To solve the problems of long process and large amount of pollutants in metal extraction of waste zinc-based desulfurizer and copper-zinc-based catalyst,a technical method of efficient and clean synergistic separation and utilization of the copper and zinc in the two materials by vacuum carbothermal reduction method was proposed.On the basis of the characterizations of the chemical composition and main phase of the waste desulfurizer and copper-zinc-based catalyst,the experimental study of vacuum carbothermal synergistic extraction and separation of copper and zinc was carried out.The optimum zinc volatilization process conditions were obtained by adjusting the heating temperature,holding time and batch ratio,and the process mechanism was analyzed in depth.The results showed that the waste desulfurizer with ZnS as the main phase and the scrap copper-zinc-based catalyst with CuO and ZnO as the main phase could effectively reduce and volatilize the zinc in the two materials during vacuum carbothermal reduction.The mixture of copper-zinc-based catalyst,desulfurizer,and carbon with C∶(ZnO+CuO)as 1∶1(molar ratio)and CuO∶ZnS as 2∶1(molar ratio)was heated to 1100℃for 60min,the reduction and volatilization rate of zinc reached 99.56%,and the copper grade in the reduced slag was 59.46%with the copper existing mainly as Cu1.96S,which could be used as ice copper blowing raw materials.
The presence of various furan aldehydes in cellulose hydrolysate affects the fermentation of 1,2,4-butanetriol (BT) in a similar way. In this study, furfural was used as a representative for the modification of BT-producing E. coli for tolerance. The engineered Escherichia coli harboring the recombinant BT pathway had decreased the biomass by 58% and the BT titer by 52% in the presence of 0.4 g/L furfural. To improve the tolerance of the strain and the efficiency of BT synthesis in the hydrolysate, seven furfural tolerance genes, ucpA , fucO , groESL , lpcA , pncB , nadD , and nadE were introduced into the BT-producing E. coli . All these genes differentially improved the furfural tolerance performance of the cells. Overexpression of these tolerance genes reduces the accumulation of reactive oxygen species and promotes glycolysis. Oxidoreductase UcpA was the best candidate for improving cell growth. UcpA also increased the activities of Xdh and YqhD and the RNA levels of YjhG and KivD, leading to a 32% increase in BT yield per biomass and the best BT titer of 14.4 g/L in the presence of 0.4 g/L furfural. In the shaker and 5 L fermenter, the BT titer reached 5.2 g/L and 11.2 g/L, respectively, by using corn cob cellulose as substrate.
Bioplastics are polymers made from sustainable bio-based feedstocks. While the potential of producing bio-based monomers in microbes has been investigated for decades, their economic feasibility is still unsatisfactory compared with petroleum-derived methods. To improve the overall synthetic efficiency of microbial cell factories, three main strategies were summarized in this review: firstly, implementing approaches to improve the microbial utilization ability of cheap and abundant substrates; secondly, developing methods at enzymes, pathway, and cellular levels to enhance microbial production performance; thirdly, building technologies to enhance microbial pH, osmotic, and metabolites stress tolerance. Moreover, the challenges of, and some perspectives on, exploiting microorganisms as efficient cell factories for producing bio-based monomers are also discussed.
The gas sulfur reduction of phosphogypsum in the acid co-production of sulfoaluminate cement clinker is a new process for treating phosphogypsum. The reduction furnace of this system was studied and analyzed by combining computational fluid dynamics (CFD) and experimental validation. The effects of n(CaSO4)/n(S2), particle residence time, and kiln tail flue gas temperature on the performance of the reduction furnace were obtained. A second-order response model based on the response surface methodology was developed using a three-factor Box–Behnken design (BBD). The results show that the comparison error between the simulation and test data of the reduction furnace is acceptable. The above three conditions arranged in order of significance in terms of their effect on the performance of the reduction furnace is n(CaSO4)/n(S2) > particle residence time > kiln tail gas temperature. Finally, by optimizing the response surface model, the predicted optimal operation parameter combination is n(CaSO4)/n(S2) = 3.04, with the particle residence time and flue gas temperature at the kiln end given as 8.90 s and 1265.39 K, respectively.
