Eco-friendly approach on wool pretreatment and effect on the wool structure and dyeability

This research investigated the effect of various proteolytic enzymatic pretreatment on morphological and chemical features and the dyeability properties of wool fibres. Scoured merino wool fibres are treated with protease, papain, trypsin, and pepsin in specified conditions. Each enzyme activity measurement was provided by appropriate methods such as Bradford, BAPNA (N-benzoyl-1-arginine-p-nitroanilide), and BSA (Bovine Serum Albumin). Enzymatic processes were carried out for 24 h in the incubator set at 40°C, 100 rpm, and specified pH with 1 mg/ml enzyme concentration. Whiteness index (Stensby) and yellowness index (ASTM D 1925) were examined after enzymatic pretreatment. Pepsin and trypsin-treated wool fibres showed the highest whiteness index as 61.3 and 61.1, respectively whilst untreated wool fibres had 52.2. Fourier-transform infrared (FTIR) analysis revealed the increase in the intensity of amide-related bands and hydroxyl bands after enzymatic treatment. Scanning electron microscopy (SEM) photomicrographs manifested the cuticle layer is partially removed in enzyme-treated fibres. Elemental identification was provided by SEM–energy-dispersive X-ray spectroscopy (EDX). It appears that the sulphur bonds decreased after the treatment and the pepsin-treated fibres have fewer bonds of all. To examine the damage to the structure, photomicrographs were taken using fluorescence and light microscopes. The alkali solubility test (ASTM D1283) was also conducted to compare different enzyme types. Wool fibres were dyed in 2.0% concentration with reactive dyestuff. Dyeability and colorimetric features of fibres were measured by a spectrophotometer. The washing fastness test showed that all the samples have good results and the colour change after washing was better in enzyme-treated samples (grade 5) compared to untreated wool fibres (grade 4–5).     

Effect of electrolyte pH and Cu concentration on microstructure of electrodeposited Ni-Cu alloy films

Single Ni and Ni-Cu alloy films were electrodeposited on polycrystalline Ti substrates from electrolytes with different pH values under potentiostatic control. The deposition processes of the films were evaluated by the current-time transients recorded during deposition. The analysis of the transients clearly showed that the initial deposition of Ni is affected by the electrolyte pH, while in the Ni-Cu alloys the Cu concentration of the electrolyte is more effective than the electrolyte pH. The microstructural analysis by X-ray diffraction (XRD) indicated that the texture degree in both Ni and Ni-Cu alloy films, which have face-centered cubic (fcc) structure, changes with the electrolyte pH. The surface morphology of the samples was investigated using the scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was observed from SEM and AFM studies that the surface roughness of Ni deposits is not considerably affected by the electrolyte pH, while in Ni-Cu alloy films it changes significantly with both the electrolyte pH and the Cu concentration. Accordingly, the surface roughness of the Ni-Cu alloy films increased as electrolyte pH decreased and Cu concentration increased.     

Optimization-based source apportionment of PM2.5 incorporating gas-to-particle ratios

A modified approach to PM2.5 source apportionment is developed, using source indicative SO2/PM2.5, CO/PM2.5, and NOx/PM2.5 ratios as constraints, in addition to the commonly used particulate-phase source profiles. Additional information from using gas-to-particle ratios assists in reducing collinearity between source profiles, a problem that often limits the source-identification capabilities and accuracy of traditional receptor models. This is especially true in the absence of speciated organic carbon measurements. In the approach presented here, the solution is based on a global optimization mechanism, minimizing the weighted error between apportioned and ambient levels of PM2.5 components, while introducing constraints on calculated source contributions that ensure that the ambient gas-phase pollutants (SO2, CO, and NOy) are reasonable. This technique was applied to a 25-month dataset of daily PM2.5 measurements (total mass and composition) at the Atlanta Jefferson Street SEARCH site. Results indicate that this technique was able to split the contributions of mobile sources (gasoline and diesel vehicles) more accurately than particulate-phase source apportionment methods. Furthermore, this technique was able to better quantify the direct contribution (primary PM2.5) of coal-fired power plants to ambient PM2.5 levels.     

