The glycolytic recycling of waste PET presents a challenge for the production of secondary value-added products, such as alkyd resins. A way to overcome the unsatisfactory mechanical, drying and ...chemical resistance properties of alkyds obtained from difunctional glycolyzates was proposed. Waste PET was glycolyzed using multifunctional alcohols: glycerol (G), trimethylolethane (TME), trimethylolpropane (TMP) and pentaerythritol (PE), giving tetra- and hexa-functional glycolyzates and, for comparison, using diethylene glycol (DEG), propylene glycol (PG) and dipropylene glycol (DPG) giving di-functional glycolyzates. The obtained glycolyzates were examined by
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H and
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C NMR, FTIR spectroscopy and elemental analysis and further used in the synthesis of alkyd resins. The properties of the prepared alkyd resins (acid, hydroxyl and iodine values, color, average molar masses and molar mass distributions, viscosity, drying time, hardness, flexibility, gloss, adhesion and chemical resistance) were investigated with respect to the functionality and the structure of the used glycolyzates. Alkyd resins derived from multifunctional glycolyzates (TME and TMP) showed considerably enhanced properties compared to those produced from difunctional glycolyzates and also to conventional general purpose resins.
A new perspective for mass production of alkyd resins from multifunctional glycolyzates obtained from waste PET - a step up to greener production and excellent applicative properties.
Biomass is deemed to be the main source of renewable energy in Serbia. Over the past couple of years, considerable efforts have been made to develop a technology which would enable biomass bales of ...various sizes and shapes to be used for energy production. A hot water boiler with cigarette type of combustion was constructed and used in the experimental investigation of biomass combustion phenomena. During the experiments performed, numerous parameters were measured: flue gas temperature, water temperature at the boiler inlet and outlet, while O2, CO2, CO, SO2, and NOx content in the flue gas was measured at the boiler outlet. Experiments were performed with biomass feed rate of 0.12 kg/s, mean boiler output of 1.56 MW and mean excess air coefficient of 2.1. During the steady state boiler operation, exhaust gas temperature was measured to be around 150–160 °C and obtained CO and NOx emission rates were found to be quite acceptable. In addition, combustion of biomass bales in cigar burners was modelled by the means of appropriate numerical simulation. A good agreement between experimental and numerical results was obtained.
•We developed a 1.5 MW hot water boiler with cigarette type of combustion.•We tested baled soybean and rapeseed biomass combustion in this boiler.•All necessary measurements were performed during investigations.•Effect of different additives was tested on various type of biomass.•We modelled combustion of biomass bales in cigar burners by the means of appropriate numerical simulation.
A simple and efficient method for the separation and determination of dimethylarsenate DMAs(V) was developed in this work. Two resins, a strong base anion exchange (SBAE) resin and iron-oxide coated ...hybrid (HY) resin were tested. By simple adjustment of the pH value of water to 7.00, DMAs(V) passed through the HY column without any changes, while all other arsenic species (inorganic arsenic and monomethylarsonate, MMAs(V)) were quantitatively bonded on the HY resin. The resin capacity was calculated according to the breakthrough point in a fixed bed flow system. At pH 7.00, the HY resin bonded more than 4150 mu g g super(-1) of As(III), 3500 mu g g super(-1) of As(V) and 1500 mu g g super(-1) of MMAs(V). Arsenic adsorption behavior in the presence of impurities showed tolerance with the respect to potential interference of anions commonly found in natural water. DMAs(V) was determined in the effluent by inductively coupled plasma mass spectrometry (ICP-MS). The detection limit was 0.03 mu g L super(-1) and the relative standard deviation (RSD) was between 1.1-7.5 %. The proposed method was established by application of standard procedures, i.e., using an external standard, certified reference material and by the standard addition method.
The effects of protic and aprotic solvents on the reactivity of picolinic, nicotinic and isonicotinic acid, as well as of some substituted nicotinic acids, with diazodiphenylmethane (DDM) were ...investigated. In order to explain the kinetic results through solvent effects, the second-order rate constants for the reaction of the examined acids with DDM were correlated using the Camlet-Taft Solvatochromic Equation. The correlations of the kinetic data were realized by means of multiple linear regression analysis and the solvent effects on the reaction rates were analyzed in terms of the contributions of the initial and the transition state. The signs of the coefficients of the Equation support the already known reaction mechanism. Solvation models for all the investigated acids are suggested and related to their specific structure.
The removal of copper(II) ion from aqueous solution by the granular activated carbon, obtained from hazelnut shells (ACHS) (Corylus avellana L. var. lunga istriana), was investigated. The ACHS was ...prepared from ground dried hazelnut shells by specific method carbonisation and water steam activation at 950°C for 2 h. The granular activated carbon produced from hazelnut shells has a high specific surface area (1 452 m2·g-1) and highly developed microporous structure (micropore volume: 0.615 cm3·g-1). In batch tests, the influences of solution pH, contact time, initial metal ion concentration and temperature on the sorption of copper(II) ion on ACHS were studied. The results indicate that sorption of copper(II) ion on ACHS strongly depends on pH values. The adsorption data can be well described by the Langmuir isotherm and Redlich-Peterson model. The monolayer adsorption capacity of the ACHS-copper(II) ion, calculated from the Langmuir isotherms, is 3.07 mmol·g-1. The time-dependent adsorption of copper(II) ion could be described by the pseudo second-order and Elovich kinetics, indicating that the rate-limiting step might be a chemical reaction. The intra-particle diffusion model indicates that adsorption of copper(II) ions on ACHS was diffusion controlled.
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