静电纺聚偏氟乙烯@硅藻土锂离子电池隔膜的制备及性能

以聚偏氟乙烯(PVDF)和硅藻土为原料,通过静电纺丝法制备PVDF@硅藻土复合纤维膜,用于锂离子电池隔膜。 研究了隔膜的吸液率、热稳定性和电化学性能等。 添加硅藻土可有效提高复合膜的电解液吸收率和电化学性能,其中吸液率可达623.6%,相比于PVDF膜和聚丙烯(PP)膜具有优异的循环性能和倍率性能。     

Application of Nanocrystalline Iranian Diatomite in Immobilized Form for Removal of a Textile Dye

The aim of the present investigation was to immobilize nanocrystalline diatomite within calcium alginate matrix for the adsorption of Direct Red23 (DR23) in aqueous media. Scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy were used to characterize the samples. As a result, the adsorption process obeyed pseudo-second-order kinetic model (R² = 0.9934) and Langmuir isotherm model (R² = 0.9732) with a maximum adsorption capacity of 24.10 mg/g. The value of mean free energy (15.81 kJ/mol) demonstrated that the process has been taken place chemically. As the adsorbent dosage increased from 0.5 to 3.0 g/L, the decolorization efficiency (%) increased from 26.0 to 75.5%, respectively. Inversely, the decolorization efficiency (%) decreased from 98.0 to 29.0% with increasing initial dye concentration from 5 to 160 mg/L, respectively. The negative values obtained for Gibbs free energy (ΔG°) and positive value of enthalpy change (ΔH°) indicated spontaneous and endothermic nature of the process.     

以天然矿物为全部硅铝源低成本绿色合成ZSM-5分子筛的研究

ZSM-5分子筛被广泛地应用于催化、吸附分离、离子交换和绿色化工等领域,但目前其合成主要是以无机化学品为硅铝源,从源头来看是非绿色化的过程.我们以热活化的硅藻土和亚熔盐活化的累托土为全部硅铝源,通过调变两种矿物的加入比例调变合成体系的硅铝比,在水热合成体系中制备ZSM-5分子筛.系统地考察模板剂用量、碱度、投料硅铝比、晶化时间等合成条件对产物结构和性质的影响,并对在最优条件下合成的ZSM-5分子筛的物化性质进行了详细地表征,结果表明：以天然矿物为全部硅铝源可以合成出具有较高结晶度、晶粒尺寸约为4 μm的六面体挛晶形貌的ZSM-5分子筛,该分子筛比商业ZSM-5分子筛具有更高的水热稳定性和更优的加氢异构性能.     

硅藻土原位负载网状纳米结构硅酸镁及其对Cr(Ⅵ)吸附性能

采用MgCl_2·6H_2O作为镁源,NH_3·H_2O作为沉淀剂,十六烷基三甲基溴化铵(CTAB)作为模板剂,以水热法在硅藻土表面原位生长纳米花状Mg(OH)_2,随反应时间增加,转变成单斜晶系网状结构Mg_3Si_4O_(10)(OH)_2纳米花。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、氮气吸附-脱附测试、傅里叶红外光谱(FT-IR)、X射线光电子能谱(XPS)等测试手段对样品进行了表征,结果显示:反应时间为0.5～2.0 h时硅藻土表面以生长Mg(OH)_2为主,样品的比表面积为180 m~2·g~(-1);反应时间至3h时,硅藻土表面Mg(OH)_2转化成网状结构Mg_3Si_4O_(10)(OH)_2,样品比表面积增大到350 m~2·g~(-1),此复合结构对Cr(Ⅵ)最大吸附量可达570 mg·g~(-1)。     

临江某硅藻土酸浸煅烧增白工艺试验研究

采用酸浸-煅烧方法对临江某一级硅藻土进行了增白试验研究,探讨了酸浸温度、酸浸时间、硫酸浓度、固液比、煅烧温度、煅烧时间对硅藻土增白效果的影响,并通过扫描电镜及化学成分分析等对增白前后硅藻土进行了表征.结果表明:硅藻土增白适宜工艺条件为:酸浸温度100℃,酸浸时间4h,固液质量比1∶3.28,酸浓度5 mol/L,煅烧温度650℃,煅烧时间1.5h;优化工艺条件下,一级硅藻土白度由67.2;提升至88.4;,SiO2含量由89.78;提升至95.01;,Fe2O3含量由1.07;降低至0.21;.     

