Synthesis and Properties of Nonionic Surfactants from Rosin-Imides Maleic Anhydride Adduct

Ester-adduct derivatives of rosin were synthesized by reacting rosin with polyethylene glycol 600 (PEG 600) or 2000 (PEG2000) and maleic anhydride (MA) at elevated temperature. These derivatives were evaluated for acid number, FTIR spectroscopy, molecular weight (Mw), and polydispersity. The derivatives were soluble in organic solvents; aqueous solubility was pH dependent. Rosin-imides were synthesized from a rosin ester-maleic anhydride adducts. It was condensed with diaminobutane or triethylene tetramine to obtain rosinimides. This imide was etherified by reaction with PEG in the presence of β,β′-dichlorodiethyl ether as a linking agent and NaOH as a catalyst. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The surface tension, critical micelle concentration and surface activities were determined at different temperatures. Surface parameters such as surface excess concentration (Γmax), the area per molecule at interface (Amin), and the effectiveness of surface tension reduction (πCMC) were determined from the adsorption isotherms of the prepared surfactants. Some thermodynamic data for the adsorption process were calculated and are discussed.     

Highly Efficient Nano-Structured Polymer-Based Membrane/Sorbent for Oil Adsorption from O/W Emulsion Conducted of Petroleum Wastewater

Wastewater disposal has been an important issue from an environmental perspective in terms of the serious damages and harms its contaminants may cause. Treatment of the wastewater, through the pollutants removal, either before disposal or for the reuse in certain industrial or agricultural purposes, is an essential process. In response to this environmental claim, a novel nano-structured, macro-porous, polymer-based membrane/sorbent was prepared, in terms of its highly open and porous structure with nano-structured sorbent interconnecting walls and based on high internal phase emulsion polymerization. This sorbent was used to remove the oil from polluted wastewater in a laboratory-scale through the application of a new method called flotation–nano-filtration. In order to avoid the water flux decline and simultaneously enhance the oil removal efficiency from the wastewater, the polymeric material, after being prepared and used in sheet form (membrane), was ultimately introduced to the wastewater system as small pieces, as with the intention of physically increasing the area of surface for the oil removal. The material performance studies applied several variables, namely, the physical sectioning of the material surface area, sorbent concentration, mixing speed, and mixing time. An efficiency of 99.75% for the oil removal from the polluted water was successfully achieved at 75 minutes mixing time, a sorbent concentration of 0.158 g/200 mL (each piece with dimensions of 2 mm × 3 mm × 1 mm), and 300 rpm mixing speed. The sorbent structure before and after the oil removal process was examined using scanning electron microscope and x-ray diffraction analysis.     

On the uniqueness of a positive stationary state in the dynamics of a population with asymmetric competition

For a nonlinear model of the dynamics of a size-structured (exploited) population with asymmetric form of competition, we prove a uniqueness theorem for a positive stationary solution under sufficiently general assumptions on the parameters of the model.     

Effect of UV irradiation on Cu+-containing glasses

Optical absorption spectra of copper-containing silicate glasses were determined and the effects of UV irradiation on the spectra were studied. Oxalic acid was used as a reducing agent in order to obtain monovalent copper ions. Several absorption bands were observed as a result of UV irradiation at wavelengths of 430–480, 565–570, 620–690, 720–790, 800–900 and 307–310 nm. These bands were interpreted in terms of photochemical reaction and attributed to color centers, cupric ions (Cu¹⁺⁺), metastable copper atoms (Cu^o), and aggregates of copper atoms which were induced by UV irradiation.     

TG/DTG/DTA/DSC as a tool for studying deposition by the sol-gel process on materials obtained by rapid prototyping

In rapid prototyping (RP), building 3D physical prototypes involves the addition of material in layers. The sol-gel route is an alternative to produce multicomponent oxide materials with chemical, physical and thermal properties that cannot be obtained by other processes. The sol-gel method allows for the preparation of coatings on several kinds of materials, directly influencing the materials’ properties. In this work, metal oxides were prepared by the sol-gel process and deposited further by dip-coating technique on ABS and Nylon substrates obtained by RP. The resulting coating presented good adhesion to the substrates. The obtained materials were characterized by scanning electron microscopy (SEM) and thermal analysis (TA).     

Effect of superficial velocity on pressure fluctuations in a gas–solid fluidized bed: A stochastic analysis

The characteristics of a gas–solid fluidized bed are influenced by complicated and stochastic phenomena, e.g. jetting and the bubbling of the fluidizing medium and the motion of the fluidized particles. In this study pressure fluctuations due to the bubble movement were measured by means of a pressure probe over a range of time. The resultant time series have been analysed by determining their autocorrelation function and power spectrum with emphasis on the examination of the effect of the superficial velocity of the fluidizing gas. A stochastic model of bubble motion in a fluidized bed has been developed. This model visualizes the bubble motion in a fluidized bed to consist of the random movement, generating irregular signals, and the linear movement, generating wave-like signals. A theoretical autocorrelation function and a power spectral density function have been derived based on the model.     

Large set of CI spreading codes for high-capacity MC-CDMA

In this letter, a large set of spreading codes that doubles capacity in multicarrier code-division multiple-access (MC-CDMA) systems without any cost in bandwidth and with negligible cost in performance is introduced. This large set is comprised of: 1) complex spreading codes instead of conventional real-valued spreading codes and 2) two sets, each made up of orthogonal complex spreading codes, with minimum cross correlation between sets. Simulations performed over Rayleigh fading channels demonstrate 100% gains in terms of MC-CDMA capacity with negligible loss in performance.