Bromine chloride is an important halogenating reagent in industry.Its synthesis has many challenges such as high heat release,low production efficiency and serious potential safety hazards.The continuity and miniaturization of producing equipment is an important development direction of bromine chloride synthesis technology.To develop microreaction technology for preparing bromine chloride via absorbing chlorine by means of dichloromethane solution of bromine,the mass transfer performances of Corning G1 reactor,Jinde C1 reactor and self-made micromixer + micro packed reactor were investigated.Continuous and stable preparation of bromine chloride was realized and the space-time yield of the microreactors reached 2.25g/(min∙mL).Bromination of polystyrene was implemented using the bromine chloride prepared from microreactors,and brominated polystyrene products with mass percentage>66% bromine content and 5% thermogravimetric temperature>370℃ were obtained.
高效、紧凑的换热方式需求日益增大,具有高度方向速度梯度大的窄缝通道成为最有前景的方式之一.本文以质量分数为55%的乙二醇水溶液为工质,针对钛窄缝通道在负压工况进行流动沸腾换热实验.实验在质量流率750～2000kg/(m2·s)、饱和温度为80～90℃、入口温度60～70℃的条件下进行.结果表明,钛需要更高的热流密度激活大量成核点,从而其过冷沸腾起始点(ONB)前后平均换热系数h基本不变;质量流量对于ONB和沸腾充分发展阶段的平均换热系数影响很大;在高过冷度时,沸腾充分发展阶段,钛窄缝通道换热性能对于入口温度不敏感;提高进口温度降低过冷度可以极大提高平均换热系数,70℃条件下平均换热系数在沸腾充分发展阶段可以提高65%;背压对于换热性能的影响主要在沸腾充分发展阶段,背压越低平均换热系数越大.
硝化反应是典型的快速强放热反应,是生产含能化学品的重要反应,但也是安全事故频发的反应,因此"谈硝色变"是含能化学品生产面临的重大挑战.本文指出:与国外比,我国硝化工艺和装备都存在明显差距,连续硝化是卡脖子技术.文中总结了清华大学微化工团队提出绝热微反应连续硝化思路,提出其在芳香化合物绝热微反应硝化研究中取得的进展,指出该技术创新主要涉及微反应工艺安全系统评价方法、硝化动力学、绝热反应工艺、微化工系统构建和硝化全流程工艺再造.
传统搅拌反应器运行模式匹配度较差,缺乏对搅拌装备的智能化诊断、控制和匹配能力监测.近年来,工业互联网的兴起引起了各个行业内巨大的研究兴趣,并取得了相对可喜的进展.本文首先概述了工业物联网兴起的背景及其特征优势,然后简述了搅拌反应器智能化需解决的关键技术难题,而后采用工业物联网技术,对表征搅拌反应器内部物料混合状态的时变信号进行数据智能化采集、分析和处理,并预测设备内部物料未来状态的变化趋势.结合流体混沌混合特性、宏观混合行为以及搅拌反应器结构参数和操作参数进行大数据分析,形成了智能监测与混沌同步体系,并建立搅拌反应器智能监测的操作平台,主要包括风险动态管控、在线监测预警和实时反馈控制三大功能模块.最后,总结了该搅拌反应器智能终端在化工领域存在的挑战,并且对未来发展方向及应用前景进行了展望.希望通过本文能吸引化工方面不同研究背景的学者进入这个多学科交叉领域,共同为推动节能减排、发展智能化工装备与安全做出一定贡献.
化工行业作为国家的支柱性产业，不断地积极响应国家号召，推动行业数字化、智能化发展。实验室和研究院作为化学工程核心技术支撑，是化工行业智能化转型中必不可少的一部分。站在智能化变革的起点，本文调研归纳了目前国内外化工实验室的智能化转型最新进展，围绕科研创新展望了化工实验室的智能化转型蓝图，提出了从信息化、数字化到智能化过渡，涵盖不同发展层级的智能研究院建设大纲，为规划智能研究院建设的具体方案提供指导，并展望了人工智能全面赋能的化工科研范式变革。
According to “Montreal Protocol on Substances that Deplete the Ozone Layer”, waste refrigerants will be phased out and destroyed due to their greenhouse effect and ecological hazards. At present, there is no efficient and low-cost method to treat waste refrigerant. We propose a new strategy for the photocatalytic treatment of waste refrigerant. BiPO 4 /GA aerogels were prepared, which showed excellent adsorption capacity of graphene and efficient photocatalytic capacity of BiPO 4 . The rapid adsorption and complete mineralization of pollutants were realized. The process of photocatalytic degradation of typical refrigerant tetrafluoroethane（CH 2 FCF 3 , R134a） was monitored online by in situ infrared spectroscopy. The process of bond breaking and complete degradation of R134a was analyzed. It was clear that the final product of photocatalytic degradation of R134a was HF and CO 2 . The results showed that R134a could be completely mineralized and decomposed under the photocatalysis of BiPO4/GA aerogel. The research provided an effective way to degrade waste refrigerants, and the application of in-situ infrared spectra would also be a reliable method for monitoring the decomposition process of waste refrigerants.
