疏水纤维素/SiO2复合气凝胶的制备和表征

以微晶纤维素和正硅酸乙酯(TEOS)为原料,通过溶胶-凝胶法制备了4种再生纤维素/SiO₂复合气凝胶,并利用十八烷基三氯硅烷(OTS)对复合气凝胶进行疏水改性,利用X射线衍射(XRD)、能谱仪(EDS)、傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)等对4种再生纤维素/SiO₂复合气凝胶及其疏水改性产物进行表征分析。结果表明:4种再生纤维素/SiO₂复合气凝胶均为白色固体,密度范围43.6~50.7 mg/cm³;XRD、EDS和FT-IR分析表明4种再生纤维素/SiO₂复合气凝胶中均含有硅元素,疏水纤维素/SiO₂复合气凝胶中均含有硅、氯元素;SEM分析表明4种再生纤维素/SiO₂复合气凝胶及其改性产物均呈现三维网状结构,改性产物的三维网状结构的孔隙变小。疏水纤维素/SiO₂复合气凝胶的接触角测试结果表明,4种样品接触角均大于90°,达到疏水状态,且随着TEOS用量的增加,接触角逐渐增大(最大接触角144.5°),疏水性能提高。     

再生纤维素气凝胶的疏水性能表征

以微晶纤维素为原料,溶胶-凝胶法制备再生纤维素气凝胶(RCA)。利用十八烷基三氯硅烷(OTS)对再生纤维素气凝胶进行疏水改性得到再生纤维素疏水改性气凝胶(RCHMA)。采用扫描电子显微镜(SEM)、能谱(EDS)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)分别对样品进行表征分析。结果表明RCA为纤维素Ⅱ型,呈现三维网状结构;RCHMA与RCA结构相似,但RCHMA的孔隙较RCA的孔隙小。能谱(EDS)分析结果表明RCHMA中有硅、氯元素。接触角测试结果表明RCHMA达到疏水状态,且随着十八烷基三氯硅烷用量的增多,接触角逐渐增大,接触角最大为140°,具有良好的疏水性能,可以在水油共存的状态下选择性吸附油性试剂。     

疏水纤维素/氧化铁复合气凝胶的制备和表征

利用Na OH/尿素体系对微晶纤维素进行溶解,得到再生纤维素溶液。通过溶胶凝胶法共混氧化铁溶液制备纤维素/氧化铁复合气凝胶。采用扫描电子显微镜(SEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)对纤维素/氧化铁复合气凝胶进行表征分析,分析结果表明氧化铁掺杂在纤维素气凝胶里,纤维素/氧化铁复合气凝胶呈现网状结构,氧化铁的添加并没有影响纤维素气凝胶的微观形貌。利用十八烷基三氯硅烷(OTS)对纤维素/氧化铁复合气凝胶进行疏水改性,接触角测试结果表明改性纤维素/氧化铁复合气凝胶均达到疏水状态。     

纤维素纤维/SiO2复合气凝胶的结构性能表征及应用

本文以纤维素纤维为骨架,原位生成SiO_2气凝胶,从而制备出纤维素纤维/SiO_2复合气凝胶。采用红外光谱(FTIR)、扫描电镜(SEM)、比表面积测试(BET)等手段表征了复合气凝胶的结构,通过热失重分析仪、接触角测量仪、纺织品热阻测试仪测试了复合气凝胶的基本性能,进而用复合气凝胶制作了保温服装,并采用暖体假人和红外热成像仪测试了其保温性能。研究结果表明,该纤维素纤维/SiO_2复合气凝胶具有优越的保温性能,轻薄柔韧,有望用于航空航天、极地科考、滑雪登山、以及时尚保暖服上。     

纤维素气凝胶及其疏水改性研究进展

纤维素气凝胶具有的低密度(≥8 kg/m~3)、低热导率(0.0201~0.0295 W/m·K)、高孔隙率(≤99.5%)、高比表面积(100~605 m~2/g)等使其在隔热、吸附、催化、储能等领域应用广泛,是多功能、轻质、纳米多孔材料。纤维素表面存在大量的羟基,氢键和亲水性使纤维素气凝胶在吸附油污等应用受限。利用三甲基氯硅烷(TMCS)、十八烷基三氯硅烷(OTS)等进行纤维素气凝胶的疏水改性,拓展其应用范围。     

