Mercury, generally found in natural gas, is extremely hazardous. Although average mercury levels are relatively low, they are further reduced to comply with future mercury regulations,which are stringent in order to a...Mercury, generally found in natural gas, is extremely hazardous. Although average mercury levels are relatively low, they are further reduced to comply with future mercury regulations,which are stringent in order to avoid releasing to the environment. Herein, vapor mercury adsorption was therefore investigated using two kinds of supports, granular activated carbon（GAC） and titanium dioxide（Ti O2）. Both supports were impregnated by silver（5 and 15 wt.%）,before testing against a commercial adsorbent（sulfur-impregnated activated carbon, SAC）. The adsorption isotherm, kinetics, and its thermodynamics of mercury adsorption were reported.The results revealed that Langmuir isotherm provided a better fit to the experimental data.Pseudo second-order was applicable to describe adsorption kinetics. The higher uniform Ag dispersion was a key factor for the higher mercury uptake. Ti O2 supported silver adsorbent showed higher mercury adsorption than the commercial one by approximately 2 times.Chemisorption of mercury onto silver active sites was confirmed by an amalgam formation found in the spent adsorbents.展开更多
For the first time, a series of alkynyl carbon materials（ACMs） were prepared via the mechanochemical reaction of CaC2 with six polyhalogenated precursors, namely CCl4,C2Cl6, C2Cl4, C6Cl6, C6Br6, and C14H4Br10（ACM-1...For the first time, a series of alkynyl carbon materials（ACMs） were prepared via the mechanochemical reaction of CaC2 with six polyhalogenated precursors, namely CCl4,C2Cl6, C2Cl4, C6Cl6, C6Br6, and C14H4Br10（ACM-1, ACM-2, ACM-3, ACM-4, ACM-5, and ACM-6,respectively） and used for the adsorptive removal of mercury from aqueous solutions.Based on preliminary investigations, the adsorption of mercury on ACM-5 was studied in depth. Specifically, the effect of p H on mercury adsorptivity, adsorption kinetics,thermodynamics, isotherms, and recyclability was studied. The adsorptivity of mercury on ACMs was found to be closely related to the hydrocarbon precursor, specific surface area of sorbent, and the alkynyl content. ACM-5 showed the best performance and is among the best raw carbonaceous sorbents reported so far, with a Langmuir saturated adsorption capacity of 191.9 mg g-1. The promising mercury adsorption performance mainly arises from the strong Lewis soft acid–soft base interactions between the alkynyl groups and mercury ions. The adsorption isotherms could be satisfactorily correlated with the Langmuir equation. The results show that the ACMs can be used as efficient sorbents for the removal of mercury and may also be useful for the adsorption of other heavy metals.展开更多
The interest in curtailing environmental pollution issues through physical separation processes has inspired an extensive search for novel nanoporous materials with exceptional adsorption capabilities.Covalent triazin...The interest in curtailing environmental pollution issues through physical separation processes has inspired an extensive search for novel nanoporous materials with exceptional adsorption capabilities.Covalent triazine frameworks(CTFs),emerged as a class of crystalline covalent organic frameworks(COFs),have been widely examined for various separation applications,owing to their large porosity,high stability,and rich nitrogen(N)doping.The development of CTFs for efficient adsorption of mercury(Ⅱ)(Hg^(2+))is of great importance for the field,whereas it is rarely attempted,on account of limited synthetic strategies and unknown structural-property relations of conventional CTFs derived from ionothermal approaches.Herein,we report rational synthesis of a crystalline CTF with methylthio pendant arms for efficient removal of Hg^(2+)with an exceptional capacity of 751 mg·g^(-1),ranking at the top among previously-reported adsorbents.This work may open up new possibility in the synthesis of COFs for various separations.展开更多
