for the lignocellulosic material, that the apparent density stabilizes after 60 minutes.展开更多
Alloy nanoparticles(NPs)with numerous exposed catalytic active sites have been extensively studied as efficient heterogeneous catalysts.However,it is challenging to synthesize alloy NP catalysts with high activity whi...Alloy nanoparticles(NPs)with numerous exposed catalytic active sites have been extensively studied as efficient heterogeneous catalysts.However,it is challenging to synthesize alloy NP catalysts with high activity while avoiding aggregation.Herein,we report a facile method to encapsulate alloy NPs loaded metal–organic framework(MOF)catalysts(alloy NPs/MOFs)within an ultrathin metal–organic layer using a terephthalic acid(BDC)assisted method.A series of metal-BDC encapsulated PtM/MOFs(M=Fe,Co,and Ni)catalysts were synthesized successfully and showed significantly enhanced catalytic performance toward selective hydrogenation reaction.展开更多
The present work investigated the effect of polyethylene terephthalate (PET) plastic waste on the physico-mechanical and thermal properties of cement-stabilized laterite bricks to see the durability of the modified br...The present work investigated the effect of polyethylene terephthalate (PET) plastic waste on the physico-mechanical and thermal properties of cement-stabilized laterite bricks to see the durability of the modified bricks (CSLB). Samples were formulated by mixing laterite, cement, and different percentages of PET (0%, 3%, 5%, and 7%) by volume. The bricks were produced using the M7MI Hydraform standard interlocking block and kept in the shade for a curing period of 28 days. The addition of 3% to 5% PET to the laterite stabilized with 10% cement results in a decrease in both dry and wet compressive strength, which is determined using the Controlab compression machine. However, the obtained results are in concordance with the standards. The thermal conductivity of CSLB, determined using the box method with the EI700 measurement cell, decreases as the PET content of the mixture increases. A decrease in bulk density from 1.67 to 1.58 g/cm<sup>3</sup> was observed.展开更多
Synthetic plastics are often considered to be materials that cannot be broken down by natural processes.One such plastic,polyethylene terephthalate(PET),is commonly used in everyday items but when these products are d...Synthetic plastics are often considered to be materials that cannot be broken down by natural processes.One such plastic,polyethylene terephthalate(PET),is commonly used in everyday items but when these products are discarded,they can cause serious harm to the environment and human health.In this study,PET plastic waste was used to create activated carbon using a physical activation process that involved using CO2 gas.The researchers investigated the effects of different temperatures,carbonization,and activation times on the resulting activated carbon’s surface area.The activated carbon was then analyzed using scanning electron microscopy(SEM),X-ray diffraction(XRD),FTIR,and BET.The activated carbon created from PET plastic waste showed excellent absorption properties for methylene blue in aqueous solutions across a wide range of pH levels.By creating activated carbon from plastic waste,not only are environmental issues addressed,but high-value activated carbon is produced for environmental remediation purposes.展开更多
Chelate tetra(acetylacetonato) tin(Ⅳ) was prepared and used as catalyst for polytrimethylene terephthalate synthesis.It exhibited higher catalytic activity than tetrabutyl titanate,butyltinhydroxide oxide and dibutyl...Chelate tetra(acetylacetonato) tin(Ⅳ) was prepared and used as catalyst for polytrimethylene terephthalate synthesis.It exhibited higher catalytic activity than tetrabutyl titanate,butyltinhydroxide oxide and dibutyltin oxide.Decrease in reaction time, content of terminal carboxyl group,color intensity and increase in intrinsic viscosity were observed.The unique molecular structure can be considered as factor remarkably improving the catalytic activity of tetra(acetylacetonato) tin(Ⅳ).展开更多
