The addition of biochar to soil in grasslands and cultivated areas has emerged as a promising way of mitigating global warming. Porous carbon, such as biochar and activated carbon, has been widely used as an adsorbent for gaseous and liquid phases. In recent years, there has also been a growing interest in investigating the adsorption activity of biochar. This review summarizes kinetic models to evaluate the adsorption performance by measuring the amount adsorbed as a function of time. Key kinetic models such as pseudo-first order, pseudo-second order, Elovich, and intraparticle diffusion are presented, and their uses reported in the literature are stated. Using these models, we have investigated phosphate adsorption on a Ca-loaded rice husk biochar prepared by carbonizing rice husk immersed in a CaCl₂ solution at 1000 °C and discuss the results.

Carbon aerogels are promising materials for the electrodes in electric double-layer capacitors, catalyst supports, and adsorbents because they are monolithic and have a high mesoporosity, high electric conductivity, and excellent chemical stability. The most representative carbon aerogels are obtained by carbonizing resorcinol-formaldehyde (RF) aerogels derived from the sol-gel reaction of RF aqueous solutions and supercritical drying with carbon dioxide. Since these aerogels are neither fusible nor soluble, the macroscopic shape of the carbon aerogels can be controlled only during the sol-gel reaction. The reaction, which requires long-term heating, should be conducted in a closed container to suppress the evaporation of water. Large blocks of RF wet gels can be easily recovered from closed containers, which is why most prior work has been on carbon aerogels with a blocky shape. When attempting to obtain carbon aerogels in the form of spheres, fibers, or films, special techniques are required. In the first half of this review, we summarize previous reports on RF-based carbon aerogels in the form of spheres, hollow-fibers, and films, and in the latter half, we describe recent studies on organic and carbon aerogel films derived from polyimides.

省資源，低コスト，高い安全性などの利点を有する二次電池正極材料の候補として，充電時にアニオンの貯蔵反応を利用する炭素系正極が挙げられる。例えば黒鉛ではリチウム金属基準で約4.5 V以上の高電位でアニオンが挿入し，黒鉛層間化合物(Graphite Intercalation compounds: GICs)を形成する。電解液として高濃度の酸，有機電解液，イオン液体を用いたアニオン挿入型GICに関する報告は多いが，より安全性が高く，安価で環境への負荷が小さい中性水溶液における合成報告はほとんどない。本学位論文では，高安全な中性水系電解液における黒鉛へのアニオン挿入・脱離反応に関するその場構造解析に取り組んだ。アニオン挿入型GICのもう一つの課題は，挿入されるアニオンのサイズが大きいため容量が小さいことである。そこで，本学位論文では，サイズが小さいフッ化物イオンが正極反応に関与するLi金属-フッ化黒鉛一次電池に着目し，その二次電池化の検討と反応メカニズムの解明に取り組んだ。

本学位論文は5つの章で構成されている。第1章では，水溶液電解質中でその場X回折(Operando XRD)測定とその場Raman分光(Operando Raman)測定を行い，アニオン挿入・脱離挙動を構造が異なる複数のアニオンについて比較して検討した。2章では，イオン液体中でのアニオン挿入・脱離反応速度に，アニオンとカチオンの相互作用が強く影響することを述べた。また，3, 4章ではLi金属-フッ化黒鉛電池の二次電池化への検討を行い，充放電前後の電極をXRD，Raman，X線高電子分光(XPS)測定等の解析を通して，二次電池反応のメカニズム解析に取り組んだ内容について述べた。5章ではLi-フッ化黒鉛電放電後のフッ化黒鉛正極と黒鉛負極を用いた新規デュアル炭素電池の電池特性の評価を行った内容について述べた。