溶剂体积对甜面酱中挥发性成分分析的影响

采用顶空固相微萃取(HS-SPME)与气质联用(GC-MS)相结合对甜面酱中挥发性成分进行了初步分析,比较了溶剂体积(4,5,6,7,8mL)对甜面酱挥发性成分的萃取效果和特点。结果表明:在相同实验条件下,当溶剂体积为6mL时萃取到的色谱总峰面积和化合物种类最多,因此最适合甜面酱挥发性成分检测的溶剂体积为6mL。

聚L-乳酸在大分子体积溶剂中的结晶性能

聚L-乳酸(PLLA)的结晶性能影响着其生物降解速度和机械强度。采用广角X射线衍射(XRD)和差示扫描量热(DSC)方法研究溶剂分子体积对PLLA结晶性能的影响。以分子摩尔体积较大的聚乙二醇(PEG)为溶剂,PLLA在较高质量分数溶液(10%)中仍具有高的结晶度(73%)、高的非等温结晶温度和快的结晶速度,结晶速度系数CRC为0.659,高于从质量分数10%小分子溶剂中结晶的结晶速度。溶剂分子的摩尔体积对聚合物分子的构象有明显的影响,从而直接影响着PLLA的结晶速度和结晶度。

用脂肪测定仪萃取土壤中石油烃的研究

《土壤和沉积物石油烃(C_(10)-C_(40))的测定气相色谱法》(HJ 1021-2019)索氏提取法提取溶剂体积为100 mL,提取时间为16~18 h。本文使用脂肪测定仪,探究在缩短提取时间和减少提取溶剂体积的情况下萃取石油烃(C_(10)-C_(40))的可行性。结果表明,在提取时间为2 h、3 h、4 h,提取溶剂体积为50 mL、65 mL、80 mL的情况下,空白加标样回收率满足方法中70%~120%的要求,样品加标样的回收率满足方法中50%~140%的要求。标准样品的测定结果均在不确定度范围以内。本研究结果可为使用脂肪测定仪提取土壤中石油烃(C_(10)-C_(40))提供参考。

城市景观用高分子材料的制备与性能研究

共制备了4组不同取代率的城市景观涂料、功能薄膜用树枝状高分子材料(ADPs),研究了溶液的散射光频率随着甲醇质量浓度的变化关系、散射光频率与聚集体流体力学半径与时间的关系曲线、胶束中单分子的聚集数随时间的变化,并观察了不同取代率下高分子材料的微观形貌。结果表明,随着甲醇质量浓度增加,不同取代率的试样溶液的散射光频率呈现先稳定不变而后迅速增加的趋势,在取代率为38%、41%、51%和60%时,溶液的临界选择性溶剂体积分数分别为49%、47%、44%和44%,临界胶束质量浓度分别为0.57 mg/mL、0.40 mg/mL、0.20 mg/mL和0.16 mg/mL,胶束平均尺寸分别为68 nm、59 nm、53 nm和45 nm;随着临界胶束质量浓度下高分子材料中取代率D A的增大,胶束尺寸逐渐减小;取代率越高则胶束中单分子的聚集数越小,其自组装机制为单分子胶束聚集。

由1,6-二溴己烷制备六亚甲基-1,6-双硫代硫酸钠的研究

本文利用1,6-二溴己烷和五水硫代硫酸钠的亲核取代反应,以水及乙醇为反应介质,在适当条件下合成六亚甲基-1,6-双硫代硫酸钠水合物,并研究了溶剂的不同比值对六亚甲基-1,6-双硫代硫酸钠收率的影响。实验结果表明,当反应体系的温度为80oC,溶剂比即乙醇与水的比为2:5时,反应的收率可达到94.89%。

