Bauxite residue is an alkaline waste material in the process of alumina production due to its characteristics of higher salinity and alkalinity,which results in environmental issues and extremely restricts the sustain...Bauxite residue is an alkaline waste material in the process of alumina production due to its characteristics of higher salinity and alkalinity,which results in environmental issues and extremely restricts the sustainable development of alumina industries.In this work,we conduct a column experiment to study the effects of two amendments on aggregate stability and variations in alkaline minerals of bauxite residue.The two amendments are phosphogypsum(PG)and phosphogypsum and vermicompost(PVC).The dominant fraction in aggregate is 1–0.25 mm in diameter on the surface,which takes up 39.34%,39.38%,and 44.51%for CK,PG,and PVC,respectively.Additions of PG and PVC decreased pH,EC,ESP,exchangeable Na^+concentration and the percentage of alkaline minerals,and then increased exchangeable Ca^2+concentration in bauxite residue.There was significant positive correlation between pH and exchangeable Na^+concentration,the percentage of cancrinite,tricalcium aluminate and calcite;while negative correlation was found in pH value versus exchangeable Ca^2+concentration.Theses findings confirmed that additions of phosphogypsum and vermicompost have a stimulative effect on aggregate stability in bauxite residue.In particular,amendment neutralization(phosphogypsum+vermicompost)in column represents an advantage for large-scale simulation of vegetation rehabilitate in bauxite residue disposal areas.展开更多
In order to effectively improve the properties of anion exchange membrane(AEM)materials,a series of novel poly(aryl ether nitrile)s with flexible side-chain-type quaternary phosphonium cations(PAEN-TPP-x)were designed...In order to effectively improve the properties of anion exchange membrane(AEM)materials,a series of novel poly(aryl ether nitrile)s with flexible side-chain-type quaternary phosphonium cations(PAEN-TPP-x)were designed and prepared on the basis of considering the influences of polymer backbone,cationic group species and the connection way between the cations and polymer chains.The synthetic method,structure and ion-exchange capacity,water absorption,swelling,hydroxide conductivity and alkaline stability of the obtained AEMs were studied.A comparative study with other reported AEMs was also performed for further exploration of the relationship between the structure and properties.These AEMs with flexible side-chain-type quaternary phosphonium cations displayed good comprehensive properties.Their water uptakes and swelling ratios were in the range of 11.6%–22.7%and 4.4%–7.8%at 60℃,respectively.They had hydroxide conductivity in the range of 28.6–45.8 mS cm^-1 at 60℃.Moreover,these AEMs also exhibited improved alkaline stability,and the hydroxide conductivity for PAEN-TPP-0.35 could remain 82.1%and 80.6%of its initial value at 60 and 90℃in 2 mol L^-1 NaOH solution for480 h,respectively.展开更多
Building well-developed ion-conductive highways is highly desirable for anion exchange membranes(AEMs).Grafting side chain is a highly effective approach for constructing a well-defined phaseseparated morphological st...Building well-developed ion-conductive highways is highly desirable for anion exchange membranes(AEMs).Grafting side chain is a highly effective approach for constructing a well-defined phaseseparated morphological structure and forming unblocked ion pathways in AEMs for fast ion transport.Fluorination of side chains can further enhance phase separation due to the superhydrophobic nature of fluorine groups.However,their electronic effect on the alkaline stability of side chains and membranes is rarely reported.Here,fluorine-containing and fluorine-free side chains are introduced into the polyaromatic backbone in proper configuration to investigate the impact of the fluorine terminal group on the stability of the side chains and membrane properties.The poly(binaphthyl-co-p-terphenyl piperidinium)AEM(QBNp TP)has the highest