超临界CO_2络合萃取去除乳酸钙中痕量金属

研究了超临界络合萃取法去除乳酸钙中铝、砷汞等痕量金属,考察了络合剂种类、萃取压力、萃取时间对去除率的影响。结果表明,不同络合剂对不同金属的萃取效果有明显差异;在非溶解度制约阶段,单纯增加萃取压力对萃取率的提高没有明显影响;萃取时间比萃取压力的影响更为明显,表明该过程是络合萃取反应控制过程。较佳的工艺条件为:萃取温度20℃,CO2流速15.5L/h,萃取压力20MPa,萃取时间30min,溴化四丁基铵与二乙基二硫代氨基甲酸钠的复配物用量为试样质量的2%,加入乙醇作为极性溶剂。在此条件下,铅、汞、砷的总去除率达82.8%。     

Vibrationally Excited CO2 Formed in CO + NO Reaction on Pd(110) Surface in High Surface Temperature Range

The infrared chemiluminescence spectra of CO₂ formed during steady-state CO+NO reaction over Pd(110) indicated that the temperature of the bending vibrational mode was much higher than that of the antisymmetric one at higher surface temperatures such as 800–850 K. Especially, in the high temperature range, more vibrationally excited CO₂ was formed from CO+NO reaction than CO+O₂ reaction. On the basis of the result, we propose the model structure of reaction intermediates for CO₂ formation in CO+NO reaction, which is different from that in CO+O₂ reaction.     

PROCESS ASPECTS OF THE EXTRACTION OF HOPS WITH LIQUID CARBON DIOXIDE

The time course of the extraction of α-acids by liquid carbon dioxide was investigated and it has been established that there are two zones with greatly differing rates of extraction. The rate in the first zone is governed by ‘solubility’ effects, while in the second zone the rate is limited by ‘diffusional’ effects. Consequently the rate of extraction in the first zone depends upon the flow rate of liquid carbon dioxide while that in the second zone depends upon the time of extraction. The effects on extraction performance of the depth of the bed of hops and the extent of milling were also explored.     

Evaluation of lysozyme stability in young red wine and model systems by a validated HPLC method

Hen’s egg lysozyme (LYZ) is added to red wine for preventing malolactic activity. Sulphur dioxide and polyphenolic compounds can depress LYZ solubility and effectiveness, likely by sulphonation of enzyme disulphide bonds or protein binding, respectively. These phenomena were evaluated in either young red wine or model wine systems. A reliable and validated HPLC method was first developed in order to quantify soluble LYZ in wine (r_95% = 10.7 mg l⁻¹). The amount of insolubilized LYZ in red wine was related to the content of non-anthocyan flavonoids of low molecular weight and enzyme precipitation occurred in few minutes when flavonoid concentration exceeded 50 mg l⁻¹. Interaction between sulphur dioxide and LYZ occurred in polyphenol-free model wine systems and for the first time the formation of mono-thiosulphonated LYZ was demonstrated. This reaction was favoured by increasing pH value and sulphur dioxide concentration. Nevertheless, sulphonation alone did not fully explain LYZ instability in model wine systems.     

Rapid determination of formaldehyde and sulfur dioxide in food products and Chinese herbals

Simple, sensitive and rapid methods for the determination of formaldehyde and sulfur dioxide were developed. The formaldehyde determination is based on the reaction between formaldehyde and acetylacetone solution, producing yellow 3,5-diacetyl-l-1,4-dihydrolutidine. Sulfur dioxide was detected as the deoxidize of sulfurous acid by zinc in acidic medium, which produces sulfureted hydrogen that make lead acetate paper blackening due to lead sulfide formation. The detection limits were 0.8 μg mL⁻¹ and 6.0 μg mL⁻¹ for formaldehyde and sulfur dioxide, respectively. The linear range were 0.8–20.0 μg mL⁻¹ for formaldehyde and 6.0–100.0 μg mL⁻¹ for sulfur dioxide determination. The main advantages of the new analytical procedure are the low background level, high selectivity, and very little sample preparation for on-site analysis of formaldehyde and sulfur dioxide in food or Chinese herbal samples with reference color card for qualitative or semi-quantitative determination. The results from these methods correlated well with those obtained from the standard methods.     