The solvothermal reaction of CdCl2·2.5H2O with terephthalic acid yields two new three-dimensional(3D)cadmium(II)coordination polymers(CPs),namely{[Cd(C8H4O4)Cl]·C2H8N}n and[Cd(C8H4O4)]n,we use the abbreviati...The solvothermal reaction of CdCl2·2.5H2O with terephthalic acid yields two new three-dimensional(3D)cadmium(II)coordination polymers(CPs),namely{[Cd(C8H4O4)Cl]·C2H8N}n and[Cd(C8H4O4)]n,we use the abbreviations CP1 and CP2 to refer to them,respectively.The compounds are characterized in detail by single-crystal X-ray diffraction,powder X-ray diffraction,IR spectroscopy,elemental analysis and thermogravimetric analysis(TGA).The results indicate that compounds CP1 and CP2 are 3D frameworks,and both the compounds feature a uninodal 4-connected framework with a dia net.The empty spaces of such 3D framework are filed by the other two identical frameworks,leading to a 3-fold interpenetrated network.In addition,the photochemical properties of the frameworks are also investigated.The two frameworks show strong solid-state fluorescence emission at 463 and 503 nm,respectively,which are obvious red-shift compared to the emission of ligand.展开更多
Aromatics have a broad application in our everyday life ranging from plastics, coatings and fibres, to food and pharmaceuticals. To date the bulk of these aromatics is derived from naphtha-based pet-rochemistry. Howev...Aromatics have a broad application in our everyday life ranging from plastics, coatings and fibres, to food and pharmaceuticals. To date the bulk of these aromatics is derived from naphtha-based pet-rochemistry. However, recent progress in the fermentative production of metabolites using renew-able resources and engineered microbes has enabled the production of bio-precursors, such as 4-amino benzoic acid (pABA) and 2-amino benzoic acid (oABA). In this work we explored the feasibility of Sandmeyer reactions for the conversion of pABA to terephthalic and oABA salicylic acid, providing two very important platform chemicals for the chemical and pharmaceutical industries. We could demonstrate that both acids can be obtained from the amino benzoic acids derived from the shikimate pathway in microbes and plants. Good conversions could be achieved using Sandmeyer reactions at mild conditions with biodegradable reagents and without organic solvents.展开更多
The classical crystallization theories proposed by Avrami, Evans, and Mandelkern wereextended to the nonisothermal situation. The expressions derived from the classical equations canbe expressed in either the differen...The classical crystallization theories proposed by Avrami, Evans, and Mandelkern wereextended to the nonisothermal situation. The expressions derived from the classical equations canbe expressed in either the differential form or the integral form. A method was provided so as toobtain the parameters characterizing the crystallization rate and mechanism from DSC curves withseveral constant heating or cooling rates. The rate constants of crystallization obtained from bothisothermal and nonisothermal curves of poly(ethylene terephthalate)were compared.展开更多
Waste plastics,such as waste polyethylene terephthalate(PET)beverage bottles and waste rubber tyres are major municipal solid wastes,which may lead to various environmental problems if they are not appropriately recyc...Waste plastics,such as waste polyethylene terephthalate(PET)beverage bottles and waste rubber tyres are major municipal solid wastes,which may lead to various environmental problems if they are not appropriately recycled.In this study,the feasibility of collectively recycling the two types of waste into performance-increasing modifiers for asphalt pavements was analyzed.This study aimed to investigate the recycling mechanisms of waste PET-derived additives under the treatment of two amines,triethylenetetramine(TETA)and ethanolamine(EA),and characterize the performances of these additives in modifying rubberized bitumen,a bitumen modified by waste tyre rubber.To this end,infrared spectroscopy and thermal analyses were carried out on the two PET-derived additives(PET–TETA and PET–EA).In addition,infrared spectroscopy,viscosity,dynamic shear rheology,and multiple stress creep recovery tests were performed on the rubberized bitumen samples modified by the two PET-derived additives.We concluded that waste PET can be chemically upcycled into functional additives,which can increase the overall performance of the rubberized bitumen.The recycling method developed in this study not only helps alleviate the landfilling problems of both waste PET plastic and scrap tyres,but also turns these wastes into value-added new materials for building durable pavements.展开更多
