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从六偏磷酸钠、焦磷酸钠、三聚磷酸钠等几种不同大宗原料中筛选出六偏磷酸钠作为合成单氟磷酸钠的原料.以六偏磷酸钠为原料,采用单因素试验,考察了原料干燥时间、合成温度、合成时间和原料氟磷比[n(F)/n(P)]对反应的的影响.通过正交试验优选,确定了最佳工艺条件:原料干燥温度475℃,原料干燥时间22 min,原料氟磷比1.10,合成温度760℃,合成时间22 min.在最佳条件下,产品纯度达到99.86%,原料转化率99.74%,产品游离氟浓度7.8 mmol/L.研究结果为工业生产提供了实验数据. 相似文献
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与传统工艺(经由EDTA中间体)比较,氰化钠法生产EDTA钠盐先进工艺具有如下优点:由EDTA四钠原液生产二钠盐,减少3道工序,硫酸(100%)和氢氧化钠(100%)单耗分别降低0.350t/t和0.216t/t;由二钠盐生产四钠盐减少一道工序,硫酸和氢氧化钠单耗分别降低0.272t/t和0.173t/t;产品纯度99.3%~99.5%,产率93%~95%(以乙二胺计),达到文献水平。 相似文献
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采用一水硫酸氢钠作催化剂 ,合成了肉桂酸乙酯。当醇酸摩尔比为 5∶1,催化剂用量占肉桂酸质量的2 0 % ,反应温度 14 0℃ ,回流时间为 2h时 ,产率可达 91 1%。 相似文献
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《Ceramics International》2021,47(20):28260-28267
Piezoelectric materials are an indispensable part of modern life. Yet the existing environmental issues with conventional lead-based piezoelectrics has motivated scientist to develop novel substitutes including lead-free piezoelectric polymer composites. Following this path, the present research has focused on the fabrication of ternary composites of Polyvinylidene fluoride (PVDF)/Potassium Sodium Niobate (KNN)/nano-Silicon carbide (SiC) via hot compression molding and studying the effect of additives on the PVDF structure and the electrical properties of the composite. The obtained scanning electron micrographs and density measurements showed that the fabrication method provided dense samples. The activated polarization phenomena in the prepared samples enhanced dielectric permittivity and dielectric loss at a constant frequency with increasing KNN and SiC contents. Besides the expected dipole polarization, the presence of interfaces in the composites gave rise to the Maxwell–Wagner–Sillars effect and its corresponding polarization phenomenon. The semiconductive nature of SiC also promoted space charge polarization. However, these properties were frequency-dependent because the first two polarization mechanisms are deactivated at high frequencies. XRD patterns showed that SiC addition can alter the primary crystalline structure of PVDF and promote β-phase formation in the poled samples. Piezoelectric measurements confirmed the significant role of SiC addition to PVDF-KNN composites. The most significant increase in the piezoelectric properties was observed in PVDF-60KNN-1SiC, with a 183% increase in d33 value. The PVDF-80KNN-1SiC had the highest d33 value of 30.5 pC/N. It also had the best piezoelectric voltage coefficient and hence the highest figure of merit. Higher SiC contents restrict the efficiency of poling by forming a conductive path across the sample which would deteriorate the piezoelectric performance of the material. The present findings show that PVDF-KNN-SiC composites can be considered as a potential flexible piezoelectric material for future applications. 相似文献
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《Ceramics International》2015,41(7):8637-8642
