Growth characteristics of Ramichloridium apiculatum and its effect on Ca2+and Mg2+leaching from anorthite
The carbon dioxide mineral sequestration is constrained by the leaching rate of Ca2+and Mg2+in the raw materials,so the raw materials need to be pretreated.The traditional pretreatment methods(high temperature,acid leaching,etc.)have disadvantages such as high energy consumption and easy pollution,and the use of microbial leaching pretreatment can avoid these disadvantages.A strain well adapted to anorthite was isolated from soil and identified as the fungus Ramichloridium apiculatum.The effects of culture conditions on fungal growth and metabolism were investigated using czapek's medium.Anorthite leaching experiments were carried out under three environments,deionized water,czapek's medium,czapek's medium and fungus,analysis of anorthite changes before and after fungal action by XRD,FTIR,and SEM-EDS.Dialysis was used to further investigate the differences in element release from anorthite under direct/indirect contact modes of the fungus.The results indicate that the optimum growth environment for the fungus is:4wt％inoculum quantity,glucose as carbon source,NH4C1 as nitrogen source and initial pH of 7.5.The addition of fungus significantly improved the leaching rate of Ca2+and Mg2+in anorthite.Compared with deionized water,the leaching rate of Ca2+and Mg2+under the action of fungus was 10.04 and 10.11 times that of deionized water.In the direct/indirect leaching experiment,the concentration of Ca2+and Mg2+in the direct experiment was always higher than that in the indirect experiment,after 21 days,the leaching rate of Ca2+and Mg2+in the direct experiment was 2.94 times and 2.51 times that in the indirect experiment.These results suggest that Ramichloridium apiculatum promotes the leaching of Ca2+and Mg2+from anorthite in at least two ways,the first being proton exchange and complexation of fungal metabolites,and the second being physical interaction between the fungus and the mineral.
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