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51.
52.
Supitcha Rungrodnimitchai 《Macromolecular Symposia》2010,295(1):100-106
Summary: Cellulose in rice straw was chemically modified by phosphorylation using conventional heating or microwave heating. Rice straw pretreated by NaOH solution gave the highest phosphorus content when it was phosphorylated using microwave heating at 450 watt (7.07%P, ion exchange capacity 2.60 meq/g). The 3 hour-reaction in oil bath yielded the modified rice straw with lower of phosphorus content (6.32%P) and higher ion exchange capacity (2.99 meq/g) than that of microwave heating. The feasibility of the modified rice straw as cation sorbents for removing heavy metal was investigated. Cd2+, Cr3+ and Pb2+ were used as sorbates. In sorption test of 40 ppm with 2.0 g/L of the modified rice straw, both modified rice straws could adsorb metal ions faster than the commercial ion exchange resin (dowax) at the time less than 60 min. The modified rice straw prepared by microwave heating (A-MCW2) could remove 90% of Cd2+ and Cr3+ in 60 minutes and remove 99% of Pb2+ after 30 min. 相似文献
53.
In this paper, the seven acid-insoluble lignin preparations from barley straw were first extracted with alkaline hydrogen peroxide in order to study how the delignification and degradation of the lignin is influenced by aqueous 1.5% H2O2 extractant to straw ratios. The results showed that treatment of dewaxed barley straw with 1.5% H2O2 at 45°C for 14 h (pH 12.0) under the extractant to straw ratios of 10:1, 13:1, 15:1, 18:1, 20:1, 25:1, and 30:1 resulted in dissolution of 65.8%, 68.4%, 68.4%, 69.0%, 69.7%, 71.6%, and 72.3% of the original lignin and 78.7%, 79.8%, 82.3%, 83.4%, 84.8%, 85.3%, and 85.3% of the original hemicelluloses, respectively. The degraded seven lignin samples were analyzed with respect to their chemical compositions, content of chemically linked polysaccharides, molecular weights and structural changes. It was found that the alkaline peroxide treatment under the conditions given led to a noticeable increase in a amount of carboxyl groups due to the oxidation. The results from 13C-NMR analyses showed that the treatment was extremely effective for isolation of highly pure lignins from the straw, and the treatment under the conditions used did not affect the overall structure of lignin. The β-O-4 ether bond and β-β carbon-carbon linkage were found to be the major linkages between lignin units. Hydroxycinnamic acids, such as p-coumaric and ferulic acids, appeared to be strongly linked to lignin molecules, in which p-coumaric acid was found to be bonded to lignin by ester linkage, while ferulic acid was linked by its phenolic group via ether bond to lignin and also principally linked by its carboxyl group via ester bond to lignin and/or hemicelluloses. 相似文献
54.
建立全自动石墨消解- 电感耦合等离子体质谱(ICP-MS)法检测农作物土壤中的镉、锡、锰、锑、钒、钛、锶金属污染物残留的分析方法.随机采集农作物土壤,取约200 g,置于烘箱中烘干,烘干后的样品用粉碎机粉碎,精密称取粉碎后的样品约0.25 g,置于聚四氟乙烯材质的消解罐内,按既定消解程序进行自动消解处理,得样品溶液,上... 相似文献
55.
以双室微生物燃料电池为反应器,铁氰化钾为阴极液,研究污水处理厂活性污泥菌液和玉米秸秆水解液对MFC的产电性能的影响。结果表明,随着阳极中活性污泥菌液体积(1.5、3.0、4.5、6.0 mL)增加,MFC的产电量逐渐增加,当活性污泥的体积增加至7.5 mL时,产电量开始呈下降趋势;玉米秸秆水解液在底物中的浓度为0、10、15、20、30、40 g/L时,电池的稳定电压分别为54、157、248、208、170、146 mV。当阳极活性污泥菌液体积为6 mL、玉米秸秆水解液浓度为15 g/L时,微生物燃料电池的产电性能最佳,此时MFC的功率密度为54.6 mW/m2,内阻为496 Ω。同时,循环伏安曲线(C-V)和交流阻抗曲线(EIS)测试可知,MFC的电极过程由电荷传递和扩散过程共同控制,反应过程受电子传递控制。 相似文献
56.