Adsorption of Anionic Dyes onto Chitosan-modified Diatomite

The purpose of this work is to study the possibility of anionic dyes Reactive Red M-8B(RR) and Direct Green B(DG) adsorbed on chitosan-modified diatomite. The characteristics of adsorbent, adsorption isotherms and the influence of adsorption time, temperature and pH were researched in this work. The results show that the mo- dified diatomite had a much better adsorption capability than the natural diatomite. The adsorption capacities of chitosan-modified diatomite for RR and DG were 94.46 and 137.0 mg/g, respectively. Both adsorption time and adsorption temperature provided a positive effect on the dye adsorption. Within the experimental pH range, the adsorbance was enhanced at lower pH but reduced sharply at high pH. On the basis of the experimental results and discussion, electrostatic attraction is considered as the main mechanism of this chemisorption.     

High-Loading Pt Single-Atom Catalyst on CeO2-Modified Diatomite Support

Single-atom catalysis has become a new branch in heterogeneous catalysis. Although the naturally produced SiO₂-based materials are abundant and stable, fabrication of single-atom catalysts on such supports with high loading remains as a formidable challenge due to the lack of bonding sites to anchor the isolated metal species. Herein, modifying the diatomite, a kind of pure SiO₂ mineral, with CeO₂ nanoparticles is demonstrated to increase the defect sites on the support. The enhanced metal-support interaction maintains the atomic dispersion of Pt species with above 1 wt.% loading, exhibiting good performance in the selective hydrogenation of phenylacetylene to styrene.     

Hierarchical Porous ZSM‐5 Zeolite Synthesized by in situ Zeolitization and Its Coke Deposition Resistance in Aromatization Reaction

Hierarchical ZSM‐5 zeolites with micro‐, meso‐ and macroporosity were prepared from diatomite zeolitization through a vapor‐phase transport process on solid surfaces. The aromatization performance of the catalysts was investigated on a fixed bed reactor by using FCC gasoline as feedstock. The crystal phase, morphology, pore structures, acidity and coke depositions of the hierarchical ZSM‐5 zeolites were characterized by means of X‐ray diffraction (XRD), scanning electron microscope (SEM), N₂ adsorption/desorption, Fourier transform infrared (FT‐IR) and thermogravimetry‐mass spectrogram (TG‐MS), respectively. The results show that the prepared hierarchical ZSM‐5 zeolite possesses excellent porosity and high crystallinity, displaying an improved aromatization performance and carbon deposition resistance due to its meso‐ and macroporous structures.     

碱性染料-硅藻土复合粉末制备及用于手印显现的综合化学实验

基于物理吸附原理,采用硅藻土和碱性染料（亚甲基蓝、藏红T）制备新型手印显现粉末。利用扫描电子显微镜和傅里叶变换红外光谱表征硅藻土的形貌与结构,通过紫外可见吸收光谱测试硅藻土对碱性染料的吸附性能,使用制得的复合粉末显现出不同客体表面的手印。该综合化学实验涉及多个领域,包括分析化学的数据处理和仪器使用、物理化学的表面吸附机理、法庭科学的手印显现与提取,有利于拓展学生的科学视野,提升学生的科学素养。     

Reverse atom transfer radical random copolymerization of styrene and methyl methacrylate in the presence of diatomite nanoplatelets

Diatomite nanoplatelets were used for in situ random copolymerization of styrene and methyl methacrylate by reverse atom transfer radical polymerization to synthesize different well‐defined nanocomposites. Inherent features of the pristine diatomite nanoplatelets were evaluated by Fourier transform infrared spectroscopy, nitrogen adsorption/desorption isotherm, scanning electron microscope, and transmission electron microscope. Gas and size exclusion chromatography was also used to determine conversion and molecular weight determinations, respectively. Considerable increment in conversion (from 81% to 97%) was achieved by adding 3 wt% diatomite nanoplatelets in the copolymer matrix. Moreover, molecular weight of random copolymer chains was increased from 12 890 to 13 960 g·mol⁻¹ by addition of 3 wt% diatomite nanoplatelets; however, polydispersity index (PDI) values increases from 1.36 to 1.59. Proton nuclear magnetic resonance spectroscopy was used to evaluate copolymers composition. Thermal gravimetric analysis results indicate that thermal stability of the nanocomposites is improved by adding diatomite nanoplatelets. Differential scanning calorimetry shows an increase in glass transition temperature from 66°C to 71°C by adding 3 wt% of diatomite nanoplatelets.