纤维素基气凝胶制备及其超疏水改性研究进展

随着工业化快速发展对能源需求的急剧增加,海上输油管线的泄露溢油和工业有机废水处理故障风险提高,溢油和工业有机废水泄露给海洋水体生态系统带来了巨大危害。为了应对这一海洋生态风险,开发绿色环保、低成本、高效的原油和有机污染物清除方法和材料意义重大。采用吸附材料处理有机污染物被认为是有效的方法之一。纤维素基气凝胶具有轻质、多孔、可生物降解和环境友好等特点,对其进行超疏水改性并应用于吸附处理原油和有机污染物泄露事故,具有较好的应用前景。本文综述了纤维素基气凝胶的制备及其疏水改性方法与试剂,并对纤维素基超疏水气凝胶材料的发展进行了展望。     

基于原位生长法制备纤维素气凝胶@ZIF-8复合材料及其对溶菌酶固定化的研究

随着生物化学和生命科学等领域的快速发展,酶工程成为研究热点;然而由于游离酶的结构敏感、易失活失效、且回收利用困难等,极大限制了它的发展和应用。通过吸附等手段将酶固定到特定载体中,可以提高酶活性和稳定性。本研究采用原位生长法制备结构规整的纤维素气凝胶@沸石咪唑酯骨架材料-8（ZIF-8）复合材料,并通过ZIF-8与蛋白之间的多重相互作用成功将溶菌酶固定;考察了pH值、盐浓度、吸附时间和吸附浓度对复合材料吸附性能及对固定化性能的影响。研究结果表明,纤维素气凝胶@ZIF-8对溶菌酶的最大固定化值为111.3 mg/g,并可在40 min内即可达到吸附平衡。催化实验研究结果发现,与游离酶相比,纤维素气凝胶@ZIF-8固定的溶菌酶具有更佳的催化效果。     

纳米纤维素气凝胶构建及其过滤聚苯乙烯微塑料性能研究

以漂白桉木浆为原料,分别通过2,2,6,6-四甲基哌啶氧化物（TEMPO）和2,3-环氧丙基三甲基氯化铵（EPTMAC）对其化学改性,并借助高压均质处理得到改性纤维素纳米纤丝（CNF）,最后采用冷冻干燥法制备得到改性CNF气凝胶。研究了聚苯乙烯微塑料（PSMPs）种类和浓度对改性CNF气凝胶过滤性能的影响。结果表明,EPTMAC改性气凝胶（QCNF）对羧基化聚苯乙烯（PS-COOH）的过滤效率为99%;TEMPO氧化改性气凝胶（TCNF）对氨基化聚苯乙烯（PS-NH₂）的过滤效率为75%。改性CNF气凝胶对PSMPs的过滤性能得益于材料本身的超亲水性、独特的三维多孔结构和表面丰富的活性结合位点。此外,QCNF气凝胶经过8次循环过滤后,QCNF气凝胶对PS-COOH的过滤效率始终保持在99%以上,过滤通量稳定且超过20.2 L/（m²·h）,具有良好的稳定性和可重复利用性。     

SiO2气凝胶隔热保温涂料研究及保温结构优化设计

石油化工行业是国家节能减排重点工程之一，如果相关设备设施保温不当，不仅会造成严重的热量散失，还会对油水分离和输送等产生影响。本文系统介绍了传统的以中空玻璃微珠或陶瓷微珠为主要隔热功能填料的隔热保温涂料的保温机理、性能及其存在的问题；以 SiO₂气凝胶为主要功能填料的新型隔热保温涂料研究现状及研究中的技术难点；针对不同应用环境，开发兼具防腐、防开裂、隔热保温功能的复合保温结构设计。本文为研制新型耐高温、高效水性无机隔热保温涂料的研究提供了参考方向，为隔热保温涂料在石油化工领域的工程应用提供分析。     

常压干燥合成水玻璃基SiO_2气凝胶

以水玻璃和双氧水为原料一步合成二氧化硅湿凝胶,经老化、溶剂置换及三甲基氯硅烷修饰后,并于常压干燥后获得二氧化硅气凝胶。样品经低温N_2吸附-脱附、红外光谱和扫描电镜测试表明所得二氧化硅气凝胶具有三维多孔结构,且其比表面积可达482 m~2·g~(-1)、平均孔径为24.9nm及表观密度为0.12g·cm~(-3)。     

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.     