煤液化残渣可溶有机质中杂原子结构片段的赋存特征

煤液化残渣(CLR)是一种典型的煤化工固废。但煤液化残渣中的可溶有机质含量高,且富含缩合芳环结构,又可视为一种宝贵的重质炭资源。基于CLR在有机溶剂中的优良溶解性,选择等体积甲醇/甲苯混合溶剂为萃取剂,采用超声-索氏协同萃取法,实现CLR可溶有机质(CLR-SO)的温和提取,并通过逐级钌离子催化氧化,结合气相色谱/质谱联用分析,揭示CLR-SO中的杂原子结构单元特征,为其清洁转化和高值化利用提供支撑。结果表明,在CLR-SO的氧化产物中,含杂原子的酸类化合物中杂原子主要是氧、氮、硫,所构成的官能团有甲氧基、羰基、醚桥键、硝基、氨基、乙腈、吲哚、吩嗪、硫羰基等。此外,还检测到含氮、硫、氟等杂原子的酯类化合物。除了含氧化合物以外,其他杂原子化合物基本从第3级氧化产物中出现。杂原子结构存在于CLR-SO的大分子骨架内部,在氧化过程中,受到周围芳环的电子云保护,优先氧化CLR-SO分子骨架外围的芳环结构。除了酸和酯类化合物,在CLR-SO氧化产物中还检测到其他含杂原子的化合物,主要分布在第3,4级氧化产物中,且在第4级氧化产物中的种类最多。此外还检测到氯、氟等杂原子,以共价键的形式存在于CLR-SO有机质的分子骨架结构中。通过逐级选择性氧化,实现了有机质分子结构的“层层剥离”,获取了更多的结构单元片段,丰富了CLR中的杂原子结构信息。

Study of the Liquid Phase Volume Expansion for CO_2/Organic Solvent Systems

The supercritical antisolvent （SAS） process has been developed in recent years for the tormation of nanoand micro-particles. It is necessary to study the liquid phase volume expansion （LPVE） and find the relationships between the operating conditions and the LPVE in order to develop a practical method for determining the operation conditions and selecting an organic solvent for SAS process. The PR equation of state with vdW-1 mixing rule is used to calculate the LPVE for CO2/toluene, CO2/acetone and CO2/ethyl acetate systems, and the results show that the LPVE for each CO2/organic solvent system decreases as the temperature increases. The relationship between the LPVE and the solubility of CO2 in the liquid phase for CO2/organic solvent systems is investigated, and the results show that the LPVE is determined directly by the solubility of CO2 in the liquid phase, xCO2, and can be related to xCO2 independently. No matter what system of CO2/organic solvent is and how different the temperature is, the LPVEs have little difference as long as the solubility of CO2 in the liquid phase, xCO2, keeps constant. The lower temperature is always favorable to the SAS process. The higher the solubility of CO2 in an organic solvent under certain operation condition, the more suitable it is to the SAS process.

Stability of [BMIM]HSO_4 for using as additive during zinc electrowinning from acidic sulfate solution

The stability of ionic liquid additive 1-butyl-3-methylimidazolium hydrogen sulfate （[BMIM]HSO4） during zinc electrowinning from acidic sulfate solution was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. Compared with the traditional industrial additives, gelatine and gum arabic, [BMIM]HSO4 has more excellent chemical and thermal stabilities. The inhibition effects of gelatine and gum arabic on the zinc electrocrystallization are observed to markedly weaken due to their part degradation after 12 h longtime successive electrolysis and high temperature （90 ℃） treatments. In contrast, the activity of [BMIM]HSO4 is practically unaffected after 24 h longtime successive electrolysis and high temperature treatments. These results are corroborated with the corresponding morphological analysis of the cathodic deposits.

Removal of organic solvent from cathodic electrophoretic emulsion paint by vacuum steam stripping

The production of environmental friendly emulsion paint is of great significance. Vacuum steam stripping of methyl isobutyl ketone （MIBK） and methyl ethyl ketone （MEK） from cathodic electrophoretic emulsion was studied. The effects of mass ratio of vapor to feed （V/F）, vacuum degree and feed temperature on removal rate of MIBK and MEK, emulsion size and solid volume fraction of the emulsion were investigated, and the removal of MIBK and MEK from cathodic electrophoretic emulsion by vacuum desorption was also studied. The results show that removal rates of both MIBK and MEK increase with the increase of V/F, vacuum degree and feed temperature. Removal rates of MIBK and MEK are 98.3% and 93.6%, respectively, at the operating condition V/F of 0.7, feed temperature of 27℃ and vacuum degree of 90 kPa. The emulsion size of cathodic electrophoretic emulsion increases slightly with feed temperature when temperature is below 42 ℃, and increases rapidly with feed temperature when temperature is above 42℃. Solid volume fraction increases by 10% as vacuum degree increases from 0 to 90 kPa at V/F of 0.7 and feed temperature of 27 ℃. Compared with vacuum desorption, vacuum steam stripping can get a higher removal rate of MIBK and MEK under the same feed flow, vacuum degree and feed temperature.