Manganese ferrite nanoparticles were electro-crystallized in an electrochemical cell containing two iron electrodes, and an electrolyte solution of sodium sulfate, sodium butanoate, and manganese sulfate hydrate. The samples were characterized by X-ray diffraction, electron microscopy, magnetometry, and Mössbauer spectroscopy methods. The crystal structure of the samples was studied using X-ray diffraction. Based on obtained results we found that the manganese ferrite nanoparticles are formed in the electrochemical cell containing 0.001 M manganese sulfate hydrate. Also, the formation of a paramagnetic secondary phase in the sample without manganese is suppressed by adding manganese salt in the electrochemical cell. The nanoparticle size, shape, and morphology were characterized using electron microscopy. Magnetization curves show that all samples are magnetically soft and their specific magnetization ranges from 15 A m2 kg−1 to 75 A m2 kg−1, depending on the growth conditions. Room temperature Mössbauer spectra confirm the formation of nonstoichiometric spinel ferrite of magnetite or manganese ferrite, again depending on the growth conditions. Based on Mössbauer analysis, reduction in the population of octahedral sites provides direct evidence for the presence of the manganese ions substitution in the octahedral sites. 相似文献
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Jing Liu Xiangzheng Hu Xiaocong Wang Jingxia Yao Donglan Sun Zhi Fan Minjie Guo 《Polymer International》2014,63(4):722-726
In a conventional chemical oxidative polymerization of aniline in poly(sodium 4‐styrenesulfonate) aqueous solution, hollow microspheres of polyaniline were easily prepared, instead of common particles. The morphology of the hollow microspheres was studied and confirmed using scanning electron microscopy and transmission electron microscopy. The molecular structure, room temperature conductivities and thermal stability of the resulting polyaniline were characterized using Fourier transform infrared spectroscopy, the standard DC four‐probe method, thermogravimetric analysis and differential thermal analysis. The influence of poly(sodium 4‐styrenesulfonate) and aniline on the morphology and physical properties of the resulting polymer were investigated. The results showed that the proper ratio of poly(sodium 4‐styrenesulfonate) and aniline was a critical factor in the synthesis of hollow microspheres, which may be related to the chemical structure of poly(sodium 4‐styrenesulfonate) as polyanion and of polyaniline as polycation and the electrostatic interaction between them in the doping process. A possible formation mechanism is proposed in this work. © 2013 Society of Chemical Industry 相似文献
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Rosana M. N. de Assuno Betina Royer Juliana S. Oliveira Guimes Rodrigues Filho Leila A. de Castro Motta 《应用聚合物科学杂志》2005,96(5):1534-1538
Wasted polystyrene (PS) plastic cups were used in the synthesis of sodium poly(styrenesulfonate) (NaPSS). The produced polyelectrolyte was water‐soluble. The viscosimetric molecular weight was 126,146 g mol?1. The sulfonation of the polymer was estimated through FTIR spectroscopy and chemical analysis of the number of sulfonic groups. The presence of bands at 1326 and 1188 cm?1 in the infrared spectra was characteristic for sulfonic groups. The polymer was obtained with 60.3% of sulfonation. An aqueous solution of NaPSS was used as an admixture in concrete of portland cement. The results showed that the slump increasing of the concrete was up to 300% with 0.3% content of NaPSS per weight of cement. It was possible to reduce the water content of the concrete in 13.2% using NaPSS solution as an admixture. The compressive strength gain was 23.9% after 28 days of curing. The results indicated that NaPSS, produced from waste PS cups, can be satisfactorily used either as a plasticizer or as an admixture for water reduction in concrete. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1534–1538, 2005 相似文献