The phase separation behavior of blend of Surlyn and poly(ethylene terephthalate) (PET) has been studied by scanning electron microscopy and IR. It is shown that particles of Surlyn are dispersed in PET matrix, and th...The phase separation behavior of blend of Surlyn and poly(ethylene terephthalate) (PET) has been studied by scanning electron microscopy and IR. It is shown that particles of Surlyn are dispersed in PET matrix, and this phase separation is controlled by heat-treated conditions of the blend.展开更多
基金the support of the National Natural Science Foundation of China(22005276)。
文摘Converting polyethylene terephthalate(PET)wastes to its monomer and valuable chemicals via ecofriendly chemical method is still a challenge task.Previously,phase transfer catalysts used for alkaline hydrolysis were soluble in reaction media and hardly separated after reaction.Here,we reported several pH-responsive catalysts combined alkyl quaternary ammonium units with heteropolyacid anion for achieving stepwise product/catalyst separation and catalyst recycling.The properties of homogeneous/heterogeneous transfer behavior allow catalyst to be easily separated from reaction media by adjusting of pH value.Among them,[C_(16)H_(33)N(CH_(3))_(3)]_(3)PW_(12)O_(40)(abbreviated as[CTA]_(3)PW)exhibits the highest activity and the most suitable pH responsive values.Such a pH triggered switchable catalytic system not only shows good performance for depolymerization of pure PET,but also some real PET wastes such as coloured trays and PE/PET complex films could be completely degraded into terephthalic acid.Additionally,the reaction kinetics and activation energy of PET alkaline hydrolysis also studied with and without pH-responsive[CTA]_(3)PW.
基金Funded by the Program (BG20190227001) of High-end Foreign Experts of the State Administration of Foreign Experts Affairs (SAFEA)the 2021 Innovative Training Program for College Students in Hubei Province。
文摘Terephthalic acid,2,5-furandicarboxylic acid and 1,8-octanediol were adopted as monomers and antimony trioxide as catalyst,and poly(terephthalic acid-2,5-furandicarboxylic acid-1,8-octanediol) copolyesters identified as PEOT-x,where x is the mole fraction of furandicarboxylic acid in the samples,were synthesized by direct esterification.The molecular structure of the copolyesters was characterized by FTIR and 1H NMR spectroscopy.Gel permeation chromatography (GPC),differential scanning calorimetry (DSC),and thermogravimetric analysis (TGA) were used to characterize the molecular weight,molar mass dispersity,glass transition temperature,and thermal stability of the copolyesters,respectively.The mechanical properties of the samples were also investigated.The number-average molecular weight (M_(n)) of the samples varies from 9 700-18 800 g/mol,and molar mass dispersity (■=M_(w)/M_(n)) from 2.15-3.34.The initial decomposition temperature of the copolyesters is in the 332-356 ℃ range,with maximum decomposition rates at 390-410 ℃,while the glass transition temperature (Tg) varies from 0-33 ℃.Mechanical test shows that PEOT-10 has the highest tensile strength,while PEOT-90 has the largest tensile modulus and elongation at break.The experimental results show that these copolyesters can be synthesized with relatively high molecular weights,good thermal stability,and fair mechanical properties,which makes them excellent replacements for commercial polyesters,such as PET,and these properties can be tuned through the relative amounts of biomass monomer 2,5-furandicarboxylic acid used in the reactions.
