Harvesting of Saccharomyces cerevisiae using colloidal gas aphrons

Adsorptive bubble separation using Colloidal Gas Aphrons (CGA) can be used for harvesting of microorganisms. The effect of various operating parameters, for example pH, biomass loading, dispersed and continuous phase velocity, surfactant type and concentration, has been studied on the recovery of Saccharomyces cerevisiae. The operating conditions were optimised for maximum separation. The results obtained have been compared with the prediction of an model earlier.     

Clarification of suspensions by colloidal gas aphrons

Colloidal gas aphrons (CGAs), generated from dilute solutions of four surfactants, were used to clarify palm oil mill effluent (POME), suspensions of microalgae and suspensions of three inorganic minerals. In POME and the algal suspensions, each CGA was most effective at a pH value close to the pK value of the surfactant concerned. This effect was not tested in the inorganic suspensions. The efficiency of air utilization was directly related to the concentration of solids in the suspensions, the size, density and nature of the solids having secondary effects. Comparison with data in the literature led to a general correlation embracing a variety of suspensions and flotation systems. Shedding of collected material from the foam layer was also a direct function of solids concentration. CGAs offer advantages over other systems of air-assisted flotation in relation to the requirements for equipment and to the management of process operations.     

Effect of air to solid ratio in the clarification of yeast by colloidal gas aphrons

A study on the clarification of baker's yeast suspension by Colloidal Gas Aphrons (CGA) employing a cationic surfactant, benzyl-dimethyl-hexadecyl-ammonium chloride, is presented. The variables investigated were the CGA flowrate, air flowrate and the yeast concentration. A separation efficiency as high as 95% was achieved at the optimum conditions of air flowrate and feed concentration. The mechanism of particle–bubble attachment was identified and a simple model for the monolayer adsorption of yeast cells on the bubble surface derived. © 1998 SCI     

胶体泡沫和双液泡沫体系及其在分离中的应用

胶体泡沫(CGA)和双液泡沫(CLA)作为一类新的多相分散体系,其特点是包封的皂膜较厚,皂膜内外都存在表面活性剂单分子层,与普通泡沫有很大不同,如泡径小(微米级)、稳定性高、比表面大等,其应用也日益受到关注。概述了CGA和CLA的结构、性质、表征方法、手段和研究进展以及在离子浮选、除油、萃取、蛋白质分离等过程中的应用。     

电导法研究胶质液泡稳定性

应用电导法考察了溶剂极性和溶液离子强度对胶质液泡稳定性的影响,并提出了胶质液泡的稳定性模型。测量得到的电导率值k_t随时间t的变化曲线出现a、b和c三个明显不同的区域。由增比电导率值k_r随时间变化关系曲线的陡峭程度和a区所占时间,分析了溶剂种类和溶液离子强度对胶质液泡稳定性的影响。根据电导率值变化敏感的b区的动力学分析,结合胶质液泡液滴的上升、聚并和破乳等体系不稳定因素提出了胶质液泡稳定性模型。胶质液泡体系模型拟合值与稳定性实验测量数据的符合程度是令人满意的。     

一种新型胶质液体泡沫的制备及其在处理含油污泥中的应用研究

经过两步反应合成了一种新型的磺酸盐型阴离子表面活性剂。应用红外光谱、元素分析等手段对中间体、最终产品进行了结构表征;应用电导法测定了自制的新型磺酸盐型阴离子表面活性剂cmc,运用两相滴定法测定了新型磺酸盐型阴离子表面活性剂的有效含量。接着,应用新型磺酸盐型阴离子表面活性剂构筑了一种新型的胶质液体泡沫(CLA)体系。实验发现,胶质液体泡沫(CLA)的粒径及稳定性主要受相比影响。利用电导率仪对胶质液体泡沫体系的稳定性进行初步研究。应用光学显微技术对胶质液体泡沫体系的结构进行了表征。最后,应用胶质液体泡沫体系进行含油污泥的原油脱除研究,并对脱除的原油进行了回收,并应用光学显微镜技术对原油脱除机理进行了初步探讨。正交实验的结果表明:自制的、稳定的、胶质液体泡沫体系可以有效地脱除含油污泥中的原油,最佳条件是:含油污泥处理量0.5g,稀释比为10∶1,处理温度45℃,处理时间20min,最佳条件下含油污泥中原油的脱除率可达99.60%。     

胶质液体泡沫的研究进展及其在分离工程中的应用

概述了胶质液体泡沫（CLAs）的研究发展现状；讨论了CLAs的制备及影响CLAs形成的因素；分析了CLAs内部结构特征，稳定机理及其影响因素；并就胶质液体泡沫在分离工程中的应用，特别是预分散溶剂萃取（PDSE）分离，进行了总结和评述。重点分析了CLAs内部结构的本质，对该领域的研究前景作了展望；指出了有关CLAs结构探讨的研究方向和手段。     