The heat transfer performance of a stirred tank with the four-pitched blade with stabilizing fins-Rushton combined impellers and helical coils was studied based on the combination of computational fluid dynamics(CFD)simulation and heat transfer experiments.The flow distribution,temperature distribution,temperature boundary layer and Nusselt number outside the coil were obtained.The results showed that the error of temperature between experimental measurement and numerical simulation was less than 4K.The high temperature area in the stirred tank was located in the circulating large eddy current area at the coil,and the maximum temperature difference was kept within 3K.The stabilizer fins could improve liquid axial-flow performance and make the temperature distribution of the stirred tank more uniform.The average temperature boundary layer thickness of XZ plane and YZ plane outside the inner coil was 3.01mm and 2.70mm,respectively.According to experimental data and numerical simulation,it was found that the order of influence of different factors on the Nusselt number outside the inner coil was as follows:viscosity of the mixing medium>mixing speed>blade spacing>distance from the bottom.The maximum error of Nusselt number between experiment and simulation was 14.56% ,and the minimum error was 4.23% ,which verified the feasibility of numerical simulation well.The research results can provide a reference for the application of the four-pitched blade with stabilizing fins-Rushton combined impellers in the practical industry.
Layered double hydroxides(LDHs)as new functional materials were widely used to remove pollutants due to their excellent adsorption and catalytic performances.In this study,the clustering data analysis over the past decade were conducted based on keyword retrievals.The preparation of LDHs as well as modification methods were introduced.The application in environment treatment and remediation was summarized.The modification of LDHs was studied to enhance the adsorption and catalytic performances of LDHs,thus increasing their adaptability and expanding their application.Specifically,the removal and degradation mechanisms of organic pollutants,including dyes and antibiotics by LDHs in dye,pharmaceutical and poultry wastewater were discussed in detail.The influence factors on the removal of heavy metals from mining and smelting wastewater by LDHs were analyzed.The treatment of nitrogen and phosphorus in eutrophic water body were summarized.In addition,the application of LDHs in farmland soil remediation and CO2 capture with recycling was clarified.This paper made a comprehensive summary of the application of LDHs in the field of environment,and pointed out the limitations and challenges of LDHs research,providing direction and ideas for future research.
Combustion of adding hydrogen in industrial gas boilers can reduce the use of carbon-containing fuels,but it will cause an increase in NOx emission.Therefore,this paper conducted a detailed study on the hydrogen mixed combustion characteristics of an existing industrial gas-fired HL75-2.5/260-Q boiler.The formation law and reduction path of NO and N2O were explored to provide a fundamental guide for the subsequent development of low-nitrogen burners for hydrogen mixed combustion.Firstly,based on the detailed reaction mechanism of methane Gri-mesh 3.0,the combustion characteristics and pollutant formation characteristics of gas with a hydrogen content ratio of 0-90％ were simulated.Secondly,the chemical reactor network model inside the boiler was established by Chemkin,and the generation path,sensitivity,and production rate characteristics of NO and N2O under the optimal hydrogen mixing ratio were analyzed.The results showed that when the excess air coefficient was 1.2,the high-temperature area of the flame and the outlet temperature increased with the increase of the hydrogen doping ratio.The outlet NO concentration gradually increased from 85.59mg/m3 to 249.85mg/m3.The N2O emission first decreased and then increased,and the N2O emission was at least 0.16mg/m3 at the hydrogen mixed ratio of 0.2.NO mainly came from the elementary reactions R179(N + O2 ＝ NO + O)and R180(N + O2 ＝ NO + O)),and N2O mainly came from the elementary reaction R185[N2 + O(+M)＝ N2O(+M)].
