植物纤维素基碳气凝胶的制备及应用研究进展

植物纤维素基碳气凝胶具有低密度、可生物降解、优异的吸附性能和电化学性能稳定等特点。本文围绕其原料来源、制备工艺及其在环境治理和能量储存与转化方面的应用,分析了植物纤维素基碳气凝胶的性能及研究进展。详细叙述了以棉花、木材、竹纤维等为原料的植物纤维素基碳气凝胶的制备方法,如：溶胶-凝胶法、水热炭化法、直接炭化法等。分析了制备过程中干燥方法、溶剂的选择及置换、复合改性等影响因素,并介绍了碳气凝胶在空气净化、油水分离、有毒化合物、重金属离子的去除等环境治理及能量转化与储存方面的。     

纤维素基碳气凝胶研究进展

介绍了纤维素碳气凝胶原材料的主要来源及各原材料的特点,重点举例阐述可直接利用型纤维素制备纤维素基碳气凝胶材料的不同工艺方法,综合分析了纤维素基碳气凝胶作为多功能材料的一些前沿的应用研究。总结了该领域存在的挑战并展望了纤维素基碳气凝胶的发展前景。     

利用玉米秸秆纤维素制备碳气凝胶的研究

将玉米秸秆中的纤维素通过碱处理以及漂白处理的方法提取出来,再将玉米秸秆纤维素分散在水中,并通过超声以及冷冻干燥的方法制成玉米秸秆纤维素气凝胶,最后将气凝胶高温碳化制得玉米秸秆纤维素碳气凝胶。通过扫描电镜（SEM）,红外光谱（FT-IR）,X射线衍射仪,水接触角（WCA）等对玉米纤维素气凝胶以及碳气凝胶进行表征测试,并使用不同油类以及有机溶剂进行玉米秸秆纤维素碳气凝胶的吸附、解吸实验。结果表明,制备的玉米秸秆纤维素碳气凝胶（CA-200）相较于同质量比的气凝胶（AE-200）具有更好的三维结构以及优良的疏水性能。制得的碳气凝胶其水接触角能达到135°,并且其对植物油、润滑油以及乙醇的吸附性能可达自身质量的80～140倍。相较于没有经过碳化的气凝胶AE-200的吸附性能提升了50倍左右。     

海藻酸钠基碳气凝胶的染料吸附及油水分离研究

利用来源广泛、绿色无污染的海洋材料海藻酸钠为碳源,经湿法纺丝、高温碳化和水洗制备了海藻酸钠基碳气凝胶W-SACA。W-SACA具有丰富的孔洞结构和高达1 143.77 m~2/g的比表面积。以阳离子染料亚甲基蓝(MB)、阴离子染料甲基橙(MO)、溶剂染料油红O(ORO)为代表考察了接触时间、染料浓度、温度、pH对吸附效果的影响,结果表明,W-SACA对这3种染料的吸附量分别高达196.500 9、198.921 6、194.320 2 mg/g。此外,W-SACA也成功地应用于油水混合物和乳液的高效分离。     

石墨烯基分子印迹气凝胶制备及吸附性能研究

以氧化石墨烯(GO)为分子骨架,负载纳米氧化铁(γ-Fe2O3)和TiO2赋予GO磁性和光催化性;利用苯并α 芘(BaP)为模板合成具有识别吸附降解BaP性能的石墨烯基分子印迹气凝胶(GMIA).通过傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和X射线能谱(EDS)表征中间...     

冬瓜皮衍生碳气凝胶对含Pb(Ⅱ)废水吸附性能研究

以天然植物的果皮为原料,通过水热法制备冬瓜皮衍生碳气凝胶,并将其应用于处理含Pb(Ⅱ)模拟废水。采用扫描电子显微镜等仪器对冬瓜皮衍生碳气凝胶的结构和性能进行表征。同时,研究了pH值、吸附时间、吸附剂用量等因素对Pb(Ⅱ)去除率的影响。结果表明,采用煅烧温度为800℃制备的碳气凝胶,当pH为6.0,吸附时间为10 h时,去除率达到94%,能有效处理含Pb(Ⅱ)废水。     

冬瓜皮衍生碳气凝胶对含Pb(Ⅱ)废水吸附性能研究

以天然植物的果皮为原料,通过水热法制备冬瓜皮衍生碳气凝胶,并将其应用于处理含Pb(Ⅱ)模拟废水。采用扫描电子显微镜等仪器对冬瓜皮衍生碳气凝胶的结构和性能进行表征。同时,研究了pH值、吸附时间、吸附剂用量等因素对Pb(Ⅱ)去除率的影响。结果表明,采用煅烧温度为800℃制备的碳气凝胶,当pH为6.0,吸附时间为10 h时,去除率达到94%,能有效处理含Pb(Ⅱ)废水。     