Fly ash is a potential alternative to activated carbon for mercury adsorption. The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated. X-ray fluoresc...Fly ash is a potential alternative to activated carbon for mercury adsorption. The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, and other methods were used to characterize the samples. Results indicate that mercury adsorption on fly ash is primarily physisorption and chemisorption. High specific surface areas and small pore diameters are beneficial to efficient mercury removal. Incompletely burned carbon is also an important factor for the improvement of mercury removal efficiency, in particular. The C-M bond, which is formed by the reaction of C and Ti, Si and other elements, may improve mercury oxidation. The samples modified with CuBr2 , CuCl 2 and FeCl3 showed excellent performance for Hg removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury （Hg0） into its oxidized form （Hg2＋）. Cu2＋ and Fe3＋ can also promote Hg 0 oxidation as catalysts. HCl and O2 promote the adsorption of Hg by modified fly ash, whereas SO2 inhibits the Hg adsorption because of competitive adsorption for active sites. Fly ash samples modified with CuBr2 , CuCl2 and FeCl3 are therefore promising materials for controlling mercury emissions.展开更多
A fast and selective adsorbent for Hg（ll） from aqueous solutions using thiourea （TU） functionalized polypropylene fiber grafted acrylic acid （PP-g-AA）, PP-g-AA-TU fibers, was characterized by Fourier transform i...A fast and selective adsorbent for Hg（ll） from aqueous solutions using thiourea （TU） functionalized polypropylene fiber grafted acrylic acid （PP-g-AA）, PP-g-AA-TU fibers, was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The adsorption behavior of the functionalized chelating fibers for Hg（Ⅱ） was investigated by static adsorption experiments, and the effects of some essential factors on adsorption of Hg（Ⅱ） were examined, such as pH, initial concentration, adsorption time, coexisting cations, and temperature, The results showed that the adsorptive equilibrium could be achieved in 10 min, and the equilibrium adsorption quantity of PP-g-AA-TU fibers was 20 times that of PP-g-AA fibers. The PP-g-AA-TU fibers showed a very high adsorption rate and a good selectivity for Hg（Ⅱ） over a wide range of pH. The adsorption isotherm can be well described with Langmuir model, with the maximum adsorption capacity for Hg（Ⅱ） up to 52.04 mg.g-1 and the removal of Hg（Ⅱ） more than 97%. The kinetic data indicate that the adsorption process is best-fitted into the pseudo-second-order model.展开更多
Cyclic voltammetry shows that DBPPH has a pair of cathodic and anodic peaks at Hg electrode.Epc=-1.49 V and Fpa=-1.43 V(vs.Ag/AgCl).The cathodic peak shows adsorptive characteristics.The adsorbed species is DBPPH neut...Cyclic voltammetry shows that DBPPH has a pair of cathodic and anodic peaks at Hg electrode.Epc=-1.49 V and Fpa=-1.43 V(vs.Ag/AgCl).The cathodic peak shows adsorptive characteristics.The adsorbed species is DBPPH neutral molecule. The method for measuring trace amount of DBPPH by adsorptive stripping voltammetry is established.展开更多
Two kinds of novel sulfhydryl functionalized covalent organic frameworks were fabricated as adsorbents for the removal of ultra-trace concentrations of Hg^(2+)from water.The two kinds of sulfhydryl functionalized cova...Two kinds of novel sulfhydryl functionalized covalent organic frameworks were fabricated as adsorbents for the removal of ultra-trace concentrations of Hg^(2+)from water.The two kinds of sulfhydryl functionalized covalent organic frameworks were obtained via a thiol-ene click reaction between the thiol groups of trithiocyanuric acid(TTC)or bismuththiol(BMT)and vinyl groups on the surface of covalent organic frameworks.The material structure was characterized by XRD,SEM,EDS,FT-IR,BET,and TG analysis.Due to their rich sulfur content,both adsorbents(COF-SH-1 and COF-SH-2)exhibited a high level of selective Hg^(2+)removal from aqueous solution with maximum adsorption capacities of 763.4 mg g^(-1) and526.3 mg g^(-1),respectively.Furthermore,in the presence of ultra-low concentrations of Hg^(2+)both materials exhibited excellent performance,achieving rapid Hg^(2+)removal at concentrations from 10μg L^(-1) to less than 0.02 ng L^(-1).Analysis of the adsorption mechanism indicates that the sulfur containing chelating groups exhibit a strong binding capacity for Hg^(2+).Results show that the structure determines the performance,with the amount of adsorption sites being related to the adsorption capacity.Therefore,as sulfhydryl functionalized covalent organic frameworks contain an abundance of adsorption sites,these materials can effectively achieve the removal of ultra-low trace Hg^(2+)concentrations and have promising future application potential for the environmental detection of heavy metals.展开更多
