Absorption of a volatile organic compound by a jet loop reactor with circulation of a surfactant solution: performance evaluation

Biofiltration shows high efficiency for the removal of industrial waste gases and reliable operational stability at low investment and operating cost, especially when the VOC concentration is low, such as 100 ppmv (micro LL(-1)) or less. However, it has been reported that the abrupt change in VOC concentrations leads to the failure of the biofilter. Hence, the pretreatment of waste gases is necessary to ensure the stable operation of the biofilter. The objective of this study is to develop a jet loop reactor (JLR) with circulation of a surfactant solution to lower the concentration of VOCs, especially hydrophobic VOCs. Toluene and Tween 81 were used as a model industrial waste gas and a surfactant, respectively. Among several non-ionic surfactants tested, Tween 81 showed the most rapid dissolution of toluene. When a JLR is replaced with fresh Tween 81 solution (0.3% w/v) every hour, it successfully absorbed for 48 h over 90% of the toluene in an inlet gas containing toluene at 1000 ppmv (microL L(-1)) or less. Therefore, JLR with circulation of a surfactant solution is believed to ensure the stable operation of the biofilter even with the unexpected increase in the VOC concentrations.     

Fabrication of CuS nanocrystals with various morphologies in the presence of a nonionic surfactant

Shape-controlled synthesis of CuS nanorods, nanoflakes, and flowerlike structures has been achieved simply in the presence of a nonionic surfactant polyethylene glycol (PEG20000) by adjusting hydrothermal temperature. The as-synthesized CuS nanocrystals were investigated by various techniques of XRD, TEM, SEM, and UV–vis spectra. The electron diffraction pattern indicated that the CuS nanoflakes were single crystals. In the process, the temperature and the surfactant PEG20000 were found to play important roles in determining the morphology of CuS nanocrystals.     

Elastic property prediction by finite element analysis with random distribution of materials for heterogeneous solids

In the present paper, finite element method is employed to predict the effective material properties of heterogeneous materials via random distributions of the constituent materials. With the random distributing strategy, massive parametric analysis via finite element becomes feasible for multi-phase heterogeneous solids. Using a two-phase bi-continuous material as an example, the effects of the specimen size with respect to the characteristic size of the micro-structural size and the element density on the predicted effective properties are considered. The numerical predictions of the effective properties are checked by two analytical bounds which were proposed by Hashin and Shtrikemn (1963) through the principle of variation and the matrix-fiber model. Some discussions on the finite element prediction are also made to clarify the status of the present work in the composite mechanics research.     

Nucleation and crystallization of solids from solution

Over the past couple of years, important insights into the problem of nucleation from solution on the theoretical as well as on the modeling side have been achieved. Experimentally, in situ techniques applied during the nucleation and the crystallization reaction are being developed, which will help to analyze the elementary processes during these reactions. A particularly active field was that of zeolite formation.     

Effective viscosity of an emulsion in a surfactant solution

A surfactant affects the effective viscosity of an emulsion because of capillary phenomena in shear flow. The surfactant gives the emulsion non-Newtonian behavior.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 5, pp. 752—759, May, 1988.     

表面活性剂对金刚石在树脂中悬浮性及与树脂结合性的影响

用KH550硅烷偶联剂和聚电解质型表面活性剂聚乙烯亚胺(PEI)分别对金刚石进行表面改性,研究了KH550和PEI对金刚石表面电性、金刚石在聚酰胺酰亚胺树脂液中的悬浮性及与树脂结合性的影响.结果表明:改性后金刚石表面的电性能发生显著变化,在酸性条件下,zeta电位绝对值明显提高,颗粒间的静电斥力增强,改善了金刚石在树脂液中的悬浮稳定性;改善了树脂对金刚石表面润湿性及其界面结合性,提高了线锯的切割性能;KH550对金刚石的改性效果优于PEI的改性效果.     

