Such novel membranes can separate individual molecules on the basis of size and shape, which could enhance the energy-efficacy of chemical separation techniques used to prepare everything from chemicals to fuels and pharmaceuticals.
The scientists have also planned a provisional patent on the technology. “Overall, we have introduced a procedure for zeolite nanosheets crystal growth that is simpler, rapid, and yields better quality nanosheets than ever before,” says Michael Tsapatsis, a University of Minnesota chemical engineering and materials science lecturer and head scientist of the study. “Our research is another step toward enhanced energy efficacy in the petrochemical and chemical industries.”
Presently, most petrochemical and chemical purification procedures are based on heat-driven processes such as distillation. Such procedures are highly energy intensive. For instance, chemical separations based on the distillation illustrate nearly 5 percent of the total energy consumption in the United States. Numerous scientists and companies are introducing more energy-effective separations based on membranes that can separate molecules on the basis of shape and size.
In the novel study, scientists have introduced the first-ever, bottom-up procedure for direct growth of zeolite nanosheets. These nanosheets can be employed to prepare high-quality molecular sieve membranes. The novel substance is just about 5 nanometers in thickness, and numerous micrometers wide. The novel nanosheets also expand in a stable shape making it much simpler to prepare the membranes used in chemical purification.
“With our novel substance is like tiling a floor with uniform, large tiles in comparison to irregular, small chips of tile we used to have,” says Mi Young Jeon, a University of Minnesota chemical engineering and materials science Ph.D. graduate and the head author of the study.
“Precisely shaped zeolite nanosheets make a much bigger quality membrane with surprisingly high separation values that can identify impurities.” The scientists molecular dynamics estimations also support that separation values in excess of 10000 may be accomplished with these nanosheets.
For preparing the zeolite nanosheets, scientists begin with seed nanocrystals then trigger the formation of a double outgrowth that evolves to become the nanosheets. Nanosheets begin to appear from one corner of the seed crystals and then begin to expand, entirely encompassing the seed to prepare faceted nanosheets that is entirely uniform and thin in shape and size.
The stable shape of the crystals was a big surprise, when it was first identified four years ago. “In my 25 years of researching zeolite crystal growth, I would never see anything like this before,” says Tsapatsis.
“After experiencing the presence of a twin in the electron microscope, we were aware that we had found something that would be a major step in introducing ultra-slim porous crystals,” says Prashant Kumar, a University of Minnesota chemical engineering and materials science senior graduate student who performed electron microscopy studies
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