Adsorption of Cu(II) ions from aqueous solutions using ion exchange resins with different functional groups

The extraction of heavy metals from industrial effluents using efficient adsorbents is crucial for wastewater treatment and beneficial for metal recycling. In this study, the removal of Cu(II) from an acidic solution by commercial resins Dowex G-26 and Puromet™ MTS9570 was investigated. The influences of contact time, solution concentration, pH, temperature, and a resin dosage on the adsorption process were studied with batch technique. The optimum adsorption conditions were obtained at a concentration of 1100 mg/L Cu, contact time of 30 min, pH 3.5, and resin dosage of 0.025 g/ml for the removal of 99.9% and 90% of copper ions by G-26 and MTS9570, respectively. The experimental data of copper adsorption were analyzed using the Langmuir, Freundlich, and Temkin isotherm models. The highest metal uptakes of 41.67 and 37.70 mg/g were observed for Dowex G-26 and MTS9570, respectively. It was found that both resins had higher adsorption capacities than the substances reported in the literature. The adsorption kinetic studies showed that the copper adsorption process could be better described by the pseudo-second order model. Adsorption occurs spontaneously under endothermic conditions, which indicates the endothermic nature of the process.     

Stobbe Condensation of Aromatic Aldehydes with Diethyl Diglycollate

Piperonal, p-tolualdehyde, and p-chlorobenzaldehyde condense with diethyl diglycollate in the presence of sodium hydride to give predominantly the corresponding (Z)-half-esters 1. together with smaller yields of the diarylidene diacids 2 and 3 . The structure and configuration of the products was established by chemical and spectroscopic evidence.     

Thermally enhanced dislocation density improves both hardness and fracture toughness in single-crystal SrTiO3

Dislocation-tuned functionality in ceramic oxides for potential versatile applications gains increasing attention. As the widespread chemical doping suffers from poor temperature stability, dislocations in well-controlled mesoscopic structure may be an alternative to thermally stable intrinsic doping features. To this end, the dislocation density in plastic zones introduced by cyclic Brinell indentation is considered under thermal annealing conditions. The considerably enhanced dislocation density due to thermal treatment is found to impact both microhardness and fracture toughness, albeit only to a modest degree. The mechanistic understanding centers around enhanced mobility and multiplication of the pre-engineered dislocations at elevated temperatures driven by the residual indentation stress, as well as the strengthened interaction of point defects and dislocations at high temperature.     

Recovery and Amino Acid Composition of Protein Precipitates Isolated from Rice Starch Processing Liquors

Precipitates containing 47.7% and 30.5% protein were isolated from rice starch steep and sorter liquors respectively by pH adjustment of these liquors. The pH for protein precipitation from the steep liquor was 7.0 and from the sorter liquor was 5.0. The acid hydrolysates of both precipitates contained at least seventeen amino acids, Glutamic acid and arginine constitute the largest proportions of these acids. Nine essential amino acids were found to be present in variable amounts. The industrial application of this method for the preparation of protein precipitates is discussed.     

Evaluation of traditional semi-hard Brazilian cheeses using chemometric tools to identify possible denomination fraud

This study aimed to evaluate and classify some of the main traditional Brazilian semi-hard cheeses, using multivariate tools to determine possible denomination fraud. Fifty-six samples of Minas Artisanal (MA), Colonial (AC), Minas Padrão (MP) and Meia Cura (MC) cheeses were analysed. All the evaluated parameters indicated high variability. PCA and HCA confirmed two groupings (AC and MP; and MA and MC) with high similarity. The DD-SIMCA method classified the cheeses with 83% accuracy. AC (48%) and MA (20%) cheeses were the most well classified in their respective denomination. These results were efficient in classifying groups and demonstrating the lack of authenticity regarding the denominations of these cheeses.     