molecular weight and most dimensional stability due to its favorable backbone arrangement among ortho-and meta-terphenyl based AEMs.Importantly,by introducing both a fluorinated piperidinium side chain and a hexane chain into the p-terphenyl-based backbone,the prepared AEM(QBNp TP-QFC)presents an enhanced conductivity(150.6 m S cm^(-1))and a constrained swelling at 80℃.The electronic effect of fluorinated side chains is contemplated by experiments and simulations.The results demonstrate that the presence of strong electro-withdrawing fluorine groups weakens the electronic cloud of adjacent C atoms,increasing OH^(-)attack on the C atom and improving the stability of piperidinium cations.Hence QBNp TP-QFC possesses a robust alkaline stability at 80℃(95.3%conductivity retention after testing in 2 M Na OH for 2160 h).An excellent peak power density of 1.44 W cm^(-2)and a remarkable durability at 80℃(4.5%voltage loss after 100 h)can be observed.展开更多
Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the ...Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the most studied lysine decarboxylase CadA(E.coli)lost almost all activity at pH 8.0,which is the foremost challenge for the industrial-cadaverine production.In this study,we first found that the Na^(+)-microenvironment significantly improved the alkaline stability of the disulfide engineered lysine decarboxylaseΔLdcEt3(P233C/L628C)(half-life 362 h),compared to the conventional buffer(half-life 0.66 h)at pH 8.0.Meanwhile,the whole-cell conversion efficiency of the industrial-grade L-lysine withΔLdcEt3 could reach up to 99%in 2 h in the fermenter.Experi-mental investigation and molecular dynamics confirmed that Na^(+)-microenvironment could improve active-aggregation state and affect secondary structure ofΔLdcEt3.Therefore,Na^(+)-microenvironment stabilizesΔLdcEt3 providing a great potential industrial application for high-level cadaverine production.展开更多
基金Projects(41701587,41877511)supported by the National Natural Science Foundation of China
文摘Bauxite residue is an alkaline waste material in the process of alumina production due to its characteristics of higher salinity and alkalinity,which results in environmental issues and extremely restricts the sustainable development of alumina industries.In this work,we conduct a column experiment to study the effects of two amendments on aggregate stability and variations in alkaline minerals of bauxite residue.The two amendments are phosphogypsum(PG)and phosphogypsum and vermicompost(PVC).The dominant fraction in aggregate is 1–0.25 mm in diameter on the surface,which takes up 39.34%,39.38%,and 44.51%for CK,PG,and PVC,respectively.Additions of PG and PVC decreased pH,EC,ESP,exchangeable Na^+concentration and the percentage of alkaline minerals,and then increased exchangeable Ca^2+concentration in bauxite residue.There was significant positive correlation between pH and exchangeable Na^+concentration,the percentage of cancrinite,tricalcium aluminate and calcite;while negative correlation was found in pH value versus exchangeable Ca^2+concentration.Theses findings confirmed that additions of phosphogypsum and vermicompost have a stimulative effect on aggregate stability in bauxite residue.In particular,amendment neutralization(phosphogypsum+vermicompost)in column represents an advantage for large-scale simulation of vegetation rehabilitate in bauxite residue disposal areas.
基金supported by the Knowledge Innovation Program of Wuhan-Basic Research (2022010801010321)Wuhan Limo Technology Limited Company (2022420111000256 and2023420111000277)。
文摘阴离子交换膜水电解槽的阴离子交换膜成本低、无需铂族贵金属催化剂,有望取代高成本的质子交换膜水电解槽.然而,阴离子交换膜的尺寸稳定性差以及在高温、高浓度碱液中的稳定性差,阻碍了阴离子交换膜水电解槽的发展.最近,我们合成了一种具有优异碱性稳定性的聚(三苯基-N-甲基奎宁基)阴离子交换膜,为了进一步提高这种阴离子交换膜的机械强度和尺寸稳定性,在本工作中,我们添加了三氟苯乙酮来制备聚(三苯基-三氟苯乙酮-N-甲基奎宁基)阴离子交换膜.这种共聚阴离子交换膜具有超高的碱性稳定性(在80℃,10 mol L^(-1)的NaOH溶液中浸泡1600小时后OH^(-)电导率和机械强度不发生衰减),优异的尺寸稳定性(30–80℃温度下,纯水中溶胀率不超过7%;10 mol L^(-1)的NaOH溶液中溶胀率不超过2%),高氢氧根电导率(80°C时达134.5 mS cm^(-1))和高机械强度(抗拉伸强度达43.2 MPa).这种阴离子交换膜和镍合金泡沫电极组装的简易水电解槽在80°C下,2.0 V和5 mol L^(-1)的KOH水电解质中具有1780 mA cm^(-2)的优异电流密度,并且具有高耐久性.
