Foam Fractionation and Precipitate Flotation of Zinc(II)

Abstract

The hydrolytic behavior of a metal can be related to its removal by foaming. In this study the effect of pH and ionic strength on the foam separation of 0.1 mM zinc (II) was investigated using different concentrations of sodium lauryl sulfate as the collector. At low pH Zn²⁺ ion was removed by foam fractionation while above pH 8 Zn(OH)²(s) was removed by precipitate flotation. The results demonstrate that precipitate flotation is a more efficient removal process than the foam separation of soluble metal species.     

CMPSO算法在参数辨识中的应用

通过对系统数学模型的分析,将系统参数辨识问题转化为优化问题,然后利用改进粒子群优化算法实现系统参数辨识.提出的混沌变异粒子群(CMPSO)搜索算法提高了搜索效率并增强了摆脱陷入局部最优的能力.     

微粒群算法在模拟移动床色谱分离过程优化中的应用

运用微粒群算法开发出一种非线性模拟移动床(SMB)色谱分离过程的优化策略.该优化策略将模拟移动床的最大吸附剂生产率作为优化问题的目标函数,采用模拟移动床的TMB模型来计算微粒群优化算法的适应值.采用该优化算法对手性化合物萘酚对映体(bi-naphthol)的模拟移动床色谱分离操作条件进行了优化,仿真结果表明了该优化策略的有效性.     

多样性分布参数的粒子群算法及其在过程动态优化中的应用

提出一种多样性分布参数的粒子群算法(DDPPSO)。在DDPPSO算法中,每个粒子在初始化时拥有各自的惯性权重和加速因子。在迭代时由每个粒子的寻优性能决定其参数的权重,进而计算参数群体的加权平均值。根据加权平均值与自适应方差,通过正态分布产生下一代参数个体,从而实现参数群体的多样性分布,为算法的寻优提供实时最佳的控制参数。标准测试函数实验表明,在寻优性能上DDPPSO算法较新改进的PSO算法有较大提高。最后,将DDPPSO算法应用于Park-Ramirez生物反应器的动态优化,获得满意的结果。     

Synthesis of nanosized poly(ethyl acrylate) particles via differential emulsion polymerization

Nanoparticles of poly(ethyl acrylate) were synthesized via a semibatch differential emulsion polymerization method with potassium persulfate as the initiator and sodium dodecyl sulfate as the surfactant. The effects of the reaction temperature, aging time, and surfactant/initiator/monomer ratios on the polymer particle sizes were investigated. Poly(ethyl acrylate) with particle sizes of less than 20 nm was synthesized under mild conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1609–1614, 2006     

Preparation of poly(vinyl acetate) latex with ultrasonic and redox initiation

The high water solubility of vinyl acetate (VAc) monomer increases the need for a good initiator system to speed up the polymerization and remove unreacted monomers. Ultrasonic energy can be used to initiate VAc redox emulsion polymerization in the absence of an inert gas and with sodium dodecyl sulfate as a surfactant. Combining ultrasonic energy and a redox initiator at the ambient temperature leads to a higher conversion and higher rate of polymer production in comparison with just using a redox initiator. Ultrasonic energy plays an important role in synthesizing and controlling the polymer structure. The particle size distribution is an important variable in the formulation of latex paint. Ultrasonic energy has an effect on the particle size distribution and average molecular weight of VAc polymer. The particle size increases with an increase in the monomer conversion for ultrasonic polymerization, whereas the particle size stays constant with the monomer conversion for redox polymerization. An ultrasonic polymer has a broader particle size distribution than a redox polymer. The average molecular weight of poly(vinyl acetate) falls with an increase in the sonication time, whereas it increases with time for a redox polymer. Ultrasonic energy also produces a stable, milky white, opaque latex. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 812–817, 2005     

Particle features of a poly(methyl methacrylate) resin prepared by a new emulsion polymerization process