Due to the uneven distribution of pore size in coal and its wide distribution range,it is difficult to effectively characterize the multi-scale pore structure of coal by a single method.In this paper,the multi-scale p...Due to the uneven distribution of pore size in coal and its wide distribution range,it is difficult to effectively characterize the multi-scale pore structure of coal by a single method.In this paper,the multi-scale pore structure characteristics of coal were analyzed comprehensively by using scanning electron microscope,low-temperature liquid nitrogen adsorption,high-pressure mercury intrusion and constant-rate mercury intrusion.In addition,the effects of metamorphism on the volume and specific surface area of pores in coal were revealed,and the relationships between coal rock permeability and pore structure characteristic parameters were described.And the following research results were obtained.First,with the increase of coal metamorphism,the volume and specific surface area of nanopores in coal decrease first and then increase,and they reach the minimum value when Ro,max is about 1.8%.Second,the pore and throat radii of coal samples are overall in the form of normal distribution.And with the increase of coal metamorphism,the pore radius corresponding to the maximum distribution frequency increases.Third,the samples of low-rank bituminous coal are the highest in throat radius distribution range,connected throat radius and average throat radius.Fourth,the samples of anthracite coal are the lowest in throat radius distribution range and connected throat radius.Fifth,there is a single main peak in the distribution of pore-throat ratios of low-and medium-rank bituminous coal samples,and the pore-throat ratios corresponding to the main peak is relatively low.Sixth,the permeability of coal is in a positive correlation with porosity and an average throat radius,and in a negative correlation with an average pore-throat ratio,but in no obvious correlation with an average pore radius.展开更多
Polythioureas with great potential in precious metal recovery materials,dielectric materials,light refractive materials,self-healing materials,and adhesives have become a group of popular polymer materials.While vario...Polythioureas with great potential in precious metal recovery materials,dielectric materials,light refractive materials,self-healing materials,and adhesives have become a group of popular polymer materials.While various synthetic approaches have been reported for different polythiourea structures,which generally involve expensive and toxic monomers,several polythiourea structures,such as asymmetric aromatic polythioureas,still have limited access.Herein,a base-catalyzed multicomponent polymerization(MCP)of elemental sulfur,diisocyanides,and diamines was developed,which was generally applicable for both aromatic amines with low reactivity and aliphatic amines with high nucleophilicity,affording polythioureas with great structural diversity,high Mw s of up to 107,700 g/mol and high yields of up to 99%.Moreover,aromatic polythioureas with different aromatic spacers installed on each side of the thiourea moiety could be facilely synthesized.Amine exchange reactions were studied for thiourea compounds or polythioureas,indicating that the C-N bonds of the thiourea moiety on the aromatic substitute side were more labile compared with those on the aliphatic substitute side,rendering the potential controllable degradation of different polythiourea structures.The polythioureas generally possess high thermal stability,with the glass transition temperatures ranging from 121 to 169℃.These polythioureas could efficiently absorb Hg2+from polluted water,and aromatic polythioureas generally showed better performance compared with semi-aromatic and aliphatic polythioureas.This work has hence provided a general synthetic approach for various aliphatic,aromatic,and semi-aromatic polythioureas with symmetric or asymmetric thiourea structures.The dynamic covalent bond nature of thioureas endowed these polymer materials with controllable degradation,making them sustainable functional polymer materials.展开更多
