Fenton试剂降解农药废水中间羟基苯甲酸的动力学和热力学研究

[目的]探讨Fenton试剂作为氧化剂,对目标污染物——除草剂类农药废水中的间羟基苯甲酸的去除效果和动力学及热力学。[方法]考察了Fenton降解间羟基苯甲酸效果的影响因素;模拟了反应动力学和热力学;讨论了间羟基苯甲酸在氧化过程中降解和去除的规律和机理。[结果]在35℃、pH3.0、H2O2浓度为0.25 mol/L、H2O2/Fe2+=20的反应条件下,反应1 h后,Fenton对间羟基苯甲酸的去除率达到最高,为97.64%;Fenton对间羟基苯甲酸的降解过程符合一级动力学方程,速率常数(K)为0.252 1/min,半衰期(t1/2)为2.54 min;反应活化能(Ea)为12.72 kJ/mol。Fenton法对间羟基苯甲酸的氧化反应较完全,乙二酸和乙酸为主要的氧化反应终产物。[结论]为将来的实际工程应用提供了理论依据。     

京郊2种生物质气化工程的比较及经济性分析

对目前农村推广的生物质气化工程主要采用的氧化法和热解法,从原材料、主燃气体、热值、产气效率、农户日用气量和副产品上进行比较,并在此基础上,对该2种方法气站的经济规模、最低气价、投资回收期等进行了分析测算。结果表明,热解法气站的效益好于氧化法气站,最后提出了主推热解法、解决副产品回收问题、对农户实行用气补贴等对策及建议。     

静脉注射53Cr标记吡啶甲酸铬对仔猪脂质和DNA氧化的影响

选取体重15.0±1.0kg、健康的瘦肉型三元杂交 (杜×长×大)仔猪30头,按体重、遗传背景相近的原则随机分成5组,每组6头,单笼个体饲养。每天早8:00-10:00分别对各组猪进行静脉注射,Ⅰ（对照）、Ⅱ、Ⅲ、Ⅳ、Ⅴ组分别注射0、8、200、400和800μg Cr /d的53Cr标记吡啶甲酸铬,试验期14d。检测指标为肝肾中示踪剂铬、抗氧化酶和丙二醛（MDA）、尿中8-羟基脱氧鸟苷（8-OHdG）。结果表明,吡啶甲酸铬在肝、肾中的蓄积量随着静脉注射吡啶甲酸铬水平的升高而增加,且在200?g以上达到显著（P<0.05）;与对照组相比,仔猪的血清、肝、肾中MDA都无显著升高(P>0.05),除血清SOD和肾脏CAT活性显著下降（P<0.05）外,其他抗氧化酶也无显著变化(P>0.05)。但肾脏中, 800μg组MDA水平显著高于8μg组（P<0.05）。尿液中8-羟基脱氧鸟苷的水平未发生显著变化。结果显示,本试验剂量范围内（800μgCr/d,14d）,吡啶甲酸铬在仔猪肝脏、肾脏内显著沉积,肾脏中沉积量高于肝脏;肾脏脂质过氧化与肾中铬浓度之间存在显著量效关系;静脉注射不同水平吡啶甲酸铬未引起机体DNA氧化损伤和肝脏脂质过氧化。      

海水养殖废水中氨氮测定方法的影响因素及改进研究

采用酒石酸钾钠溶液-氢氧化钠溶液作为屏蔽剂排除海水中钙、镁离子对测定的干扰,将纳氏试剂比色法用于对海水养殖废水中氨氮的测定,最佳测定条件为200 g/L的氢氧化钠溶液用量2.5 mL,纳氏试剂1.5 mL,显色时间25 min.该方法对盐度为10～32的海水可以直接测定,氨氮质量浓度在0.01～0.04 mg/L符合比尔定律,检出限为0.01 mg/L,加标回收率在91%～108%.     

Fatty acid composition and oxidation stability of hemp (Cannabis sativa L.) seed oil extracted by supercritical carbon dioxide

Supercritical carbon dioxide (SC-CO₂) was employed to extract oil from hemp (Cannabis sativa L.) seeds. For ground seeds, the supercritical extraction was carried out at temperatures of 40, 60 and 80 °C and pressures of 300 and 400 bar. Different solvent-ratios were applied. Supercritical CO₂ extractions were compared with a conventional technique, n-hexane in Soxhlet. The extraction yields, fatty acid composition of the oil and oxidation stability were determined. The seed samples used in this work contained 81% PUFAs, of which 59.6% was linoleic acid (ω-6), 3.4% γ-linolenic (ω-3), and 18% α-linolenic (ω-6). The highest oil yield from seeds was 22%, corresponding to 72% recovery, at 300 bar and 40 °C and at 400 bar and 80 °C. The highest oxidation stability corresponding to 2.16 mM Eq Vit E was obtained at 300 bar and 80 °C.     