疏水SiO2气凝胶制备

以自制的硅溶胶为原料，通过三甲基氯硅缈六甲基二硅氧烷（trimethylehlorosilsne／hexamethyldlsiloxane，TMCS／HMDSO）混合液对制得的水凝胶直接进行表面改性，用乙醇洗涤以后，在常压条件下干燥后得到疏水的SiO2气凝胶。研究表明；当溶胶液pH值从3变到5，最终得到的气凝胶的密度随pH值的增大逐渐减小到最低点后又有所增大，而气凝胶的比表面积则呈相反的变化趋势。当改性剂TMCS／H20的摩尔比大于0．1时，最终可得到疏水的气凝胶，当其大于0．2后气凝胶的密度和疏水性变化不大。Si02气凝胶密度和比表面积分别在100-160kg／m^3和539-720m^2／g范围。     

木质纤维素气凝胶的制备及性能表征的研究

纤维素是自然界中储量最为丰富的一种天然高分子,纤维素气凝胶作为无机气凝胶和合成聚合物气凝胶之后的第三代气凝胶,兼具绿色可再生的纤维素材料和多孔气凝胶材料的优点,成为纤维素材料研究与应用的一个热点。本文内容包括木质纤维素的提取、碱性溶剂(尿素/NaOH)的溶解、纤维素气凝胶的制备与表征,包括sol-gel的形成、冷冻干燥工艺的制定、SEM、FTIR、BET等性能的测试表征,对木质纤维素气凝胶用MTMS硅烷进行疏水改性,对纤维素气凝胶在物流、港口行业应用的展望。     

疏水SiO2气凝胶制备

以自制的硅溶胶为原料，通过三甲基氯硅缈六甲基二硅氧烷（trimethylehlorosilsne／hexamethyldlsiloxane，TMCS／HMDSO）混合液对制得的水凝胶直接进行表面改性，用乙醇洗涤以后，在常压条件下干燥后得到疏水的SiO2气凝胶。研究表明；当溶胶液pH值从3变到5，最终得到的气凝胶的密度随pH值的增大逐渐减小到最低点后又有所增大，而气凝胶的比表面积则呈相反的变化趋势。当改性剂TMCS／H20的摩尔比大于0．1时，最终可得到疏水的气凝胶，当其大于0．2后气凝胶的密度和疏水性变化不大。Si02气凝胶密度和比表面积分别在100-160kg／m^3和539-720m^2／g范围。     

纤维素/硅藻土复合气凝胶球的制备及其吸附性能的研究?

以碱脲试剂作为溶解体系,采用冷冻干燥法制备出不同质量分数的纤维素/硅藻土复合气凝胶球,并通过扫描电子显微镜(SEM)和傅里叶变换红外光谱仪(FT-IR)检测手段对复合气凝胶进行表征。结果表明复合气凝胶内部仍呈现出疏松多孔的三维网状结构,硅藻土附着在纤维素链上,同时复合气凝胶具有纤维素Ⅱ型特征峰。此外考察了硅藻土含量、亚甲基蓝溶液浓度以及pH对复合气凝胶吸附性能的影响,结果表明在最佳条件下,复合气凝胶对亚甲基蓝的最大吸附量可达71.942 4 mg/g,吸附过程满足伪二级动力学方程学。     

细菌纤维素/热塑性聚氨酯复合气凝胶纤维制备及性能

使用绿色有机材料细菌纤维素(BC),并掺杂增强材料热塑性聚氨酯弹性体(TPU)经过湿法纺丝制备复合气凝胶纤维,通过傅里叶变换红外光谱(FTIR)、X射线衍射光谱(XRD)、热重分析(TG)、扫描电子显微镜(SEM)、全自动比表面孔隙度分析仪和单丝强力仪对制备的气凝胶纤维进行结构分析和性能表征,结果表明复合气凝胶纤维具有多孔结构,良好的力学性能和隔热性能,断裂强度达到24.69Mpa,断裂伸长为38.54%。     

