Sorption mechanisms of chromate with coprecipitated ferrihydrite in aqueous solution

Abdullah Al Mamun, Masao Morita, Mitsuaki Matsuoka, Chiharu Tokoro*


研究成果: Article査読

52 被引用数 (Scopus)


Hexavalent chromium (Cr(VI)) attracted researchers’ interest for its toxicity, natural availability and removal difficulty. Nevertheless, its sorption mechanism is not clearly understood yet. In this work, we elucidated the sorption mechanism of the co-precipitation of chromates with ferrihydrite through quantitative analysis. The influence of Cr/Fe molar ratio on sorption was investigated by zeta potential measurements, X-ray diffraction (XRD) and X-ray adsorption fine-structure analysis (XAFS). Coprecipitation at pH 5 showed almost twice the sorption density of adsorption at pH 5. In co-precipitation, a shift of the XRD peak due to inner-sphere sorption of chromate was observed at Cr/Fe molar ratio 0.5. For adsorption, the same peak shift was confirmed at Cr/Fe molar ratio of 1. Zeta potential at pH 5 suggested that the sorption mechanism changed at Cr/Fe molar ratio 0.25 for coprecipitation and at Cr/Fe molar ratio of 1 for adsorption. Fitting of Cr and Fe K-edge extended X-ray adsorption fine-structure suggested that ferrihydrite immobilized Cr(VI) via outer sphere surface complexation for lower Cr/Fe ratios and via inner-sphere surface complexation for higher molar ratios. At higher molar ratios, bidentate binuclear Cr[sbnd]Fe bonds were well established, thus resulting in the expansion of the ferrihydrite structure.

ジャーナルJournal of Hazardous Materials
出版ステータスPublished - 2017

ASJC Scopus subject areas

  • 環境工学
  • 環境化学
  • 廃棄物管理と処理
  • 汚染
  • 健康、毒物学および変異誘発


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