蜉金龟堆肥和自然堆肥类胡敏酸的表征及特性研究

Characteristics of humic-like acid of Aphodius-processed cow manure and natural cow manure compost

  • 摘要: 分别用焦磷酸钠和氢氧化钠浸提新鲜牛粪、蜉金龟堆肥(APCM)和自然堆肥(腐熟牛粪)产物中的类胡敏酸, 采用元素组成、红外光谱及差热分析研究了其结构特征。元素分析结果表明, 蜉金龟堆肥焦磷酸钠浸提物--类胡敏酸(NaHLA)的芳香性低于新鲜牛粪和自然堆肥, 而碳水化合物及氮元素含量增加。蜉金龟堆肥氢氧化钠浸提物--类胡敏酸(PAHLA)的碳水化合物和氮元素含量也高于新鲜牛粪和自然堆肥, 而自然堆肥PAHLA的芳香性略低于新鲜牛粪和蜉金龟堆肥。红外光谱分析结果表明, 与自然堆肥NaHLA相比, 蜉金龟堆肥NaHLA中羧酸脂类化合物、酮类化合物、脂肪族化合物及碳水化合物有所增加。与新鲜牛粪PAHLA相比, 蜉金龟堆肥和自然堆肥PAHLA的碳水化合物、脂肪族化合物、酚类化合物及纤维素酯类减少, 同时蜉金龟堆肥PAHLA的酰胺化合物在蜉金龟消化过程中被其吸收。差热分析结果表明, 自然堆肥NaHLA的热稳定性高 于新鲜牛粪和蜉金龟堆肥, 而蜉金龟堆肥NaHLA的脂族化合物、外围官能团和分子内部芳香结构含量较高, 分子结构较复杂。蜉金龟堆肥PAHLA存在两个放热峰, 而新鲜牛粪和自然堆肥的中温放热峰消失。综上, 蜉金龟堆肥和自然堆肥采用两种提取液浸提出类胡敏酸的结构特征存在差异性。

     

    Abstract: With further increase in aquaculture industry, it is predicted that annually total emissions of livestock feces will reach 42.44 billion tons by 2020. The pollution problems of livestock and poultry feces have become an increasing concern in the international community. It has therefore become imperative to recycle use of livestock and poultry feces. Currently, research has focused mainly on earthworm-processed animal manure and sporadic reports on Aphodius sp. There have also been studies on community species, mouthparts, and morphological and gut characteristics of Aphodius sp. Although intensive studies have been conducted on the structural characteristics of soil humus, humic-like acid has received little focus. The carbon, nitrogen dynamics and humus characteristics of adding decomposed cow dung and Aphodius larval composting have been reported in previous study. However, little has been done on the characteristics of humic-like acid of Aphodius-processed cow-manure (APCM) and natural cow manure compost. To understand cow manure utilization and develop basic data for structural characterization, humic-like acids from two different inorganic extractions were characterized in elemental analyzer, infrared spectrometer and differential thermal analyzer. The humic-like acid samples were extracted from APCM and natural cow manure compost with 0.1 mol·L-1 NaOH and 0.1 mol·L-1 Na4P2O7, respectively. Elemental analysis showed that the aromaticity of humic-like acid (Na4P2O7-extracted, NaHLA) from APCM was lower than that from fresh cow manure and natural cow manure compost. The C and N contents of humic-like acid (NaOH-extracted, PAHLA) from APCM were higher than those from fresh cow manure and natural cow manure compost. Also the aromaticity of natural cow manure compost was lower than those of fresh cow manure and APCM. In terms of NaHLA of natural cow manure compost, infrared spectrometry suggested that larger carboxylic acid lipid compounds, ketone compounds, aliphatic compounds and carbohydrates existed in NaHLA of APCM. The carbohydrates, aliphatic compounds, phenolic compounds and cellulose esters of PAHLA from APCM and natural cow manure compost were higher than those from fresh cow manure. Amide compounds of PAHLA from APCM were absorbed in Aphodius digestive process. Thermal analysis suggested that NaHLA from natural cow manure compost had larger thermal stability than that from fresh cow manure and APCM. The aliphatic compound, peripheral functional groups and intra-molecular aromatic structures of NaHLA from APCM were higher than those from fresh cow manure and natural cow manure compost. However, the molecular structure of NaHLA from APCM was of higher complexity than that of NaHLA. PAHLA from APCM had two exotherm peaks whereas mid-temperature exotherm peak disappeared in fresh cow manure and natural cow manure compost. In summary, some differences existed in humic-like acid characteristics from APCM and natural cow manure compost.

     

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