Semiempirical thermodynamic modeling of a direct methanol fuel cell system

In this study, a thermodynamic model of an active direct methanol fuel cell (DMFC) system, which couples in‐house experimental data for the DMFC with the mass and energy balances for the system components (condenser, mixing vessel, blower, and pumps), is formed. The modeling equations are solved using the Engineering Equation Solver (EES) program. This model gives the mass fluxes and thermodynamic properties of fluids for each state, heat and work transfer between the components and their surroundings, and electrical efficiency of the system. The effect of the methanol concentration (between 0.5 and 1.25 M) and air flow rate (between 20 and 30 mL cm^?2 min^?1) on the net power output and electrical efficiency of the system and the condenser outlet temperature is investigated. The results essentially showed that the highest value for the electrical efficiency of the system is 23.6% when the current density, methanol concentration, and air flow rate are taken as 0.2 A cm^?2, 0.75 M, and 20 mL cm^?2 min^?1, respectively. In addition, the air flow rate was found to be the most significant parameter affecting the condenser outlet temperature.     

Preparation and characterization of nano‐enhanced myristic acid using metal oxide nanoparticles for thermal energy storage

Fatty acids have been broadly used as phase change materials (PCMs) for thermal energy storage. However, low thermal conductivity limits their performances. This paper investigates the influence of metal oxide nanoparticle addition on myristic acid (MA) as nano‐enhanced PCM (NEPCM). Stability, chemical, and thermal properties were considered. Four types of nanoaprticles, TiO₂, CuO, Al₂O₃, and ZnO, were dispersed in MA at 0.1, 0.5, 1, and 2 wt%. Stability and dispersion were checked by sediment photograph capturing and scanning electron microscopy/energy‐dispersive spectroscopy. The Fourier‐transformed infrared (FTIR) and X‐ray diffraction analysis confirmed no chemical interaction between the nanoparticles and MA. The results revealed a ratio of thermal conductivity of 1.50, 1.49, 1.45, and 1.37, respectively, for 2 wt% of ZnO, Al₂O₃, CuO, and TiO₂. The T‐history method confirmed this enhancement. The latent heat thermal energy storage (LHTES) properties of the nano‐enhanced MA were evaluated using differential scanning calorimetry. The latent heat capacities of nano‐enhanced MA samples have dropped between 9.64 and 5.01 % compared with pure MA, and phase change temperature range was not affected significantly. The NEPCM was subjected to 500 thermal cycling, it showed a good thermal reliability as LHTES properties remained unchanged, while FTIR analysis showed similar characteristics compared with uncycled samples, indicating a good chemical stability. Based on the results regarding with the LHTES properties, cycling thermal reliability, and higher thermal conductivity improvement, it can be achieved that the MA/Al₂O₃ (2.0 wt%) and MA/ZnO (2.0 wt%) composites could be better PCMs for solar TES applications.     

Experimental and numerical investigation of effects of CNG and gasoline fuels on engine performance and emissions in a dual sequential spark ignition engine

