scholarly journals Water-Ionic Liquid Binary Mixture Tailored Resorcinol-Formaldehyde Carbon Aerogels without Added Catalyst

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4208 ◽  
Author(s):  
Balázs Nagy ◽  
István Bakos ◽  
Erik Geissler ◽  
Krisztina László
Keyword(s):  
Ionic Liquid ◽  
Water Content ◽  
Sol Gel ◽  
Structural Defects ◽  
Carbon Aerogels ◽  
Process Conditions ◽  
Scanning Electron Micrographs ◽  
Initial Water ◽  
Resorcinol Formaldehyde ◽  
Bead Size

The potential applications of mesoporous carbon aerogels are wide-ranging. These gels are often obtained from resorcinol-formaldehyde (RF) hydrogel precursors. The sol-gel method in this synthesis provides an efficient and versatile means of product control through systematic variation of process conditions, such as pH, stoichiometry, concentration, catalyst, further additives, etc., in addition to the drying and pyrolytic conditions. Here, a novel means of tuning the texture of carbon aerogels is proposed. Water-1-ethyl-3-methylimidazolium ethyl sulfate ([emim][EtSO4] mixtures constitutes a polycondensation medium that requires no added catalyst, thus yielding an intrinsically metal-free carbon aerogel after pyrolysis. We also show that the carbon morphology is tailored by the supramolecular structure of the aqueous ionic liquid. The results of scanning electron micrographs, low-temperature nitrogen adsorption/desorption isotherms, and small-angle X-ray scattering (SAXS) confirm that changing the initial water concentration from 9 to 55 wt % gives rise to systematic alteration of the mesopore size and volume, as well as of the bead size. The pore structure becomes consolidated only when the water content exceeds 25 wt %. When the water content reaches 55 wt %, the bead size increases by two orders of magnitude. The electrocatalytic performance, however, is compromised, most probably by structural defects.

Fabrication of Carbon Aerogels

2006 ◽  
Vol 11-12 ◽  
pp. 19-22 ◽  
Author(s):  
Y.N. Feng ◽  
Lei Miao ◽  
Yong Ge Cao ◽  
T. Nishi ◽  
Sakae Tanemura ◽  
...  
Keyword(s):  
Pore Size ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Limited Range ◽  
Molar Ratio ◽  
Carbon Aerogels ◽  
Resorcinol Formaldehyde ◽  
Catalyst Content ◽  
Fabrication Parameters ◽  
Pyrolysis Processes

RF (Resorcinol-Formaldehyde) aerogels and carbon aerogels were prepared through the sol-gel method following the routes of polymerization, gelation, supercritical drying and pyrolysis processes. The influence of fabrication parameters on the textural structure of the samples, e.g., specific surface area, pore size, and pore size distribution, etc., were systematically investigated. With a decrease in the R/F molar ratio, or an increase in the catalyst content within a limited range, the porosity of the nanostructure materials increases. The optimal temperature of pyrolysis for RF aerogel was investigated by TGA (Thermogravimetric Analysis).

The Effect of Carbonization Temperature on Carbon Aerogels Structure

2020 ◽  
Vol 842 ◽  
pp. 182-185
Author(s):  
Sha Sha Wang ◽  
Yue Long Xu ◽  
Li Hui Zhang ◽  
Zhen Fa Liu
Keyword(s):  
Pore Size ◽  
Network Structure ◽  
Sol Gel ◽  
Carbonization Temperature ◽  
Carbon Aerogels ◽  
Sem Images ◽  
Resorcinol Formaldehyde ◽  
Graphitization Degree ◽  
Adsorption Amount ◽  
Xrd Patterns

Phloroglucinol–resorcinol–formaldehyde (PRF) carbon aerogels were synthesized by sol–gel reaction. The results of condition of shrinkage showed a degree of crosslinking more obvious with the increasing of the carbonization temperature. CA900 displays the highest adsorption amount and the biggest loops, as well as an increase in pore size and volume in comparison to the others samples. The SEM images of carbon aerogels under different carbonization temperature possess closer network structure and excellent connectivity, the holes between the network are abundant. The XRD patterns show that the high carbonization temperature can enhance the graphitization degree of carbon aerogels.

