Fe(Ⅲ)供应速率对无定型施氏矿物形成的影响

Effect of Fe(Ⅲ) Supply Rate on the Formation of Amorphous Schwertmannite

施氏矿物(schwertmannite)已被证实是一种具特异性能的重(类)金属吸附新材料。但在直接由Fe3+或用强氧化剂氧化Fe2+合成该矿物时,常因夹有黄铁矾类物质而降低产品纯度。通过模拟FeSO4-K2SO4-H2O临界成矾体系,发现在嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)作用下存在无定型施氏矿物和晶型黄钾铁矾的合成反应竞争,其中Fe3+供应速率是一个影响铁矿物形成的重要因素,较低的Fe3+供应可以抑制K+的利用,这种变化趋势对无定型施氏矿物合成是有利的。当存在少量K+等成矾导向离子时,可通过合理调低Fe3+供应速率,有利于溶液中Fe3+平缓释放,改善施氏矿物纯度,这为A.ferroxidans菌生物法中直接使用无机盐培养基合成施氏矿物提供了可能。

Schwertmannite has been proven to be a novel material which has specific adsorbability for heavy metals or metalloid.However the chemically synthesized schwertamnnite often contained impurities such as jarosite when this mineral was formed by using Fe3＋ directly or oxidizing Fe2＋ with the strong oxidant.It was observed that either amorphous schwertmannite or crystalline jarosite existed at the critical point of jarosite formation in FeSO4-K2SO4-H2O system by Acidithiobacillus ferrooxidans,depended on the rate of Fe3＋ supply.The lower supply rate of Fe3＋ obviously inhibited K＋ incorporation into iron hydroxysulfate mineral to form jarosite,consequently improved the generation of amorphous schwertmannite in the system.With the presence of K＋,a monovalent cation capable of facilitating strongly jarosite formation,schwertmannite with higher purity also could be synthesized with lowering the rate of Fe3＋ supply and resulting in the gentle releases of Fe3＋ into the solution.Therefore,this study provided the possibility for synthesizing pure biogenic schwertmannite in conventional inorganic salt medium system by A.ferrooxidans cells.