An efficient and mild recycling of waste melamine formaldehyde foams by alkaline hydrolysis

Melamine formaldehyde foam(MFF)generates many poisonous chemicals through the traditional recycling methods for organic resin wastes.Herein,a high MFF degradation ratio of ca.97 wt.%was achieved under the mild conditions(160℃)in a NaOH–H2O system with ammelide and ammeline as the main degradation products.The alkaline solvent had an obvious corrosion effect for MFF,as indicated by scanning electron microscopy(SEM).The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and ^(13)C nuclear magnetic resonance(NMR).Besides,the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins(MUFs).Moreover,the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times.The degradation process generated few harmful pollutants and no pre-or post-treatments were required,which proves its feasibility in the safe removal or recovery of waste MFF.

PtNi-W/C with Atomically Dispersed Tungsten Sites Toward Boosted ORR in Proton Exchange Membrane Fuel Cell Devices

The performance of proton exchange membrane fuel cells is heavily dependent on the microstructure of electrode catalyst especially at low catalyst loadings.This work shows a hybrid electrocatalyst consisting of PtNi-W alloy nanocrystals loaded on carbon surface with atomically dispersed W sites by a two-step straightforward method.Single-atomic W can be found on the carbon surface,which can form protonic acid sites and establish an extended proton transport network at the catalyst surface.When implemented in membrane electrode assembly as cathode at ultra-low loading of 0.05 mgPt cm^(−2),the peak power density of the cell is enhanced by 64.4%compared to that with the commercial Pt/C catalyst.The theoretical calculation suggests that the single-atomic W possesses a favorable energetics toward the formation of*OOH whereby the intermediates can be efficiently converted and further reduced to water,revealing a interfacial cascade catalysis facilitated by the single-atomic W.This work highlights a novel functional hybrid electrocatalyst design from the atomic level that enables to solve the bottle-neck issues at device level.

Life cycle assessment of high concentration organic wastewater treatment by catalytic wet air oxidation

There have been many studies on life cycle assessment in sewage treatment,but there are scarce few studies on the treatment of industrial wastewater in combination with advanced oxidation technology,especially in catalytic wet air oxidation(CWAO).There are no cases of using actual industrialized data onto life cycle assessment.This paper uses Simapro 9.0 software to establish a life cycle assessment model for the treatment of high-concentration organic wastewater by CWAO,and comprehensively explains the impact on the environment from three aspects:the construction phase,the operation phase and the demolition phase.In addition,sensitivity analysis and uncertainty analysis were performed.The results showed that the key factors affecting the environment were marine ecotoxicity,mineral resource consumption and global warming,the operation stage had the greatest impact on the environment,which was related to high power consumption during operation and emissions from the treatment process.Sensitivity analysis showed that electricity consumption has the greatest impact on abiotic depletion and freshwater aquatic ecotoxicity,and it also proved that global warming is mainly caused by pollutant emissions during operation phase.Monte Carlo simulations found slightly higher uncertainty for abiotic depletion and toxicity-related impact categories.

CFD simulation of gas–liquid flow in a high-pressure bubble column with a modified population balance model

In this study,based on the Luo bubble coalescence model,a model correction factor C_e for pressures according to the literature experimental results was introduced in the bubble coalescence efficiency term.Then,a coupled modified population balance model(PBM) with computational fluid dynamics(CFD) was used to simulate a high-pressure bubble column.The simulation results with and without C_e were compared with the experimental data.The modified CFD-PBM coupled model was used to investigate its applicability to broader experimental conditions.These results showed that the modified CFD-PBM coupled model can predict the hydrodynamic behaviors under various operating conditions.

The effect of operating conditions on acylation of 2-methylnaphthalene in a microchannel reactor

Acylation of 2-methylnaphthalene(2-MN) is a very important reaction in organic synthesis,and the effiency of the continuous reactor is more than one of the batch reactor.Considering that the Friedel–Crafts acylation is a rapid exothermic reaction,in this study,we perform the acylation of 2-MN in a stainless steel microchannel flow reactor,which is characterized by high mass and heat transfer rates.The effect of reactant ratio,mixing temperature,reaction temperature,and reaction time on product yield and selectivity were investigated.Under the optimal conditions,2-methyl-6-propionylnaphthalene(2,6-MPN) was obtained in 85.8% yield with 87.5% selectivity.Compared with the conventional batch system,the continuous flow microchannel reactor provides a more efficient method for the synthesis of 2,6-MPN.