The influence of system parameters on the stability of colloidal liquid aphrons

An investigation was carried out on the effect of process parameters involved in Pre‐Dispersed Solvent Extraction (PDSE) on the stability and interactions in dilute dispersions of Colloidal Liquid Aphrons (CLAs). The aim of this work was to derive empirically‐based engineering relationships that could be used in the design of PDSE processes. For this investigation, CLAs were formulated with an Aliquat 336/n‐octanol/Softanol 120 solvent phase, and a Synperonic A20 aqueous phase. These CLAs were intended for use in the reactive pre‐dispersed solvent extraction of polar solutes such as phenylalanine. Light scattering measurements over a range of continuous aqueous and CLA phase conditions were used as a method of obtaining a measure of the rate of disappearance of CLAs from dispersion (a measure of stability), and a comparison of stability under different conditions. Two forms of CLA interaction occurring by independent mechanisms were identified – CLA break‐up, and CLA flocculation. Break‐up was found to be a first order process, allowing CLA stability to be characterised by a first order half‐life (typical half‐life 15–40 min). This was proposed to occur on collision of CLAs with sufficient energy to overcome the stabilising forces provided by the surfactants at the interfaces of the CLAs. It was shown that flocculation occurred at high ionic strengths (>0.1 M NaCl), and that it was not part of the break‐up mechanism. An apparent size dependent CLA half‐life was proposed to be due to smaller particles having a lower collision energy on average. The data suggested that the resistance to CLA break‐up was not charge repulsion, but derived from an interaction between molecules of one of the surfactants making up the aqueous ‘shell’ of the CLAs (Synperonic A20). Finally, the basis for a semi‐empirical design equation for prediction of CLA half‐life developed from the Arrhenius equation was proposed. © 1999 Society of Chemical Industry     

利用胶质气体泡沫分离细微颗粒

This paper presents a method of separation of fine particles, of the order of a few microns or less, from aqueous media by flotation using colloidal gas aphrons (CGAs) generated in aqueous solutions. More than 150 experiments were conducted to study the effects of surfactant type, surfactant concentration, CGAs flow rate, and particle concentration on the removal efficiency (fine particles of polystyrene were used as a target compound). The results indicate that CGAs, generated from cationic surfactant of hexdecyltrimethyl ammonicum bromide (HTAB) and anionic surfactant of sodium dodecylbenzne sulfonate (SDBS), are an effective method for the separation off ine particles of polystyrene from wastewater. The flotation yields are higher than 97%.     

Factors influencing the stability of a novel enzyme immobilisation support – colloidal liquid aphrons (CLAs)

A key factor in the immobilisation of enzymes is the stability of the support. An investigation was carried out on the stability of colloidal liquid aphrons (CLAs) in dilute dispersion, looking particularly at the effects of process parameters and CLA composition. CLAs were formulated from a Softanol 30/decane solvent phase and sodium dodecyl sulfate (SDS)/β‐galactosidase aqueous phase. The aim of this work was to gain an understanding of the mechanisms stabilising CLAs, and to characterise the effects of process parameters on stability such that the knowledge gained could be used in the design of a membrane bioreactor. CLA stability was measured using a light scattering technique (defined by a first order CLA half‐life). It was proposed that CLA break‐up occurred by the collision of CLAs with sufficient energy to overcome the forces stabilising the CLAs. Stability was found not to be dependent on the bulk aqueous phase ionic strength, but increasing the concentration of the ionic surfactant increased stability, indicating that stability was influenced by charge repulsion. Stability was also found to increase for increasing enzyme (β‐galactosidase) concentration, indicating steric interactions and elastic effects were also important. Finally, the effect of process parameters (reactor temperature, CLA concentration and circulation velocity) were assessed, and their effect was explained in terms of their influence on collision energy and the activation energy necessary for CLA break‐up; increasing CLA concentration was found to improve stability considerably. © 2000 Society of Chemical Industry     

A model for harvesting of microorganisms using colloidal gas Aphrons

A theoretical study of the harvesting of microorganisms using Colloidal Gas Aphrons (CGA) is presented. A model for predicting the separation factor of the CGA contactor is proposed which involves parameters that may be estimated through simple experiments.     

Scaling-up from first principles of a photocatalytic reactor for air pollution remediation

A proposal for scaling-up photocatalytic reactors is described and applied to catalytic walls coated with a thin layer of titanium dioxide and irradiated with near UV radiation. The method is exclusively based on the fundamentals of chemical reaction engineering and radiative transfer theory, without the use of adjustable parameters in going from the laboratory information to a pilot scale apparatus. Mathematical modeling has been utilized. From kinetic information obtained in experiments performed in a flat plate of , operating at steady state in a continuous, well-mixed reactor with recycle, predictions for a continuous flow, multi-annular reactor having a catalytic surface of agree very well with the validation tests. Thus, the achieved scale-up implies a change in size, shape, configuration and operating conditions of both employed reactors. Requirements to apply satisfactorily the proposed methodology are reported in detail. The root mean square error in the verification of conversion predictions for the larger scale photocatalytic reactor when compared with experimental data is less than 5.6%.     