基金TheNationalNaturalScienceFoundationofChina !(No .395 70 10 1)andNSFofJiangsuProvince (No .BK 990 33)
文摘The fungi Phanerochaete chrysosporium (PC) and Saccharomyces cerevisiae Y99 and the native bacterium YZ1 were the three parental strains for construction of hybrid cells through protoplast fusion to degrade terephthalic acid (TPA) wastewater. The results showed that the native bacterium YZ1 protoplasm could integrate with that of PC to form the hybrid cell Fhh and the fungus Y99 protoplasm also could integrate with that of Fhh to form the hybrid cell Fhhh. The protoplasts of YZ1 and Y99 could change the morphology of PC spore and mycelium for two times. The hybrid cell Fhhh got the best growth and degradation abilities in the wastewater. It suggested that the hybrid strains obtained from the inter\|kingdom protoplast fusion of the three parental strains could create potential for the purification of TPA wastewater.
文摘The paper provides a critical comparison between mesophilic and thermophilic anaerobic treatment of PTA wastewater through diagnosis of a case study. Aspects covered are bioavailability, biodegradability, microbial population, thermodynamics, kinetics involved and bio-reactor design for PTA wastewater treatment. The results of the case study suggests that one- stage thermophilic anaerobic reactor coupled with coagulation-flocculation pre-treatment unit and an aerobic post treatment unit could be techno-economically viable for PTA wastewater treatment to ensure that the final effluent quality conforms to the international standard. The in-formation emanated from this study could be useful and thought provoking to the professionals and academia in the area of PTA wastewater treatment and can serve as impetus toward the development of research lines in similar problems like the treatment of other petrochemical wastewater such as phenol-con- taining wastewater, benzene/benzoic acid-con- taining wastewater or wastewater from other similar industrial settings.
文摘A series of complexes of europium (III)/gadolinium (III) with 2-thienyltrifluoroacetonate (HTTA), terephthalic acid (TPA) and phenanthroline (Phen) were synthesized by coprecipitation. The resulting complexes including Eu2(TPA)(TTA)4Phen2, Eu1.4Gd0.6(TPA)(TTA)4Phen2, Eu1.0Gd1.0(TPA)(TTA)4Phen2 and Eu0.8Gd1.2(TPA)(TTA)4Phen2 were characterized by elemental analysis, IR spectroscopy and thermal stability analysis. The results of analysis indicate that the complexes obtained have similar binuclear structure with each other. The thermal stability analysis indicates that the complexes Eu2(TPA)(TTA)4Phen2and Eu1.0Gd1.0(TPA)(TTA)4Phen2 possess good thermal stability, which melt at ~241°C and decompose at ~370°C - 430°C corresponding to the formation of the complexes. The fluorescence spectra of Eu2(1-x)Gd2x(TPA)(TTA)4Phen2 (x = 0 - 1) complex powders and their doped silica gels were studied. The co-fluorescence effect of Gd3+ ions in complex powders is different from that of their doped silica gels. The optimum concentration of Gd3+ for complex powders and their doped silica gels is 0.5 and 0.3 (molar fraction), respectively. The co-fluorescence distinction of Gd3+ ions for complex powders and their doped silica gels is preferably interpreted from the proposed binuclear structure together with monomolecular compositions of the complexes for the first time. Both intermolecular energy transfer and intra molecular energy transfer in cross binuclear monomolecular EuGd(TPA)(TTA)4Phen2 are thought to be responsible for the co-fluorescence effect of the complex powders;yet only the latter is thought to be responsible for the co-fluorescence effect in silica gels, for the complex molecules in this case are isolated from each other.
基金support from the Beijing Municipal Natural Science Foundation(2222012)the National Natural Science Foundation of China(Grant No.52070116)+1 种基金the Key-Area Research and Development Program of Guangdong Province(2020B1111380001)the Tsinghua University-Shanxi Clean Energy Research Institute Innovation Project Seed Fund is gratefully acknowledged.
文摘Plastic waste puts a huge burden on the ecosystem due to the current lack of mature recycling technology.Poly(ethylene terephthalate)(PET)is one of the most produced plastics in the world.Enzymatic decomposition holds the promise of recovering monomers from PET plastic,and the monomers can be used to regenerate new PET products.However,there are still limitations in the activity and thermal stability of the existing PET hydrolases.The recent study by Lu et al.introduced a novel PET hydrolase via machine learning-aided engineering.The obtained PET hydrolase showed excellent activity and thermal stability in the hydrolysis of PET and is capable of directly degrading large amounts of postconsumer PET products.This approach provides an effective method for recycling PET waste and is expected to improve the current state of plastic pollution worldwide.