Hydrogenation of carbon-oxygen bonds to produce alcohol is a significant hydrogenation reaction with wide applications,such as the hydrogenation of CO,CO2,esters,carboxylic acids,anhydrides,and furfural.In the reaction process,the catalyst is the key to determine the degree of reaction and the distribution of hydrogenation products.The development of copper-based catalysts with high activity and selectivity to replace precious metals has research value and reference significance for the industrial application.Based the most two serious problems of copper-based catalysts,i.e.facile sintering and agglomeration at high temperatures,the researches of copper-based catalysts in the carbon-oxygen bond hydrogenation reaction are reviewed.The methods to avoid catalyst inactivation and increase catalyst stability are introduced,and the stability enhancement of copper-based catalysts by adding different additives,support effects,and constructing special catalyst structures,are discussed.The factors influencing the catalyst stability such as high oxygen vacancy to promote defect and adsorption sites,and confinement to restrict metal migration and aggregation,are summarized.
In order to efficiently utilize the spent bleaching earth produced by the edible oil industry,a novel adsorbent was prepared by transforming spent bleaching earth into BE500 and BE700 to remove the copper ions(Cu2+)and tetracycline(TC)that commonly existed in livestock and poultry wastewater.The effects of adsorbent dosage,pH,ionic strength,and competition adsorption under the binary system was investigated.The results showed that BE700 was more suitable for Cu2+ adsorption,while BE500 exhibited higher removal efficiency for TC.Compared with Cu2+,the adsorption capacity of TC was less sensitive to the changes in the pH of the reacted solution.The results of kinetic models pointed out that the adsorption of BE500 and BE700 for Cu2+ and TC could be mainly attributed to the chemical reaction,and the liquid-film diffusion controlled the whole adsorption rate.The adsorption isotherms and thermodynamics model indicated that Cu2+ and TC were multi-layered immobilized on the surface of BE500 and BE700,and the adsorption was spontaneous with an endothermic process.In addition,the ion interference experiment showed that the co-existed of Cl-and Na+ posed an insignificant role in influencing the adsorption performance for Cu2+ and TC.The Cu2+ and TC adsorption capacity of BE500 and BE700 was significantly enhanced under the binary system compared to that in the single system,which meant that the Cu2+ and TC presented a synergistic effect due to the reaction between Cu2+ and TC.The characterizations suggested that the pore-filling,ion exchange,complexation,hydrogen bond and π-π electron donor-acceptor interaction might participated in the removal mechanism of Cu2+ and TC.
Silica scaling led to irreversible decline of the nanofiltration/reverse osmosis(NF/RO)membrane permeation flux and severely limited the water productivity of the membrane system,which was widely considered as a difficult challenge in water treatment process.Two types of silica scale on NF/RO membrane were introduced firstly,namely inorganic scale and combined inorganic-organic scale.Then,the effects of influent water quality,membrane surface chemical properties and topology on the formation of silica scale on membrane surface were emphatically reviewed,as well as the control strategies for the formation of silica scale on membrane surface,including influent pretreatment,scale inhibitor addition,membrane surface chemical modification and morphology regulation.Finally,the existing problems and future research directions of silica scaling control on membrane surface were summarized,mainly including the research on silica scaling behavior using model substrates with controllable surface properties,the in-depth exploration of the relationship between membrane surface chemical properties and silica scaling potential,the thorough research on the delay and inhibition mechanism of polymer scale inhibitors at the molecular level,the development of novel membrane materials to simultaneously inhibit silica scaling and organic fouling,and the establishment of a comprehensive database related to membrane surface properties and silica scaling under different influent water quality conditions,which were of important guiding significance for the development of efficient silica scale control strategies.