农作物秸杆中钾元素的回收与利用 总被引:1,自引:0,他引:1
土壤钾素亏缺严重限制了我国农业生产的发展,现有钾资源已经不能满足我国农业需要,目前钾资源的开发主要集中在海水和钾矿,而农作物秸杆作为我国的富钾资源,其利用效率和质量都不尽人意,对秸杆的利用大多还停留在田间焚烧、直接还田以及用作牲畜饲料等传统途径,其利用率还不足40%,秸杆的进一步开发应该引起足够的重视。 相似文献
57.
M. Bär J. Leonhardt G. Flachowsky A. Hennig I. Wolf K. Nehring 《Isotopes in environmental and health studies》2013,49(10):339-340
In der Welt fallen jährlich ca. 2 Milliarden t Getreidestroh an, die nur partiell für die Fütterung genutzt werden, weil seine Verdaulichkeit gering ist. Durch verschiedene chemische und physikalische Methoden ist seit den neunziger Jahren des vorigen Jahrhunderts versucht worden, die Verdaulichkeit des Strohs zu erhöhen (Übersicht Flachowsky [1]). 1962 berichteten Pritchard u. a. [2] über den Aufschlußeffekt von Gamma-Strablen bei Stroh. 相似文献
58.
Analysis of graphene-like activated carbon derived from rice straw for application in supercapacitor
Activated carbons with large surface area, abundant microporosity and low cost are the most commonly used electrode materials for energy storage devices. A very slack activated carbon with ultra-thin two-dimensional (2D) layer structure was prepared by our proposed approach in this work, which includes a pre-treatment process and potassium hydroxide activation at high temperatures. 相似文献
59.
Nirankar Singh Ravinder Agarwal Amit Awasthi Prabhat K. Gupta 《International journal of environmental analytical chemistry》2013,93(10):829-843
Ground-based ambient air monitoring was conducted at five different locations in and around Patiala city (29°49′–30°47′N Latitude, 75°58′–76°54′E Longitude) in Northern India in order to determine the impact of open burning of rice (Oriza sativa) crop residues on concentration levels of suspended particulate matter (SPM), sulphur dioxide (SO2) and nitrogen dioxide (NO2). Covering sensitive, residential, agricultural, commercial and urban areas, sampling of these pollutants was organised during August 2006 to January 2007 and August 2007 to January 2008 casing two rice crop residue burning periods (October–November) using a high volume sampling technique combined with gaseous sampling systems. Gravimetric analysis was used in the estimation of total suspended particulate matter (TSPM) whereas SO2 and NO2 concentration was determined using spectrophotometer (Specord205, Analytikjena). Monthly average concentrations of SPM, SO2 and NO2 have shown significant up and down features at all the selected sampling sites during the study period. Monthly average concentrations (24 hour) of SPM, SO2 and NO2 varied from 100 ± 11 µg m?3 to 547 ± 152 µg m?3, 5 ± 4 µg m?3 to 55 ± 34 µg m?3 and 9 ± 5 µg m?3 to 91 ± 39 µg m?3. Substantially higher concentrations were recorded at the commercial area site as compared to the other sampling sites for all the targeted air pollutants. Levels of SPM, SO2 and NO2 showed clear increase during the burning months (October–November) incorporated with the effect of meteorological parameters especially wind direction, precipitation and atmospheric temperature. 相似文献
60.
该文构建了玉米秸秆粗蛋白定量分析模型,并对光谱特征波段选取方法进行探讨及验证。首先对107个样本进行预处理,剔除两个异常样本后采用DB2小波缺省阈值4层分解方式进行光谱重构,预处理后粗蛋白模型交互验证决定系数R2CV从0.788 9提高至0.920 8,采用间隔偏最小二乘(IPLS)及其改进型方法后向区间间隔偏最小二乘(BIPLS)、组合间隔偏最小二乘(SIPLS)进行特征波段选取,并对比主成分分析、竞争性自适应重加权采样法、相关系数法、遗传算法、移动窗口最小二乘等结果,发现基于IPLS及其改进型BIPLS、SIPLS均可有效、准确定位特征波段区间,其中采用SIPLS 30 波段间隔在10 128~10 398 cm-1与11 196~11 462 cm-1时具有最优模型,验证集相关系数(rp)为0.978 4,验正集决定系数(R2P)为0.957 2,验正集均方误差根(RMSEP)为0.221 1,相比于其他波段选取方法表现出较好的实时准确性,该方法可为玉米秸秆氨碱化最优条件判定提供重要的数据支撑。 相似文献