Compared to widening usage of CNG in commercial gasoline engines, insufficient but increasing number of studies have appeared in open literature during last decades while engine characteristics need to be quantified in exact numbers for each specific fuel converted engine. In this study, a dual sequential spark ignition engine (Honda L13A4 i-DSI) is tested separately either with gasoline or CNG at wide open throttle. This specific engine has unique features of dual sequential ignition with variable timing, asymmetrical combustion chamber, and diagonally positioned dual spark-plug. Thus, the engine led some important engine technologies of VTEC and VVT. Tests are performed by varying the engine speed from 1500 rpm to 4000 rpm with an increment of 500 rpm. The engine’s maximum torque speed of 2800 rpm is also tested. For gasoline and CNG fuels, engine performance (brake torque, brake power, brake specific fuel consumption, brake mean effective pressure), emissions (O₂, CO₂, CO, HC, NO_x, and lambda), and the exhaust gas temperature are evaluated. In addition, numerical engine analyses are performed by constructing a 1-D model for the entire test rig and the engine by using Ricardo-Wave software. In the 1-D engine model, same test parameters are analyzed, and same test outputs are calculated. Thus, the test and the 1-D engine model are employed to quantify the effects of gasoline and CNG fuels on the engine performance and emissions for a unique engine. In general, all test and model results show similar and close trends. Results for the tested commercial engine show that CNG operation decreases the brake torque (12.7%), the brake power (12.4%), the brake mean effective pressure (12.8%), the brake specific fuel consumption (16.5%), the CO₂ emission (12.1%), the CO emission (89.7%). The HC emission for CNG is much lower than gasoline. The O₂ emission for CNG is approximately 55.4% higher than gasoline. The NO_x emission for CNG at high speeds is higher than gasoline. The variation percentages are the averages of the considered speed range from 1500 rpm to 4000 rpm.     

Modifying the structure of red mud by simple treatments for high and stable performance in COx-free hydrogen production from ammonia

Red mud (RM) modified by various treatments was used as a catalyst for ammonia decomposition. Catalytic activity measurements performed at 500 °C and differential conversions illustrated that the rate increases with a decrease in the size of Fe₃N_y nanoparticles formed during activation in NH₃ flow. Measurements at 700 °C showed that a catalyst prepared by digesting RM in 6 M HCl followed by calcination at 900 °C provides a stable ammonia conversion of 98.8 ± 0.5% for more than 70 h at a space velocity of 120 000 cm³ NH₃ h^?1 g_cat^?1. This rate is premier among all iron-based catalysts in terms of both activity and stability and even on par with the performance of other non-noble metal catalysts. Detailed characterization indicated Fe₃N_y species readily available on the surface as the active species. Results provided here enable the utilization of RM as an environmentally-friendly, highly efficient, and almost cost-free catalyst for CO_x-free hydrogen production.     

The technical and economical feasibility study of offshore wind farms in Turkey

Clean Technologies and Environmental Policy - A large part of the electricity generation is from imported fossil fuels, which makes Turkey heavily dependent on fossil fuels. For this reason, Turkey...     

Thermal energy storage properties of polyethylene glycol grafted styrenic copolymer as novel solid-solid phase change materials

Polymeric solid-solid phase change materials (S-SPCMs) are functional materials with phase transition-heat storing/releasing ability. With this respect, a series of polyethylene glycol (PEG) grafted styrenic copolymer were produced as novel S-SPCMs. PEGs with three different molecular weights were used for synthesis of isocyanate-terminated polymers (ITPs). To achieve cross-linking S-SPCMs, the ITPs were grafted with styrene-co-ally alcohol) (PSAA) at three different PSAA:PEG mole ratios. The produced polymers were characterized using Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (¹H NMR), and X-ray diffraction (XRD) technique. The crystalline-amorphous phase transitions of the polymers were examined using polarized optical microscopy (POM). The FT-IR, NMR, and XRD results confirmed the expected chemical structures and crystallization performances of the polymers. Thermal energy storage (TES) properties of the S-SPCMs were determined by differential scanning calorimetry (DSC). The DSC results revealed that the polymers with grafting ratio of PSAA:PEG(1:1) had phase transition enthalpies between about 74 and 142 J/g and phase transition temperatures between about 26°C and 57°C. Thermogravimetric analysis (TGA) measurements demonstrated that the S-SPCMs were resistant to thermal decomposition until about 300°C. Thermal conductivities of the produced S-SPCMs were measured in a range of about 0.18 to 0.19 W/mK. Furthermore, TES properties of the S-SPCMs were slightly changed as their chemical structures were remained after 5000 thermal cycles. By overall evaluation of the findings, it can be foreseen that particularly PSAA-g-PEG(1:1) polymers can be considered as promising S-SPCMs for some TES practices such as air conditioning of buildings, thermoregulation of food packages, automobile components, electronic devices, and solar photovoltaic panels.