Adsorption of anionic textile dye Acid Green 9 from aqueous solution onto weak or strong base anion exchangers

The aim of this work is to study the thermodynamic and kinetic studies with regard to the adsorption of Acid Green 9 (AG9) on the most efficient resin, namely, acrylic weak base anion exchange resin with ethylenediamine‐functional groups (A1) selected from several anion exchange resins. The influence of the various experimental parameters such as, pH, initial dye concentration, contact time, temperature, and adsorbent dose was investigated by batch experiments. The extent of the dye adsorption increased with the decrease of the initial dye concentration and the increase of the contact time, temperature, and amount of the adsorbent. Adsorption process was quantitative and very fast at low concentrations of the dye. To investigate the mechanism of the adsorption and potential rate‐controlling steps, pseudo first‐ and second‐order, as well as intraparticle diffusion kinetic equations have been used. The adsorption kinetic of AG9 dye from aqueous solution onto A1 could be described by the pseudo second‐order reaction model. The obtained results are in agreement with the Langmuir and Freundlich models. In the optimum conditions established, an adsorption capacity of 500 mg textile dye (72% purity) g^?1 adsorbent (at 293 K) was reached. Desorption experiments by batch and dynamic methods were performed using a solution of 0.05 mol L^?1 NaOH. A series of 13 adsorption–desorption cycles were carried out by the dynamic method with a quantitative adsorption and the desorption efficiency higher than 95%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The kinetics of Maillard reaction in lactose-hydrolysed milk powder and related systems containing carbohydrate mixtures

The kinetics of Maillard reaction in lactose-hydrolysed skim milk powder and related systems containing carbohydrate mixtures were analysed. The effect of the increase of water activity and temperature during storage of the commercial product was also evaluated. In systems with two and three carbohydrates, a marked decrease of the reaction rate was observed when monosaccharides were partially replaced by lactose, notwithstanding the fact that the former still remained in a higher proportion than lysine. The rate of available lysine loss in lactose-hydrolysed milk was mostly affected by the presence of galactose. The reaction rate constants at a_w 0.52 and at 37 and 50 °C were higher than at a_w 0.33. However, no significant differences were observed at 60 °C. Temperature is the most important factor to be controlled in order to minimise nutritional deterioration during storage.     

Discrimination between defective and non-defective roasted coffees by diffuse reflectance infrared Fourier transform spectroscopy

The objective of this work was to evaluate the feasibility of employing Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) for discrimination between defective and non-defective coffees after roasting and grinding. Defective (black, immature and sour) and non-defective Arabica coffee beans were submitted to light, medium and dark roasts at 220, 235 and 250 °C. Principal Components Analysis of the DRIFTS spectra (normalized or not) and of the first derivatives of the spectra provided separation of the samples into four groups: non-defective, black, dark sour and light sour, with immature beans scattered among the sour samples. Classification models were developed based on Linear Discriminant Analysis and recognition and prediction abilities of these models ranged from 95 to 100%. Such results indicate that DRIFTS presents potential for the development of a fast and reliable analytical methodology for discrimination between defective and non-defective coffee after roasting and grinding.     

Optimal design of reverse osmosis‐based water treatment systems

We address the problem of optimal design of reverse osmosis (RO)‐based water treatment systems. A superstructure optimization method is proposed to solve the problem, where the superstructure for a RO system is structurally enhanced with additional features. We formulate the problem as mixed‐integer nonlinear program which is solved to yield optimal results. A case study on desalination is considered in this work, and the numerical results obtained using our approach are validated using a commercial simulation tool. We further extend the problem by considering the effects of degradation of membrane performance over time and solve it by representing the problem as a two‐stage stochastic program. This new approach is highly useful for identifying minimum cost robust designs for membrane‐based water purification systems, which are especially important in desalination applications. © 2012 American Institute of Chemical Engineers AIChE J, 2012     

Morphological, structural, microhardness and electrochemical characterisations of electrodeposited Cr and Ni-W coatings

This study examines the corrosion of electrodeposited Cr and of two electrodeposited Ni-W coatings in 0.1 mol L⁻¹ NaCl solution, as well as the influence of heat treatment on the crystallographic structure and microhardness properties of these coatings. Physical characterisation is carried out using scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis. Electrochemical characterisation is carried out using both the potentiodynamic linear polarization technique and open circuit measurements during long-term immersion tests. The corrosion products on the coating surfaces are characterised by ex situ Raman spectroscopy. As-electrodeposited Ni-W samples do not present defects, and the surface evolves from fine globular grains to rough polycrystalline morphology with decreasing electrodeposition current density. All the studied coatings corrode in the chloride medium and the corrosion is non-uniform for the Ni-W coatings. Raman analyses carried out after the immersion tests reveal Cr₂O₃ and Cr(OH)₂ corrosion products on the Cr coating surface, and Ni(OH)₂, NiO and WO₃ corrosion products on the Ni-W coating surfaces. Ni, Ni₄W and Ni-W phases are formed after heat treatment of the Ni₈₆W₁₄ coating at 600 °C. Although all the annealed Ni-W layers are cracked, their microhardness increases as the annealing temperature increases, suggesting that Ni-W coatings are potential substitutes for chromium in industrial applications in which good microhardness properties and stability at temperatures higher than 100 °C are required.     