In order to clarify the effect of NaCl content on the formation and stability of CO2 hydrate,this paper used silica gel as the porous medium to form hydrate under the initial temperature and pressure of-0.5℃ and 3.3MPa,respectively,and carried out hydrate decomposition experiments under the conditions of 1.5℃ and 0MPa.The formation and decomposition rules of CO2 hydrate in the system with different concentrations of NaCl(0.18-0.53g/L)were determined.The experimental results showed that:the induced nucleation time of CO2 hydrate shortened with the increase of NaCl concentration,and the nucleation time was smaller than that of the pure ice powder system when the concentration was greater than 0.48g/L,but the amount of hydrate generation and the induced nucleation time showed an opposite trend with the change of NaCl concentration;NaCl was not conducive to the rapid formation of hydrate during the primary pressurization,and during the secondary pressurization,only 0.28-0.38g/L NaCl promoted the hydrate formation rate.Meanwhile,it was found that the addition of NaCl enhanced the stability of CO2 hydrate,the stability of hydrate increased and then decreased with the increase of NaCl concentration,and the stability was best at 0.38g/L NaCl concentration.
Leakage prevention and thermal conductivity improvement of phase change materials are two key issues for energy storage of phase change materials.In this work,nano-TiO2@n-docosane microcapsules were prepared by fine emulsion interfacial polymerization using tetrabutyl titanate(TBT)as precursor.The formation process was observed by biomicroscopy,and the properties of nano-TiO2@n-docosane microcapsules were characterized by scanning electron microscope(SEM),differential scanning calorimeter(DSC),thermal conductivity meter and thermogravimetric analyzer.The experimental results showed that the formation process of nano-TiO2@n-docosane microcapsules was that the number of nano-microcapsules changed from less to more,the particle size from small to large,the interface of microscopic solution from blurred to clear,and the aging and cooling process of solution was gradually from gelation suspension state to powder precipitation state.The results of SEM test indicated that the particle size of nano-TiO2@n-docosane microcapsules was significantly related to rotational speed,and the appearance was closely related to the dosage of TBT,hydrochloric acid(HCl)and sodium dodecyl sulfate(SDS).The DSC results showed that the melting and solidification temperatures were 41.3℃ and 42.4℃ ,respectively.The latent heat of nano-TiO2@n-docosane was 178J/g.The coating rate and the coating efficiency were 70.7% and 69.0% ,respectively with the heat storage capacity of 97.6% .The average thermal conductivity of nano-TiO2@n-docosane microcapsules was 215% of n-docosane.It was found from the infrared spectrum test that there was no chemical reaction when n-docosane and TiO2 were physically combined.The results of thermogravimetric analysis indicated that TiO2 formed a physical protective barrier and slowed down the diffusion of n-docosane outside the capsule.
Due to the worsening global climate change and the increasing extreme weather events,CO2 capture and separation has important strategic significance and relates to human survival.In recent years,new materials for CO2 capture and separation have emerged.Among them,ionic liquids(ILs),as a new alternative to organic solvents,have received tremendous interest due to the tunable chemical structures and unique physicochemical properties,such as low volatility,high thermal stability and excellent solubility.And metal-organic frameworks(MOFs)have also been considered as fascinating porous materials for CO2 capture and separation.In this paper,the research progress of CO2 capture and separation by ILs/MOFs composites is summarized.The adsorptive separation via MOFs-supported ILs,ILs-modified MOFs,dispersing MOFs in ILs to form porous liquids,and membrane separation are all discussed,as well as the advantages and disadvantages of each method.In addition,the application prospect and development of ILs/MOFs composites in CO2 capture and separation are also discussed.
Membrane technology has been widely applied in the wastewater treatment;however,membrane fouling hinders its further applications.The exploitation of antifouling membranes to achieve energy saving and consumption reduction has been a one of hot topics.As a kind of surface modification strategy,the layer-by-layer(LbL)self-assembly technique has been explored in the antifouling membrane preparation due to its characteristics of diverse assemble-materials,widely practical scenarios,mild preparation conditions and molecular-scale controllability.In this review,on the basis of clarifying the mechanism of LbL self-assembly technique applied in the membrane fouling control,the effects of selection and pretreatment of base membranes,types of antifouling units and its combination with membranes,the number of assemble layers and preparation methods on the antifouling performance of membranes were summarized.Overall,perspectives of development on the antifouling membranes based on LbL self-assembly technique for wastewater treatment were proposed,such as excavation of the mechanism of assembly process,optimization of membrane fabrication process,reduction of preparation cost and enhancement of long-term stability.
