Adsorption Characteristics of Congo Red from Aqueous Solution onto Tea Waste

The feasibility of using tea waste (TW) as a low-cost adsorbent for the adsorption of an anionic dye (Congo red) from aqueous solution has been investigated. Adsorption in a batch process was conducted to study the effect of adsorbent dosage, initial dye concentration, contact time, pH, and temperature. The experimental data were analyzed by the Langmuir, Freundlich, and Temkin models. The adsorption system was best described by the Langmuir isotherm (R ² > 0.99). Adsorption kinetics followed a pseudo-second-order model (R ² > 0.99). The effect of mechanical treatment (vibratory mill) was also studied. The experimental results showed that using this physical treatment leads to an increase in the adsorption capacity of TW from 32.26 to 43.48 mg/g. Thermodynamic analyses revealed that the adsorption of Congo red on TW was endothermic and spontaneous in nature. The results indicated that TW can be employed as a potential low-cost adsorbent for the removal of Congo red from aqueous solution.     

Prediction of Particle Deposition Using a Simplified Particle Model in Fully Developed Channel Flow

In this study the Eulerian particle model was modified to predict the particle deposition rate in fully developed channel flow. The modified model is less complicated and has much lower computation time. The performance of the simplified model was examined by comparing the particle deposition rate in a vertical channel with the experimental data for fully developed channel flow available in the literature. The effects of turbophoretic force, thermophoretic force, electrostatic force, gravitational force, Brownian/turbulent diffusion, and the wall roughness on the particle deposition rate were examined. The predictions of the modified particle model were in agreement with the experimental data.     

The joint reaction of methanol and i-butane over the HZSM-5 zeolite

The effects of i-butane addition to methanol in MTP reaction were investigated over an in-house prepared HZSM-5 catalyst. It was observed that, propylene yield would be enhanced when i-butane fed to the reactor along with methanol. The rising growth of the propylene yield continued to peak on till the balance in thermal condition established. Similar trends have been observed when water was added to the mixture. The effect of WHSV with fixed water composition on product distribution was also studied. The optimum point where the highest amount of propylene yielded was shown to be high depended upon the temperature and residence time.     

Tie‐simplex based compositional space parameterization: Continuity and generalization to multiphase systems

A theoretical analysis is provided of the continuity of multiphase compositional space parameterization for thermal‐compositional reservoir simulation. It is shown that the tie‐simplex space changes continuously as a function of composition, pressure, and temperature, and this justifies the Compositional Space Adaptive Tabulation (CSAT) framework, in which a discrete number of tie‐simplexes are constructed, tabulated, and reused in the course of a simulation. The CSAT is extended for thermal‐compositional displacements for mixtures that can form an arbitrary number of phases. In particular, the construction is described of three‐phase tie‐simplex tables, and it is shown how the degeneration of multiphase regions can be accurately captured over wide ranges of temperature and pressure. Several challenging multiphase examples are used to demonstrate the accuracy and effectiveness of phase‐state identification using tabulated tie‐simplexes. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1684–1701, 2013     

CPFD flow pattern simulation in downer reactors

This study contributes with a computational fluid dynamic simulation based on the numerical solution of continuity and momentum balance equations in a three‐dimensional (3‐D) framework. The proposed down flow gas–solid suspension model includes a unit configuration and C_D drag coefficients recommended for these units. Computational particle fluid dynamics (CPFD) calculations using suitable boundary conditions and a Barracuda (version: 14.5.2) software allow predicting local solid densification and asymmetric “wavy flows.” In addition, this model forecasts for the conditions of this study higher particle velocity than gas velocity, once the flow reaches 1 m from the gas injector. These findings are accompanied with observations about the intrinsic rotational character of the flow. CPFD numerical 3‐D calculations show that both gas and particle velocities involve the following: (a) an axial velocity component, (b) a radial velocity component (about 5% of axial velocity component), and (c) an angular velocity component. The calculated velocity components and the rotational flow pattern are established for a wide range of solid flux/gas flux ratios. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1635–1647, 2013     

Various nano-particles influences on structure,viscoelastic, Vulcanization and mechanical behaviour of EPDM nano-composite rubber foam

ABSTRACT

In this study, the effect of various nano-particle type and concentration on the structure, curing, viscosity variation during vulcanisation, and mechanical characteristics of ethylene–propylene–diene monomer (EPDM) rubber foam is reported. Three types of nanoparticle with various dimensional aspects (1D carbon nanotubes, 2D nano clay, and 3D nano silica) are employed to investigate their effect on the fabrication of EPDM rubber foam. It is observed that the properties of the foams were efficiently influenced by the nano-particle shapes and content in the matrix. Nanoparticles may increase cell density and change cell structures. In addition, they can change the curing behaviour of foam rubber by affecting curing rate and scorch time of rubber. In the end, mechanical properties of EPDM foam rubbers investigated by experimental tests and implementing few empirical and constitutional mechanical models. It is very helpful to use suitable nanoparticle to achieve desired properties out of fabricated foams.     