Superporous collagen‐sericin scaffolds

Superporous materials based on two proteins, collagen and sericin were synthesized by freeze‐drying considering various ratios between the two proteins. To evaluate the influence of sericin content on the structure/properties relationship, the obtained scaffolds were further characterized using spectroscopic analysis, thermal, and mechanical techniques. Scanning electron microscopy was used to investigate the morphological structure of the scaffolds and the swelling properties as well as the stability of the scaffolds were also assessed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Identification of Cyclopropaneoctanoic Acid 2-Hexyl in Human Adipose Tissue and Serum

Fatty acids containing a cyclopropane ring in their structure (cyclopropane FA) have been found in a wide variety of bacteria, a number of protozoa, and Myriapoda. Little is known about cyclopropane FA in mammal, especially in human tissues. The present study deals with the identification of cyclopropane FA in adipose tissue and serum of humans and rats. Fatty acids extracted from the adipose tissue and serum obtained from obese women during bariatric surgery were methylated and analyzed on GC–MS. We have identified: cyclopropaneoctanoic acid 2-hexyl, cyclopropaneoctanoic acid 2-octyl, cyclopropanenonanoic acid, and 2-[[2-[(2-ethylcyclopropyl)methyl]cyclopropyl]methyl] acid in human adipose tissue. We confirmed the presence of cyclopropaneoctanoic acid 2-hexyl by derivatization of FA extracted from human adipose tissue to picolinyl esters. Cyclopropaneoctanoic acid 2-hexyl was the main cyclopropane FA (approximately 0.4 % of total fatty acids in human adipose tissue, and about 0.2 % of total fatty acids in the serum). In adipose tissue cyclopropaneoctanoic acid 2-hexyl was found mainly in triacylglycerols, whereas in serum in phospholipids and triacylglycerols. The cyclopropaneoctanoic acid 2-hexyl has also been found in serum, and adipose tissue of rats in amounts comparable to humans. The content of cyclopropaneoctanoic acid 2-hexyl decreased in adipose tissue of rats maintained on a restricted diet for 1 month. In conclusion, we demonstrated that cyclopropaneoctanoic acid 2-hexyl is present in human adipose tissue and serum. Adipose tissue cyclopropaneoctanoic acid 2-hexyl is stored mainly in triacylglycerols and the storage of this cyclopropane FA is affected by food restriction.     

Synthesis,characterization, and adsorption behavior of aminophosphinic grafted on poly(styrene‐Co‐divinylbenzene) for divalent metal ions in aqueous solutions

In the present work, two novel aminophosphinic acid ligands grafted on poly(styrene‐1%divinylbenzene) (St‐1%DVB) have been synthesized by reacting polymer precursors bearing primary amino groups with benzaldehyde (or propionaldehyde) and phenylphosphinic acid by the “one‐pot” Kabatachnik‐Fields reaction. The resins functionalized with aminophosphinic pendant groups were characterized by means of Fourier transform infrared spectroscopy (FTIR), thermal analysis, energy dispersive X‐ray microanalysis (EDX), and Scanning electron microscopy (SEM) imaging. Its adsorption capacity for divalent metal ions such as Cu(II) and Ni(II) were investigated. The adsorption procedure of Cu(II) and Ni(II) ions on polymer‐grafted aminophosphinic acid ligands was carried out by batch experiments. The result also shows that the adsorption process was best described by a pseudo‐second‐order kinetic equation and by the Langmuir adsorption isotherm. The best maximum adsorption capacity was obtained for resin with aminobenzylphosphinic acid groups [1.46 mg Cu(II)/g and 1.36 mg Ni(II)/g]. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

The effect of polymerization mode on mechanical properties of commercial self-adhesive cements associated with hydroxyapatite

This study aimed to evaluate the mechanical properties of self-adhesive resin cements mixed with hydroxyapatite, as a function of the polymerization activation mode among a variety of commercial self-adhesive cements. Four cements (MaxCem Elite, Bifix SE, G-Cem, and RelyX U200) were mixed, combined with hydroxyapatite, dispensed into molds, and distributed into three groups, according to polymerization protocols: IP (immediate photoactivation for 40 s); DP (delayed photoactivation, 10 min self-curing plus 40 s light-activated); and CA (chemical activation, no light exposure). After polymerization, the specimens were stored at 37 °C for 24 h. After storage, a three-point bending test was performed at 0.5 mm/min. Flexural strength (S) and flexural modulus (E) were calculated. The fractured surfaces were analyzed with scanning electron microscopy (SEM) technique. Data were analyzed by two-way ANOVA/Tukey’s test (5%). The tested parameters varied according with the resin cements and polymerization protocols. Regarding the S means, MaxCem Elite, G-Cem, and RelyX U200 demonstrated dependence on photoactivation (immediate or delayed), whereas Bifix SE exhibited no dependence on the polymerization protocol. The same was observed for Bifix SE for the E means, which presented the best balanced formulation, irrespective of the activation protocol. SEM analysis exhibited the presence of bubbles and porosities in all of the fractured surfaces. Chemical activation is not a guarantee of a complete polymerization for most of the cements tested. Only one of the cements maintained its mechanical properties when chemically activated, important characteristic in clinical situations in which the curing light penetrating the bulk material can be attenuated or scattered.     

Strategies for In Situ Home Improvement in Romanian Large Housing Estates

Socio-economic and physical change have visibly affected post-socialist cities, yet the state of decay of their inherited large housing estates has only deepened throughout the 1990s, despite the change in tenure through policies of large-scale privatisation. Housing disrepair has now reached a critical stage that requires rapid private and public intervention. This paper examines the extent to which Romanian block residents have been able to improve in situ their housing conditions since 2000, the strategies they employed and the challenges they faced. It focuses on the often ignored private domain of housing, flats and blocks, where changes are also likely to be less visible. By analysing the process of individual utility metering and the practice of collective block management, I argue that besides economics, the unregulated housing context and a relaxed legal culture have challenged individual and collective action and have generated a framework of housing privatism.