Applied Mechanics and Materials Vols. 752-753

Abstract: Complex formation processes of polyelectrolytes with surfactant ions are close model to protein - lipid interactions in living organisms. Furthermore, polymer – surfactant complexes are widely used as stabilizers of industrial dispersions and structurants of soil. When using the polymer-surfactant complexes the hydrophilic-lipophilic balance has the great importance. The interaction of polyacrylic acid with alkylammonium salts of different hydrophobicity: cetyltrimethylammonium bromide, dilaurildimethylammonium bromide and dioctadecyldimethylammonium chloride was studied by potentiometry, spectrophotometry, viscometry and electrophoresis methods. It was established that the complex formation of polyacrylic acid with cationic surfactants is carried out due to the electrostatic interaction between carboxyl groups of the polymer and cations of surfactants, which stabilized by hydrophobic interactions between their non-polar parts. The phenomenon of hysteresis in the change of the reduced viscosity of system surfactant /polyacrylic acid with temperature variation in the range of 20-60 °C was found. The possibility of using the complex formation process for water purification from CTAB has been shown. The degree of purification is 99.6-99.8%.

Abstract: Although nanoimprint lithography (NIL) can successfully fabricate structures down to 10 nm [1], it is difficult to produce perforated pores with diameters less than 100 nm in freestanding polymer membranes. Since it requires molding using a stamp with extremely high aspect ratio to achieve high mechanical stability for the membrane fully released from a substrate. We utilized silicon microneedle structures as an imprinting mold that overcomes these issues. Also, pressed self-perfection (PSP) process was employed after nanoimprinting to further reduce the pore size. Additionally, the membranes were integrated with microfluidic devices to measure current-voltage curves in order to determine pore size indirectly.

Abstract: Efficient and well-grown SrAl₂O₄:Eu,Dy phosphors were synthesized by an innovative melt synthesis method. The luminescent intensity and after-grow intensity of the SrAl₂O₄:Eu,Dy phosphors synthesized by the melt synthesis method are comparable to those of the sample synthesized by a conventional solid state reaction. Sintered phosphor balls with excellent luminescent characteristics were obtained.

Abstract: The electret state stability in composite polymer materials based on polypropylene and polyethylene with various dispersed inclusions was investigated. It is shown that the surface potential relaxation time of a polymer increases significantly when hydrophilic inclusions are added into its composition. It is assumed that the surface potential relaxation in the initial films occurs due to the volume conductivity which is catalyzed by water molecules within the polymer volume. Introduction of hydrophilic inclusions decreases the volume conductivity of the films as a results of which the stability of their electret state increases.

Abstract: Nitrogen is a naturally occurring element that is essential for growth and reproduction in both plants and animals. Excessive concentrations in the water body can cause excessive growth of algae and other plants, leading to accelerate eutrophication of lakes, and occasional depletion of dissolved oxygen. To remove nitrogen conventionally from domestic wastewater requires a high cost technology due to consumption of chemicals, high operational and maintenance cost. Therefore, an alternative low cost treatment technology particularly for nutrient removal including nitrogen removal system has been developed to improve the final effluent quality that is an aerated rock filter system. However, the optimization study under warm climate has not yet been developed. Hence, the present study was carried out to investigate the removal of ammonia nitrogen (AN) from domestic wastewater through nitrification process using a lab-scale vertical aerated limestone filter. Domestic wastewater sample used in this study was collected from Taman Bukit Perdana Wastewater Treatment Plant (WWTP), Batu Pahat, Johor owned by IWK. The experiment has been carried out for 10 weeks. The influent and effluent of the vertical aerated limestone filter system have been sampled and analyzed on biweekly basis for selected parameters including AN, Total Kjedhal Nitrogen (TKN), pH, alkalinity, temperature and dissolved oxygen to monitor the effectiveness of the filter. Results from this study show that nitrification process has took place within the aerated limestone filter as the results from laboratory experiments show that AN in wastewater was oxidized to nitrate and efficiently removed as the removal of AN was ranged from 85 % to 92 % and the removal percentage of TKN was ranged from 83.52 % - 91.67 %. The temperature was in the average of 26.3oC±0.75, pH value average of , DO was from 6.64 mg/L to 7.75 mg/L , and the alkalinity was from 15 to 110 mg / l as CaCO₃ . Therefore, from this study it can be concluded that aerated rock filter system has high potential in removing AN and TKN. It is also able to produce a good final effluent quality which is comply with the effluent requirement for nutrient removal in wastewater under the Environmental Quality Act (Sewage) Regulations, 2009 that is safe to be released to the water body.

Abstract: In terms two-phase nanoparticles model, dependence equilibrium position of magnetic moments of parameters size and elongation nanoparticles core is investigated. Phase diagrams of magnetic states were shown and determine geometrical parameters core, in equilibrium states.

Abstract: The “average spin” method was developed in terms of Heisenberg model. The average magnetic moment’s depending average of the temperature, the number of the nearest neighbors and spin of the atom has been calculated. It’s shown that the Curie temperature decreases with the spin of the atom.

Abstract: For the production of quality autoclaved aerated concrete product is necessary to know the chemical composition of raw materials and with regard to that optimize the recipe. This paper deals with the verification of the influence raw materials mixture ́s chemical composition, the reactivity of the silica source and the molar ratio C/S on the shape and amount of tobermorite crystals in autoclaved aerated concrete.

Abstract: The potential of sodium hydroxide (NaOH) modified Petai Belalang (Leucaena leucocephala) leaf powder as a biosorbent for methylene blue removal from aqueous solutions was investigated. Adsorption parameters studied include initial dye concentration, pH, dosage, kinetics and isotherms. The pH_zpc of chemically treated Leucaena leucocephala leaf powder was 7.50 and adsorption equilibrium time was achieved after 60 min. The kinetic data was best represented by the pseudo-second order model. The maximum adsorption capacity predicted from Langmuir model was 208.33 mg g^-1. This work indicated that NaOH treated Leucaena leucocephala leaf powder can be an attractive biosorbent for MB removal from diluted industrial wastewater.

Abstract: Kovdor (Karelia) deposite vermiculites modified by acid of different concentrations and chitosan were studied using positron annihilation lifetime spectroscopy, measuring apparent density, dye adsorption, nitrogen adsorption by BET and porometry. It has been shown that after acidizing vermiculite density changes comparing to the samples’ density depending on the acid concentration. The density increases with the increasing acid concentration. Internal volume of the micropores and the value of maximum sorption of brilliant green change directly proportional to the density of the modified vermiculite.