Worldwide R&D

Department of Applied Chemistry, Graduate School of Science and Engineering, Specializing in Chemical Engineeringand Advanced Crystallization Engineering Research, Waseda University
Izumi Hirasawa, Professor
A crystal is a solid having a regular arrangement ofatoms and molecules. By creating crystals with a desired
quality, it is possible to achieve high purity that can bekept stable for a long period of time and that can be freely
controlled with complex functions. Hence, we are striving
to develop an environmental friendly crystalline productof a desired quality as a 21 s t century material forbiotechnological and environmental use. To make crystals
in a solution (known as crystallization), the concentrationof the solution is made higher than their solubility(supersaturated state) to produce seeds of a crystal(crystal nuclei). These seeds are grown to cultivate large
crystals. By controlling the number of seeds and their
growth rate during this process, it is possible to control
the size, shape and structure of the crystals. We havewitnessed the instant at which molecules and atoms in thesolution become crystals. The solution begins to quiver
and the crystals are born among the oscillations. While
crystals are inanimate, they appear like living organismsthat are born as seeds and grow as if they are alive.
Today we are conducting research for producing
desired crystalline products while attempting to better
understand basic crystallization phenomena. We haveorganized projects on pharmaceuticals and organic
crystals, nano-crystals, environment and recycling, andheat storage (storing heat in the form of crystals). Topics
of our research are discussed in greater detail below.

Environment and recycling
We are constructing processes that are capable of notonly removing but also recovering substances that haveadverse affects on the environment, including such
nutrients as nitrogen and phosphorous and such industrial
emissions as fluorine and metal ions. In collaboration withindustry and academia, we are advancing R&D aimed at
establishing optimal operations and processes for theremoval and recovery of these targeted substances in theform of crystals. The resulting process for removing andrecovering fluorine and phosphate ions is being
implemented with full-scale equipment and is contributing
to the recovery of unused resources. While fine crystals
tend to be generated in the crystallization process, wehave obtained coarse spherical crystals by efficiently
conducting supersaturation formation, attachment of finecrystals, and agglomeration.
Further, throughcollaboration with other companies, we have conductedsuccessful research on recovering nickel ions in the formof nickel metal (more than 99% pure) from a used bath ofelectroless nickel plating in the presence of a reducing
agent. We believe that this research will help in therecovery of other rare metals and the creation of nano-size
metals.

Creation of Nano-Crystals
Crystals in the nano-size (10-9 m) range have a large
surface area per gram and exhibit functions that are notseen in larger crystals. We are trying to produce a crystalof this size in a highly supersaturated region. In order toproduce functional crystals (such as those that emit blue
or red fluorescence or those with a confined distributionof nano-size particles), we are attempting to produce
nano-size crystals, focusing on crystallization with
polyelectrolytes (see photo), controlling nucleation withthe presence of heterogeneous crystals, and nucleationinduced by ultrasonic waves.

Pharmaceuticals and Organic Crystal
Control
Many crystalline products in pharmaceuticals arehydrophobic and, hence, cannot be dissolved or absorbed
in the human body efficiently. Accordingly, it is important
to obtain crystals having a desirable solubility and nanosize crystals. We are conducting research aimed atcreating such crystals.

Heat Storage Process
Latent heat storage is a method for storing heat in theform of crystals. Our laboratory is working to recoverwaste heat of various temperatures using hydrated saltcrystals. Joint research is being conducted with othercompanies on ice storage, and a new heat storage system
is currently operating at the Minato Mirai 21 District
Heating and Cooling Service Co., Ltd. located in Minato
Mirai 21 district, Yokohama. Our know-how for creating
crystals is thus applied in the effective use of thermalenergy.

http://www.sci.waseda.ac.jp/research/

Nano-size lead sulfate produced through reaction
crystallization in a polyelectrolyte environment

MICROMACHINE No. 50
MICROMACHINE is published quarterly by Micromachine Center (MMC) to promote the international exchange ofinformation related to micromachines, R&D and other technical topics, and is circulated free of change. Please send
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