羟甲基化木质素/纤维素气凝胶粒子的制备、表征及吸附性能

以羟甲基化木质素和纤维素为原料，NaOH/尿素水溶液为溶解体系，采用冷冻干燥法制备羟甲基化木质素/纤维素气凝胶粒子。采用扫描电子显微镜（SEM）、傅里叶变换红外光谱（FT-IR）仪、X射线衍射（XRD）仪、比表面积及孔径分析仪等对其结构进行了表征。研究结果表明：羟甲基化木质素分子通过氢键作用附着在纤维素骨架上，气凝胶内部仍保持三维网状结构，羟甲基化木质素的引入使得气凝胶表面出现明显收缩，网状结构的致密度随着羟甲基化木质素用量提高而逐渐降低；同时气凝胶粒子具有纤维素Ⅱ型红外吸收峰和XRD衍射峰；粒子表现出Ⅱ型吸附/脱附等温线，孔径均在15 nm以下，且随着羟甲基化木质素用量不断提高，比表面积、孔容均有所减小，HKL-4的比表面积为105.3m²/g，孔容为0.336 6cm³/g，孔径为13.67nm。吸附性能分析表明在25℃下吸附5 h，HKL-4气凝胶粒子对金胺O、亚甲基蓝和罗丹明B的吸附量分别为33.06、96.06和43.26mg/g，对亚甲基蓝的饱和吸附量可达208.7 mg/g，吸附过程更符合Langmuir等温吸附模型，主要为单分子层吸附。     

Elastic modulus prediction based on thermal conductivity for silica aerogels and fiber reinforced composites

The speed of sound is a critical parameter in the test of mechanical and thermal properties. In this work, we proposed a testing method to obtain the elastic modulus of silica aerogel from the sound speed formulas. The solid thermal conductivity of the silica aerogel is experimentally measured for predicting the sound speeds, and then the elastic modulus is calculated based on the elasticity sound speed model. The experimental data of the solid thermal conductivity of silica aerogels with different densities are employed and the obtained elastic modulus is fitted as a power-law exponential function of the density. Two existing sound speed models and three groups of available experimental data are also employed to validate the present fitting relation, and good agreement is obtained for the silica aerogel in the density range of 150–350 kg/m³. The fitting formula can also be extended to estimate the elastic modulus of the glass fiber-reinforced silica aerogel composite. The results show that the elastic modulus of the aerogel composite is sensitive to the glass fiber volume fraction, while the thermal conductivity is weakly dependent on the glass fiber volume fraction at room temperature in the studied range of fiber volume fraction.     

Electrospun nanofiber composites with micro-/nano-particles for thermal insulation

Polyacrylonitrile (PAN) nanofiber and silica aerogel (SAG) laminated composites were prepared via electrospinning for thermal insulation. Conventional single nozzle and co-axial electrospinning were used to increase the fraction of aerogel particles in the composite sheets while maintaining the mechanical strength of the sheet. When the core-shell electrospinning technique with co-axial nozzle was applied, the proportion of aerogel particles increased two fold without a deterioration of the mechanical properties. The average thermal conductivity of the laminated composite sheet was reduced by approximately 12.5% as compared to the nanofiber composite prepared using the single-nozzle electrospinning technique. For additional reduction in thermal conductivity, hollow glass microspheres (HGM) was inserted between the interlayer spacing of the electrospun sheets to increase the interlayer spacing. When HGM particles were inserted, it was observed that the thermal conductivity decreased by approximately 20% compared to that of the specimen without particles.     

Three-dimensional layered porous graphene aerogel hydrogen getters

Organic getters are often introduced into sealed systems to remove the excessive reactive hydrogen gas. In this work, the formable graphene aerogel hydrogen getters are prepared by integrating the alkyne-containing molecules (e.g., DEB) into the palladium-loaded three-dimensional layered porous graphene aerogel (Pd-GA). The performance of Pd-GA/DEB composite materials in reducing reactive hydrogen gas is examined at pressures of 0.1–1 bar at a temperature of 25 °C, and the hydrogen consumption is measured as a function of time. Results suggest that the hydrogen uptake capability of Pd-GA/DEB getters increases with the loading of Pd particles on the GA and the content of Pd⁰. The highest hydrogen absorption capacity is up to 215.5 cm³/g, and the hydrogenation rate of DEB molecules is 89.3%. This study promotes the fundamental understanding of solid-phase catalytic hydrogenation and the applications of 3D layered porous graphene aerogel in hydrogen absorption.