文摘One new Mn(Ⅱ)coordination polymer,[Mn(Htia)_(2)(H_(2)O)_(2)]_(n)·2nH_(2)O(1,H_(2)tia=4-(1,2,4-triazol-1-yl)isophthalic acid)has been synthesized in mixed solvents under solvothermal conditions.Further characterizations including single-crystal XRD,elemental analysis,IR spectroscopy,thermogravimetric analysis and powder XRD were performed to verify the structure.Complex 1 displays a one-dimensional(1D)chain and is similar to a reported Mn(II)complex 2{[Mn(Htta)_(2)(H_(2)O)_(2)]·2H_(2)O}_(n).It crystallizes in triclinic P1 space group,with a=7.5557(3),b=7.5974(3),c=11.8448(4)Å,α=90.088(1)°,β=95.863(1)°,γ=113.668(1)°,V=618.81(4)Å^(3),Z=1,M_(r)=591.36 g/mol,D_(c)=1.587 mg/m^(3),μ=0.609 mm^(-1),F(000)=303,GOOF=1.062,the final R=0.0359and w R=0.0818 for 4272 observed reflections with I>2σ(I).Based on two similar structures,Hirshfeld surface analysis confirmed both structures are mainly stabilized by O···H/H···O and C···H/H···C hydrogen bonds.Further,weak ferromagnetic behaviors between adjacent Mn(II)ions in 1D chain are obtained.
文摘Several works have been based on the study of thermal variations in biomass to derive more valuable products such as fuels capable of replacing oil in the event of a crisis or activated carbon used as an adsorbent material, widely used in industry for the elimination of unwanted materials, both in liquid and gaseous environments. A study of thermal parameters such as: heating speed, retention time, drying temperature, carbonization temperature, particle size, was carried out with the aim of determining the characteristic factors of the carbonization of Polyethylene terephthalate (PET), sawdust (SC) and sawdust/polyethylene terephthalate (CPS) mixture. The results of the immediate analysis revealed a very low level of ash in PET (0.013%) compared to the level of ash in sawdust (2.9%), as well as a high level of fixed carbon (82.960%), which suggests the presence of mineral oxides and a significant carbon matrix unlike PET, which indicates a very significant organic matrix (essentially made up of organic matter) with the absence of mineral oxides. The study of thermal parameters showed the water loss from Sawdust (SC) and the Sawdust/Polyethylene terephthalate (CPS) mixture, an increase with temperature, unlike that of PET whose variation is essentially zero. Without heat treatment, sawdust alone contains approximately 7% water. The optimal drying temperature for this study is 110˚C for a stay of 24 hours. It appears that the largest mass losses for the PET samples are between 87.19% and 96.05%, followed by that of the mixture, between 47.33% and 64.37%. And the lowest are observed, those of sawdust (from 24.02% to 62.6%). However, here we can say that the influence of the mass is not great, given the slight difference between the losses by temperature. The results of the study of the influence of grain size showed that the differences are insignificant, even if we vary the diameter of the grains from simple to triple. To better minimize physical constraints such as the intragranular diffusibility of the volatile matter and the homogeneity of the temperature in the grains, 75 μm particles are found to be optimal for our study. It can be noted when studying the heating rate that the mass loss at the end of the reaction is approximately the same depending on each precursor material. However, it has been demonstrated that the heating rate strongly influences the nature of the reaction products both for volatile materials and for the solid residue as well as on the kinetic parameters of the chemical reaction. Furthermore, the variation in apparent density shows a decrease as a function of the increase in the residence time of the materials in the reactor. As the carbonization time increases, the apparent density decreases. We note, for the lignocellulosic material, that the apparent density stabilizes after 60 minutes.