Porous structure and liquid‐phase adsorption properties of activated carbon aerogels

In this article, activated carbon aerogels (ACAs) were prepared by CO₂ activation. Their pore structures were investigated by N₂ adsorption–desorption analysis. ACAs have excellent microporosity (e.g. 0.36 cm³/g) and mesoporosity (e.g. 1.72 cm³/g). Adsorption characteristics of phenol, methylene blue, I₂, and VB₁₂ on ACAs in the liquid phase were studied by static adsorption experiments. Results showed that CO₂ activation process is an effective way to introduce micropores in carbon aerogels, which is enhanced with the increase of activation time. As a result, the adsorption capacities of the four mentioned adsorbates on ACAs were improved gradually with the increase of activation time. However, mesopore volume is also a factor on improving adsorption properties for the relatively giant molecules methylene blue and VB₁₂. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Platinum supported on resorcinol–formaldehyde based carbon aerogels for PEMFC electrodes: Influence of the carbon support on electrocatalytic properties

Two carbon aerogels with different nanopore size distributions but both with high surface area, high nanoporous volume and low bulk density have been compared as platinum support. The influence of the nanostructure of the carbon aerogel on the platinum nanoparticle deposit was investigated. The platinum was deposited on the carbon by means of two different techniques, one employing an anionic platinum precursor, the other using a cationic one. The porosity of the carbon aerogels was characterized by combining N₂-sorption and mercury porosimetry. The platinum deposit was characterized by transmission electron microscopy and rotating disk electrode experimentation to measure the platinum active surface area and its activity towards oxygen reduction reaction (ORR). The structural differences between the carbon aerogels did not yield any difference in platinum deposits in terms of Pt-surface area and ORR activity. Interestingly, the ORR mass activity of the high Pt-surface area samples, obtained by the cationic insertion technique, was several times lower than that of the samples obtained by the anionic technique. This observation was attributed to the particle size effect, detrimental in the case of platinum particle size around 1 nm.     

Preparation and electrochemical properties of pitch-based activated carbon aerogels

The porous structure of pitch-based carbon aerogels (P-CAs) can be modified by KOH activation. It is found that decreasing the carbonization temperature of precursor CAs and increasing the mass ratio of KOH to CAs help to the formation of 0.7 nm-sized micropores and 2.7 nm-sized mesopores, respectively. The origin and the pore size of micropores play an important role in controlling electrochemical properties. The carbonization-forming micropores have stronger energy storage efficiency than activation-forming micropores, and only those with diameter below 1 nm (Microp < 1 nm) are the crucial place to storage energy. Due to the substantive increase of the number of the Microp < 1 nm, the highest specific capacitance of the as-prepared activated samples can reach 187.2 F g⁻¹ at 5 mA cm⁻², 1.8 times as large as that of their precursor CAs. Furthermore, this capacitance is still up to 173.3 F g⁻¹ when increasing the current density to 50 mA cm⁻², indicating that the activated samples have a high-rate charge–discharge performance.     

负载途径对炭气凝胶载Pt催化剂性能的影响

选择孔隙率高、孔隙尺寸小、比表面积大、电导率高、孔径大小及分布可控的新型炭材料炭气凝胶(CAs)为载体,通过在成品CAs表面负载和在CAs制备过程中同步负载两种途径制备了CAs负载的Pt催化剂,利用XRD、TEM、ICP及电化学循环伏安测试等手段对比讨论了负载途径对CAs载Pt催化剂物化性能及甲醇氧化催化活性的影响。结果表明,同步负载虽然可以简化制备工艺,但所制得的催化剂样品中催化活性组分Pt颗粒大、团聚严重、分散性差、负载量低,而且有许多Pt颗粒被包裹在CAs内部,因而导致了催化剂的有效利用率和催化性能降低。相反,通过在成品CAs表面负载的方法可以制得Pt颗粒小、分散均匀、实际负载量接近理论设计的高性能催化剂。     

对苯二酚-甲醛有机气凝胶的结构测试及性能研究

首次用溶胶-凝胶法和CO2超临界干燥技术制备了对苯二酚-甲醛有机气凝胶,并经高温碳化处理得到其碳气凝胶,测得气凝胶的比表面积由碳化前的375.28 M2/G增大到碳化后的468.66 M2/G,碳气凝胶的孔径集中分布在15NM以内。观察到其表观形貌,以及碳气凝胶中存在微晶结构。研究了不同反应物配比对凝胶性能的影响,并发现碳气凝胶具有良好导电性。     