CuS-functionalized cellulose based aerogel as biocatalyst for removal of organic dye

CuS-functionalized cellulose based aerogel (CBA) with 3D macroporous structure was synthesized by in situ deposition of visible light responsive CuS photocatalyst. Hexagonal CuS was deposited onto the outer and inner walls of CBA matrix. CuS/CBA composite catalyst has hierarchical porous structure and abundance in functional groups supporting CuS on CBA surface that enhance photodecomposition of methylene blue (MB). The CuS/CBA composite was characterized by XRD, FTIR, SEM-EDS, Atomic Absorption Analysis, and XPS analysis. Photodegradation rate of MB by CuS/CBA composite catalyst in visible light was 94.1%, whereas, 67.4% for pure CuS. Initial MB concentration effects, pH change, and variations in CuS/CBA dosage on overall reaction kinetics were also studied. CuS/CBA composite catalyst carried out Photo-Fenton like reactions which decomposed 97% MB within 6 min, by producing hydroxyl radicals from chemical and photocatalytic reactions. CuS/CBA composite catalyst was recycled and reused. It retained over 80% MB degradation rate even after five consecutive cycles. CuS/CBA composite can be used as biocatalyst for removal of organic dyes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47404.     

Removal behavior and mechanism of silver from low concentration wastewater using cellulose aerogel modified by thiosemicarbazide

Due to the low concentration of silver in water, most of the cellulose adsorbents exhibited low removal efficiency, which greatly limited their practical applications. Herein, a cellulose aerogel modified by thiosemicarbamide (CAT) was fabricated for reducing and adsorbing silver ions from low concentration wastewater. The characterization results concluded that CAT owned a three-dimensional spongy structure with many circular microspheres and a better specific surface area (19.37 m² g⁻¹), as well as the functional groups of ─C═N⁺─H and ─(C═S)─N. The static batch adsorption experiments demonstrated that CAT could reached the maximum removal percentage of 94.94% and adsorption capacity of 42.12 mg g⁻¹ under the initial concentration of Ag(I) was 15 mg L⁻¹ and the pH value was 7. Meanwhile, the adsorption of Ag(I) on CAT was second-order reaction, and the Langmuir model could better fit the adsorption process. In addition, CAT exhibited wide pH values (1–9) adaptability and excellent adsorption performance for silver through electrostatic interaction, chelation, and reduction. This study probably provides a new method as well as important experimental data and theoretical reference for the removal of silver ions and other metals.     

Fabrication of paper based carbon/graphene/ZnO aerogel composite decorated by polyaniline nanostructure: Investigation of electrochemical properties

The cellulose derived carbon/graphene/ZnO aerogel composite was prepared as an electrode in order to investigate the electrochemical properties. Carbon aerogel was synthesized using paper as an available cellulose source, and the composite was obtained through a new and simple preparation method including the immersion of monolithic carbon aerogel in graphene oxide/Zn²⁺ suspension and subsequent chemical reduction and freeze drying. The morphology, functional groups and crystalline structure of the samples were studied with Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction Spectroscopy (XRD), respectively. Electrochemical performance of the prepared binder free electrodes was examined using Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS). The data revealed that flexible carbon/graphene/ZnO composite resulted in a low density (0.035 g cm⁻³) electrode with the capacitance of 900 mF cm⁻² at a high current density of 10 mA cm⁻², lower IR drop and high cyclic stability (capacitance retention of 96%) after 1000 cycles, at 10 mA cm⁻². These features were due to the presence of 3D porous conductive network, highly reduced graphene oxide, and the formation of ZnO nanoparticles on graphene sheets. Moreover, polyaniline (PANI) was introduced to carbon/graphene/ZnO composite electrode using electro-oxidation method at different reaction time and aniline concentration in order to achieve remarkably improved capacitance of 2500 mF cm⁻² (at 10 mA cm⁻²) and low charge transfer resistance. Also, after the supercapacitor device assembly, the capacitance was retained. Based on the results, the synthesized composite is a promising material for new generation of lightweight freestanding electrodes with the high electrochemical performance.     