基金supported by funding from the National Key R&D Program of China(no.2018YFA0108300)the Overseas High-level Talents Plan of China and Guangdong Province,the Fundamental Research Funds for the Central Universities+3 种基金the 100 Talents Plan Foundation of Sun Yat-sen Universitythe Program for Guangdong Introducing Innovative and Entrepreneurial Teams(no.2017ZT07C069)the NSFC Projects(nos.22075321,21821003,and 21890380)the China Postdoctoral Science Foundation(nos.2019M653141 and 2020M682042).
文摘Alloy nanoparticles(NPs)with numerous exposed catalytic active sites have been extensively studied as efficient heterogeneous catalysts.However,it is challenging to synthesize alloy NP catalysts with high activity while avoiding aggregation.Herein,we report a facile method to encapsulate alloy NPs loaded metal–organic framework(MOF)catalysts(alloy NPs/MOFs)within an ultrathin metal–organic layer using a terephthalic acid(BDC)assisted method.A series of metal-BDC encapsulated PtM/MOFs(M=Fe,Co,and Ni)catalysts were synthesized successfully and showed significantly enhanced catalytic performance toward selective hydrogenation reaction.
文摘The present work investigated the effect of polyethylene terephthalate (PET) plastic waste on the physico-mechanical and thermal properties of cement-stabilized laterite bricks to see the durability of the modified bricks (CSLB). Samples were formulated by mixing laterite, cement, and different percentages of PET (0%, 3%, 5%, and 7%) by volume. The bricks were produced using the M7MI Hydraform standard interlocking block and kept in the shade for a curing period of 28 days. The addition of 3% to 5% PET to the laterite stabilized with 10% cement results in a decrease in both dry and wet compressive strength, which is determined using the Controlab compression machine. However, the obtained results are in concordance with the standards. The thermal conductivity of CSLB, determined using the box method with the EI700 measurement cell, decreases as the PET content of the mixture increases. A decrease in bulk density from 1.67 to 1.58 g/cm<sup>3</sup> was observed.
基金The Ministry of Natural Resources and Environment(No.TNMT.2022.05.04).
文摘Synthetic plastics are often considered to be materials that cannot be broken down by natural processes.One such plastic,polyethylene terephthalate(PET),is commonly used in everyday items but when these products are discarded,they can cause serious harm to the environment and human health.In this study,PET plastic waste was used to create activated carbon using a physical activation process that involved using CO2 gas.The researchers investigated the effects of different temperatures,carbonization,and activation times on the resulting activated carbon’s surface area.The activated carbon was then analyzed using scanning electron microscopy(SEM),X-ray diffraction(XRD),FTIR,and BET.The activated carbon created from PET plastic waste showed excellent absorption properties for methylene blue in aqueous solutions across a wide range of pH levels.By creating activated carbon from plastic waste,not only are environmental issues addressed,but high-value activated carbon is produced for environmental remediation purposes.
基金the National High Technology Research and Development Program of China(No. 2003AA321010)the Innovation Research Fund of Graduate University,Chinese Academy of Sciences(2006)
文摘Chelate tetra(acetylacetonato) tin(Ⅳ) was prepared and used as catalyst for polytrimethylene terephthalate synthesis.It exhibited higher catalytic activity than tetrabutyl titanate,butyltinhydroxide oxide and dibutyltin oxide.Decrease in reaction time, content of terminal carboxyl group,color intensity and increase in intrinsic viscosity were observed.The unique molecular structure can be considered as factor remarkably improving the catalytic activity of tetra(acetylacetonato) tin(Ⅳ).