The high catalytic activity and strong stability of 3%Fe/AC catalysts for catalytic wet peroxide oxidation of m-cresol: The role of surface functional groups and FeO_(x) particles

FeO;supported on activated carbon(AC) has been shown to be an ideal catalyst for catalytic wet peroxide oxidation(CWPO) due to its high CWPO reaction activity and stability. Although there have been some studies on the mechanism of Fe/AC catalysis in CWPO, the specific contribution of each component(surface oxygen groups and FeOxon AC) inside an Fe/AC catalyst and their corresponding reaction mechanism remain unclear, and the reaction stability of CWPO catalysts has rarely been discussed. Then the optimal CWPO catalyst in our laboratory, 3%Fe/AC, was selected.(1) By removing certain components on the AC through heat treatment, its contribution to the reaction and the corresponding reaction mechanism were investigated. With the aid of temperature-programmed desorption–mass spectrometry(TPD–MS) and the CWPO reaction, the normalized catalytic contributions of components were shown to be: 37.3%(carboxylic groups), 5.3%(anhydride), 19.3%(ether/hydroxyl),-71.4%(carbonyl groups) and 100%(FeOx),respectively. DFT calculation and EPR analysis confirmed that carboxylic groups and Fe_(2)O_(3) are able to activate the H_(2)O_(2) to generate·OH.(2) The catalysts at were characterized at different reaction times(0 h, 450 h, 900 h, 1350 h, and 1800 h) by TPD–MS and M?ssbauer spectroscopy. Results suggested that the number of carboxylic goups gradually increased and the size of paramagnetic Fe_(2)O_(3) particle crystallites gradually increased as the reactions progressed. The occurrence of strong interactions between metal oxides and AC was also confirmed. Due to these effects, the strong stability of 3%Fe/AC was further improved. Therefore, the reasons for the high activity and strong stability of 3%Fe/AC in CWPO were clearly shown. We believe that this work provides an idea of the removal of cresols from wastewater into the introduction to show the potential applications of CWPO.

In-depth investigation on the factors affecting the performance of high oil-absorption resin by response surface method

A series of high oil-absorption resins with low cross-linking degree were synthesized by suspension polymerization using stearyl methacrylate(SMA),2-Ethylhexyl methacrylate(EHMA),and styrene(St)as monomers.Response surface methodology(RSM)with central composite design(CCD)was also applied to determine the optimal parameters that are mainly known to affect their synthesis.Thus,the effects of the monomer mass ratio(EHMA:SMA),the rigid monomer(St)dosage,the porous agent(acetone)dosage,and their pairwise interaction on the resin's oil-absorption capacity were analyzed,highlighting PSES-R_(2) as the resin with the optimum performance.The pure oil-absorption rates of PSES-R_(2) for gasoline,diesel,and kerosene were 11.19 g·g^(-1),16.25 g·g^(-1),and 14.84 g·g^(-1),respectively,while the oil removal rates from oily wastewater were 98.82%,65.11%,and 99.63%,respectively.

席夫碱法制备大孔聚合物肝素亲和层析介质

肝素亲和层析介质因其专一性好、操作条件温和等特点,广泛应用于蛋白分离纯化,本工作以大孔聚丙烯酸酯微球为基质,肝素为配基,利用席夫碱法制备了肝素亲和层析介质。配基偶联经过三步完成,首先将大孔聚丙烯酸酯微球表面环氧基团通过0.5 mol/L H_(2)SO_(4)水解为邻羟基,然后将邻羟基氧化为醛基,最后利用醛基与肝素分子的胺基反应将肝素分子固定于微球表面。以溶菌酶为模型蛋白,主要考察了肝素偶联反应的各因素对蛋白结合容量的影响规律,包括肝素浓度、缓冲液pH及浓度、反应时间等,建立了最优偶联肝素配基的方法。所得亲和介质静态结合容量可达40.3 mg/mL,比商品GP-肝素介质高约36%,经1.0 mol/L的氯化钠洗脱,其蛋白回收率达到95%。通过扫描电子显微镜表征微球表面形貌,观察到偶联肝素后的微球仍能保持其大孔结构。考察了该类亲和介质在不同操作流速(31.8~318 cm/h)下的动态结合容量,发现操作流速提高10倍后介质结合容量仅下降12%。经10次重复使用后,动态结合容量仍可保持初始容量的81%。用于混合蛋白模型中分离乳铁蛋白,结果表明具有良好的分离效果。

