Role of membrane pore size in tertiary flocculation/adsorption/ultrafiltration treatment of municipal wastewater

Flocculation, adsorption onto powered activated carbon (PAC), and ultrafiltration (UF), alone and in combination, were tested for tertiary treatment of the secondary effluent from municipal wastewater treatment at the Ashkelon plant (in southern Israel). Encouraging and reliable results of total organic carbon (TOC) of <3 mg/l were achieved with a combination of 130 mg/l FeCl₃, 0.6 g/l PAC and UF. The relative contribution of the UF membrane to the reduction of TOC changed with the molecular weight cut-off (MWCO) of the membrane, from a negligible 2.9% for a 100-kDa-MWCO membrane to 17% for 10- and 2-kDa membranes. The latter membranes, however, developed significant fouling, with a 35% drop in flux during first 30 min of the filtration cycle. The flux drop for the 50- and 100-kDa membranes was in the low range of 3%. The optimal MWCO interval of 20- to 50-kDa in combination with flocculation/PAC pretreatment gave a significant reduction in organic content with minimal membrane fouling. Detailed GC–MS analysis showed that the combined treatment gave very efficient retention of organic compounds with molecular weights below 800 Da, with the consequent absence of harmful compounds in the tertiary effluent. It was therefore concluded that the recommended flocculation/adsorption protocol constitutes an effective pretreatment for UF and that the obtained tertiary effluent can be used for unrestricted irrigation.     

Surface functionalization of poly(lactic acid) film by UV‐photografting of N‐vinylpyrrolidone

The photoinitiated grafting of N‐vinylpyrrolidone (NVP) onto poly(lactic acid) (PLA) film with the use of benzophenone (BP) as the initiator, modified the natural hydrophobic PLA behavior to an hydrophilic film with desirable wettability. The surface photografting parameters‐percent conversion of monomer to overall photopolymerization (Cp), percent conversion of monomer to the photograft polymerization (Cg), and grafting efficiency (Eg) were calculated. The resulting film surface was analyzed using ATR‐FTIR and UV spectroscopy, derivative spectroscopy and water contact angle. Besides, we demonstrated that the grafted polyvinylpyrrolidone chains could easily react with iodine to form a complex as the homopolymer does with antibacterial activity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Recycling of CRT panel glass as fluxing agent in the porcelain stoneware tile production

In the present work, the feasibility to substitute feldspar raw material in a porcelain stoneware body with Panel Cathode Ray Tube (CRT) glass was investigated. A standard batch and a composition, where 35 wt.% Na-feldspar was substituted by CRT glass, were sintered at different temperatures in the range of 1000–1250 °C. The degree of the densification was studied by evaluation of the closed and total porosity, while the sintering rate was estimated by non-isothermal dilatometric measures. The variation of the crystalline phase composition was evaluated by XRD analysis. From the preliminary study other ceramic samples with different percentages of CRT glass (i.e. 2.5, 5 and 10 wt.%) were prepared and fired in industrial kiln. The sintering parameters, the microstructure and the mechanical properties were measured and compared with the standard composition.     

Cold Spray Deposition of Freestanding Inconel Samples and Comparative Analysis with Selective Laser Melting

Cold spray offers the possibility of obtaining almost zero-porosity buildups with no theoretical limit to the thickness. Moreover, cold spray can eliminate particle melting, evaporation, crystallization, grain growth, unwanted oxidation, undesirable phases and thermally induced tensile residual stresses. Such characteristics can boost its potential to be used as an additive manufacturing technique. Indeed, deposition via cold spray is recently finding its path toward fabrication of freeform components since it can address the common challenges of powder-bed additive manufacturing techniques including major size constraints, deposition rate limitations and high process temperature. Herein, we prepared nickel-based superalloy Inconel 718 samples with cold spray technique and compared them with similar samples fabricated by selective laser melting method. The samples fabricated using both methods were characterized in terms of mechanical strength, microstructural and porosity characteristics, Vickers microhardness and residual stresses distribution. Different heat treatment cycles were applied to the cold-sprayed samples in order to enhance their mechanical characteristics. The obtained data confirm that cold spray technique can be used as a complementary additive manufacturing method for fabrication of high-quality freestanding components where higher deposition rate, larger final size and lower fabrication temperatures are desired.     