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细菌内毒素检测方法的有效性必须能充分证明该方法对反应无增强和抑制作用,对整个检测过程无其他干扰。通过一系列实验,验证不同浓度的膦甲酸钠溶液对鲎试剂(LAL)的抑制效果,证明该细菌内毒素检测方法对最终产品中细菌内毒素的检测是有效的。 相似文献
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Cuprous oxide(Cu_2 O) thin films have been grown by electrodeposition technique onto ITO-coated glass substrates from aqueous copper acetate solutions with addition of sodium thiosulfate at 60 ℃. The effects of sodium thiosulfate on the electrochemical deposition of Cu20 films were investigated by cyclic voltammetry and chronoamperometry techniques. Deposited films were obtained at-0.58 V vs. SCE and characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), and optical, photoelectrochemical and electrical measurements. X-ray diffraction results indicated that the synthesized Cu20 films had a pure cubic phase with a marked preferential orientation peak along(200) plane and with lattice constants a = b = c = 0.425 nm. FTIR results confirmed the presence of Cu_2 O films at peak 634 cm~(-1) SEM images of Cu_2 O films showed a better compactness and spherical-shaped composition. Optical properties of Cu20 films reveal a high optical transmission(80%) and high absorption coefficient(α 10~4 cm~(-1)) in visiblelight region. The optical energy band gap was found to be 2.103 eV. Photoelectrochemical measurements indicated that Cu20 films had n-type semiconductor conduction, which confirmed by Hall Effect measurements.Electrical properties of Cu20 films showed a low electrical resistivity of 61.30 Ω·cm~(-1), carrier concentration of-4.94 × 10~(15)cm~(-3) and mobility of 20.61 cm~2· V~(-1)·s~(-1).The obtained Cu_2 O thin films with suitable properties are promising semiconductor material for fabrication of photovoltaic solar cells. 相似文献
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本文利用单宁可与金属离子形成稳定配合物的性质,以不同的单宁为模板,水热合成了纳米二氧化钛(T-NTO),用FT-IR,XRD,BET,SEM,TEM对合成的T-NTO的结构及形貌进行表征,并探究其对铀的吸附性能。结果表明,以单宁为模板水热法合成可以明显提高纳米二氧化钛的比表面积,从而提高其吸附容量;所制备的T-NTO对铀有较强的吸附能力,并且以不同单宁为模板制备的T-NTO对铀(UO22+)的吸附容量存在明显差异,杨梅单宁为模板合成的纳米二氧化钛(BT-NTO)粒径最小,比表面积达到96.61 m2/g;T-NTO对铀的吸附等温线符合Langmuir方程,BT-NTO在318K时对铀的吸附容量高达0.7054 mmol/g;而吸附动力学符合准二级动力学方程,吸附速率较快;共存阳离子Zn2+、Mg2+、Pb2+、Cu2+、Mn2+、Na+及共存阴离子Cl-、SO42-、CO32-对BT-NTO吸附铀的影响很小,而F-的影响较大,但可通过引入Al3+来减小F-的影响。解吸实验表明, 0.1 mol/L的HNO3溶液可使吸附的铀解吸下来,BT-NTO可多次重复使用。 相似文献
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N. J. Ajongwen P. E. Barker 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,56(1):113-118