Effects of protein oxidation on gelatinization characteristics during rice storage

Gliadin and glutelin are major rice storage proteins. In this study, we evaluated changes in these proteins to determine the influence of pasting properties on rice storage. Notably, the physical and chemical properties of these proteins changed steadily. We analyzed protein oxidation indexes and determined correlations between the protein oxidation index and gelatinization property index. The results showed that significant oxidation of gliadin and glutelin occurred during the process of rice storage (P < 0.05). Protein oxidation had a significant impact on pasting properties. For glutelin, changes in the structure and function of the protein during rice storage had a significant impact on the five rice pasting property indexes, including peak viscosity (PV), holding strength (HS), breakdown, final viscosity (FV), and setback (SB; P < 0.05). In particular, the levels of carbonyl compounds and active sulfur and the surface hydrophobicity of glutelin were significantly correlated with rice pasting property indexes (P < 0.05). However, gliadin only significantly affected three indexes, i.e., PV, HS, and FV (P < 0.05). Thus, these findings suggested that the carbonyl compounds, active sulfur, and surface hydrophobicity of glutelin could be used as sensitive indexes for changes in rice quality evaluation.     

茶儿茶素体外氧化产物分析

采用体外模拟发酵, 对从绿茶中提取的茶多酚( 其中儿茶素含量为78-09 % ) 进行酶促氧化、化学氧化和自动氧化, 制取茶色素, 经HPLC分析, 结果表明, 酶促氧化和化学氧化的产物吸收峰均能得到明确分辨, 其保留时间与红茶汤中茶色素成分相吻合, 而自动氧化的产物中则缺少TFs。优化的化学氧化法制得的茶色素中, TFs 和TRs1 含量高于酶促氧化制品。     

Assessing soil carbon lability by near infrared spectroscopy and NaOCl oxidation

The feasibility of near infrared (NIR) spectroscopy for quantifying labile organic matter (OM) in arable soils and for predicting soil refractory OM fractions was tested on 37 soils varying in texture and soil carbon (C) content. Three sets of arable soils (0-20 cm depth) were sampled from 1) long-term field experiments with different OM inputs, 2) individual sites with inherent with-in field gradients in soil texture and/or C content, and 3) from a range of different sites covering variations in management and geological origin. The labile OM fraction was defined by the CO₂ evolved from the soils incubated for 34 weeks while refractory OM was obtained by NaOCl oxidation.The labile fraction of the soil C accounted for 2-12% of the total soil C content. No systematic relationship between labile C content and total soil C or clay was found, but NIR spectra could be correlated well with the labile C fraction. A distinct, close linear relationship was found for C in soil before and after the NaOCl oxidation, indicating that this method was unable to reveal any additional information not contained in the total soil C measurement. NIR was also correlated with the NaOCl resistant C fraction, but this was considered to relate to the ability of NIR to predict total soil C contents. Thus NIR seemed to have the potential to estimate labile OM determined under laboratory incubations, while it still remains open how to identify and quantify refractory pools of soil OM.     

Oxidation of chlorpyrifos, azinphos-methyl and phorate by myeloperoxidase

The present paper deals with the investigations of optimal conditions for the myeloperoxidase (MPO) mediated oxidation of chlorpyrifos, azinphos-methyl and phorate, organophosphorous pesticides (OPs) containing phosphorothionate group, from thio- to oxo-forms, in the presence of hydrogen peroxide. The aim of the work was to apply this oxidation method in the AChE based bioanalytical tests for OPs determination. The maximum concentration of oxo-forms for all tested pesticides was achieved after 10 min incubation of OPs in 50 mM phosphate buffer (pH 6.0) with 100 nM MPO in the presence of 50 μM H₂O₂. Optimal temperature for obtaining maximal concentration of oxo-forms was 37 °C. Only the parent compounds and their oxo-forms were identified chromatographically in the OPs samples after their exposure to MPO. Moreover, no hydrolysis products were detected in the time interval of 1 h after the MPO catalyzed reaction was stopped by catalase. The efficiency of OPs transformation from thio- to oxo-forms was measured using acethylcholinesterase (AChE) test, by comparison of percent of AChE inhibition before and after exposure to the oxidized sample.     

基于时域太赫兹光谱技术的橄榄油氧化程度检测研究

文章通过设定特定储藏条件加速橄榄油氧化酸败,获得不同氧化程度的橄榄油样品,并对样品的脂肪酸变化进行分析.采用太赫兹系统对不同储藏期的橄榄油样品进行检测,选择0.3THz～2.0 THz范围内的THz吸收光谱作为建模数据,结合支持向量机(SVM)、反向传播神经网络(BPNN)、偏最小二乘(PLS)、随机森林(RF)建模方...