Nashrieh Shimi va Mohandesi Shimi Iran

Nashrieh Shimi va Mohandesi Shimi Iran

Fabrication of Graphene Aerogel by Freeze Casting under Ambient Pressure and Investigation of Its Properties

Document Type : Research Article

Authors
Mansoor Farbod
Mohadeseh Madadi Jaberi
Morteza Zargar Shoushtari
Seyyedeh Saadat Shojaeenezhad
physics department, faculty of science, Shahid Chamrn university of Ahvaz, Ahvaz, I.R. Iran
Abstract
Graphene aerogels are ultralight 3D graphene structures with a density of about 10 mg/cm3, unique electrical properties, and high compression capability. In order to produce them, first graphene hydrogel is produced, then the liquid in the graphene hydrogel is replaced by air so that the volume and structure of the gel do not change. For graphene hydrogel drying, special drying methods such as freeze drying or super-critical drying, or the newest drying method, which is ambient pressure drying using ice templating are needed. In this study, graphene aerogels were produced by ambient pressure drying without the need for special apparatus or specific pressure and temperature with a density of 10.6 g/cm3 and the preparation parameters were optimized. It was found that for the preparation of graphene aerogels with higher porosity and lower density, it is appropriate to select the initial concentration of graphene oxide 4 mg/ ml, the gelation time of 7 h, and the ice templating time of 48 h. It was also found that the lower-density aerogels were more compressive. As the stresses on the specimens increased, their electrical conductivity increased and their electrical resistance decreased. Their thermal conductivity was also measured as 0.029 W/m.K, which is in the range of good thermal insulation. The adsorption capacity of diesel oil, petroleum, edible oil, and ethanol by graphene aerogels was measured 88.5, 59.6, 42.6, and 55.2 g/g, respectively. Regarding the methylene blue adsorption, it was observed that the highest adsorption occurs in the first 15 minutes, so the graphene aerogels can be used as adsorbent of methylene blue and other dyes with similar structures from water and industrial effluents.
Keywords
Graphene aerogel
Freeze casting drying
Adsorption coefficient
Electrical conduction
Thermal conduction
Subjects
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