EDTA型キレート繊維による銅,ニッケル及びコバルトの固相抽出(<特集>高度分離へのたゆまぬ挑戦)  [in Japanese] Solid Phase Extraction of Cu, Ni and Co by EDTA Type Chelating Cellulose(<Special Article>New Challenges to Advanced Separation Technology)  [in Japanese]

エチレンジアミン四酢酸(EDTA)型キレート繊維(以下EDTA-Cellと略)を合成し,水溶液中のCu,Ni,Coの吸着挙動をバッチ法及びカラム法で調べた.本吸着材の構造は,EDTAの4つのカルボキシル基のうち1つが,セルロース繊維に直接結合し,残りの3つが金属とキレートを形成していると考えられる.pH>2.9で,3金属とも定量的に吸着され,この吸着材は他の類似の吸着材と比較してより強く金属を吸着すると考えている.流量の影響を調べたところ少なくとも26mL/minまでは影響がなかった.吸着した金属は1M硝酸10mLで脱着することができた.濃縮率について検討したところ3金属とも96%以上の回収率で200倍濃縮が可能であると言うことが分かった.吸着等温線を作成し,ラングミュア式から吸着容量はCuで0.25mmol/g,Niでは 0.29mmol/g,Coでは 0.30mmol/gであることが明らかとなった.

EDTA-type chelating cellulose (abbr.: EDTA-Cell) has been synthesized and studied for its adsorption properties with respect to Cu, Ni and Co from aqueous solutions in both batch and column experiments. This adsorbent has a structure such that one of the carboxyl groups of EDTA directly binds with cellulose fiber, and it is considered that the remaining three carboxyl groups form a chelate with metal ions. This structure is suggested to be favorable to adsorb metals more strongly as compared to other analogous adsorbents. The above-mentioned three metal ions were quantitatively retained on the adsorbent at pH>2.9. No effect of the flow rate on the adsorption performance was observed for at least by a rate of 26mL/min. The retained metal ions could easily be desorbed with 10mL of 1M nitric acid. The recovery values were greater than 96% and the preconcantration factor was 200 for all analyte ions. The adsorption isotherm of an element when it adsorbs by a monolayer from a diluted aqueous solution can be understood by the Langmuir method. The maximum sorption capacities were found to be 0.25mmol/g for Cu, 0.30mmol/g for Co and 0.29mmol/g for Ni, respectively.