溶剂气浮法去除水中的刚果红的研究

以十六烷基三甲基溴化铵为表面活性剂, 与阴离子型染料刚果红形成缔合物, 对该缔合物的溶剂气浮过程进行研究. 研究多种参数对溶剂气浮过程的影响, 如气浮速率、共存溶质的量、pH等参数对溶剂气浮去除率的影响. 研究表明表面活性剂与染料的物质的量之比为2∶1, 约24 min水中刚果红的去除率可达97%;NaCl会大大降低溶剂气浮的去除率;溶剂气浮的速率随着气流速率的增加而增加, 但高速率反而降低溶剂的去除率;共存溶质乙醇存在会使去溶剂去除率降低, 有机溶剂的量对溶剂气浮影响较小;pH中性去除率最佳;考察了不同温度下溶剂气浮的热力学及动力学, 研究表明, 溶剂气浮过程遵从一级动力学, 计算了该过程中的气浮表观活化能为7.48 kJ/mol.     

Removal of 2,4-Dichloro phenoxy acetic acid pesticide by solvent sublation: Experimental and theoretical studies

The removal of the pesticide 2, 4 D from water using solvent sublation process was investigated in this paper. A lab scale unit was set up and various experimental runs were carried out to study the efficiency of the removal process. The experimental findings show that the method is very effective (>90% removal) in removing traces (ppb level) of the pesticide which is not easily removable by simple air stripping. In addition a mathematical model was developed to describe the experimental findings. Some parameters of the model were measured or calculated while others such as the aqueous mass transfer coefficient and the solute partition coefficient were adjusted to fit the experimental data. The calibration of the model was carried out using the experimental results of change in gas flow rate (the easiest parameter to vary). A numerical sensitivity analysis was carried out using the calibrated model to study the effect of various parameters such as the bubble radius, aqueous phase drag-up by air, column radius and ratio of organic to aqueous volume phases.     

The recent progress of solvent sublation

Solvent sublation is a kind of adsorptive bubble separation technique in which the surface-active (or hydrophobic) compounds in aqueous phase are adsorbed on the bubble surfaces of an ascending gas stream and then collected in an organic layer placed on top of the aqueous phase. The technique has many advantages, such as high separation efficiency, high concentration coefficient, low dosage of organic solvent, soft separation process, and simple operation. Thus, this technique has been widely applied in many fields. The present article reviews solvent sublation's theoretical research and some applications in the last 10 years, and gives the development trend in the future.     

Critical bubble radius in solvent sublation

The complex compound of dithizone-Co(Ⅱ) was separated and concentrated from the aqueous phase to n-octanol by solvent sublation.From the analysis of the coalescence behavior of bubbles on water-organic interface,the conception of critical bubble radius was proposed,and the value of the critical bubble radius in the water-octanol system was obtained:1.196×10~(-3)m.The simulation of the mathematical model using CBR and experimental data is completed with perfect results,and the simulation of the mathematical model using CBR is very different with the classic one.The analytical results proved that the critical bubble radius should be adequately considered in mathematical model of solvent sublation.     

溶剂浮选法分离富集葛根中大豆甙元的研究

采用溶剂浮选法分离富集葛根中的大豆甙元。考察了浮选溶剂、氮气流速、试液pH、浮选时间及电解质（KC1）等因素对浮选效率的影响,优选出最佳浮选条件;对最佳条件下的浮选效果进行了评价,并与溶剂萃取法进行了对照,前者明显优于后者。     

溶剂气浮法分离水中的Zn离子的研究

以双硫腙为配体,溴化十六烷基三甲基铵（CTAB）为表面活性剂。对Zn离子在无机相中形成的Zn-双硫腙-CTAB体系的溶剂气浮进行了研究。研究表明表面活性剂与Zn离子的物质的量之比为5：1,约1h水中的锌离子去除率可达98％。0．5mol／L NaCl大大提高体系的溶剂气浮的去除率,溶剂气浮的速率随着气流速率的增加而增加,共存溶质乙醇存在会使去除率降低,有机溶剂的量对溶剂气浮影响较小,溶剂气浮过程遵从假一级动力学。考察了不同温度下溶剂气浮的回收速率,计算了该过程中的气浮表观活化能为9．037kJ／mol。     