Crack problems in magnetoelectroelastic solids. Part I: exact solution of a crack

This paper presents an exact treatment on the problem of an elliptic hole or a crack in a magnetoelectroelastic solid subject to the farfield loadings. First, based on the extended version of Eshelby-Stroh’s formulation, the general solution of an elliptical hole is obtained according to exact boundary conditions at the rim of the hole. Then, when the hole degenerates into a crack, explicit solutions are given for the field intensity factors and electric-magnetic fields inside the crack. It is shown that all the singularities of fields are dependent on the applied mechanical loads, not on the applied electric-magnetic loads. Due to its explicitness, the present solution for a crack can also serve as a benchmark to test the validity of various analysis approaches or assumptions to more complicated crack problems in magnetoelectroelastic media.     

Synthesis and characterization of CuO nanowhiskers by a novel one-step, solid-state reaction in the presence of a nonionic surfactant

A novel and simple one-step, solid-state reaction in the presence of a nonionic surfactant, PEG 400, has been developed to synthesize CuO nanowhiskers with diameters of approximately 2-10 nm and lengths of more than 100 nm. The CuO nanowhiskers were characterized by XRD, TEM, HRTEM and XPS.     

纳滤膜及其表面活性剂分离特性的研究

制备了不同规格的ＣＡ－ＣＴＡ混合纤维素纳滤膜，在１．０ＭＰａ下，对１０００ｍｇ／ＬＮａＣｌ截留率达５０％～８０％，透水率２０～６０Ｌ／ｍ２·ｈ．对１００ｍｇ／ＬＭｇＳＯ４截留率达９０％～９８％，透水率２０～６０Ｌ／ｍ２·ｈ．对１０００ｍｇ／Ｌ葡萄糖截留率达９０％～９５％，透水率２０～６０Ｌ／ｍ２·ｈ．并用该膜对十二烷基苯磺酸钠的分离特性进行了初探．ＣＡ－ＣＴＡ混合纤维素钠滤膜适用于阴离子表面活性剂的分离，其截留率达９６％～９８％，透水率２０～４０Ｌ／ｍ２·ｈ．     

Selective adsorption and partitioning of nonionic surfactants onto solids via liquid chromatograph mass spectra analysis

The sorption characteristics of three Triton series surfactants (Triton-100, Triton-305, and Triton-405) from aqueous solution onto four different solids with a wide range of organic matter (OM) content were studied through the liquid chromatograph mass spectrometry (LC-MS) analysis. The examined surfactant concentrations ranged from below to above the critical micelle concentration (CMC) of the selected surfactants. A parameter, Phi, defined as the ratio of the average ethylene oxide (EO) number of surfactant on the adsorbed phase to that in the aqueous solution, was used to distinguish the controlling mechanism (adsorption or partitioning) of surfactants from aqueous solution onto the solids. For solids with very low OM content, adsorption was the primary mechanism and the Phi values were found to be larger than 1.0 and might reduce to 1.0 with the increasing surfactant concentration. On the other hand, the Phi values for solids with very high content of OM were equal to or less than 1.0 and remained constant as the surfactant concentrations varied, in which partitioning was the most likely dominant mechanism. For solids with an intermediate content of OM, adsorption and partitioning mechanisms coexisted and the Phi values could be larger or less than 1.0 and decreased with the increasing surfactant concentration.     

Estimation of distribution function and distribution parameter from incomplete data

In this paper, in order to estimate the distribution parameter from incomplete data, a method based on Marquardt's least squares method used to estimate nonlinear parameters is proposed. Using the Euclid distance and the principle of nearness of fuzzy set theory, the hypothesis concerning the distribution function of a parent population is tested in the incomplete data case.     

The Galerkin vector solution for a mixture of two elastic solids and Boussinesq problem

This work is concerned with the linear theory of a binary mixture of two elastic solids. Using the constitutive equations for the mixture which are given by Green and Steel, the displacement equations in the case of isotropic mixture of two elastic solids are derived. By use of the Galerkin vector solution, the displacement vector of each component in the mixture is obtained. Finally, an equilibrium solution for the Boussinesq problem of the mixture of two elastic solids in an infinite half-space is examined.     

