Development of materials to separate minor metals efficiently

Rare metals play an important role in our lives and a variety of industries. Among them, six kinds of metals classified as platinum group metals (PGM) are contained in automotive catalysts, industrial catalysts, electric devices and dental materials, etc.

For their rarity, recycling minor metals from used products is crucial for their stable supply. Either precipitation separation through cementation, adsorption using ion exchange resin or solvent extraction is applied to separate PGM from used products, depending on the concentration of PGM contained in the target solution to be separated.

Solvent extraction is a method to separate metals from each other through contacting solutions containing PGM and organic solvent containing extractants that can make complexes with specific metals then moving these metal-solvent complexes to organic solvent.

To solve the above problems, our lab’s focus is acid leaching solution derived from spent automotive catalysts, and develops extractants to effectively and selectively separate PGM. So far, we have succeeded in developing extractants based on calixarene-based extractants (macrocyclic compounds) and pincer-type extractants (acyclic compounds).




溶媒抽出法は、特定の金属と複合体を形成し得る化合物(抽出剤)を含む有機溶媒(有機相)と、PGMを含む水溶液(水相)を接触させ、金属 – 抽出剤の複合体を有機相に移動させることで、金属を相互分離する手法です。


Development of organic crystals that can selectively recognize and absorb specific organic compounds

Our lab aims to develop supramolecular organic crystals that can selectively recognize and absorb specific organic compounds based on the cluster of thiacalixarene, cyclodextrin, and cucurbituril.

Alkanes play an important role in a variety of industries as the materials for resin, organic solvent for rubber, paint and fuel. Alkane isomers have linear, branch and cyclic structures. The differences in boiling points enable alkanes to be separated from each other through distillation. However, not so many effective separation methods have been reported due to the weak interaction between alkane and other molecules.

We have accidently discovered that channel-like supramolecular organic crystals based on thiacalixarene assembly can selectively recognize the vapors of branch and cyclic alkanes while developing organic crystals that can effectively separate alkane isomers. The above both crystals are with preorganized voids and absorb specific vaporous molecules in branch and cyclic alkanes. For the C-C and C-H bonds in organic compounds, these thiacalixarene organic crystals are expected to extend their functions as the materials to separate and store gas molecules in organic compounds



 有機化合物であるアルカンは 、樹脂の原料やゴムの有機溶剤、塗料、燃料などの工業的に幅 広い分野で利用される重要な化合物です。アルカン異性体には、直鎖や分岐、環状構造の3種類が存在します。沸点の差が大きいアルカン同士の分離は蒸留により分離が可能ですが、そうでない場合、アルカンはほかの分子との相互作用が弱いため、効果的に分離できる手法はあまり報告されていません。