Physicochemical stability of calcium alginate beads immobilizing TiO2 nanoparticles for removal of cationic dye under UV irradiation

Recently, there have been considerable interests to immobilize photocatalyst in alginate beads for removing pollutants from water sources. However, the feasibility of using alginate beads in industry largely depends on its long‐term stability during operation. This study investigated the physicochemical stability of alginate/titanium dioxide beads (Alg/TiO₂) when exposed to UV irradiation in aqueous environment. The degradation of Alg/TiO₂ beads was evident because the diameter and mass of the beads was reduced by 12% and 40%, respectively, after 120 h of irradiation. A substantial amount of TiO₂ was leached into the external medium. Consequently, the removal efficiency of model cationic dye was found to reduce after every process cycle. Morphological analysis showed the formation of cavities on the surface of the Alg/TiO₂ beads. Interestingly, the blank alginate beads degraded more rapidly than the Alg/TiO₂ beads, confirming the UV‐shielding effect of TiO₂. Nevertheless, this study reveals the need to improve the UV stability of alginate‐based beads before they can be considered for practical application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45002.     

A research on sintering characteristics and mechanisms of dried sewage sludge

This study investigates the sintering behavior of dried sewage sludge and the related sintering mechanisms, considering sintering temperature and sintering time. Experimental results indicate that the characteristics are primarily influenced by sintering temperature. When the sintering temperature is increased from 1020 to 1050 °C, the specimens’ compressive strength and bulk density increase significantly, while water absorption decreases obviously, indicating an improvement of densification due to sintering. However, the compressive strength cannot meet the requirement for traditional ceramic products due to the release of organic matters and the formation of big pores in the products. Phosphorus in sewage sludge initially takes reactions with the formation of calcium magnesium phosphate and aluminum phosphate during sintering, which are helpful for enhancing the compressive strength. So, some materials with high contents of Al could be used to enhance the compressive strength of products. Heavy metals are fixed primarily inside the sintered specimens, with the As, Pb, Cd, Cr, Ni, Cu, Zn concentrations in the leachate found to be in the range of China regulatory requirements. These results reveal the feasibility of recycling dried sewage sludge by sintering as a construction material.     

A novel approach to the Poisson’s ratio of the yarn

Abstract

The Poisson’s ratio is a fundamental and inherent property of the materials in their reaction to loading. Determining the correct value of the Poisson’s ratio leads to more accurate predictions of the mechanical behavior of the material, especially in employing mechanical or numerical finite element modeling methods. In this study, seven different types of medium and coarse yarn were digitally filmed in seven sections from three various angles while tensile strength testing. Then, longitudinal and transverse strains and consequently, momentary deformation index and Poisson’s ratio of the yarns were calculated. Significance level of the mean Poisson’ ratio was also determined at different angles and sections using statistical comparison test. The results showed that the transverse strain has a convergent state at the end of the test and the start of the yarn breaking occurs at the convergence point. Additionally, in upper sections of yarn near to the movable jaw of the strength tester, the amount of the longitudinal strain increases which leads to reduce in momentary deformation index and Poisson’s ratio of the yarn. Moreover, a sectional mode to measure the Poisson's ratio was presented.     

Lessons from metal oxides to find why Nature selected manganese and calcium for water oxidation

The problem of finding a way to store energy from abundant sources such as sunlight, wind or geothermal heat is critical. Water splitting toward hydrogen production is a very promising way for the goal. Although the cathodic reaction is of major interest in hydrogen production, the concurrent anodic water oxidation, which provides cheap electrons for the cathodic reaction, is a limitation for hydrogen formation. The best water-oxidizing catalyst was found by Nature million years ago and used in plants, algae and cyanobacteria. We believe learning from the natural system is very promising, because Nature has been successfully splitting water for millions of years, using an inexpensive and environmentally friendly MnCa oxido cluster. Herein we study the phenol oxidation by some nano-sized metal oxides in the presence of H₂O₂. As metal oxides are functional and structural models for the water-oxidizing complex in Photosystem II, the results can be expanded for the natural site. We suggest that low organic compound oxidation under water oxidation is an important issue to select manganese and calcium ions for water oxidation.     