Shrinkage of an oxygen bubble rising in a molten glass

The mechanisms controlling the evolution of a bubble surrounded by molten glass are important to understand in order to improve melting in glass furnaces, particularly during a change in composition. In order to provide insight into this phenomenon, the behavior of an isolated bubble rising in molten glass is examined both experimentally and numerically.An experimental procedure developed specifically to observe, in situ, a rising bubble is described. Two soda-lime-silica compositions are tested, with low and high iron content, respectively.The numerical model used to describe bubble shrinkage is based on the results recently proposed in Pigeonneau (2009). A specific mass transfer coefficient is used for oxygen where the oxidation–reduction reaction of iron oxides is taken into account.A comparison between the experimental and numerical results shows the importance of the oxidation–reduction reaction of iron in the mass transfer of oxygen. The shrinkage rate of a pure O₂ bubble is enhanced with reduced molten glass iron content.     

Experimental fire analysis of steel‐to‐timber connections using dowels and nails

The paper describes and discusses the results of an extensive testing programme on the structural behaviour of timber connections under ISO‐fire. The results of reference tests performed at normal temperature are also presented. From the variety of timber connections multiple shear steel‐to‐timber connections with dowels and slotted‐in steel plates and connections with steel side plates and annular ringed shank nails were experimentally studied. Particular attention was given to the analysis of the efficiency of different strategies in order to increase the fire resistance of the timber connections. The test results showed that unprotected multiple shear steel‐to‐timber connections with dowels designed for normal temperature reached a fire resistance of about 30 min. A reduction of the load level applied during the fire did not lead to a significant increase of the fire resistance. By increasing the side timber members as well as the end distance of the dowels by 40 mm the connections reached a fire resistance of more than 70 min. Connections protected by timber boards or gypsum plasterboards showed a fire resistance of around 60 min. Thus, from a fire design point of view these strategies were favourable in order to increase the fire resistance of the connections significantly. Unprotected connections with steel side plates and annular ringed shank nails failed already after about 12 min due to large deformations of the nails and the steel side plates directly exposed to fire. By protecting the steel side plates using an intumescent paint the fire resistance of the connections was increased to around 30 min. The test results enlarged the experimental background of timber connections in fire significantly. Copyright © 2009 John Wiley & Sons, Ltd.     

Investigations for the Validation of the Defect Based Scale Failure Diagrams—Part I: Nickel Oxide

Mechanical stresses imposed on protective oxide scales can lead to cracking and failure of the scale and consequently to a loss of the protective properties. Therefore, an assessment of the mechanical stability limits is of great interest. In this work, a new concept using defect based oxide scale stability diagrams to assess the mechanical stability limits is discussed. In contrast to mechanical failure diagrams proposed earlier, the presented model is based on physical defect size instead of scale thickness. Nickel oxide scales on high purity (99.99 %) nickel were thermally grown in dry and humidified synthetic air to provide a model oxide system. SEM investigations were carried out to examine the physical defect structure in the oxide scales and mechanical 4-point bend testing was used to measure the critical strain for through scale cracking. The data served for establishing a data base for the validation of the defect based scale failure model.     

Synthesis and Characterization of Nanostructured Cerium Dioxide Thin Films Deposited by Ultrasonic Spray Pyrolysis

Nanostructured thin films of cerium dioxide have been prepared on single-crystalline silicon substrates by ultrasonic spray pyrolysis using cerium acetylacetonate as a metal–organic precursor dissolved in anhydrous methanol and acetic acid as an additive. The morphology, structure, optical index, and electrical properties were studied by X-ray diffraction, scanning electron microscopy, atomic force microscopy, ellipsometry, and impedance spectroscopy. The use of additives is very important to obtain crack-free films. The substrate temperature and flow rate was optimized for obtaining smooth ( R _a<0.4 nm), dense ( n >2), and homogeneous nanocrystalline films with grain sizes as small as 10 nm. The influence of thermal annealing on the structural properties of films was studied. The low activation energy calculated for total conductivity (0.133 eV) is attributed to the nanometric size of the grains.