Effects of nanoclay and coupling agent on the physico‐mechanical,morphological, and thermal properties of wood flour/polypropylene composites

This article presents the effects of coupling agent and nanoclay (NC) on some properties of wood flour/polypropylene composites. The composites with different NC and maleic anhydride grafted polypropylene (MAPP) contents were fabricated by melt compounding in a twin‐screw extruder and then by injection molding. The mass ratio of the wood flour to polymer was 40/60 (w/w). Results showed that applying MAPP on the surface of the wood flour can promote filler polymer interaction, which, in turn, would improve mechanical properties of the composite as well as its water uptake and thermal stability. Composite voids and the lumens of the fibers were filled with NC, which prevented the penetration of water by the capillary action into the deeper parts of composite. Therefore, the water absorption in composites fabricated using NC was significantly reduced. Scanning electron microscopy has shown that the treatment of composites with 5 wt% MAPP, promotes better fiber–matrix interaction, resulting in a few numbers of pull‐out traces. In all cases, the degradation temperatures shifted to higher values after using MAPP. The largest improvement on the thermal stability of composites was achieved when NC was added. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Study on the structure and properties of nanocomposites based on high-density polyethylene/starch blends

The effects of nanoclay on the structure and final properties of high density polyethylene (HDPE)/thermoplastic starch (TPS) blends were investigated. Neat blends as well as nanoclay containing samples were prepared by melt blending in an internal mixer. Also, a poly (ethylene-g-maleic anhydride) (PE-g-MA) copolymer was used as compatibilizer in some of the formulations. Nanocomposites with intercalated structures were obtained in the samples lacking the compatibilizer, based on the rheological, X-ray diffraction (XRD) and transmission electron microscopy (TEM) results. However, some of the silicate layers were nearly exfoliated in the presence of the compatibilizer. The nanoclay was located preferably in the HDPE matrix as well as at the interface of the HDPE matrix and TPS dispersed phase. The ability of the nanoclays in decreasing the average size of TPS phase in the HDPE matrix was confirmed by scanning electron microscopy (SEM) observations. Furthermore, thermo-gravimetric analysis (TGA) showed that the nanoclays could enhance the thermal stability of the samples. It seems that nanoclays performed as an insulator and mass transport barrier to the small molecules generated during decomposition, and assisted in the formation of char after thermal decomposition of the polymer matrix. All the samples containing the compatibilizer possessed higher tensile strength and elongation at break, but lower modulus, compared to the corresponding un-compatibilized samples. Finally, incorporation of the nanoclays was found to be in favor of developing nanocomposites with higher biodegradability as evidenced through a biodegradation test by fungi as well as water uptake experiments.     

Investigation on the correlation between rheology and morphology of PA6/ABS blends using ethylene acrylate terpolymer as compatibilizer

Phase morphology and rheological behavior of polyamide 6 (PA6)/acrylonitrile butadiene styrene (ABS) polymers blends was studied using scanning electron microscopy and rheometry. The results showed that the phase morphology and rheological properties depends on blend composition. We evaluated the effect of addition of ABS as dispersed phase and EnBACO‐MAH (ethylene n‐butyl acrylate carbon monoxide maleic anhydride) as a compatibilizer on the morphological and rheological behaviors of PA6/ABS blends. It was concluded that there is a good agreement between the results obtained from rheological and morphological studies. As a consequence, addition of the ABS and compatibilizer weight percent led to a significant change in morphological structure and a great mounting in the viscosity as well as the elasticity. The rheological properties results demonstrate that adding compatibilizer to polymer blends led to increasing the crossover point, which shows a transition from a high viscous to a considerably more elastic behavior. Also, the slow transition of relaxation time peak from the peak of the PA6 to the peak of the ABS implies increasing the miscibility of the PA6/ABS blend components by increasing compatibilizer content. In addition, the Carreau–Yasuda model was used to extract information on rheological properties (zero shear viscosity and relaxation time) for PA6/ABS/EnBACO‐MAH blends by fitting the experimental data with this model. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Relationship between droplet size and fluid flow characteristics in miniemulsion polymerization of methyl methacrylate

Static mixer (SM) can be applied for emulsification, but the fundamental understanding of the nature of fluid flow and mixing in static mixers, is however poor. Droplet size is a very important parameter in miniemulsion systems and affects strongly the mechanism of particle formation in polymerization reactions. In this study, static mixer was used as homogenization device for emulsification of methyl methacrylate (MMA). Re number (Re) was obtained for SM inserted tube in different flow rates. It was demonstrated the nature of fluid flow was turbulent under our experimental conditions. The relationship between droplet size—the most important variable in our study—and Weber number (We) was investigated. The results showed that the ratio of the droplet size to the pipe diameter was fit as an exponential function with an order of −0.35. The polymerization of created droplets under certain We values by SM showed that it is possible to obtain a reasonable 1 : 1 copy of droplets to the particles. All these, indicate that using relationship between We and droplet size allow one to obtain acceptable condition of droplet nucleation in miniemulsion polymerization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011