国内土壤污染现状、特点和一些修复浅见

介绍了国内土壤污染现状及其特点,以及欧美等国对土壤修复概况,并对各种修复技术方法进行对比。现国内对此刚起步,无成熟经验,先选取几个土壤污染类型修复进行示范,待取得成功经验再推广。     

土壤重金属污染修复技术及前景分析

作为土壤常见污染,重金属污染不仅影响土壤固有性质和质量安全,对于周边生态环境和农业发展效果也有极大影响。首先介绍土壤重金属污染修复技术,了解各类修复技术特点。之后阐述土壤重金属污染修复前景,强化土壤修复力度,满足我国各地区土壤污染治理要求,确保各地区生态环境维护水平和土壤污染治理效果有所提升。     

Reduction of amine mist emissions from a pilot-scale CO2 capture process using charged colloidal gas aphrons

In the CO₂ capture process from coal-derived flue gas where amine solvents are used, the flue gas can entrain small liquid droplets into the gas stream leading to emission of the amine solvent. The entrained drops, or mist, will lead to high solvent losses and cause decreased CO₂ capture performance. In order to reduce the emissions of the fine amine droplets from CO₂ absorber, a novel method using charged colloidal gas aphron (CGA) generated by an anionic surfactant was developed. The CGA absorption process for MEA emission reduction was optimized by investigating the surfactant concentration, stirring speed of the CGA generator, and capture temperature. The results show a significant reduction of MEA emissions of over 50% in the flue gas stream exiting the absorber column of a pilot scale CO₂ capture unit.     

Coflotation Separation for the Determination of Heavy Metals in Water Using Colloidal Gas Aphrons Systems

Abstract

The separation and preconcentration of metal traces using CGA in connection with coflotation processes is described. A 4:1 mixture of anionic surfactants consisting of sodium dodecylsulfate and potassium oleate has been used to generate the CGA system, and Fe(OH)₃ has been used as a collector. The separation process has been optimized using the Simplex Method (COFLOT computer program) complemented with a factorial design to investigate the influence of the different parameters in the investigated process. The results obtained evidenced recovery yields over 90% for the elements investigated (Cu, Co, Cd, and Ni), implying flotation times under 5 minutes as applied to samples of varying salinity, concentration, and volume.     

气相色谱法测定污染源中的苯系物

采用活性炭采样管富集气污染源中的苯系物，以二硫化碳为解吸剂，经毛细管柱测定样品中的苯系物，以保留时间定性，峰面积定量。通过对样品的采样和前处理方法法方法进行了不同条件的探讨，得出了最佳的实验条件。本方法中苯系物各组分线性方程的相关系数均大于0．999，方法的最低检出浓度在15-39μg/m^3，加标回收率在95.3～101％之间，相对标准偏差小于4．5％（n=6），能满足实际工作的需要。     

松南气田2种脱碳技术的应用总结

介绍了气体膜分离技术和NCMA脱碳技术在松南气田天然气处理装置上的应用情况。膜分离法脱碳工艺具有占地面积小、工厂内预制、现场组装简便快捷、单级膜分离装置无动设备、操作简便等优点,但产品气不能满足国标商品气中妒（CO2）〈3％的要求,天然气的损失高达15％～18％。NCMA法具有吸收能力大,再生能耗低等优点,适合于大规模天然气脱碳。NCMA法脱碳工艺装置投资少,且具有CO2净化度高、能耗低和溶剂损失少等优势,该装置年平均稳定完好运行达350天,净化气中φ（CO2）〈1．5％,完全满足下游用户对气质的要求。     

The resistance of interphase mass transfer in colloidal liquid aphron systems

Colloidal liquid aphrons (CLAs) provide very large interfacial area and thus could enhance interphase mass transfer in multiphase processes. This work characterized the mass transfer behavior of CLAs during mass transfer of benzoic acid from cyclohexane in CLAs to water in a small stirred vessel. From experimental data the overall mass transfer coefficient K_L of the surfactant-stabilized CLAs was determined. The influence of stirring speed and concentration of surfactant used for formulating CLAs on K_L was investigated. The experimental results show that surfactant adsorbed on the interface of CLAs influences greatly the value of K_L, and when the surfactant concentration is below its CMC, the overall CLAs mass transfer coefficient K_L (mainly varying with the interfacial mass transfer resistance) could be fitted to the following expression:

K_L=H₁+H₂ln[C+H₃].