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1.
为开发具有高效过滤性能的膜材料,以超支化季铵盐(HBP-HTC)为枝化促进剂,利用静电纺丝技术一步法制备了聚偏氟乙烯(PVDF)树枝状纳米纤维膜,探讨了纺丝工艺对纤维膜成形结构的影响,分析了树枝状纳米纤维膜的力学性能及其空气过滤性能。结果表明:由于HBP-HTC表面丰富的季铵基团具有对电荷的稳定富集作用,可获得比用小分子季铵盐制成膜更多的树枝状纳米纤维结构,当PVDF质量分数为12%,季铵基团添加量为 0.10 mol/L, 纺丝电压为25 kV时,制得的纤维膜树枝状覆盖率高达78.32%,且具有较好的力学性能;所制备的纳米纤维膜厚度为40 μm时,其过滤效率高达99.995%,而压降为122.4 Pa。  相似文献   
2.
目的 合成一种二苯乙酮咪唑啉季铵盐(PPLB)化合物,研究其在0.5mol/LHCl溶液中对Q235钢的缓蚀性能,探讨其吸附动力学过程及可能的缓蚀机制。方法 以有机胺、硬脂酸、苯乙酮和氯化苄等为原料,经脱水环化、曼尼希反应和季铵化制备季铵盐。通过腐蚀失重、动电位极化曲线测试、电化学阻抗和表面形貌分析等手段,研究了二苯乙酮咪唑啉季铵盐在HCl介质中对Q235钢的缓蚀性能。结果 HCl溶液中PPLB对碳钢具有优异的缓蚀性能,缓蚀效率随浓度和介质温度的升高而增加。在353 K下,PPLB添加量为4.8×10–4 mol/L时,缓蚀效率可达98.9%,表明缓蚀剂在高温酸性介质中仍可有效抑制碳钢的腐蚀。电化学研究结果证明,PPLB可同时降低阴阳极的腐蚀电流密度,即抑制了腐蚀的阴阳极过程,是一种通过“几何覆盖效应”起作用的混合型缓蚀剂,其在碳钢表面的吸附遵循Langmuir吸附等温规律,为典型的化学吸附。结论 合成的二苯乙酮咪唑啉季铵盐化合物是一种优异的酸性介质缓蚀剂,独特的分子结构使其通过多中心化学吸附在碳钢表面生成保护性吸附膜,从而有效抑制了HCl对碳钢的腐蚀。  相似文献   
3.
Pb2+作为一种具有生物蓄积毒性的重金属离子,严重危害着环境和人体健康,微痕量Pb2+的分离富集工作一直是研究热点。固相萃取技术虽能够获得较高的富集率,但材料的制备较为繁琐,应用上受到了限制。实验利用钼酸铵作为微痕量Pb2+的沉淀剂,建立了一种以微晶酚酞作吸附剂分离富集微痕量Pb2+的方法。分别考察了钼酸铵溶液的用量、酚酞溶液用量、酸度、盐的类型及用量、吸附温度、吸附时间、Pb2+的初始浓度对富集率的影响。结果表明,当体系中Pb2+的含量为100 μg时,控制体系的pH=3~7,加入1.0 mL 5.0×10-4 mol/L钼酸铵溶液,1.0 g 硝酸铵,0.3 mL 70 g/L酚酞乙醇溶液,震荡摇匀后,静置10 min,Pb2+与钼酸铵反应生成的离子缔合物被定量吸附到微晶酚酞表面上,从而实现了微痕量Pb2+的分离富集。方法成功应用于合成水样中微痕量Pb2+的定量分离,富集率在95%~105%,能够满足微痕量Pb2+的分离富集要求。  相似文献   
4.
The flame retardant polypropylene containing the micro-envelope core-shell structure flame retardant, which encapsulated ammonium polyphosphate into melamine-formaldehyde resin and sodium silicate through in situ polymerization was prepared with polyamide 6, added as a carbon-forming agent. The composition of ammonium polyphosphate, encapsulated ammonium polyphosphate with melamine-formaldehyde resin and the micro-envelope core-shell structure flame retardant were characterized. The fire safety and thermal stability were investigated and showed an improvement including limiting oxygen index, thermogravimetric analysis, vertical burning tests, and microscale combustion calorimeter. The burned compounds were also studied to confirm the burning mechanism. The results showed the flame retardant performance had been greatly improved, while polyamide 6 had better char-forming effect. Besides, the water solubility of flame retardants and their influence on the mechanical properties of polypropylene were also investigated. The results on the effects of additives demonstrated a high efficiency flame retardant to polypropylene. A core-shell flame retardant that sodium silicate and melamine-formaldehyde resin-coated ammonium polyphosphate had been constructed. The effect of the built flame retardant system on the combustion performance of polypropylene was studied from the mechanism and performance. The LOI of the most flame retardant polypropylene reached 28.6%, and UL-94 reached the V-0 level.  相似文献   
5.
