生物纳米FeS包覆层对灰岩中和能力的影响

The effect of bio-nano FeS coating layer on neutralization capability of limestone

本文采用硫酸盐还原菌(SRB)和嗜酸铁还原菌(JF-5)合成纳米FeS,并将其包覆在灰岩表面,采用溶解动力学实验研究了不同纳米FeS包覆层对灰岩溶解和中和能力的影响。结果表明,X射线衍射表面包覆层矿物为纳米的四方硫铁矿,光电子能谱(XPS)结果进一步显示包覆层中Fe的价态为+2,S的价态为-2;包覆层对灰岩的溶解有明显的钝化影响,中和能力随厚度的增加而降低,最厚包覆层的存在能够使最终中和p H值降低1.5个单位。利用Frick第一定律推导了包覆层存在下灰岩的溶解过程公式,建立了包覆层溶解动态模型。

Desulfovibrio vlugaris miyazaki SRB and Acidiphilumcryptum JF-5 are two common reductive microorganisms in the wastewater and sediments of acid mines. The two bacteria were used to synthesize the nano FeS and coat it on the surface of limestone. Dissolution kinetics experiments were conducted to investigate the influence of different nanometer FeS cladding layers on limestone dissolution and neutralization capacity, and dissolving model was set up based on the Frick＇s first law. The result of X-ray diffraction of coating layer on limestone surface indicates that it is mackinawite. The photoelectron spectroscopy（ XPS） result further shows that the valence of Fe in coating layer is ＋ 2, and S valence is-2, the coating layer has obvious passive effect on the dissolution of limestone, the neutralization capability decreases with the increase of the layer ＇s thickness, and the existence of the thick coating layer can make the final p H decrease to 1. 5 p H compared with the final pH 6. 5 of pristine limestone.The dissolution behavior of limestone in the presence of the coated mackinawite can be described as nCa,sol= At1/2-nCa,grp, in which nCa,grpvalue could represent the amount of secondary CaSO_4 formed on the surface.