Production of a transformer oil from paraffinic basestocks

The work described in this paper is concerned with the production of a high quality transformer oil from local Egyptian paraffinic basestocks. Analysis showed that a neutral base oil 70N was most suitable for producing transformer oils. This neutral base oil was chemically treated with a sulphonation process. Optimum sulphonation conditions were achieved by using oleum or SO₃ at a concentration of 6 wt. %. The sulphonation reaction was carried out in three stages, each with an equal portion of the sulphonating agent. The acidic oil was then neutralised with an alkaline solution. Oil colour improvement was effected using activated clay as an absorbent. Laboratory results and field trials indicated that such a treated neutral paraffinic oil meets the IEC 296 international specifications for transformer oils, with the exception of pour point (−12°C). However, such a pour point is not relevant in certain hot climatic conditions. Comparative evaluation of the treated oil with commercial transformer oils has shown its suitability.     

Load ratio effects on the structural fire behaviour of glass fibre-reinforced polymer-reinforced concrete beams with mid-span bar lap splices – Experimental study

Fibre-reinforced polymer (FRP)-reinforced concrete members have been gaining attention as an alternative to conventional steel-reinforced concrete members due to their advantageous characteristics. A few to mention are excellent resistance to corrosion, high strength-to-weight ratio, and reduced maintenance cost in the long term. Nevertheless, FRPs are often limited in use mainly due to fire safety considerations since they can encounter significant deprivation of strength and bond with concrete in fire conditions. This paper presents the results of an experimental study aimed to investigate the effects of the applied load level on the structural behaviour of glass fibre-reinforced polymer (GFRP)-reinforced concrete beams having mid-span bar lap splices when exposed to standard fire. Two 2750-mm long beams with cross-sectional dimensions of 300 mm wide × 350 mm high were exposed to elevated temperatures that followed the CAN/ULC-S101 standard fire time–temperature curve while being subjected to a load level equivalent to 85% of the beam ultimate design load. The experimental results of the two beams were compared to those obtained for identical beams but subjected to a lower load level that is equivalent to only 40% of the beam's ultimate design load. Results show that the increased load level (slightly more than double the load ratio) unexpectedly did not impact the fire resistance time of the GFRP-reinforced concrete beams but affected other structural responses of the beam, such as its midspan deflections and cracking patterns.     

Comment on “Lubauer J,Lohbauer U,Henrich M,Munz M,Lube T,Belli R. Intricacies involving the evaluation of fracture toughness obtained by the surface-crack-in-flexure method. J. Am. Ceram. Soc., 2022;105(12) 7582–7599”

We have evaluated over fifty materials using small semi–elliptical controlled surface flaws with the Newman–Raju factors. Although occasionally there were nuances and peculiarities, the results were sound and comparable to other methods. So, despite the lengthy discussions and numerous plots in Lubauer et al.’s paper, what is evident is that if one simply follows the guidelines in ASTM C 1421 and the other standards for most ceramics including the SL200B sintered silicon nitride, and polish off the recommended 4.5 to 5 h material, one will obtain the correct results. Excessive indentation forces and excessive material removal to obtain sharp corner, shallow surface cracks are unwise. Removing more than 5 h should only be done to remove lateral cracks. In such cases the Strobl et al. solutions may be useful. These solutions are an interesting alternative to the reputable Newman–Raju factors, but much more experience and verification is needed before they can be accepted. They and the extension of their analysis for precrack angles χ < 70° need to be vetted in a major engineering journal.     

From Crystalline to Low-cost Silicon-based Solar Cells: a Review

Silicon - Renewable energy has become an auspicious alternative to fossil fuel resources due to its sustainability and renewability. In this respect, Photovoltaics (PV) technology is one of the...     

Stresses near the edges of ring-loaded plates

Strength testing of brittle materials often employs beams or plates loaded in bending. Solutions are provided for the in-plane stresses between the support ring and edge of ring-loaded circular plates (i.e., disks) having a diameter larger than the support ring. The region overhanging the larger support ring stiffens the plate and reduces the edge tangential stress. Its consideration is thus crucial to an accurate solution. For typical ceramic disks with little overhang, the edge stress is less than ~50% of the maximum, central stress. With a large overhang, the edge stress can be reduced to ~25% of the central stress. The radial stress reverses the sign outside the support ring, whereas that of the tangential stress remains the same, and thus tensile failure can occur from either face of the disk.