Song Yongwei, Liu Yelin, Wang Heru
School of Information and Safety Engineering, Zhongnan University of Economics and Law, Wuhan 430073, China.
Materials (Basel). 2018 Sep 15;11(9):1739. doi: 10.3390/ma11091739.
Schwertmannite is an environmental mineral material that can promote the natural passivation of heavy metal elements, thereby reducing environmental pollution from toxic elements. However, the fundamental reason for the difference between the chemically (H₂O₂-FeSO₄) and biologically (-FeSO₄) synthesized schwertmannite is still unclear. In this study, X-ray diffraction, scanning electron microscopy, the Brunauer⁻Emmett⁻Teller method, and X-ray fluorescence spectrometry were used to compare the structure, specific surface area, and elemental composition of schwertmannite synthesized by biological and chemical methods. The removal capacity of As(III) by the two kinds of schwertmannite and the effects of extracellular polymeric substances (EPS) on biogenetic schwertmannite were also investigated. At a consistent Fe oxidation efficiency, the chemical method synthesized more schwertmannite than the biological method over a 60-h period. The biosynthesized schwertmannite had a "chestnut shell" shape, with a larger particle size and specific surface than the chemically synthesized schwertmannite, which was relatively smooth. The saturated adsorption capacities of the biologically and chemically synthesized schwertmannite were 117.0 and 87.0 mg·g, respectively. After exfoliation of the EPS from , the biosynthesized schwertmannite displayed a "wool ball" shape, with rough particle surfaces, many microporous structures, and a larger specific surface area. The schwertmannite yield also increased by about 45% compared with that before exfoliation, suggesting that the secretion of EPS by can inhibit the formation of schwertmannite.
施韦特曼石是一种环境矿物材料，能够促进重金属元素的自然钝化，从而减少有毒元素对环境的污染。然而，化学法（H₂O₂ - FeSO₄）和生物法（-FeSO₄）合成的施韦特曼石之间存在差异的根本原因仍不清楚。在本研究中，采用X射线衍射、扫描电子显微镜、布鲁诺尔-埃米特-泰勒法和X射线荧光光谱法，比较了生物法和化学法合成的施韦特曼石的结构、比表面积和元素组成。还研究了两种施韦特曼石对As(III)的去除能力以及胞外聚合物（EPS）对生物成因施韦特曼石的影响。在铁氧化效率一致的情况下，在60小时内化学法合成的施韦特曼石比生物法更多。生物合成的施韦特曼石呈“板栗壳”形状，粒径和比表面积比化学合成的相对光滑的施韦特曼石更大。生物合成和化学合成的施韦特曼石的饱和吸附容量分别为117.0和87.0 mg·g。从……去除EPS后，生物合成的施韦特曼石呈“羊毛球”形状，颗粒表面粗糙，有许多微孔结构且比表面积更大。施韦特曼石产量也比去除前增加了约45%，这表明……分泌的EPS可抑制施韦特曼石的形成。