Sediment greenhouse gases (methane and carbon dioxide) in the Lobo-Broa Reservoir, São Paulo State, Brazil: Concentrations and diffuse emission fluxes for carbon budget considerations

Carbon gases (methane, CH₄, and carbon dioxide, CO₂) were measured for the first time in sediments of the Lobo‐Broa Reservoir, near São Carlos in São Paulo State, Brazil. It is believed these are the first measurements of this kind in any of the many reservoirs located in Brazil. Even though the Lobo‐Broa Reservoir is classified as oligotrophic, the sediment gas concentrations were exceedingly high, ranging from 0.4–3 mmol L^?1 for CH₄ and 1–9 mmol L^?1 for CO₂. Both gases exceeded their in situ gas saturation values at these shallow water depths (7 m in central basin; 11 m at dam), resulting in numerous sediment bubbles. Organic matter was highly concentrated in the reservoir sediments, averaging 25.5% loss on ignition (LOI) (dam) to 26.9% LOI (central basin) for the 0–12 cm depth interval, with values as high as 29–30% LOI (12% organic carbon) in the surface 0–5 mm layer. The theoretical flux of dissolved pore water carbon gases to the sediment–water interface (SWI) averaged 3.4 mmol L^?1 m^?2 day^?1 CH₄ and 7.3 mmol L^?1 m^?2 day^?1 CO₂ for the surface 0–10 mm. From gas emission measurements at the water surface, it was calculated that 90% of CH₄ is consumed either at the SWI or in the water column, resulting in a loss of 0.31 mmol L^?1 m^?2 day^?1 of CH₄ to the atmosphere. However, only 20% of the total CO₂ gas transported across the water–atmosphere interface (36.3 mmol L^?1 m^?2 day^?1, or 1600 mg CO₂ m^?2 day^?1) was produced in the sediments. The remaining 80% of CO₂ probably comes from other carbon sources. With CH₄ oxidation in the aerobic water column, close to 30% of the carbon gas flux to the atmosphere could be accounted for by gas production of CO₂ and CH₄ in the sediments and their diffuse transport to the water column.     

玉米胚芽油的超临界CO2提取技术研究

从事了超临界ＣＯ２萃取玉米胚芽油的试验研究。结果表明，降低玉米胚芽原料的粒度，改变原料的形状，降低原料的自然堆积比重，采用塔板式装料方式可以明显提高传质效果，使出油率大大提高。     

Theoretically based data assessment for the correlation of the thermal conductivity of dilute gases

This paper presents two schemes for a theoretically based data assessment of the thermal conductivity of dilute polyatomic gases. The first employs the simplified Thijsse expression, combined with accurate experimental data obtained from a transient hot-wire apparatus, as reference. The second makes use of theoretical results for the temperature dependence of the ratio D _int/D. Both methods lead to mutually consistent results for linear molecules and to useful criteria for discriminating between experimental data sets. The paper also demonstrates the influence of data burdened with systematic errors upon the final results of different correlation schemes.     

Modelling of the kinetic of 2-chlorophenol catalytic photooxidation

The photoassisted oxidation of dilute aqueous solutions of 2-chlorophenol (2-CP) is investigated over a solid catalyst (TiO₂) at laboratory level in an annular photocatalytic reactor. In order to characterise the reaction, different kinetic models are proposed, being related to the attack of the reagent by ^.OH radicals. The model based on the competitive adsorption between oxygen and 2-chlorophenol does not lead to satisfactory results. For the other models it was assumed that oxygen adsorption occurs at different sites. The model with the adsorption isotherms of reagent and oxygen being proposed of a Langmuir type is the only one able to justify the observed dependence of the pollutant disappearance rate on dissolved 2-CP concentration, oxygen partial pressure and absorbed light intensity with adsorption parameters deduced from direct measurements.     

济阳坳陷花沟CO2气藏形成与高青断裂活动性关系分析

利用三维地震资料,对济阳坳陷花沟CO2气藏区高青断裂走向上不同区段的活动性进行了分析，指出：花沟CO2气藏所对应的高青断裂区段,在馆陶组—明化镇组沉积时期活动性强，而气藏的东、西两侧,馆陶组—明化镇组沉积时期断裂基本上不活动；花沟CO2气藏与馆陶组—明化镇组沉积时期高青断裂活动性强的区段在平面上有着良好的对应关系；花沟CO₂气藏的运聚过程分为2个阶段，在第1阶段，幔源岩浆成因的CO₂、N₂和He等气体进入高青断裂后,在浮力或压差作用下向断裂顶端运移,并发生重力分异，由于断裂顶端封闭、两侧封堵,CO₂、N₂和He等气体在高青断裂中实现了一定程度的聚集，而在第2阶段，当CO2、N2和He等气体在断裂中聚集到一定程度,便在压力驱动下向断裂两侧砂岩储层运移,并在其中聚集成藏。认为气源断裂走向上活动性的差异决定着CO₂气藏的平面分布位置,断裂活动性强的区段所对应的储层是CO₂气成藏的有利场所。 