Effect of low-molecular-weight organic acids on hematite dissolution promoted by desferrioxamine B.
Siderophores, as strong chelators specific to iron, have been intensively studied in relation to the facilitation of biological iron acquisition from iron oxides. In this study, the dissolution of hematite in the presence of the siderophore desferrioxamine B (DFOB) and three low-molecular-weight organic acids (LMWOAs, i.e., oxalic, citric, or malic acid) was investigated at three pH conditions (3.0, 5.5, and 9.0). Hematite dissolution was pH-dependent and LMWOA-specific. The adsorption of DFOB on hematite was significantly higher at pH 9.0 than at the other pH values. The adsorption of oxalic acid on hematite, however, showed a descending trend as pH was increased, and adsorption of citric and malic acids was not significantly affected by pH. The Fourier transform infrared (FTIR) results also indicated the occurrence of these ligands' adsorption. After acidification, dissolved iron was detected only in suspensions of hematite pre-adsorbed with oxalic acid at pH 5.5 and 9.0 or pre-adsorbed with citric acid at pH 5.5, indicating that these LMWOAs promoted the formation of labile iron on the hematite surface. Based on previous research and the results of this study, a hypothetical model is proposed. These results provide insight into the effect of LMWOAs on the dissolution of hematite promoted by DFOB.
['Lin|Qingqi|Q|', 'Wang|Yingli|Y|', 'Yang|Xiuhong|X|', 'Ruan|Dishen|D|', 'Wang|Shizhong|S|', 'Wei|Xiange|X|', 'Qiu|Rongliang|R|']
D000327:Adsorption D019343:Citric Acid D003676:Deferoxamine D005290:Ferric Compounds D006863:Hydrogen-Ion Concentration D007501:Iron D008293:Malates D008970:Molecular Weight D019815:Oxalic Acid D017262:Siderophores D012995:Solubility
Hematite Dissolution Desferrioxamine B (DFOB) Low-molecular-weight organic acids (LMWOAs)