碳纳米管-石墨烯气凝胶制备及其对水中乳化油的吸附特性

以改进的Hummers-Offeman法制备出的氧化石墨（GO）与羧基化多壁碳纳米管（CNTs-COOH）为原料,聚乙烯吡咯烷酮（PVP）为交联剂,乙二胺（EDA）为还原剂,水热还原法制得羧基碳纳米管-石墨烯复合气凝胶（CGA）。调整GO与CNTs-COOH的质量比获得密度在8.40～14.42 mg·cm^-3之间的气凝胶,并确定在GO：CNTs-COOH=3：1（质量）时得到的气凝胶的机械强度最优。通过扫描电子显微镜（SEM）、X射线衍射（XRD）、X射线光电子能谱（XPS）对所制备的CGA进行表征,得知GO与CNTs-COOH已成功还原组装成多孔状三维气凝胶结构。以水中乳化柴油作为研究对象,考察CGA样品在不同温度下对乳化柴油的吸附特性。结果表明,CGA的吸附量在前6 min迅速上升,在30 min左右达到吸附平衡,且平衡吸附量随温度升高而增加。吸附过程遵循准二级动力学模型,体系表观活化能为7.10 kJ·mol^-1。利用颗粒内扩散模型分析得出,CGA对乳化油的吸附分为外表面吸附过程和内部孔道吸附过程（内部大孔道吸附、中孔道和微孔道内扩散3个阶段）。     

自乳化型水性醋酸纤维素乳液的制备与性能研究

以二羟甲基丙酸(DMPA)为亲水扩链剂,以醋酸纤维素(CA)、异佛尔酮二异氰酸酯(IPDI)和三乙胺(TEA)等为主要原料,成功制备出一种自乳化型WCA(水性醋酸纤维素)乳液,并采用正交试验法优选出制备WCA乳液的最佳工艺条件。研究结果表明:当n(DMPA)∶n(IPDI)=0.40∶1、n(CA)∶n(IPDI)=3∶1、中和度为0.9、第一(第二)阶段反应温度和反应时间分别为50℃(75℃)和60 min(90 min)时,该环保型WCA乳液的耐水性、柔韧性和粘接强度(2.9 N/mm)俱佳,并且其制备工艺简单、可室温粘接以及成本较低,具有良好的应用前景。     

Sorption and other properties of polytetrafluoroethylene/cellulose composite aerogels

Polytetrafluoroethylene/cellulose composite aerogels containing PTFE from 0 to 40 wt.% were obtained by drying the corresponding suspension mixtures at a temperature of 50°C. Cellulose isolated from the stem of Sosnowski hogweed was used as the main component of the aerogels. In present work, the composite aerogels were heated in an inert atmosphere at a temperature of 370°C to partially hydrophobize cellulose and remove surfactants that were present in the initial PTFE suspension. It was found that at this temperature, the thermal degradation of cellulose proceeded differently in the presence and absence of PTFE. The maximum water contact angle (156°) was obtained for the sample with 10 wt.% PTFE. Hydrophobized samples of aerogels were studied with the help of infrared spectroscopy, scanning electron microscopy, and powder x-ray diffractometry and tested as sorbents for various solvents. It was found that the volume of solvent absorbed by the aerogel, in the case of a sample with a PTFE content of 40 wt.%, can even exceed the initial volume of the absorber.     

蔗渣活性炭去除糖蜜酒精废水COD的实验研究

通过单因素与正交实验,研究了蔗渣活性炭处理糖蜜酒精废水的工艺条件及其影响因素.结果表明,最佳工艺条件为蔗渣活性炭投加质量0.30 g、吸附时间120 min、溶液的pH=7.3(中性)和温度为30℃(常温),在此条件下糖蜜酒精废水COD去除率达74.3%.     

预处理蔗渣纤维素水解糖化研究

采用两段稀酸水解法对用质量分数为5%氢氧化钠溶液预处理后的蔗渣进行了水解糖化研究,考察了液固比、硫酸体积分数、反应时间及催化剂硫酸亚铁对葡萄糖得率及纤维素水解率的影响。结果表明:第一段主要是半纤维素水解,以及少量纤维素水解,最优条件为液固比10 mL/g,硫酸体积分数3%,在121℃下反应3 h,葡萄糖得率为22.16%,纤维素水解率为25.98%;对残渣继续第二段水解,最优条件为液固比8 mL/g,硫酸体积分数为8%,硫酸亚铁质量分数1%,在121℃下反应5.5 h,葡萄糖得率为41.05%,纤维素水解率为56.36%;采用两段稀酸水解法水解蔗渣,葡萄糖总得率为52.68%,纤维素总水解率为67.70%。