溶剂浮选法分离富集工业废水中痕量有机污染物的研究

采用溶剂浮选法对工业废水中痕量有机污染物进行分离富集，用气相色谱-质谱(GC-MS)联用法对其进行鉴定。针对废水中几种主要有机污染物，对影响溶剂浮选的参数进行了优化。所述方法用于分析某石化工业废水中主要存在的39种痕量有机污染物，结果表明这是一种简便、可行的水质分析前处理方法。     

溶剂浮选-高效液相色谱法同时测定水体中痕量4-硝基甲苯、二苯甲酮和正丁苯

建立了一种同时测定水体中痕量4-硝基甲苯、二苯甲酮和正丁苯含量的新方法, 即采用溶剂浮选法分离富集水体中的痕量 4-硝基甲苯、二苯甲酮和正丁苯类环境激素, 用高效液相色谱法测定其含量. 考察了浮选溶剂、试液 pH、氮气流速、浮选时间等因素对浮选效果的影响, 优选出最佳浮选条件. 采用所述方法对石化地区水体中 4-硝基甲苯、二苯甲酮和正丁苯类环境激素进行测定, 样品加标回收率为92.7%～114.3%, RSD为4.8%～8.4%.     

溶剂浮选-紫外分光光度法测定厚朴中总厚朴酚

建立了一种测定厚朴中总厚朴酚的新方法,即采用溶剂浮选法分离富集厚朴中的总厚朴酚,用紫外分光光度法测定其含量。考察了浮选溶剂、试液pH、氮气流速、浮选时间及电解质NaCl等因素对浮选效果的影响,优选出最佳浮选条件。采用所述方法对不同产地厚朴样品中总厚朴酚含量进行测定,样品加标回收率为94.9%-100.8%,RSD为2.8-4.1%。     

Effects of the relative humidity and water droplet on adhesion of a bio-inspired nano-film

Inspired by geckos' adhesion, the effect of water membrane forming due to the environmental humidity, on the adhesion between a bio-inspired nano-film and a substrate is investigated first. The disjoining pressure is considered, which results in an enhancing adhesion between the nano-film and substrate. When the thickness of water membrane increases, water droplets will form and a repulsive capillary force between the nano-film and substrate is produced. The total adhesion force decreases with an increasing volume of water droplets. The two opposite results in the two different models are consistent well with two seemingly inconsistent experimental observations by Huber et al. (2005) [4] and Sun et al. (2005) [5], respectively, and may be significant for the development of artificial biomimetic attachment systems.     

Permeation of water as a tool for characterizing the effect of solvent, film thickness and water solubility in cellulose acetate membranes

Cellulose acetate membranes have been used in many applications; of particular interest are reverse osmosis systems, and as a neutral matrix for incorporation of different polymers (e.g., conducting polymers), inorganic ions (e.g., lanthanides) and organic (e.g., pharmaceutical) compounds. The properties of the new polymers derived from cellulose acetate or blends depend on those of cellulose acetate. This work presents an attempt to find links between thermodynamic and kinetic properties of cellulose acetate membranes in equilibrium with water. Water diffusion coefficients in cellulose acetate membranes are reported, measured with a simple water permeation technique. The comparison of these values with the percentage of water uptake and polymer thickness leads to interesting conclusions related with different polymer properties.     

The removal of humic acids from water by solvent sublation

The application of solvent sublation in the removal of humic acids was investigated in the present study. The humic acids (HA) were removed from an aqueous solution by solvent sublation of humic acid-hexadecylpyridium chloride (HPC) complex (sublate) into isopentanol. Several parameters were examined towards the optimization of humic acid removal; the dosage of a surfactant was found to be the major one, controlling the overall efficiency of the progress. The removal rate was somewhat enhanced by higher airflow rate and almost independent of the volume of the organic solvent floating on the top of the aqueous column. The effects of electrolytes (e.g., NaCl), nonhydrophobic organics (e.g., ethanol), and pH of the solution upon the process were studied. Under the optimized condition, the treatment performance was found to be very efficient, reaching almost 100%, indicating that solvent sublation can serve as a possible alternative technology for the removal of humic acids. The solvent sublation process follows first-order kinetics. A characteristic parameter, apparent activation energy of attachment of the sublate to bubbles, was estimated at a value of 9.48 kJ/mol. Furthermore, the simulation of a mathematical model with the experiments on the solvent sublation of humic acid-HPC was described here.     

