Electrosynthesis of 4,4′-dinitroazobenzene on PbO2 electrodes

Parameters which affect the electrosynthesis of 4,4-dinitroazobenzene from p-nitroaniline on platinum and PbO₂ electrodes were investigated and optimum conditions were determined. Maximum conversion efficiency for electrosynthesis was 95% with a pure -PbO₂ electrode. It was found that the electrocatalytic activity of a PbO₂ electrode depends upon its / ratio and its degree of crystallinity. The effects of the added base and water on the conversion efficiency were also elucidated.     

Optimization of specific energy consumption for Bomaplex Red CR-L dye removal from aqueous solution by electrocoagulation using Taguchi-neural method

In this investigation, firstly, Taguchi method was applied to determine the optimum specific energy consumption (SEC) for dye removal from aqueous solution by electrocoagulation using aluminum electrodes. An orthogonal array (OA₁₆) experimental design that allows to investigate the simultaneous variations of five parameters (Initial dye concentration, Initial pH of the solution, Supporting electrolyte concentration, Supporting electrolyte type and Current density) having four levels was employed to evaluate the effects of experimental parameters with two replicates. According to Taguchi-neural method, while the optimum conditions that dye removal efficiency equals to 62.71 % were found to be initial dye concentration 600 mg/L, initial pH of the solution 6, supporting electrolyte concentration 7.0 mM, supporting electrolyte type NaCl, and current density 0.10 mA/cm². Under these optimum conditions, energy consumption is 0.38 kW h/m³. Alternatively, it can be said that optimum conditions can be modified as follows supporting electrolyte concentration of 10.0 mM and supporting electrolyte type CaCl₂, for 600 mg/L, initial dye concentration initial pH of the solution 6, and current density 0.10 mA/cm². Under these optimum conditions, SEC and dye removal efficiency are 0.45 kW h/m³ and 69.18 %, respectively.     

Preparation of single-site tin(IV) compounds and their use in the polymerization of ε-caprolactone

Butyltin(IV) carboxylate compounds were obtained by reactions of butyltrichlorotin(IV) with potassium pivalate, perfluoroheptanoate, methacrylate, 2,6-pyridinedicarboxylate, and phthalate. The synthesized complexes were fully characterized by nuclear magnetic resonance (¹H-, ¹³C-NMR), Fourier transform infrared (FTIR), mass spectroscopies (MS) and elemental analysis. These tin complexes were used as catalysts for the ring opening polymerization of ε-caplolactone and the conversion of monomers to polymers was completed in just 1 h. The structures of polymers were characterized by a combination of spectroscopic techniques (NMR, FTIR, MS), differential scanning calorimeter (DSC) and gel permeation chromatography. In this study, the ε-caplolactone polymers with different average molecular weights between 5000 and 40,000 Da having a regular structure were obtained.     

Recycling and Oligomerization Activity of Ni/Al Catalyst in a Biphasic System with Ionic Liquids

The catalyst decomposition in homogeneously catalyzed reactions is a very important factor that has been studied for the oligomerization of n‐butenes in a system of two liquid phases. A highly active catalyst [NiCl₂(PMe₃)₂] was investigated with an emphasis on the long‐term catalyst activity using N‐methylpyrrole as a buffer. The recycling experiments indicated that this catalyst is viable for five runs. Furthermore, introducing aluminum chloride or an ionic liquid in small concentrations led to increased stability, though fine adjustments were necessary to arrive at optimal results.     

Series solution of low Dean and Germano number flows in helical rectangular ducts

The flow in a helical duct with rectangular cross-section is analyzed. A series solution based on curvature and torsion is introduced. The components of the series are determined analytically using appropriate eigenfunction expansions. The resulting solution is limited to flows in the low Dean number, low Germano number regime. An analytical friction factor relation is established and compared with previous numerically determined correlations.     

Numerical modeling of Kelvin–Helmholtz instability using smoothed particle hydrodynamics

This paper presents a Smoothed Particle Hydrodynamics (SPH) solution for the Kelvin–Helmholtz Instability (KHI) problem of an incompressible two‐phase immiscible fluid in a stratified inviscid shear flow with interfacial tension. The time‐dependent evolution of the two‐fluid interface over a wide range of Richardson number (Ri) and for three different density ratios is numerically investigated. The simulation results are compared with analytical solutions in the linear regime. Having captured the physics behind KHI, the effects of gravity and surface tension on a two‐dimensional shear layer are examined independently and together. It is shown that the growth rate of the KHI is mainly controlled by the value of the Ri number, not by the nature of the stabilizing forces. It was observed that the SPH method requires a Richardson number lower than unity (i.e. Ri?0.8) for the onset of KHI, and that the artificial viscosity plays a significant role in obtaining physically correct simulation results that are in agreement with analytical solutions. The numerical algorithm presented in this work can easily handle two‐phase fluid flow with various density ratios. Copyright © 2011 John Wiley & Sons, Ltd.     

Drying of apricots in a rotary column cylindrical dryer (RCCD) supported with solar energy

Rapid deterioration of fruits and vegetables necessitates their consumption in a limited area. The solutions to this problem may be provided by technological precautions, which not only increase economic efficiency but also motivates agricultural developments. Among the technological operations applied to increase the market life of the foods, drying operation is of prime importance which is applicable to almost all the agricultural products. In this work, drying of apricots in a newly developed rotary column cylindrical dryer (RCCD) equipped with a specially designed air solar collector (ASC) was investigated to find optimum drying air rate and rotation speed of dryer, to maintain uniform and hygienic drying conditions and to reduce drying times. For this purpose, the changes in the moisture contents of the Sugarpiece ( ekerpare) foods were studied. Drying is an operation of prime importance used for almost all the agricultural products. Type apricots dried in the present dryer were compared to those of the same type apricots dried open on the ground. It was shown that co-operation of RCCD and ASC increased drying rate, reduced drying times and rotation of drying chamber provided gains in both time and labour.     

Miniemulsion polymerization of styrene in the presence of macromonomeric initiators

Macromonomeric azo initiators (macroinimers, MIM) which have the properties of macromonomers, macrocrosslinkers and macroinitiators in a macrostructure were used in miniemulsion polymerization of styrene in the presence or absence of any other stabilizer and initiator. MIMs were prepared from the reaction of 4,4′-dicyano-4,4′-azovaleryl chloride, with poly(ethylene glycol) (PEG) of different molecular weights (400 and 2000 g/mol) and with 4-vinylbenzyl chloride. The stabilizing and initiator efficiency of MIMs and the effect of the chain length of PEG units were evaluated.     

Examination of Dyeing Properties of the Dyed Cotton Fabrics with Barberry (Berberis vulgaris L.)

ABSTRACT

In this study, it was aimed at investing the cotton fabrics dyed with different percentages of the roots of barberry (Berberis vulgaris L.) via gall oak (Quercus infectoria Olivier; 10% and 20%) and aluminum sulfate (Al₂(SO₄)₃; 6%) mordants. The dyeing process was performed with the roots of barberry in the range of 10–100%. A reversed phase high performance liquid chromatography with diode array detection method was utilized for the identification of dyes present in the sample extracts. Natural yellow-dyed cotton samples were studied calorimetrically and their color coordinates L*, a*, b*, C*, h, K/S, and ?E* values were given.