Production of Levulinic Acid from Bagasse and Paddy Straw by Liquefaction in the Presence of Hydrochloride Acid     

Lifeng Yan  Naikun Yang  Hao Pang  Bing Liao 《洁净——土壤、空气、水》2008,36(2):158-163

A method of levulinic acid production from bagasse and paddy straw is presented. Biomass waste was mixed with hydrochloride acid and water, and then liquefied at about 200°C in a pressurized reactor. Both the mass of the biomass and the amount of hydrochloride acid were kept as constants, and the effects of temperature, reaction time, and acid concentration on the levulinic acid yield were studied. It was found that the yield of levulinic acid was maximum when the reaction temperature was carried out for 45 min at 220°C using 4.45% concentration of hydrochloride acid, and the maximum yields of levulinic acid were 22.8 and 23.7% for bagasse and paddy straw, respectively. The products were analyzed using NMR, HPLC, and GC/MS.  相似文献   

Differential developmental toxicity of naphthoic acid isomers in medaka (Oryzias latipes) embryos   总被引：1，自引：0，他引：1  

Michael W. Carney  Kyle Erwin  Ron Hardman  Bonny Yuen  David C. Volz  David E. Hinton  Seth W. Kullman   《Marine pollution bulletin》2008,57(6-12):255

Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA > 2H1NA > 2H3NA > 6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations.  相似文献   

The volcanic acidification of glacial Lake Caviahue,Province of Neuquen,Argentina     

Johan C. Varekamp 《Journal of Volcanology and Geothermal Research》2008

Lake Caviahue (northern Patagonia, Argentina) is a large glacial lake acidified by volcanic fluids from Copahue volcano. The lake and the feeding rivers were sampled annually from 1997 till early 2006, including the eruptive period of 2000. Lake Caviahue waters evolved over time, with the most concentrated waters in 2000 during the eruptive period, followed by gradual dilution that was interrupted by renewed acidification in 2003–2004. Inversion of the lake water data and application of a dynamic non-steady state model for the lake provides our best quantitative estimates for the variation in element fluxes over the 9-year period. The model flux results agree well with most of the measured fluxes. The Copahue hydrothermal system had gently declining element fluxes between 1997 and mid-1999, although the lake was still becoming more concentrated. About 2–3 months before the 2000 eruption, element fluxes increased strongly, but the hydrothermal fluxes almost shutoff directly after the main eruptive events. The fluxes of several elements recovered post-2001, with an increase in element fluxes in 2003–2004; the lake became more dilute between 2004 and 2006. The intrusion of new magma into the hydrothermal system just prior to the 2000 eruption led to enhanced water rock interaction, with higher concentrations of the rock forming elements in the fluids, and the hot spring flow rate increased as a result of the higher pressure in the reservoir. The fluids became saturated in alunite and jarosite, and they were already saturated with anhydrite. Precipitation of these minerals possibly led to a decreased permeability of the hydrothermal reservoir, leading to the strongly reduced element fluxes just after the eruption. In addition, K, Al and S were retained in the newly precipitated minerals as well, further diminishing their export. The acidification in 2003–2004 may have resulted from a new small intrusion of magma or resulted from seismic activity that created new permeability and fresh rock surfaces for water rock interaction. The volcano is a significant source of toxic trace elements such as F, As, B and Li as well as a nutrient (P) for the local watershed. Monitoring of the hydrothermal fluids in the river that drains Copahue, especially the S/Cl, Mg/Cl and Mg/K values as well as the magnitude of the element fluxes would provide the best information for eruption forecasting for this volcano.  相似文献   

环境因子对2种南极绿藻脂肪含量和脂肪酸组成的影响   总被引：3，自引：1，他引：2  

缪锦来  王波  阚光锋  丁燏  姜英辉  侯旭光  李光友 《海洋科学》2005,29(1):4-11

通过气相色谱方法对南极冰藻的脂肪酸进行了分析,发现环境因素对2种绿藻总脂含量有一定的影响：(1)温度对Pymmixtomonas sp,总脂含量影响不大,一般为8．3％～8．9％,Chlorophyceae L-4在2℃时的总脂含量最高为10.33％;(2)光强显著地影响这2种绿藻脂肪在细胞内的积累。随着光强由限制生长的39 lx增加到3900 lx,2种绿藻的脂肪酸含量降低：(3)盐度的提高有利于2种绿藻脂肪的积累;(4)营养盐的限制也利于2种绿藻脂肪的积累。在氮源缺乏条件下,Pyramidomonas sp,和Chlorophyceae L-4细胞内脂肪大量积累,含量分别是以NH4Cl为氮源的2．2和3.2倍。环境因素对2种绿藻脂肪酸组成和含量的影响不同,其脂肪含量的改变反映了南极冰藻生长的改变。环境因子能够影响这2种绿藻的脂肪含量,同样也影响到它们的生长。在适合南极冰藻生长的条件下,脂肪酸积累降低;反之,在南极冰藻生长受到限制的条件下,脂肪合成增加。这表明2种绿藻的脂肪含量随生存环境的变化而变化。环境因子同样影响到2种绿藻的脂肪酸组成,尤其是不饱和脂肪酸的组成和含量,但组成和其生长不存在相关性。环境因子(温度、光强、盐度和营养盐)对2种绿藻脂肪酸的测定结果表明,在2种绿藻中,多不饱和脂肪酸的含量高于单不饱和脂肪酸和饱和脂肪酸。因此。这2种绿藻可望为多不饱和脂肪酸的开发利用提供藻种资源。  相似文献   

Sulfuric acid as an agent of carbonate weathering constrained by δC_DIC: Examples from Southwest China     

Si-Liang Li  Damien Calmels  Guilin Han  Jrme Gaillardet  Cong-Qiang Liu 《Earth and Planetary Science Letters》2008,270(3-4):189-199

  相似文献   

Physical sedimentology experiments with sulfuric acid solutions: Implications for Mars?     