Preconditioned Krylov subspace methods for boundary element solution of the Helmholtz equation

Discretization of boundary integral equations leads, in general, to fully populated complex valued non-Hermitian systems of equations. In this paper we consider the efficient solution of these boundary element systems by preconditioned iterative methods of Krylov subspace type. We devise preconditioners based on the splitting of the boundary integral operators into smooth and non-smooth parts and show these to be extremely efficient. The methods are applied to the boundary element solution of the Burton and Miller formulation of the exterior Helmholtz problem which includes the derivative of the double layer Helmholtz potential—a hypersingular operator. © 1998 John Wiley & Sons, Ltd.     

Bioimpedance sensor to detect water content in milk based on van Der Pauw method

Milk fraud poses serious problems for the dairy industry and consumers'' health. The main aim of this study was to reveal the effect of water added to milk by measuring its electrical impedance spectrum. The required sensor was designed based on the van der Pauw method to measure the electrical conductivity of milk at the frequency band of 10 Hz to 5 MHz. The bioimpedance spectrum of the milk of five different cows showed that the electrical impedance spectrum has a high potential for detecting water added to the milk (P < 0.01). The area under the Nyquist curve was introduced as a suitable index to detect water‐added milk. In addition, the characteristic frequency of the bioimpedance spectrum was used as an important index to differentiate water‐added milk from waterless milk. An electrical model was introduced to interpret the amount of water added to the milk using the characteristic frequency. Results showed that it is possible to detect raw milk from boiled milk by measuring its electrical impedance.     

Corrosion of Copper in 0.1 M Hydrochloric Acid Solution with Benzotriazole as Corrosion Inhibitor

Protection of Metals and Physical Chemistry of Surfaces - Corrosion inhibition properties of benzotriazole were studied in 0.1 M hydrochloric acid solution for copper samples with different...     

A new mathematical modeling and a genetic algorithm search for milk run problem (an auto industry supply chain case study)

The idea of Milk Run has been used in the context of logistic and supply chain problems in order to manage the transportation of materials. In this paper, we propose a new Milk Run method, as a mixed integer approach, to manage supply chain problems. Since the resulted problem formulation is NP-Hard, we use some meta-heuristic and compare the results with the optimal solutions of the proposed Milk Run method. The mathematical modeling of this paper is purposely customized for a special case of an auto industry. We implement the mathematical formulation and the meta-heuristic using some actual data and compare the results with the current strategy. The preliminary results indicate that the proposed method could provide a practical tool to significantly reduce the cost of logistic.     

Preparation of the γ-Al2O3/PANI nanocomposite via enzymatic polymerization

Peroxidase-catalyzed template-guided polymerization of aniline in the presence of γ- alumina nanosheet (NS) particles have been carried out in aqueous media and γ-Al₂O₃/PANI nanocomposite was obtained. The polymerization of aniline occurred in aqueous solution in the presence of SPS (sulfonated polystyrene) as a template and SDS (sodium dodecyl sulfate) as a surfactant. Both obtained nanocomposites were comparable by SEM images. It was demonstrated that the γ-Al₂O₃ NS/PANI-SPS nanocomposite has higher conductivity and the γ-Al₂O₃ NS/PANI-SDS nanocomposite has higher void areas. The higher conductivity of γ-Al₂O₃ NS/PANI-SPS nanocomposite is attributed to the higher coated areas of γ-Al₂O₃ NS during polymerization in comparison with γ-Al₂O₃ NS/PANI-SDS which are not coated efficiently as the former. The FT-IR studies showed that the γ-Al₂O₃ NS/PANI nanocomposite was formed by interaction of the polyaniline (PANI) and γ-Al₂O₃ NS. FTIR also showed that the amount of PANI in γ-Al₂O₃ NS/PANI-SPS is more than in γ-Al₂O₃ NS/PANI-SDS. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Application of Geo-electrical Tomography in Coupled Hydro-mechanical–Chemical Investigations in Heap Leaching

Mine Water and the Environment - A shortcoming of the heap leaching process is its inherent limited metal recovery rate, due primarily to preferential pathways, which reduces the efficiency of the...