摘要
This study deals with the pre-treatment of coal fly ash (CFA) by using alkaline substance to improve water solubility of Si which in turn readily available to the plants. Selected weight ratios of CFA/NaOH (s:s) were tested and the highest H<sub>4</sub>SiO<sub>4</sub> yield ratio was selected for further study. X-ray diffraction and scanning electron microscopy analyses were performed to confirm the evidence of structural changes of the CFA upon alkaline treatment. To improve SiO<sub>2</sub> dissolution, seven Si-solubilizing fungi, <em>i.e.</em>, <em>Aspergillus niger</em> BCC194, <em>A</em>. <em>niger</em> K0909, <em>A</em>. <em>niger</em> A1601, <em>Trichoderma polysporum</em>, <em>T</em>. <em>viride</em>, <em>T</em>. <em>pseudokoningii</em>, and <em>Trichoderma</em> spp, were each inoculated onto pre-treated ash. The results indicated that the relationships between ratio of CFA/NaOH and total and soluble Si were linier (R<sup>2</sup> = 0.97** and 0.96**, respectively). Total SiO<sub>2</sub> values range from 10.43% to 13.02%, whereas soluble Si contents were 2.30% - 2.64% improved about 300 times compared to un-treated CFA. Both XRD and SEM analyses indicated that alkaline treatment to CFA caused particle damages resulting in increasing soluble Si. Inoculation of pre-treated CFA by <em>T</em>. <em>polysporum</em> up to twelve days of incubation yielded the highest soluble Si. Each fungal species grown on Bunt & Rovira solid media enriched with CFA as Si-source expressed significantly different ability in solubilizing Si from CFA. Citric acid was shown to be stronger compared to acetic and oxalic acids in solubilizing Si from CFA.
This study deals with the pre-treatment of coal fly ash (CFA) by using alkaline substance to improve water solubility of Si which in turn readily available to the plants. Selected weight ratios of CFA/NaOH (s:s) were tested and the highest H<sub>4</sub>SiO<sub>4</sub> yield ratio was selected for further study. X-ray diffraction and scanning electron microscopy analyses were performed to confirm the evidence of structural changes of the CFA upon alkaline treatment. To improve SiO<sub>2</sub> dissolution, seven Si-solubilizing fungi, <em>i.e.</em>, <em>Aspergillus niger</em> BCC194, <em>A</em>. <em>niger</em> K0909, <em>A</em>. <em>niger</em> A1601, <em>Trichoderma polysporum</em>, <em>T</em>. <em>viride</em>, <em>T</em>. <em>pseudokoningii</em>, and <em>Trichoderma</em> spp, were each inoculated onto pre-treated ash. The results indicated that the relationships between ratio of CFA/NaOH and total and soluble Si were linier (R<sup>2</sup> = 0.97** and 0.96**, respectively). Total SiO<sub>2</sub> values range from 10.43% to 13.02%, whereas soluble Si contents were 2.30% - 2.64% improved about 300 times compared to un-treated CFA. Both XRD and SEM analyses indicated that alkaline treatment to CFA caused particle damages resulting in increasing soluble Si. Inoculation of pre-treated CFA by <em>T</em>. <em>polysporum</em> up to twelve days of incubation yielded the highest soluble Si. Each fungal species grown on Bunt & Rovira solid media enriched with CFA as Si-source expressed significantly different ability in solubilizing Si from CFA. Citric acid was shown to be stronger compared to acetic and oxalic acids in solubilizing Si from CFA.
