Holdup and characteristic velocity in a Hanson mixer–settler extraction column

The hydrodynamic behavior of a pilot plant Hanson mixer–settler extraction column has been studied for three different liquid–liquid systems with and without mass transfer conditions. The dispersed phase axial holdup profile is investigated and an empirical correlation for prediction of dispersed phase holdup is recommended in terms of physical properties of liquid systems and operating conditions. A comparison between several correlations and experimental results shows that Pratt equation is more suitable for prediction of slip velocity because of its simplicity. On this basis, an empirical correlation is derived for prediction of characteristic velocity in terms of physical properties of liquid systems and operating conditions.     

Classroom furniture and anthropometric characteristics of Iranian high school students: Proposed dimensions based on anthropometric data

The study evaluated the potential mismatch between classroom furniture dimensions and anthropometric characteristics of 978 Iranian high school students (498 girls, 480 boys), aged 15-18 years. Nine anthropometric measurements (stature, sitting height, sitting shoulder height, popliteal height, hip breadth, elbow-seat height, buttock-popliteal length, buttock-knee length and thigh clearance) and five dimensions from the existing classroom furniture were measured and then compared together (using match criterion equations) to identify any potential mismatch between them. The results indicated a considerable mismatch between body dimensions of the students and the existing classroom furniture, with seat height (60.9%), seat width (54.7%) and desktop height (51.7%) being the furniture dimensions with a higher level of mismatch. The levels of mismatch varied between the high-school grade levels and between genders, indicating their special requirements and possible problems. The proposed dimensions of the classroom furniture more appropriate for the students were given. This additional information on students' anthropometry can be used by local furniture industries as a starting point for designing more appropriate furniture for school children, or used by schools to aid in furniture selection.     

Effect of CO<Subscript>2</Subscript> concentration on the performance of different thermodynamic models for prediction of CH<Subscript>4</Subscript>+CO<Subscript>2</Subscript>+H<Subscript>2</Subscript>O hydrate equilibrium conditions

Accurate prediction of phase equilibria regarding CH₄ replacement in hydrate phase with high pressure CO₂ is an important issue in modern reservoir engineering. In this work we investigate the possibility of establishing a thermodynamic framework for predicting the hydrate equilibrium conditions for evaluation of CO₂ injection scenarios. Different combinations of equations of state and mixing rules are applied and the most accurate thermodynamic models at different CO₂ concentration ranges are proposed.     

Kinetic study of styrene atom transfer radical polymerization from hydroxyl groups of graphene nanoplatelets: Heterogeneities in chains and graft densities

Confinement effect of graphene nanoplatelets on the kinetics of styrene atom transfer radical polymerization was studied by a “grafting from” reaction. Graphene oxide was modified by different amounts of (3‐aminopropyl) triethoxysilane and then alpha‐bromoisobutyryl bromide from the hydroxyl groups. Polymerization of styrene in the presence of modified graphene and free initiator, ethyl alpha‐bromoisobutyrate, was accomplished at 110°C. Then, effect of various graft densities and different graphene loadings on the heterogeneous graft and free polystyrene chains characteristics and also kinetics of polymerization was studied by gas and gel permeation chromatographies. Efficiency of grafting reactions along with the graft contents was studied by X‐ray photoelectron spectroscopy, elemental analysis, and thermogravimetric analysis. Confinement effects of graphene on the relaxation behavior of polystyrene chains and also morphology of the graphenes were studied by differential scanning calorimetry and transmission electron microscopy, respectively. POLYM. ENG. SCI., 55:1720–1732, 2015. © 2014 Society of Plastics Engineers     

Synthesis and characterization of exfoliated poly(styrene‐co‐methyl methacrylate) nanocomposite via miniemulsion atom transfer radical polymerization: an activators generated by electron transfer approach

Exfoliated poly(styrene‐co‐methyl methacrylate) nanocomposites were synthesized using activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP). Miniemulsion polymerization was used for its abundant advantages to encapsulate inorganic materials and eliminate organic solvents from products for environmentally friendly purposes. Cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, which is an effective surfactant at higher temperatures, was used to stabilize the miniemulsion system. Successful miniemulsion AGET ATRP was carried out by using 4,4'‐dinonyl‐2,2'‐bipyridine (dNbPy) as a hydrophobic ligand. Formation of monodispersed droplets and particles with sizes in the range of 200nm was examined by dynamic light scattering (DLS). Conversion and molecular weight study were also carried out using gravimetry and gel permeation chromatography, respectively. By adding clay content, a decrease in the conversion and molecular weight of the nanocomposites are observed. However, an increase in the PDI values of nanocomposites was observed by the addition of nanoclay content. Thermogravimetric analysis results demonstrate that thermal stability of all the nanocomposites in comparison with the neat copolymer increases. Differential scanning calorimetry results show that T_g decreases by increasing clay content. Monodisperse distribution of spherical shape particles with sizes in the range of ∼ 200 nm was demonstrated by using scanning electron microscopy images of nanocomposite containing 1 wt% of nanoclay, which is more compiled with DLS results. Transmission electron microscopy results shows well‐dispersed exfoliated clay layers in the polymer matrix of PSMNM 1, which is coincidence with X‐ray diffraction data. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Nanodiamond-containing polyethyleneimine hybrid materials for lead adsorption from aqueous media

This study describes the preparation of new surface-modified nanodiamond (ND) particles containing urethane-based hybrid materials by photopolymerization of aliphatic urethane acrylate, trimethylolpropane triacrylate, glycidyl methacrylate monomers, and their usage for lead adsorption from aqueous media. ND and synthesized surface-modified ND were characterized by atom transfer radical addition Fourier transform infrared spectroscopy (ATR-FTIR) and scanning transmission electron microscopy analysis. Crosslinked adsorbent nanocomposites were then treated with polyethylene imine and all adsorbent nanocomposites were characterized by ATR-FTIR, scanning electron microscopy, thermogravimetric analysis, and contact angle measurements. The metal ion binding capacity of the surfaces of the nanocomposites containing high amine content was investigated. The effects of the percentage of functional monomer, pH, and contact time on adsorption, and the interaction of foreign metal ions have been tested. Optimum contact time was found to be 7 h at pH 5. The adsorption capacity of the synthesized nanocomposite adsorbent for lead (II) was determined as 17.12 mg g⁻¹. Langmuir and Freundlich isotherms were used to determine the adsorption behaviors and Langmuir isotherm model was found to be the most suitable model (R²: 0.9988). The amount of adsorption of Pb (II) ions of UV curable adsorbent film prepared in river water samples was investigated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48241.