Directly suspended droplet microextraction in a rotating vial

In this paper, a novel suspended droplet microextraction method was developed for the detection of trace of organic compounds in water samples. The process was executed in a rotating extraction vial without the use of a stir bar. A single drop of octan-1-ol placed on top of the water sample was used as the solvent. The droplet remained on top of the water sample as a thin layer with an expanding surface area during the extraction stage, while during the sampling stage, the droplet was collected and sampled by inserting a needle. The volume of the microdroplet used was 3 μL or less, to ensure high organic compound sensitivity. The microextraction experimental setup was simple, utilizing centrifugal forces and possesses the advantages of low cross-contaminant/interference and applicability to water samples apt to emulsification. Nitrobenzene was selected as a model organic compound, and samples were analyzed using gas chromatography (GC) or UV-vis spectrometry. Analysis of the microextraction method results showed a relative standard deviation (RSD) less than 3.82%.     

Static and dynamic contact angles of water droplet on a solid surface using molecular dynamics simulation

The present study investigates the variation of static contact angle of a water droplet in equilibrium with a solid surface in the absence of a body force and the dynamic contact angles of water droplet moving on a solid surface for different characteristic energies using the molecular dynamics simulation. With increasing characteristic energy, the static contact angle in equilibrium with a solid surface in the absence of a body force decreases because the hydrophobic surface changes its characteristics to the hydrophilic surface. In order to consider the effect of moving water droplet on the dynamic contact angles, we apply the constant acceleration to an individual oxygen and hydrogen atom. In the presence of a body force, the water droplet changes its shape with larger advancing contact angle than the receding angle. The dynamic contact angles are compared with the static contact angle in order to see the effect of the presence of a body force.     

溶剂浮选吸光光度法测定微量铂

本文应用溶剂浮选吸光光度原理,拟定了微量铂的分析方案。用CTMAB作捕收剂,捕收〔Pt(SnC1_3)5〕~(3-)离子,浮选至有机溶剂乙酸乙酯中,在398nm处用1cm的比色皿测定吸光度,可以测定ppb级的铂。富集比为40,表观摩尔吸光系数为2.6×10~5,铂的回收率接近100％。     

溶剂浮选法分离富集茶叶中茶多酚的研究

采用溶剂浮选法分离富集了茶叶中的茶多酚。考察了浮选溶剂、氮气流速、试液pH及浮选时间等因素对浮选效率的影响,优选出最佳浮选条件;对最佳条件下的浮选效果进行了评价,并与溶剂萃取法进行了比对,前者明显优于后者。     

The kinetics and thermodynamics of surfactants in solvent sublation

Solvent sublation has been performed on very dilute solutions of one cationic surfactant, hexadecylpyridinium chloride (HPC), and one anionic surfactant, dodecylbenzenesulfonic acid (LBS). Some thermodynamic values were obtained, e.g. molecular areas, A0, which are 50.0 and 47.7 A2/molecule, respectively, for HPC and LBS, and free adsorption energies, delta G(o)ads, which are -33.17 and -43.58 kJ mol(-1), respectively, for HPC and LBS. The kinetics were determined for a range of temperatures and gas flow-rates. Although the processes of solvent sublation of the two surfactants obey first-order kinetics, the respective adsorption mechanisms of HPC and LBS in the solvent sublation process were different. The pH and the presence of KCl and ethanol had no effect on the solvent sublation of LBS. The apparent active energy was calculated as 8.11 kJ mol(-1).     

The kinetics and thermodynamics of surfactants in solvent sublation

Solvent sublation has been performed on very dilute solutions of one cationic surfactant, hexadecylpyridinium chloride (HPC), and one anionic surfactant, dodecylbenzenesulfonic acid (LBS). Some thermodynamic values were obtained, e.g. molecular areas, A₀, which are 50.0 and 47.7 Ų/molecule, respectively, for HPC and LBS, and free adsorption energies, ΔG°_ads, which are –33.17 and –43.58 kJ mol^–1, respectively, for HPC and LBS. The kinetics were determined for a range of temperatures and gas flow-rates. Although the processes of solvent sublation of the two surfactants obey first-order kinetics, the respective adsorption mechanisms of HPC and LBS in the solvent sublation process were different. The pH and the presence of KCl and ethanol had no effect on the solvent sublation of LBS. The apparent active energy was calculated as 8.11 kJ mol^–1.     

Preparation of aminals in water

Aminals, which are used as protecting groups in syntheses and are part of many biologically active compounds, are normally prepared from aldehydes and diamines under conditions that remove water in order to shift the equilibrium to the side of the aminal. Here we report for the first time that aminals can be prepared and isolated in pure water without a catalyst in high yield and purity.