| 王楠,王帅,徐俊平,王语,窦森.添加金属(氢)氧化物对木质素腐殖化作用的影响机理[J].农业环境科学学报,2019,38(11):2528-2535. |
| 添加金属(氢)氧化物对木质素腐殖化作用的影响机理 |
| Mechanism behind the influence of metal(hydr)oxides on humification of lignin |
| 投稿时间：2019-06-28 |
| DOI：10.11654/jaes.2019-0717 |
| 中文关键词: 针铁矿 三羟铝石 δ-MnO2 木质素 腐殖化作用 |
| 英文关键词: goethite bayerite δ-MnO2 lignin humification |
| 基金项目:国家重点研发计划项目（2018YFD0300207-1）；国家自然科学基金项目（41401251，41571231）；吉林农业科技学院种子基金项目（吉农院合字[2018]第7004号） |
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| 中文摘要: |
| 为研究金属（氢）氧化物在木质素腐殖化作用中的催化作用，采用液体摇瓶培养法，在木质素培养液中添加针铁矿、三羟铝石和δ-MnO2，接种混合菌株悬液后启动110 d的培养试验，动态收集沉淀物质并用H2O2去除氧化物表面的有机成分，应用SEM、FTIR和XRD技术对其结构特征进行分析。结果表明：针铁矿参与木质素腐殖化作用后，小颗粒比例增加且边缘棱角锐化，表面水合羟基与微生物及其转化的木质素间形成氢键，使表面水合羟基（-OH2+）及结晶水O-H的缔合程度增强。Fe-OH的质子化使Fe-O的振动频率增强，配体交换和氢键作用是针铁矿催化木质素腐殖化作用的主要机制；三羟铝石参与木质素腐殖化作用后，晶粒轮廓更加清晰，粒径减小且有聚集趋势，表面Al-OH以氢键形式与微生物及其转化的木质素结合，增加了水合基振动频率，部分OH基团还可被微生物及其转化木质素的羧基取代，弱化了AlO4四面体和AlO6八面体上的Al-O键，水桥键及螯合物的形成使Al-OH2+的振动频率增强；疏水作用是δ-MnO2参与木质素转化的主要机制，反应后颗粒结合更加松散，微纳米球边缘锐化，表面结晶水脱除，Mn-OH的去质子化使O-Mn-O的振动频率增加。研究表明，上述3种金属（氢）氧化物均是通过表面羟基与金属含氧基团来催化木质素的腐殖化作用，而其本身并未发生物相改变。 |
| 英文摘要: |
| Metal(hydr) oxides have a catalytic role in lignin humification, and the related abiotic mechanisms remain to be revealed. The method of liquid shake flask culture was adopted; during the process, goethite, bayerite and δ-MnO2 were added to the fluid medium containing lignin, and then a microbial suspension was inoculated for the culture period of 110 d. Precipitates were collected dynamically, and the organic components attached on the metal(hydr) oxides were removed using H2O2 solution and their structural characteristics were analyzed by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), and X-ray diffraction analysis(X-ray diffraction, XRD). The results showed that the proportion of small particles was increased, and their edges were sharpened after the participation of goethite in lignin humification. Hydrated hydroxyl groups on the surface of goethite could form H-bonds with the inoculated strains and their transformed lignin, enhancing the degree of association between surface hydrated hydroxyl groups(-OH2+) and O-H of crystal H2O. Protonation of Fe-OH enhanced the vibration frequency of Fe-O. Ligand exchange reactions and H-bonds were the main mechanisms by which goethite catalyzed the humification of lignin; After participating in lignin humification, crystal particles of bayerite had a clearer profile, and particles of smaller size had a tendency to aggregate. Al-OH on the surface of bayerite could combine with the inoculated strains and their transformed lignin through H-bonds to enhance the vibration frequency of hydrated hydroxyl groups; simultaneously, a part of OH groups of bayerite could also be replaced by the carboxyl groups from microbial strains and their transformed lignin, which could weaken Al-O bonds in AlO4 tetrahedron and AlO6 octahedron. The vibration frequency of Al-OH2+ was enhanced by the water bridges and the formation of a chelate complex. Hydrophobic interaction was the main mechanism of δ-MnO2 involvement in lignin transformation. After the transformation, the particle binding strength of δ-MnO2 tended to weaken, edges of micro-nanospheres were sharpened, and surface crystal H2O tended to get removed. Protonation of Mn-OH increased the vibration frequency of O-Mn-O. All the above three metal(hydr) oxides catalyze the humification of lignin by the action of surface hydroxyl groups and metal oxygen-containing groups, without themselves undergoing any phase change. |
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