超强碱催化剂载体结构对丙烯二聚生成4-甲基-1-戊烯反应性能影响的研究

负载碱金属K固体超强碱为催化丙烯二聚生成4-甲基-1-戊烯(4MP1)过程的催化剂,该反应过程中催化剂载体发挥着不可忽视的作用,本工作系统地研究了4MP1生成过程中催化剂载体的作用及不同载体性能的影响规律。采用压汞仪、扫描电子显微镜(SEM)等手段对载体物质的比表面积、孔径分布等孔道结构进行表征。结果表明,当二聚反应的目标产物是4MP1时,以K_(2)CO_(3)为载体负载碱金属K所制备的催化剂具有较好的4MP1选择性,达87.38%;各载体表现出的催化性能差异主要是因为不同载体的孔道结构会产生内扩散阻力,影响丙烯二聚反应的产物分布;针对丙烯二聚反应路径及4MP1异构化反应,丙烯二聚高选择性生成4MP1应首选具有低比表面积、较大孔径、孔径分布窄的物质作为载体。

The Active Sites and Corresponding Stability Challenges of the M-N-C Catalysts for Proton Exchange Membrane Fuel Cell

Proton exchange membrane fuel cells(PEMFCs)as promising alternatives to traditional internal combustion engines have attracted massive concerns to promote their wide application in society.However,the biggest challenge to the commercialization of PEMFCs remains the high cost due to the adoption of the platinum group metal(PGM)catalysts in the cathode.

β-甲基萘合成2-甲基-1,4-萘醌绿色氧化反应工艺

2-甲基-1,4-萘醌(2-MNQ)是K族维生素的重要中间体,广泛应用于医药、农药、饲料添加剂等领域。本工作以2-甲基萘(2-MN)为原料,(NH_(4))_(2)S_(2)O_(8)为引发剂,用30%H_(2)O_(2)与冰醋酸在硫酸催化下制备过氧乙酸并滴加至反应液中,氧化合成2-甲基-1,4-萘醌(2-MNQ),通过ICIR,GC-MS,LCMS对其结构进行表征,并验证氧化反应机理及中间产物。考察了催化剂、反应温度、反应时间、氧化剂与引发剂用量对产品2-MNQ收率、转化率的影响,采用HPLC (外标法)测定产品2-MNQ的转化率和收率,得到最佳工艺条件为反应温度65℃、反应时间5 h、n(H_(2)O_(2)):n(2-MN)=26:1,此时,2-甲基萘的转化率为99%,产品收率为34%。本工作的创新点是使用原位红外技术验证反应机理和中间过程,即原料2-甲基萘经过氧乙酸氧化,发生环氧化反应生成中间体,之后重排生成2-甲基羟醌,继续氧化生成目标产物2-甲基-1,4-萘醌。该工艺具有简单环保、操作条件温和、原料易得等特点。

新型耐碱蛋白A介质的制备与性能

以蛋白A结构中耐碱性更好的C区为基础,构建一种新型耐碱蛋白A,并偶联至琼脂糖基质,获得新型耐碱蛋白A亲和层析介质,分别用激光共聚焦显微镜和石英晶体微天平研究了人免疫球蛋白(h Ig G)与蛋白A介质的结合过程。结果表明,该介质具有较商品配基更高的结合力和稳定的再生性能,hIgG动态载量达62.0 mg/mL,40次再生操作后载量为初始载量的84%。该介质在抗体纯化领域具有较好的应用前景。

Prussian-blue materials:Revealing new opportunities for rechargeable batteries

The demand to increase energy density of rechargeable batteries for portable electronic devices and electric vehicles and to reduce the cost for grid-scale energy storage necessitates the exploration of new chemistries of electrode materials for rechargeable batteries.The open framework-structure of Prussian-blue materials has recently been demonstrated as a promising cathode host for a variety of monovalent and multivalent cations with the tunable working voltage and discharge capacities.Recent progress toward the application of Prussian-blue cathode materials for rechargeable batteries is reviewed,with special emphasis on charge-storage mechanisms of different insertion species,factors influencing electrochemical performances,and possible approaches to overcome their intrinsic limitations.

Distribution characteristics of holdups in a multi-stage bubble column using electrical resistance tomography

Based on the principle of chemical reaction engineering, the addition of perforated plates can improve the performance of conventional bubble column and decrease the backmixing behaviors. The distribution characteristics of gas holdup in a multi-stage bubble column embedded with five types of sieve plates and three types of tongue plates were studied using electrical resistance tomography （ERT）. The effects of superficial gas velocity and the geometric design of perforated plates on the gas holdup and its radial distribution above and below the plates of the bubble column were discussed. Experimental results show ERT is suitable as an online monitoring tool to provide useful information on the hydrodynamic param-eters of multi-stage bubble columns. With increasing superficial gas velocity, local gas holdup increases, and gas holdup below the plate increases with decrease of free area （%FA）, hole diameters or angle of tongue plates. ERT technique facilitates noninvasive and nonintrusive visualization of cross-sectional distribution of gas holdup in a bubble column.