A new emulsion polymerization process, in which water acted as the dispersed phase and a mixture of methyl methacrylate (MMA) and cyclohexane acted as the continuous phase, was applied to the preparation of a poly(methyl methacrylate) (PMMA) resin. The primary (latex) particles were formed in the early stage of polymerization and coagulated as the polymerization conversion increased. Scanning electron micrographs showed that the final PMMA particles were porous and composed of loosely aggregated primary particles. The porosity characterized by cold di(2‐ethylhexyl) phthalate absorption increased as the water/oil and cyclohexane/MMA mass ratios increased. The PMMA primary particles were smaller than the primary particles in the PMMA resin prepared by suspension polymerization in the presence of cyclohexane. Because of the phase composition of the reaction system, the solubility of PMMA in a mixture of cyclohexane and MMA, and the particle morphology of PMMA, a particle formation mechanism, including the formation, growth, and coagulation of primary particles in dispersed water droplets, was proposed. The primary particles formed mainly through a homogeneous nucleation mechanism and increased in size as MMA diffused from the oil phase to the water phase to the primary particles. The coagulation of the primary particles occurred because of the lower colloidal stability and the space limitations of the primary particles. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1905–1911, 2004     

Foam Separation of Lead(ll) and Cad mi urn (II) from Waste Water

Abstract

Foam separation techniques are evaluated to determine if they would be feasible for removing lead(II) and cadmium(II) from highly contaminated waste water. Variables such as pH, ionic strength, collector concentration, and interfering ions were studied to determine their effects on ion flotation. Increased ionic strength, calcium(II), and phosphate interference made ion flotation impractical. Precipitate flotation of lead sulfide and cadmium sulfide left approximately 0.20 ppm lead(II) and 0.08 ppm cadmium(II) in the bulk solution under optimum conditions—somewhat above the levels considered safe to release into the environment. Adsorbing colloid flotation gave excellent results; lead sulfide and cadmium sulfide were adsorbed to ferrous sulfide which was then removed by foaming with hexadecyltrimethylam-monium bromide. Lead(II) levels were reduced from 0.80 to 0.025 ppm in 34 min foaming with 15 ppm iron(III) added. Cadmium(II) levels were reduced from 1.0 to 0.008 ppm in 45 min foaming with 25 ppm iron(III) added.     

Emulsion grafting of vinyl acetate onto preirradiated poly(3‐hydroxybutyrate) film

Vinyl acetate (VAc) was grafted onto poly(3‐hydroxybutyrate) film by a preirradiation method. Grafting reactions were carried out in VAc/water/surfactant emulsion, VAc/water, and VAc/methanol systems. For emulsion grafting, Nonion L‐4 was ascertained to be the optimum surfactant with respect to the stability of a single emulsion layer. The emulsion with a 10 : 1 (w/w) ratio of VAc to surfactant yielded the highest degree of grafting: 23%. The grafting efficiency in the emulsion and the water and methanol solvents were evaluated. The results indicated that the grafting efficiency of the emulsion was 100 times that of VAc/methanol when the same 2 wt % VAc was used in the grafting reaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of monodisperse magnetic poly(styrene butyl acrylate methacrylic acid) microspheres in the presence of a polar solvent

Magnetic poly(styrene butyl acrylate methacrylic acid) [P(St–BA–MAA)] microspheres were prepared by emulsifier‐free emulsion polymerization in the presence of a polar solvent and a ferrofluid prepared by a coprecipitation method. The effects of some polymerization parameters, such as the medium polarity, reaction temperature, initiator content, and surfactant content in the ferrofluid, on the particle diameter and particle size distribution of magnetic P(St–BA–MAA) microspheres were examined in detail. The results showed that the electrostatic repulsion in the polymerization system significantly affected the monodispersity of the resulting magnetic polymer microspheres. The proper electrostatic repulsion, achieved through changes in the medium polarity and amount of surfactant in the polymerization system, improved the monodispersity, but a higher or lower repulsion led to a decrease in the monodispersity. Although the existence of surfactant and magnetite particles reduced the monodispersity more or less, the polymerization behavior of an emulsifier‐free emulsion polymerization in the presence of the ferrofluid was analogous to that of a conventional emulsifier‐free emulsion polymerization. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1733–1738, 2003     