Developing new chemically recyclable polymers is important for a circular plastics economy.Herein,we prepared a class of 1,4-dithian-2-one(DTO)with thioether and thioester functionalities.These sulfur-substituted mono...Developing new chemically recyclable polymers is important for a circular plastics economy.Herein,we prepared a class of 1,4-dithian-2-one(DTO)with thioether and thioester functionalities.These sulfur-substituted monomers(DTO)showed excellent reactivity for ring-opening polymerization(turnover frequency(TOF)up to 2.3×10^(4)h^(-1)),which afforded poly(thioetherthioester)s(P(DTO)s)with high air stability,high crystallinity,and commercial high-density polyethylene-like mechanical property(σB=29.59±1.08 MPa andεB=749%±36%).Intriguingly,chemical recycling of P(DTO)to monomer could be accomplished with excellent efficiency in dilute solution(1 min)at room temperature or even from a commodity plastic waste mixture under catalyst-free thermal bulk condition(180°C),thus establishing its circular life cycle.P(Me-DTO)could be applied for selective removal of Hg^(2+)with>99%removal efficiency.More importantly,Me-DTO could be recovered in high yield after utilization for Hg^(2+)adsorption.展开更多
Polyacrylamide/silica （PAM/SiO2） composite capsules were synthesized by inverse Pickering emulsion polymerization. Silica nanoparticles modified with methacryloxypropyltrimethoxysilane （MPS） were used as a stabili...Polyacrylamide/silica （PAM/SiO2） composite capsules were synthesized by inverse Pickering emulsion polymerization. Silica nanoparticles modified with methacryloxypropyltrimethoxysilane （MPS） were used as a stabilizer. Transmission electron microscopy （TEM）, scanning electron microscopy （SEM）. Fourier transform infrared （FTIR） spectroscopy, and thermal gravimetric analysis （TGA） were used to characterize the morphology and composition of the composite capsules. SEM and TEM images showed that capsules consisted of a particle shell and a polymer inner layer. The capsule size depends on the nanoparticle concentration in the continuous phase. The composite rigidity largely depends on the acrylamide concentration. FTIR and TGA results indicated the existence of polyacrylamide and SiO2 in the composite particles. Aqueous Hg（ll） removal testing by the PAM/SiO2 composite capsules indicated promising potential for removing heavy metal ions from wastewater.展开更多
基金Petroleum Authority of Thailand (PTT) and Thailand Research Fund through the Royal Golden Jubilee Ph.D. Program (Grant no. PHD/0371/2552) for their financial supports
文摘Mercury, generally found in natural gas, is extremely hazardous. Although average mercury levels are relatively low, they are further reduced to comply with future mercury regulations,which are stringent in order to avoid releasing to the environment. Herein, vapor mercury adsorption was therefore investigated using two kinds of supports, granular activated carbon（GAC） and titanium dioxide（Ti O2）. Both supports were impregnated by silver（5 and 15 wt.%）,before testing against a commercial adsorbent（sulfur-impregnated activated carbon, SAC）. The adsorption isotherm, kinetics, and its thermodynamics of mercury adsorption were reported.The results revealed that Langmuir isotherm provided a better fit to the experimental data.Pseudo second-order was applicable to describe adsorption kinetics. The higher uniform Ag dispersion was a key factor for the higher mercury uptake. Ti O2 supported silver adsorbent showed higher mercury adsorption than the commercial one by approximately 2 times.Chemisorption of mercury onto silver active sites was confirmed by an amalgam formation found in the spent adsorbents.