基金supported by the National Natural Science Foundation of China (21404016)the Key Research Program of Jiangsu Province (BE2017645)+1 种基金the Six Talent Peaks Project of Jiangsu Province (XCL-078)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘In order to effectively improve the properties of anion exchange membrane(AEM)materials,a series of novel poly(aryl ether nitrile)s with flexible side-chain-type quaternary phosphonium cations(PAEN-TPP-x)were designed and prepared on the basis of considering the influences of polymer backbone,cationic group species and the connection way between the cations and polymer chains.The synthetic method,structure and ion-exchange capacity,water absorption,swelling,hydroxide conductivity and alkaline stability of the obtained AEMs were studied.A comparative study with other reported AEMs was also performed for further exploration of the relationship between the structure and properties.These AEMs with flexible side-chain-type quaternary phosphonium cations displayed good comprehensive properties.Their water uptakes and swelling ratios were in the range of 11.6%–22.7%and 4.4%–7.8%at 60℃,respectively.They had hydroxide conductivity in the range of 28.6–45.8 mS cm^-1 at 60℃.Moreover,these AEMs also exhibited improved alkaline stability,and the hydroxide conductivity for PAEN-TPP-0.35 could remain 82.1%and 80.6%of its initial value at 60 and 90℃in 2 mol L^-1 NaOH solution for480 h,respectively.
基金the financial support from the National Natural Science Foundation of China(22078272&22278340)。
文摘Building well-developed ion-conductive highways is highly desirable for anion exchange membranes(AEMs).Grafting side chain is a highly effective approach for constructing a well-defined phaseseparated morphological structure and forming unblocked ion pathways in AEMs for fast ion transport.Fluorination of side chains can further enhance phase separation due to the superhydrophobic nature of fluorine groups.However,their electronic effect on the alkaline stability of side chains and membranes is rarely reported.Here,fluorine-containing and fluorine-free side chains are introduced into the polyaromatic backbone in proper configuration to investigate the impact of the fluorine terminal group on the stability of the side chains and membrane properties.The poly(binaphthyl-co-p-terphenyl piperidinium)AEM(QBNp TP)has the highest molecular weight and most dimensional stability due to its favorable backbone arrangement among ortho-and meta-terphenyl based AEMs.Importantly,by introducing both a fluorinated piperidinium side chain and a hexane chain into the p-terphenyl-based backbone,the prepared AEM(QBNp TP-QFC)presents an enhanced conductivity(150.6 m S cm^(-1))and a constrained swelling at 80℃.The electronic effect of fluorinated side chains is contemplated by experiments and simulations.The results demonstrate that the presence of strong electro-withdrawing fluorine groups weakens the electronic cloud of adjacent C atoms,increasing OH^(-)attack on the C atom and improving the stability of piperidinium cations.Hence QBNp TP-QFC possesses a robust alkaline stability at 80℃(95.3%conductivity retention after testing in 2 M Na OH for 2160 h).An excellent peak power density of 1.44 W cm^(-2)and a remarkable durability at 80℃(4.5%voltage loss after 100 h)can be observed.
基金supported by the National Natural Science Foundation of China (grant number 22078346)Beijing Nova Program of Science and Technology (Z201100006820141)+4 种基金Innovation Academy for Green Manufacture, CAS (IAGM2020C19)Natural Science Foundation of Beijing (2204097)Henan Key Research and Development Project (202102210046)Hebei Provincial Natural Science Foundation (B2020103010)the CAS Pioneer Hundred Program。
文摘Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the most studied lysine decarboxylase CadA(E.coli)lost almost all activity at pH 8.0,which is the foremost challenge for the industrial-cadaverine production.In this study,we first found that the Na^(+)-microenvironment significantly improved the alkaline stability of the disulfide engineered lysine decarboxylaseΔLdcEt3(P233C/L628C)(half-life 362 h),compared to the conventional buffer(half-life 0.66 h)at pH 8.0.Meanwhile,the whole-cell conversion efficiency of the industrial-grade L-lysine withΔLdcEt3 could reach up to 99%in 2 h in the fermenter.Experi-mental investigation and molecular dynamics confirmed that Na^(+)-microenvironment could improve active-aggregation state and affect secondary structure ofΔLdcEt3.Therefore,Na^(+)-microenvironment stabilizesΔLdcEt3 providing a great potential industrial application for high-level cadaverine production.