SEBS高黏度溶液气液鼓泡塔的流体力学研究

针对SBS加氢反应器开发与设计,以SEBS-1650己烷溶液为液相,采用差压法和床层塌落法研究了气液鼓泡塔中高黏度溶液的流体力学行为,考察了黏度对低表面张力溶液的气含率、大小气泡气含率、大小气泡上升速度和比表面积等因素的影响。结果表明,随黏度增加,大气泡增多,气含率明显降低,塔内流型处于湍流区;由床层塌落曲线确定鼓泡塔内存在三种类型的气泡:大气泡、小气泡及细小气泡,随黏度增加,小气泡与细小气泡逐渐减少;黏度对大小气泡的上升速度略有影响,比表面积随黏度增加而明显降低。根据实验结果给出了大小气泡气含率与平均气含率的计算公式。

Graphene Oxide Assemblies for Sustainable Clean-Water Harvesting and Green-Electricity Generation

CONSPECTUS:The urgent problems of water scarcity and the energy crisis have given rise to the development of a range of sustainable technologies with the great advancement of nanotechnologies and advent of attractive nanomaterials.Graphene oxides(GO),a derivative of graphene with an atom-thin thickness and abundant oxygen-containing functional groups(such as−OH,−COOH),are water-soluble and can be assembled into a variety of structures(such as fiber,membrane,and foam)with great potential in environmental and energy-related fields.As a typical precursor of graphene,GO can be easily reduced to graphene by chemical or thermal treatments to demonstrate excellent photothermal properties as well as tunable thermal conduction,which is highly desirable for efficient solar-driven water evaporation.The intrinsic large specific area of GO nanosheets can provide enough sites for ions adsorption and its porous assemblies facilitate the transport of water.In addition,the abundant functional groups allow the spontaneous adsorption of water molecules from the ambient environment and give birth to movable ions(usually protons)under the solvation effect.Once a chemical gradient is formed on the component,a remarkable electricity is generated from the directional transport of protons.Thanks to the excellent chemical properties of GO nanosheets,a wide range of assemblies with 1D aligned fibers,2D layered membranes and 3D porous foam can be easily fabricated by wet-spinning,solution-filtration,and freezingdrying methods.The various GO assemblies are able to exhibit abundant functions with remarkable weaving capability for GO fibers,superior flexibility for GO membranes,and exceptional adsorption capacity for GO foams.In light of all the advantages,GO and its assemblies are remarkably promising in the fields of sustainable development to meet the pressing challenges of water and energy crisis.In this Account,we will discuss the progress of clean-water production and green-electricity generation technologies based on GO assemblies.The fundamental working mechanism,optimization strategies,and promising applications are explored with an emphasis on the materials development.We also discuss the functions of GO assemblies in the water and electricity generation process and present their limitations and possible solutions.Current challenges and promising directions for the development of clean-water production and green-electricity generation are also demonstrated for their realistic implementations.We anticipate that this Account would promote more efforts toward fundamental research on graphene functionalization and encourage a broad exploration on the application of graphene assemblies in clean-water production and electric power generation systems.

Fabrication of novel bifunctional nanohybrid based on layered rare-earth hydroxide with magnetic and fluorescent properties

We demonstrate the fabrication of a novel magnetic nanohybrid involving the drug molecule 5 aminolevulinic acid(5-ALA)intercalated Gd-Eu layered rare-earth hydroxide(LRH)coated on magnesium ferrite particles(MgFe2O4).The structure,thermostability,morphology,luminescence properties,cytotoxic effect and magnetism are investigated.The 5-ALA intercalated composite may correspond to a monolayered vertical arrangement,and the thermal stability of organics is enhanced after intercalation.The LRH precursor shows red emission of Eu^3+and the maximum emission peak of the composite is at 451 nm,corresponding to the blue emission.The detection of drug molecules can be realized through the change of luminescence.The magnetic nanohybrid shows strong magnetic sensitivity,which provides an easy and efficient way to separate 5-ALA-MgFe2O4@LGd0.95H:Eu0.05 particles from a sol or a suspension system and to carry drugs to targeted locations under an external magnetic field.The cytotoxic effect of MgFe2O4@LRH is observed with a sulforhodamine B(SRB)colorimetric assay,which has low cytotoxic effects on selected cells.The fabrication of novel bifunctional drug carriers based on LRH with magnetic and fluorescent properties has potential applications in drug detection and drug delivery.