文摘For the first time, a series of alkynyl carbon materials（ACMs） were prepared via the mechanochemical reaction of CaC2 with six polyhalogenated precursors, namely CCl4,C2Cl6, C2Cl4, C6Cl6, C6Br6, and C14H4Br10（ACM-1, ACM-2, ACM-3, ACM-4, ACM-5, and ACM-6,respectively） and used for the adsorptive removal of mercury from aqueous solutions.Based on preliminary investigations, the adsorption of mercury on ACM-5 was studied in depth. Specifically, the effect of p H on mercury adsorptivity, adsorption kinetics,thermodynamics, isotherms, and recyclability was studied. The adsorptivity of mercury on ACMs was found to be closely related to the hydrocarbon precursor, specific surface area of sorbent, and the alkynyl content. ACM-5 showed the best performance and is among the best raw carbonaceous sorbents reported so far, with a Langmuir saturated adsorption capacity of 191.9 mg g-1. The promising mercury adsorption performance mainly arises from the strong Lewis soft acid–soft base interactions between the alkynyl groups and mercury ions. The adsorption isotherms could be satisfactorily correlated with the Langmuir equation. The results show that the ACMs can be used as efficient sorbents for the removal of mercury and may also be useful for the adsorption of other heavy metals.
基金The National Natural Science Foundation of China(22078349,22005319,52170109)Self-deployment Program from Lanzhou Institute of Chemical Physics(E30159SQ).
文摘The interest in curtailing environmental pollution issues through physical separation processes has inspired an extensive search for novel nanoporous materials with exceptional adsorption capabilities.Covalent triazine frameworks(CTFs),emerged as a class of crystalline covalent organic frameworks(COFs),have been widely examined for various separation applications,owing to their large porosity,high stability,and rich nitrogen(N)doping.The development of CTFs for efficient adsorption of mercury(Ⅱ)(Hg^(2+))is of great importance for the field,whereas it is rarely attempted,on account of limited synthetic strategies and unknown structural-property relations of conventional CTFs derived from ionothermal approaches.Herein,we report rational synthesis of a crystalline CTF with methylthio pendant arms for efficient removal of Hg^(2+)with an exceptional capacity of 751 mg·g^(-1),ranking at the top among previously-reported adsorbents.This work may open up new possibility in the synthesis of COFs for various separations.
基金supported by the National Natural Science Foundation of China (No.21007073)the National Basic Research Program (973) of China (No.2013CB430005)the National Hi-Tech Research and Development Program (863) of China (No.2011AA060802)
文摘Fly ash is a potential alternative to activated carbon for mercury adsorption. The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, and other methods were used to characterize the samples. Results indicate that mercury adsorption on fly ash is primarily physisorption and chemisorption. High specific surface areas and small pore diameters are beneficial to efficient mercury removal. Incompletely burned carbon is also an important factor for the improvement of mercury removal efficiency, in particular. The C-M bond, which is formed by the reaction of C and Ti, Si and other elements, may improve mercury oxidation. The samples modified with CuBr2 , CuCl 2 and FeCl3 showed excellent performance for Hg removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury （Hg0） into its oxidized form （Hg2＋）. Cu2＋ and Fe3＋ can also promote Hg 0 oxidation as catalysts. HCl and O2 promote the adsorption of Hg by modified fly ash, whereas SO2 inhibits the Hg adsorption because of competitive adsorption for active sites. Fly ash samples modified with CuBr2 , CuCl2 and FeCl3 are therefore promising materials for controlling mercury emissions.
基金Supported by the Tianjin and MOST Innovation Fund for Small Technology-based Firms(14ZXCXGX00724,13C26211200305)Science and Technology Support Program(13ZCZDSF00100)
文摘A fast and selective adsorbent for Hg（ll） from aqueous solutions using thiourea （TU） functionalized polypropylene fiber grafted acrylic acid （PP-g-AA）, PP-g-AA-TU fibers, was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The adsorption behavior of the functionalized chelating fibers for Hg（Ⅱ） was investigated by static adsorption experiments, and the effects of some essential factors on adsorption of Hg（Ⅱ） were examined, such as pH, initial concentration, adsorption time, coexisting cations, and temperature, The results showed that the adsorptive equilibrium could be achieved in 10 min, and the equilibrium adsorption quantity of PP-g-AA-TU fibers was 20 times that of PP-g-AA fibers. The PP-g-AA-TU fibers showed a very high adsorption rate and a good selectivity for Hg（Ⅱ） over a wide range of pH. The adsorption isotherm can be well described with Langmuir model, with the maximum adsorption capacity for Hg（Ⅱ） up to 52.04 mg.g-1 and the removal of Hg（Ⅱ） more than 97%. The kinetic data indicate that the adsorption process is best-fitted into the pseudo-second-order model.