Soil flushing by surfactant solution: pilot-scale demonstration of complete technology

This paper mainly relates to the real polychlorinated biphenyl (PCB)-contaminated soil flushing process, in which an aqueous solution of anionic surfactant was passed through sandy soil having an average concentration 34.3 mg/kg of dry matter. The goal of the treatment was to decrease the PCB concentration in the soil to less than 10 mg/kg, which is a limiting value if the soil is to be used in the field of civil engineering. The laboratory part was focused on the demonstration of the suggested method for estimating the CMC value of the surfactant used for leaching the PCBs from the soil to the solution. The estimate was based on a set of batch experiments carried out with the same soil as the soil used for the pilot-scale experiments. Theoretically, all effects affecting the CMC should be considered in an estimated value. The experimental facility used for the pilot-scale demonstration consisted of a steel column (3 m in length, 1.5 m in diameter) containing 1.7 m(3) of polluted soil and a liquid circulation system, by which an aqueous solution of a surfactant was supplied to the soil. Spolapon AOS 146 (anionic surfactant) solution (40 g/L) was passing through the soil column for 2.5 months. The concentration of the surfactant and PCBs in the aqueous soil extract was monitored during this time period. The final PCB concentration profile in the soil was determined after stopping the liquid flow. After passing through the soil, the PCBs containing the aqueous extract was pumped out from the steel column bottom to a treatment unit, where it was processed by coagulation. The final PCB concentration profile in the soil was compared with the results of the theoretical model, which is also described in the paper. The time necessary to reach the limit demanded was estimated to move within the range from 6 to 12 months.     

Reliability analysis of a mechanical contact between deformable solids

The contact problems in mechanics are very complex. The behavior of a structure, where a contact occurs, depends on some assumptions on the design parameters and is in general highly nonlinear. Several deterministic numerical methods have been developed on finite element codes and give accurate solutions of contact problems. However some design variables could be random and the deterministic results could be unacceptable. Thus a new reliability analysis of a mechanical contact is presented. A reliability–mechanical combination based on an augmented Lagrangian method and a response surface method is proposed to compute the failure probability of this nonlinear problem. Then the advantages of this probabilistic approach are exposed and commentated on an Hertz numerical application.     

Transient natural convection from a horizontal cylinder confined between vertical walls—a finite element solution

A general finite element computer code is developed for transient two dimensional natural convection heat transfer in a laminar regime. This code is used to study heat transfer from a horizontal isothermal cylinder confined between two vertical adiabatic walls. Results are presented for Ra = 1000, Pr = 0.7, and for different wall spacing to cylinder diameter ratios. The time variations of the local and average Nusselt numbers along with some transient and steady state velocity and temperature fields are demonstrated. The steady state results predict the existence of an optimum wall distance for the maximum average Nusselt number. The steady state and the transient Nusselt numbers are compared with the available experimental or theoretical results for a few cases. Their agreement is very good.     

超弹性SMA复合阻尼器的计算模型及参数分析

介绍了超弹性SMA复合阻尼器的构造及工作原理,并根据它的受力特性,建立了该阻尼器的力学计算模型,针对模型中的关键参数:阻尼器内滑条槽深与接触面摩擦系数、SMA丝的预应变及缠绕量、环境温度及位移幅值等对阻尼器力学性能的影响规律进行了分析。分析结果表明:阻尼器的初始刚度、输出力和滞回面积随内滑条槽深、SMA丝缠绕量、接触面的摩擦系数的增加而增加;在不同的位移幅值下,阻尼器的荷载-位移曲线形状分别呈三角形、四边形和五边形等多边形形式,表现为变刚度的特性;阻尼器的屈服位移和输出力随环境温度的升高而线性增加;当对SMA丝施加一定的初始预应变,SMA复合阻尼器表现为摩擦型阻尼器。最后,将模型结果与实验结果进行了对比,两者基本吻合。     

Heat transfer and vaporization in the boiling of a surfactant solution in steam generators

Results are presented from an experimental study of heat transfer and vaporization in the boiling of a solution of octadecylene under atmospheric pressure at different heat fluxes and concentrations.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 5, pp. 720–723, May, 1982.