Size distribution of drops formed from nozzles in liquid-liquid systems at velocities below jetting

The size distribution of drops formed from four different diameter nozzles (d=l.O, 1.6, 2.6 and 3.5 mm) was measured over the flow rate range of 0.17 to 3.0 cm3/s (below jetting). Kerosene was used as the dispersed phase and distilled water was used as the continuous phase. The experimental drop size distributions were described adequately by the upper limit number and volume distributions. Plots of the maximum and the minimum diameters versus the mean diameter yielded straight line with slopes of 1.11 and 0.87, respectively.     

激光颗粒仪测定聚四氟乙烯细粒模压粉的平均粒径

运用激光粒度仪研究了聚四氟乙烯细粒模压粉的平均粒径和粒径分布的测定方法，通过试验确定了分散方法、分散剂用量、试样量、分散时间等影响因素，以建立稳定的测量体系。     

Intensified Effect of Reduced Pressure on the Foam Fractionation Process of Bovine Serum Albumin

A novel method to intensify the foam fractionation process by operating the column under reduced pressure was reported in this paper. It was found that a poorer foam stability, a bigger mean bubble size and a wider bubble size distribution in the foam layer, a less upward liquid flux and volumetric liquid fraction at the top of the foam layer, and a higher enrichment ratio but a lower mass recovery of the foam fractionation process were obtained under reduced pressures compared to the ones under atmospheric pressure. The most important effect of the reduced pressure on the foam layer during the foam fractionation process is the encouraged bubble coalescence process which was exhibited by those unusual foam properties discussed above. The limitations of this new method were also discussed.     

Ion-Exchange Behavior of Mercury(II) in Mixed Solvents: Separation from Zinc(ll), Cadmium(ll), Gold(lll), and Thallium(lll)

Abstract

Distribution coefficients of Zn(II), Cd(II), Au(III), Hg(II), T1(I), and Tl(III) between cation- and anion-exchangers Amberlite IR-120 and Amberlite IR-400, and aqueous solutions containing nitric or hydrochloric acid and organic solvents have been determined. The organic solvents were methanol, acetone, and tetrahydrofuran. The separation of Hg(II) from Zn(II), Cd(II), Au(III), and Tl(III) has been proposed in mixed solvents with high separation factors. Some of these separations have been actually performed using column method.     

Pulverization of rubber using modified solid state shear extrusion process (SSSE)

The challenge of reusing scrap rubber material is mainly due to its crosslinked/vulcanized structure, which prevents the material from melting and from being melt processed into new items. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. Solid state shear extrusion (SSSE), developed at Illinois Institute of Technology, is a process for continuous pulverization of rubber materials into a fine powder (Aratoopour, H. U.S. Pat. 5,704,555 15 ; Arastoopour, H.; Schocke, D. A.; Bernstein, B.; Bilgili, E. U.S. Pat. 5,904,885 11 ; Ivanov, G. Polym Eng Sci 18 ). In this work, the design of the SSSE apparatus was modified to overcome heat generation due to pulverization and the limitation from the torque/feeding rate relation and, thus, to increase the efficiency of the process in the production of finer particles at higher throughput. The modification was achieved by separating the original process into the extrusion section and the pulverization section. The extrusion section is dedicated to convey material to the pulverization section, which consists of a cylindrical housing and a rotatable cylindrical element that rotates independent of the extruder's screw. The rotatable cylindrical element can be treaded or flightless. Both sections are connected with an adapter. This new approach to the design allowed us to apply a more efficient cooling system, capable of removing the heat of pulverization and, in turn, results in the production of finer rubber particles. Furthermore, separation of the conveying process from the pulverization process resulted in a reduction in extruder's torque and a significant increase in the throughput. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 119–127, 2006     