Preparation and Characterization of Phloroglucinol-Resorcinol-Formaldehyde Carbon Aerogels

2013 ◽  
Vol 423-426 ◽  
pp. 523-527
Author(s):  
Xuan Liu ◽  
Zhen Fa Liu ◽  
Hao Lin Fu ◽  
Rui He ◽  
Li Hui Zhang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
High Specific Surface Area ◽  
Carbon Aerogels ◽  
Resorcinol Formaldehyde ◽  
Sol Gel Process ◽  
Solvent Replacement ◽  
Organic Aerogels

Phloroglucinol-resorcinol-formaldehyde organic aerogels (PRF) were prepared using phloroglucinol, resorcinol and formaldehyde in a sol-gel process, solvent replacement and drying at room temperature. The phloroglucinol-resorcinol-formaldehyde carbon aerogels (CPRF) were prepared by charring the PRF at high temperature under the aegis of helium flow. The microstructure of CPRF was characterized by infrared spectroscopy, specific surface area analyzer and scanning electron microscopy. The results showed that the CPRF had continuous network structure and high specific surface area.

Synthesis and Structural Characteristics of Organic Aerogels with Different Content of Lignin

2010 ◽  
Vol 113-116 ◽  
pp. 1837-1840 ◽  
Author(s):  
Feng Chen ◽  
Jian Li
Keyword(s):  
Structural Characteristics ◽  
Cell Structure ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Raw Material ◽  
Spherical Particles ◽  
Carbon Aerogels ◽  
Scanning Electron Micrographs ◽  
Transmission Electron ◽  
Organic Aerogels

Lignin can be used as a cheap raw material to prepare organic and carbon aerogels based upon the sol-gel reactions. Different concent lignin organic aerogels have been prepared by sol–gel polymerization of formaldehyde with resorcinol, following by the process of RF-gel production and subsequent freeze drying. The resulting materials were characterized by FT-IR analysis, nitrogen adsorption, transmission electron microscopy and Scanning electron micrographs. The structural properties organic aerogel depend on the amount of lignin added to the sol-gel system. and the LRF aerogels obtained in the experimental have an open cell structure with continuous porosity and homogeneous spherical particles.

Gas Transport in Sol-Gel Derived Porous Carbon Aerogels

1996 ◽  
Vol 464 ◽  
Author(s):  
G. Reichenauer ◽  
J. Fricke
Keyword(s):  
Sol Gel ◽  
Water Desalination ◽  
Carbon Aerogels ◽  
High Porosity ◽  
Nanoporous Carbons ◽  
Time Resolved ◽  
Resorcinol Formaldehyde ◽  
Dead End ◽  
Gas Expansion ◽  
Different Gases

ABSTRACTDue to their high electrical conductivity, their large specific surface area and their high porosity sol-gel derived nanoporous carbons are promising materials for electrodes, e.g. in water desalination systems or fuel cells. In order to optimize their properties with respect to these applications information is needed about transient and steady state transport through the interconnected pores.Dynamic gas expansion and time resolved permeation measurements allow to determine the relevantquantities, i.e. the permeability, the ratio of gas phase to surface diffusion and the volume of dead end pores along with the tortuosity.Experimental data on nanoporous carbons of different density are presented. All samples investigated were prepared via pyrolysis of resorcinol formaldehyde aerogels. The measurements were performed with different gases below 0.1 MPa.

Influence of initial water content and strain rate on remolded yield stress in marine clay

2021 ◽  
pp. 1-8
Author(s):  
Xiaobing Li ◽  
Jianpeng Chen ◽  
Xiuqing Hu ◽  
Hongtao Fu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Strain Rate ◽  
Water Content ◽  
Yield Stress ◽  
Initial Water Content ◽  
Marine Clay ◽  
Initial Water

scholarly journals Application of the Calorimetric Methods to the Characteristics of Seeds from Olives

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 90
Author(s):  
Andrzej Bryś ◽  
Joanna Bryś ◽  
Marko Obranović ◽  
Dubravka Škevin ◽  
Szymon Głowacki ◽  
...  
Keyword(s):  
Olive Oil ◽  
Water Content ◽  
Cooling System ◽  
Waste Product ◽  
Normal Pressure ◽  
Ash Content ◽  
Initial Water Content ◽  
Scanning Calorimetry ◽  
Initial Water

The olive oil industry represents an important productive sector in the Mediterranean basin countries. Olive stone is an essential by-product generated in the olive oil extraction industries and it represents roughly 10% by weight of the olive fruit. The seeds of pickled olives are also a significant waste product. In the present study, we have investigated the possibility of the use of differential scanning calorimetry for the thermal characterization of seeds from green and black pickled olives from Croatia. The differential scanning calorimeter (DSC) with a normal pressure cell equipped with a cooling system was used to determine the thermal properties of seeds from olives. The following analyses were also performed: the determination of calorific values in a pressure bomb calorimeter, the determination of initial water content, the determination of changes of water content during drying at the temperatures of 30 °C, 50 °C and 80 °C, the determination of a percentage content of seeds mass to the mass of the whole olives, and the determination of ash content. Seeds from olives are characterized by very good parameters as a biomass. The analyzed olive seeds were characterized by low water content, low ash content, and a relatively high caloric value.

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