文摘Cyclic voltammetry shows that DBPPH has a pair of cathodic and anodic peaks at Hg electrode.Epc=-1.49 V and Fpa=-1.43 V(vs.Ag/AgCl).The cathodic peak shows adsorptive characteristics.The adsorbed species is DBPPH neutral molecule. The method for measuring trace amount of DBPPH by adsorptive stripping voltammetry is established.
基金financially supported by the Fundamental Research Funds for the Central Universities(531118010314)Environmental Protection Science and Technology Project of Hunan Province(20190011)Key R&D Program of Hunan Province(2019SK2281)。
文摘Two kinds of novel sulfhydryl functionalized covalent organic frameworks were fabricated as adsorbents for the removal of ultra-trace concentrations of Hg^(2+)from water.The two kinds of sulfhydryl functionalized covalent organic frameworks were obtained via a thiol-ene click reaction between the thiol groups of trithiocyanuric acid(TTC)or bismuththiol(BMT)and vinyl groups on the surface of covalent organic frameworks.The material structure was characterized by XRD,SEM,EDS,FT-IR,BET,and TG analysis.Due to their rich sulfur content,both adsorbents(COF-SH-1 and COF-SH-2)exhibited a high level of selective Hg^(2+)removal from aqueous solution with maximum adsorption capacities of 763.4 mg g^(-1) and526.3 mg g^(-1),respectively.Furthermore,in the presence of ultra-low concentrations of Hg^(2+)both materials exhibited excellent performance,achieving rapid Hg^(2+)removal at concentrations from 10μg L^(-1) to less than 0.02 ng L^(-1).Analysis of the adsorption mechanism indicates that the sulfur containing chelating groups exhibit a strong binding capacity for Hg^(2+).Results show that the structure determines the performance,with the amount of adsorption sites being related to the adsorption capacity.Therefore,as sulfhydryl functionalized covalent organic frameworks contain an abundance of adsorption sites,these materials can effectively achieve the removal of ultra-low trace Hg^(2+)concentrations and have promising future application potential for the environmental detection of heavy metals.
基金sponsored by the National Natural Science Foundation of China“Structural evolution characteristics of microfissures in structural coal and its control on permeability of coal reservoir”(No.41772162)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province“Physical properties of coalbed methane reservoir and its geological control”(No.17IRTSTHN025).
文摘Due to the uneven distribution of pore size in coal and its wide distribution range,it is difficult to effectively characterize the multi-scale pore structure of coal by a single method.In this paper,the multi-scale pore structure characteristics of coal were analyzed comprehensively by using scanning electron microscope,low-temperature liquid nitrogen adsorption,high-pressure mercury intrusion and constant-rate mercury intrusion.In addition,the effects of metamorphism on the volume and specific surface area of pores in coal were revealed,and the relationships between coal rock permeability and pore structure characteristic parameters were described.And the following research results were obtained.First,with the increase of coal metamorphism,the volume and specific surface area of nanopores in coal decrease first and then increase,and they reach the minimum value when Ro,max is about 1.8%.Second,the pore and throat radii of coal samples are overall in the form of normal distribution.And with the increase of coal metamorphism,the pore radius corresponding to the maximum distribution frequency increases.Third,the samples of low-rank bituminous coal are the highest in throat radius distribution range,connected throat radius and average throat radius.Fourth,the samples of anthracite coal are the lowest in throat radius distribution range and connected throat radius.Fifth,there is a single main peak in the distribution of pore-throat ratios of low-and medium-rank bituminous coal samples,and the pore-throat ratios corresponding to the main peak is relatively low.Sixth,the permeability of coal is in a positive correlation with porosity and an average throat radius,and in a negative correlation with an average pore-throat ratio,but in no obvious correlation with an average pore radius.