Foam Separation of Mercury(II) and Cadmium(II) from Aqueous Systems

Abstract

Mercury(II) and cadmium(II) were separated from aqueous systems by a number of batch-type precipitate flotation and adsorbing colloid flotation techniques. HgS, CdS, and Cd(OH)₂ were removed by precipitate flotation; Fe(OH)₃, Al(OH)₃, FeS, and CuS were used as adsorbing colloids. Sodium lauryl sulfate and hexadecyltrimethylammonium bromide (HTA) were used as collectors. Dependence of separation efficiency on pH and ionic strength was investigated. Floc foam flotation of both metals with CuS and HTA was found to be quite effective, resulting in residual Hg(II) levels as low as 5 ppb and residual Cd(II) levels as low as 20 ppb. Floc foam flotation of Cd(II) with FeS and HTA yielded residual Cd(II) levels as low as 10 ppb.     

基于粒子群算法的金矿湿法冶金浸出率优化

各浸出率的合理分配对组织金矿湿法冶金浸出过程生产具有重要作用,当前各浸出率通常由精炼厂氰化车间工程师凭人工经验给出,导致对浸出过程生产的指导具有很大的模糊性与随意性,不能保证调整后的总浸出率最大。为优化确定金矿湿法冶金各浸出率,建立以总浸出率最大为目标的优化模型,并将二阶振荡粒子群算法用于模型的求解。最后通过实验研究验证了模型和算法的有效性。     

基于粒子群优化算法和非线性盲源信号分离测量两相流速度(英文)

In order to overcome the disturbance of noise,this paper presented a method to measure two-phase flow velocity using particle swarm optimization algorithm,nonlinear blind source separation and cross correlation method.Because of the nonlinear relationship between the output signals of capacitance sensors and fluid in pipeline,nonlinear blind source separation is applied.In nonlinear blind source separation,the odd polynomials of higher order are used to fit the nonlinear transformation function,and the mutual information of separation signals is used as the evaluation function.Then the parameters of polynomial and linear separation matrix can be estimated by mutual information of separation signals and particle swarm optimization algorithm,thus the source signals can be separated from the mixed signals.The two-phase flow signals with noise which are obtained from upstream and downstream sensors are respectively processed by nonlinear blind source separation method so that the noise can be effectively removed.Therefore,based on these noise-suppressed signals,the distinct curves of cross correlation function and the transit times are obtained,and then the velocities of two-phase flow can be accurately calculated.Finally,the simulation experimental results are given.The results have proved that this method can meet the measurement requirements of two-phase flow velocity.     

Narrow size‐distribution poly(methyl methacrylate) nanoparticles made by semicontinuous heterophase polymerization

The effect of surfactant (sodium dodecyl sulfate) concentration on particle size, molar masses, glass transition, and tacticity of poly(methyl methacrylate) (PMMA) nanoparticles synthesized by semicontinuous heterophase polymerization under monomer‐starved condition at constant monomer feeding rate is reported. Starved conditions are confirmed by the low amount of residual monomer throughout the reaction and by the fact that the instantaneous polymerization rate is similar to the feeding rate of monomer. Under these conditions, polymer particles in the nanometer range (20–30 nm) were obtained with narrow size distribution (1.07 < D_w/D_n < 1.18), depending of surfactant concentration. Final particle size diminishes as the surfactant concentration is increased. Glass transition temperatures and syndiotactic content (54%–59%) of the produced polymers are substantially higher than those reported for commercial and bulk‐made PMMA. Molar masses are much lower than those expected from termination by chain transfer to monomer, which is the typical termination mechanism in 0–1 emulsion and microemulsion polymerization of this monomer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011