Researchers from Rice University (Houston, Texas, USA) and the University of Calgary, Canada (UCalgary) (Calgary, Alberta, Canada) have collaborated in an effort to convert asphaltenes, a carbon-rich byproduct of crude oil production, into turbostratic (loosely aligned) graphene and mix it into composites for thermal, anti-corrosion, and 3D-printing applications.
The project, which employs Rice’s unique flash Joule heating process, makes good use of material otherwise burned for reuse as fuel or discarded into tailing ponds and landfills. Using at least some of the world’s reserve of more than 1 trillion barrels of asphaltene as a feedstock for graphene would be good for the environment as well, according to Rice.
This effort is led by Muhammad Rahman, an assistant research professor of materials science and nanoengineering at Rice and lead corresponding author of the paper in Science Advances. The other co-lead author, Rice chemist James Tour, heads the lab that developed the flash Joule heating method. Other contributing researchers include Pulickel Ajayan, Rice materials scientist and Md Golam Kibria, an assistant professor of chemical and petroleum engineering at UCalgary.
Asphaltenes are 70% to 80% carbon already. The Rice lab combines it with about 20% of carbon black to add conductivity and flashes it with a jolt of electricity, turning it into graphene in less than a second. Other elements in the feedstock—including hydrogen, nitrogen, oxygen, and sulfur—are vented away as gases.
“We try to keep the carbon black content as low as possible because we want to maximize the utilization of asphaltene,” Rahman says.
“The government has been putting pressure on the petroleum industries to take care of this,” says Rice graduate student and co-lead author M.A.S.R. Saadi. “There are billions of barrels of asphaltene available, so we began working on this project primarily to see if we could make carbon fiber. That led us to think maybe we should try making graphene with flash Joule heating.”
Assured that Tour’s process worked as well on asphaltene as it did on various other feedstocks—including plastic, electronic waste, tires, coal fly ash, and even car parts—the researchers set about making things with their graphene.
Saadi, who works with Rahman and Ajayan, mixed the graphene into composites, and then into polymer inks bound for 3D printers. “We optimized the ink rheology to show it is printable,” he says, noting the inks have no more than 10% of graphene mixed in. Mechanical testing of printed objects is also forthcoming, according to Saadi.
Source: Rice University, https://news.rice.edu.