基金supported by the National Natural Science Foundation of China(22325102 and 52173005)the Ministry of Science and Technology of China(2021YFA1501600)+2 种基金the GuangDong Basic and Applied Basic Research Foundation(2023B1515040003)the Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates(2019B030301003)the Fundamental Research Funds for the Central Universities(2024ZYGXZR004 and 2022ZYGXZR107).
文摘Polythioureas with great potential in precious metal recovery materials,dielectric materials,light refractive materials,self-healing materials,and adhesives have become a group of popular polymer materials.While various synthetic approaches have been reported for different polythiourea structures,which generally involve expensive and toxic monomers,several polythiourea structures,such as asymmetric aromatic polythioureas,still have limited access.Herein,a base-catalyzed multicomponent polymerization(MCP)of elemental sulfur,diisocyanides,and diamines was developed,which was generally applicable for both aromatic amines with low reactivity and aliphatic amines with high nucleophilicity,affording polythioureas with great structural diversity,high Mw s of up to 107,700 g/mol and high yields of up to 99%.Moreover,aromatic polythioureas with different aromatic spacers installed on each side of the thiourea moiety could be facilely synthesized.Amine exchange reactions were studied for thiourea compounds or polythioureas,indicating that the C-N bonds of the thiourea moiety on the aromatic substitute side were more labile compared with those on the aliphatic substitute side,rendering the potential controllable degradation of different polythiourea structures.The polythioureas generally possess high thermal stability,with the glass transition temperatures ranging from 121 to 169℃.These polythioureas could efficiently absorb Hg2+from polluted water,and aromatic polythioureas generally showed better performance compared with semi-aromatic and aliphatic polythioureas.This work has hence provided a general synthetic approach for various aliphatic,aromatic,and semi-aromatic polythioureas with symmetric or asymmetric thiourea structures.The dynamic covalent bond nature of thioureas endowed these polymer materials with controllable degradation,making them sustainable functional polymer materials.
基金supported by the National Key R&D Program of China(2021YFA1501700)the National Natural Science Foundation of China(51903177,U19A2095)+1 种基金the“1000-Youth Talents Program”the Fundamental Research Funds for the Central Universities(YJ201924,YJ202209)。
文摘Developing new chemically recyclable polymers is important for a circular plastics economy.Herein,we prepared a class of 1,4-dithian-2-one(DTO)with thioether and thioester functionalities.These sulfur-substituted monomers(DTO)showed excellent reactivity for ring-opening polymerization(turnover frequency(TOF)up to 2.3×10^(4)h^(-1)),which afforded poly(thioetherthioester)s(P(DTO)s)with high air stability,high crystallinity,and commercial high-density polyethylene-like mechanical property(σB=29.59±1.08 MPa andεB=749%±36%).Intriguingly,chemical recycling of P(DTO)to monomer could be accomplished with excellent efficiency in dilute solution(1 min)at room temperature or even from a commodity plastic waste mixture under catalyst-free thermal bulk condition(180°C),thus establishing its circular life cycle.P(Me-DTO)could be applied for selective removal of Hg^(2+)with>99%removal efficiency.More importantly,Me-DTO could be recovered in high yield after utilization for Hg^(2+)adsorption.
文摘Polyacrylamide/silica （PAM/SiO2） composite capsules were synthesized by inverse Pickering emulsion polymerization. Silica nanoparticles modified with methacryloxypropyltrimethoxysilane （MPS） were used as a stabilizer. Transmission electron microscopy （TEM）, scanning electron microscopy （SEM）. Fourier transform infrared （FTIR） spectroscopy, and thermal gravimetric analysis （TGA） were used to characterize the morphology and composition of the composite capsules. SEM and TEM images showed that capsules consisted of a particle shell and a polymer inner layer. The capsule size depends on the nanoparticle concentration in the continuous phase. The composite rigidity largely depends on the acrylamide concentration. FTIR and TGA results indicated the existence of polyacrylamide and SiO2 in the composite particles. Aqueous Hg（ll） removal testing by the PAM/SiO2 composite capsules indicated promising potential for removing heavy metal ions from wastewater.