基金Natural Science Foundation of Fujian Province,China(No.2019J01774)Scientific Research Start-up Foundation of Fujian University of Technology,China(No.GY-Z19168)Research Development Foundation of Fujian University of Technology,China(No.GY-Z160120)。
文摘The solvothermal reaction of CdCl2·2.5H2O with terephthalic acid yields two new three-dimensional(3D)cadmium(II)coordination polymers(CPs),namely{[Cd(C8H4O4)Cl]·C2H8N}n and[Cd(C8H4O4)]n,we use the abbreviations CP1 and CP2 to refer to them,respectively.The compounds are characterized in detail by single-crystal X-ray diffraction,powder X-ray diffraction,IR spectroscopy,elemental analysis and thermogravimetric analysis(TGA).The results indicate that compounds CP1 and CP2 are 3D frameworks,and both the compounds feature a uninodal 4-connected framework with a dia net.The empty spaces of such 3D framework are filed by the other two identical frameworks,leading to a 3-fold interpenetrated network.In addition,the photochemical properties of the frameworks are also investigated.The two frameworks show strong solid-state fluorescence emission at 463 and 503 nm,respectively,which are obvious red-shift compared to the emission of ligand.
文摘Aromatics have a broad application in our everyday life ranging from plastics, coatings and fibres, to food and pharmaceuticals. To date the bulk of these aromatics is derived from naphtha-based pet-rochemistry. However, recent progress in the fermentative production of metabolites using renew-able resources and engineered microbes has enabled the production of bio-precursors, such as 4-amino benzoic acid (pABA) and 2-amino benzoic acid (oABA). In this work we explored the feasibility of Sandmeyer reactions for the conversion of pABA to terephthalic and oABA salicylic acid, providing two very important platform chemicals for the chemical and pharmaceutical industries. We could demonstrate that both acids can be obtained from the amino benzoic acids derived from the shikimate pathway in microbes and plants. Good conversions could be achieved using Sandmeyer reactions at mild conditions with biodegradable reagents and without organic solvents.
基金This work was supported by the Tianjin Youth Science Foundation for the 21th Century,Tianjin,China.
文摘The classical crystallization theories proposed by Avrami, Evans, and Mandelkern wereextended to the nonisothermal situation. The expressions derived from the classical equations canbe expressed in either the differential form or the integral form. A method was provided so as toobtain the parameters characterizing the crystallization rate and mechanism from DSC curves withseveral constant heating or cooling rates. The rate constants of crystallization obtained from bothisothermal and nonisothermal curves of poly(ethylene terephthalate)were compared.
基金support from the Hong Kong Environment and Conservation Fund through ECF Project(84/2017)Science and Technology Project of Henan Provincial Department of Transportation(2020J6).
文摘Waste plastics,such as waste polyethylene terephthalate(PET)beverage bottles and waste rubber tyres are major municipal solid wastes,which may lead to various environmental problems if they are not appropriately recycled.In this study,the feasibility of collectively recycling the two types of waste into performance-increasing modifiers for asphalt pavements was analyzed.This study aimed to investigate the recycling mechanisms of waste PET-derived additives under the treatment of two amines,triethylenetetramine(TETA)and ethanolamine(EA),and characterize the performances of these additives in modifying rubberized bitumen,a bitumen modified by waste tyre rubber.To this end,infrared spectroscopy and thermal analyses were carried out on the two PET-derived additives(PET–TETA and PET–EA).In addition,infrared spectroscopy,viscosity,dynamic shear rheology,and multiple stress creep recovery tests were performed on the rubberized bitumen samples modified by the two PET-derived additives.We concluded that waste PET can be chemically upcycled into functional additives,which can increase the overall performance of the rubberized bitumen.The recycling method developed in this study not only helps alleviate the landfilling problems of both waste PET plastic and scrap tyres,but also turns these wastes into value-added new materials for building durable pavements.
文摘The phase separation behavior of blend of Surlyn and poly(ethylene terephthalate) (PET) has been studied by scanning electron microscopy and IR. It is shown that particles of Surlyn are dispersed in PET matrix, and this phase separation is controlled by heat-treated conditions of the blend.