Kathleen C. Benison  Deidre LaClair  Jessica Walker   《Earth and Planetary Science Letters》2008,270(3-4):330-337

Physical sedimentology experiments have shown that sulfuric acid solutions may have formed some surface features seen on Mars. Recent data returned from Mars show the presence of jarosite, sulfate salts, hematite, phyllosilicates, and opaline silica, all of which precipitate from some terrestrial sulfuric acid solutions. There is a plethora of geochemical, mineralogical, and sedimentological data indicative of past sulfuric acid systems on Mars, but there has never been a comprehensive study published regarding sulfuric acid as a physical sedimentological agent. In the laboratory, we ran liquids of various compositions over sediments in order to test how these liquids entrain, transport, and deposit sediments. Pure water and concentrated sulfuric acid solutions produced the same general features, such as channels, gullies, and alluvial fans. However, sulfuric acid solutions yielded some distinct sedimentary features not produced by pure water runs. These features, narrow, deeply incised channels of consistent widths, rounded discrete fans, and air bubble “craters”, are similar to some Martian landscape features. These experimental results indicate that acid solutions should be considered a possible sedimentological agent on Mars.  相似文献   

受酸腐蚀砂岩的物理力学性质探讨     

霍润科  杨俊卿  姚志飞  黄沛 《岩土力学》2007,28(Z1):45-48

考虑化学作用的岩土力学性质研究及其稳定性问题已成为国内外学者关注的焦点。采用酸性环境下的加速试验,研究了钙质胶结砂岩受酸腐蚀后在不同时段单轴压缩应力作用下表现出来力学特性,揭示了砂岩腐蚀过程和受酸腐蚀机制,其目的是为酸雨环境下,研究岩体的物理力学性质提供可以借鉴的思路和方法。  相似文献   

乌鲁木齐河源1号冰川表层雪的化学特征——以低分子有机酸和无机阴离子为例   总被引：3，自引：0，他引：3  

丁文慈  李心清  李忠勤  王飞腾 《冰川冻土》2007,29(5):704-709

表层雪是联系大气成分与冰芯记录的重要纽带,是研究成冰作用过程中化学组成变化的起点.为配合天山乌鲁木齐河源1号冰川成冰作用过程中化学组成变化的研究,对1号冰川积累区(海拔4130 m)一个完整年度的表层雪样品进行了低分子有机酸和无机阴离子含量的分析.结果显示:表层雪中低分子有机酸主要有HCOO^-、CH₃COO^-、C₂H₅COO^-和(COO)₂^2-,无机阴离子主要有F^-、Cl^-、NO₂^-、NO₃^-、SO₄^2-和PO₄^3-.除(COO)₂^2-外,大部分高浓度的有机酸和无机阴离子因受到周围环境和盛行风的影响呈现出明显的季节变化特征,即夏半年离子浓度变化剧烈,最大值和最小值同时出现在夏半年,冬半年的浓度则相对小而稳定;而(COO)₂^2-和低浓度的无机阴离子随季节变化的特征不明显,在全年均显示出波动性.在外界条件不变的情况下,表层雪可以长时间(至少半年时间)保存其中高含量的化学组成不被改变.  相似文献   

南极夏季沿海海藻Phaeocystis Pouchetii繁殖与海水中溶解游离型氨基酸含量的关系          下载免费PDF全文

杨和福  AndrewRMctaggrt  HarryBurton 《极地研究》1990,2(4):45-49

从1988年5月～1989年1月,对东南极维斯特福尔德丘陵地区,戴维斯考察站沿海海域水体中的溶解游离型氨基酸的含量进行了长期连续测定。结果表明,在该海域海水中溶解游离型氨基酸的总浓度略高于其他海海域、浓度变化范围在19～302nmol/dm~3之间。最大丰度出现在11月份,而从11月下旬开始氨基酸含量急剧下降,至12月底达到全年最低点,从1月初开始有所回升。 占据南极夏初海水中海藻类主导地位的海藻Phaeocystis Pouchetii,其爆发性的繁殖过程从11月底开始至翌年1月底2月初结束,高峰在1月初。在Phaeocystis Pouchetii繁殖期,溶解游离型氨基酸浓度的降低与海藻细胞数量的增加有明显的负相关关系。作者认为在Phaeocystis Pouchetii繁殖增长过程中,该藻细胞直接摄取或(和)通过附随着藻类本体迅速增长的细菌群摄取溶解游离型氨基酸。  相似文献   

长江下游江段铜鱼肌肉营养成分分析   总被引：7，自引：0，他引：7  

刘凯  徐东坡  段金荣  张敏莹  虞锐鹏  施炜纲 《广东海洋大学学报》2008,28(3)

对采自长江下游江段的铜鱼(Coreius heterodom)肌肉营养成分进行了测定和分析。结果表明,铜鱼肌肉水分、粗蛋白质、粗脂肪和粗灰分占鲜样的比例分别为:70.03%、20.54%、6.82%和1.38%;按照氨基酸评分(Amino Acid Score,AAS)和化学评分(Chemical Score,CS)标准,铜鱼限制性氨基酸为缬氨酸和异亮氨酸,必需氨基酸指数(EAAI)为81.52;不饱和脂肪酸和ω-3多不饱和脂肪酸含量分别为63.03%和2.0%;肌肉中常、微量元素含量最高分别为钾(3135μg/g)和铁(5.46μg/g),锌铜比和锌铁比分别为8.85和0.65。  相似文献