This research aims to study the effect of ammonium polyphosphate and expandable graphite on the intumescent coating formulations (ICF). The coating presented in this research article is based on carbon source expandable graphite (EG), blowing agent melamine, acid source ammonium polyphosphate (APP), epoxy resin as a binder with polyamide amine. The stability of the developed coating was verified at 950°C for 1-hour fire test. The results showed that the coating is stable and well bond with the steel substrate. The char was characterized by using FESEM, XRD, FTIR, DTA, TGA, XPS, Py-GCMS and Weathering Test. The morphology of the char was studied by SEM of the coating after furnace fire test. XRD and FTIR show the presence of graphite, borophosphate; boron oxide and sassolite in the residual char. TGA and DTG disclosed that EG improved the residual mass of coating. XPS analysis showed the char residue of IF5-APP-EG contains carbon and oxygen contents 47.50 and 40.70, respectively. Py-GCMS analysis described that the IF5-APP-EG released less gaseous compounds. The weathering test illustrated that's the char expansion of coatings samples was decreased due to the presence of a humid environment and UV light. The IF5-APP-EG showed the maximum char expansion, lower substrate temperature and high residual weight among the studied formulations.  相似文献   
6.
季铵型瓜尔胶的制备及在纸质文献加固中的应用   总被引:1,自引:1,他引:0       下载免费PDF全文
纸质文献是人类文明的瑰宝,大量的脆弱纸质文献亟待加固保护,因此急需探究一种与纸张纤维相容性好、操作简便、加固效果显著的材料。本研究对天然高分子瓜尔胶进行季铵化改性,制得取代度为0.137的季铵型瓜尔胶,改性产物具有更好的溶解性及稳定性,并将其应用于纸质文献加固。结果表明,相比未处理厚纸,加固处理后纸张的抗张强度从2.64 kN/m提升至3.16 kN/m、耐折度从7次提升至13次、撕裂度从161.5 mN提升至193.5 mN、零距抗张强度从65.0 kN/m提升至72.8 kN/m,分别提升了19.7%、85.7%、19.8%、12.0%。老化后色差变化为1.31,且不会对纸张及字迹颜色产生负面影响,证明季铵型瓜尔胶在纸质文献的加固中具有一定的应用前景。  相似文献   
7.
A novel series of cleavable alkyltrimethylammonium surfactants with different hydrocarbon chain lengths (C8–16) were synthesized. A carbonate break site inserted between the polar head and the hydrocarbon chain makes these compounds hydrolyzable. The reagents used are renewable, (bio)degradable, or reusable. The hydrolysis of these cleavable surfactants will lead to the generation of fatty alcohols and choline, which is an essential biological nutrient. The surface activities in aqueous solution of the synthesized carbonates fulfill the requirement of being good surfactants. In addition, the cleavable compounds containing n-decyl and n-dodecyl chains showed similar or higher antimicrobial activities when compared to a non-cleavable analog.  相似文献   
8.
Inspired by the incorporation of metallocene functionalities into a variety of bioactive structures, particularly antimicrobial peptides, we endeavored to broaden the structural variety of quaternary ammonium compounds (QACs) by the incorporation of the ferrocene moiety. Accordingly, 23 ferrocene-containing mono- and bisQACs were prepared in high yields and tested for activity against a variety of bacteria, including Gram-negative strains and a panel of clinically isolated MRSA strains. Ferrocene QACs were shown to be effective antiseptics with some displaying single-digit micromolar activity against all bacteria tested, demonstrating yet another step in the expansion of structural variety of antiseptic QACs.  相似文献   
9.
本文通过多次催化酯交换方法,研究了最优催化条件下脂肪酶活性和结构的关系,以及低活性脂肪酶的活性再生技术。在催化合成1,3-二油酸-2-棕榈酸甘油三酯的研究中,利用荧光光谱和傅里叶变换红外光谱,分析最优条件下不同使用次数脂肪酶的三级与二级结构,研究脂肪酶活性变化与其二级、三级结构之间的关系。使用异丙醇和混合油脂处理脂肪酶,使低活性脂肪酶的活性得以恢复。研究结果表明:随着脂肪酶活性的降低,脂肪酶荧光强度增强,氨基酸暴露面积逐渐增大,在二级结构中,α-螺旋含量降低,β-折叠含量逐渐增加。通过异丙醇处理,脂肪酶活性恢复到原脂肪酶的75.00%;再经混合油脂处理,脂肪酶活性恢复到原脂肪酶的96.60%,实现了高效催化恢复活性的目的。  相似文献   
10.
In this study,nitrogen removal performance of the denitrifying ammonium oxidation(DAO)process was investigated when treating sulfamethoxazole(SMX)-laden secondary wastewater effluent.The influent SMX concentration showed negligible effect on efficiencies for removal of nitrate and COD.However,the ammonium ions removal rate was moderately reduced,when the influent SMX concentration in wastewater reached 6 mg/L.Total nitrogen removal efficiency remained as high as 76.77%towards the day 158 at the end of experiment.Candidatus_Brocadia and Candidatus_Kuenenia were the functional anammox strains.The unclassified_f__Rhodobacteraceae sp.was predominant heterotrophic denitrifying strain in the studied reactor.The concentrations of soluble extracellular polymeric substances in sludge obviously increased from 16.76 mg/g VSS to 32.31 mg/g VSS,which might protect the nitrogen removal strains from high-concentration SMX.This result provides a theoretical and technical foundation for the application of denitrifying ammonium oxidation process in treating sulfamethoxazole-laden secondary wastewater effluent.  相似文献   
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