High activities of the enzyme dextransucrase were repeatedly produced using slowly agitated non-aerated fed-batch fermentations of Leuconostoc mesenteroides B-512(F). Activities in excess of 24.0 U cm?3 were obtained consistently in a 16 dm3 laboratory fermenter using a 6 dm3 initial work volume. Yeast extract type was identified to be one of the important factors influencing the enzyme yield. Studies on aerating the medium with different gases indicated that the presence of carbon dioxide in the medium favoured high enzyme production. Agitation rates did not appear to have significant effects on either cell growth or enzyme production. One type of antifoam (silicone antifoam) was observed to affect enzyme production but not the cell growth. Scale-up of the non-aerated process was carried out up to a 1000 dm3 scale with enzyme broths containing up to 21.0 U cm?3 being produced. Two batches of the enzyme that were produced at the large scale were used for the first time to synthesize dextran at a 50000 dm3 industrial scale. The dextran yields were up to 95.5% of the conventional industrial yields and were achieved in much shorter reaction time intervals. 相似文献
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在强酸性和水热条件下以硅酸钠(Na2SiO3·9H2O)为硅源合成表面含磺酸基的介孔分子筛催化剂SBA-15-SO3H。XRD结果表明,该分子筛具有规则的六方立柱形介孔结构。SBA-15-SO3H用于叔丁醇和乙醇合成乙基叔丁基醚(ETBE)的醚化反应研究,分别考察了反应温度、原料配比和反应时间等因素对醚化反应的影响。最佳操作条件为:温度120 ℃,n(乙醇)∶n(叔丁醇)=2∶1,反应时间5 h,m(催化剂) ∶m(原料)=1∶10。在此条件下,叔丁醇的转化率为62.83%。 相似文献
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对热法磷酸(TPA)、溶剂法净化磷酸(PPA)和联产新技术生产三聚磷酸钠的能耗进行了估算.溶剂法生产工业级w(H3PO4)85%磷酸的能耗与用新装置产的黄磷(P4)生产TPA的能耗上限值接近,为其97.5%;用PPA生产STPP的能耗是生产P4新装置TPA能耗上限值的91.9%,是联产新技术HPA的178.6%(1.7... 相似文献
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Anhydrides production is newly proposed as an additional pyrolysis mechanism of a biopolymer, poly(3‐hydroxybutyrate) (PHB). In spite of many suggestions of multiple degradation mechanisms, simple random chain scission by β‐elimination has been accepted as an exclusive mechanism of the thermal degradation of PHB. However, a wide range of activation energy value of the degradation and the deviation from the random chain scission statistics have suggested the presence of other kinds of mechanism out of the random scission. To confirm other mechanisms out of the random scission, minor pyrolyzates from PHB were characterized with 1H/13C‐NMR, Fourier transform infrared spectroscopy, and fast atom bombardment mass spectrometry. As a result, crotonic anhydride and its oligomers were detected as minor products from condensation reactions between carboxyl groups. The anhydrides production must be one reaction out of the conforming process to the random degradation statistics and contribute to the complexity of PHB pyrolysis. An expected thermal degradation pathway of PHB was proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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通过RAFT聚合,制备了低分子量的聚乙烯基苯磺酸钠(PSS);其次以低分子量的聚乙烯基苯磺酸钠为模板制备了聚3,4-二氧乙烯噻吩(PEDOT):聚乙烯基苯磺酸钠(PSS)水分散体,研究了作为模板的聚乙烯基苯磺酸钠的不同分子量对PEDOT:PSS水分散体结构和性能的影响。结果显示:通过核磁氢谱(1H NMR)表征,证明成功制备了分子量为3900,4900,9600和18300的聚乙烯基苯磺酸钠。用荧光探针法发现低分子量PSS在水中能形成胶束,临界胶束浓度在10-6g·ml-1左右。用四探针表面电阻测试发现,低分子量PSS为模板可明显提高PEDOT薄膜的导电性,最大提高了近3倍。用紫外可见分光光度计(UV)研究发现,以低分子量PSS为模板使PEDOT的透明性有一定的下降,这主要是由于RAFT试剂部分和PEDOT:PSS的相分离造成的。热稳定性的测试表明,低分子量PSS为模板对PEDOT的热稳定性没有明显的影响。 相似文献
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通过微波水热法,以沼渣为原料,合成了Fe3O4改性微波水热炭,研究了Fe3O4掺杂量对水热反应进程及反应产物的影响。为拓展水热产物的应用范围,以罗丹明B(RhB)为对象,评价改性水热炭对过硫酸钠的活化能力。结果表明,微波加热功率为400W、Fe3O4制备量为水热炭质量的20%时,反应体系14min左右即达到设定温度(200℃),较无Fe3O4条件下反应时间(27min左右)缩短了48.1%,体系压强增加了27.8%。改性水热炭添加量为0.16g、反应时间140min、溶液初始pH为6.7、过硫酸钠投加量为0.1g时,体积为150mL、浓度为40mg/L的RhB降解率可达94.6%,是水热炭单独作用时的3.3倍,过硫酸钠单独作用时的3.9倍。在反应体系中以硫酸根自由基( )的作用为主,羟基自由基(·OH)和超氧负离子( )为辅。改性水热炭具有良好的超顺磁性和稳定性。 相似文献