石墨烯气凝胶/MnO2复合材料强化电容去离子性能研究

选用石墨烯气凝胶(GA)作为载体,负载MnO2纳米颗粒,构建新型石墨烯气凝胶-MnO2复合材料(MnGA),并制备电容电极,研究复合材料的电容去离子性能。结果表明,MnO2在石墨烯片层上可形成一维线状结构,减弱石墨烯片层间的堆叠效应,提升材料电容,从而提高了电极的脱盐性能,最大电容脱盐量达到25.78 mg/g;NaCl溶液的初始浓度、供电电压和进水流速均会对电容脱盐量产生影响。     

3D石墨烯/导电聚合物气凝胶复合材料在超级电容器中的研究进展

分析了近年来超级电容器电极材料尤其是3D石墨烯/导电聚合物气凝胶复合电极材料在超级电容器方面的研究进展,详细介绍了目前3D石墨烯气凝胶的制备方法,总结了3D石墨烯/导电聚合物气凝胶复合材料的不足和在存储领域的发展方向.     

Office waste paper as cellulose nanocrystal source

Cellulose nanocrystals (CNC) are isolated from office waste paper using an alkali solution and a subsequent acid hydrolysis process. The Fourier transform infrared spectroscopy and X‐ray diffraction (XRD) results demonstrate that ink and fillers used in the papermaking industry are almost totally removed after alkali treatments. The XRD results show that CNCs obtained after 2 wt % NaOH solution treatment and a subsequent hydrolysis process exhibit only a cellulose I crystalline structure, and the crystallinity index value increases around 42% with respect to initial office waste paper. Nevertheless, CNCs obtained after 7.5 wt % NaOH solution treatment and a subsequent acid hydrolysis process show a mixture of cellulose I and cellulose II polymorphs. The thermal analysis shows that the CNCs obtained after 7.5 wt % NaOH solution treatment and a subsequent acid hydrolysis process are thermally less stable than other samples, suggesting that the cellulose chains could depolymerize into low molecular weight sugar compounds. Even though the atomic force microscopy images confirm the presence of CNCs, the optical images show that some cellulose microfibers still maintain their structure. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45257.     

One-step hydrothermal synthesis of 3D porous microspherical LiFePO4/graphene aerogel composite for lithium-ion batteries

Three-dimensional (3D) porous LiFePO₄/graphene aerogel (LFP/GA) composite was successfully prepared by an in-situ hydrothermal process. In this composite, the LiFePO₄ microspheres assembled by nanoparticles were embedded in a three-dimensional framework intertwined with the graphene sheets, which acts as a bridge for transfer of electron and diffusion of lithium ion. The large specific surface of the composite structure enables the increased infiltration area and utilization of the active material. The content of the graphene sheet is analyzed and is found important for the Li-storage characteristics of LiFePO₄. An aerogel composite with 10% of graphene displays the best electrochemical performance, with the specific discharge capacities of 168 mAh g⁻¹ and 155 mAh g⁻¹ at respectively 0.1C and 1C, and the capacity retains 96.3% for up to 800 cycles. This novel 3D porous aerogel composite is identified as a promising cathode material for the rechargeable Li battery, and the simple strategy may be applied to construct other high performing composite structure and materials.     

玻璃棉/SiO2气凝胶复合板的改性研究

通过选取无水乙醇为溶剂,以SiO₂气凝胶为溶质,制备SiO₂气凝胶改性溶液,并将其应用于改善玻璃棉的保温性能。通过浸润及常压干燥的方法制取玻璃棉/SiO₂气凝胶复合板,研究SiO₂气凝胶的质量分数和浸润时间对其性能的影响,并与溶胶-凝胶法制备的玻璃棉/SiO₂气凝胶复合板相比。研究表明SiO₂气凝胶的质量分数和浸润时间对玻璃棉/SiO₂气凝胶复合板的性能有显著影响。当SiO₂气凝胶质量分数达到8%且浸润时间为20 min时,玻璃棉/SiO₂气凝胶复合板的短期吸水率、热导率分别下降了38.09%、18.32%,抗压强度上升了102.89%。与溶胶-凝胶法相比,本方法具有制备周期短、工艺较为简洁、成本低等优点,更适宜于大规模生产应用。