Structure-property relationship in polyethylene reinforced by polyethylene-grafted multi-walled carbon nanotubes

Polyethylene-grafted multiwalled carbon nanotubes (PE-g-MWNT) were used to reinforce polyethylene (PE). The nanocomposites possessed not only improved stiffness and strength, but also increased ductility and toughness. The effects on the structure and morphology of composites due to pristine multiwalled carbon nanotubes (MWNT) and PE-g-MWNT were studied and compared using small angle X-ray scattering (SAXS), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The SAXS long period, crystalline layer thickness and crystallinity of polymer lamellar stacks were found to decrease significantly in MWNT composites, while the decreases were much smaller in PE-g-MWNT composites. PE-g-MWNT allowed a more efficient and unhindered crystallization at a lamellar level, while MWNT disrupted the order of lamellar stacks, probably because of their tendency to aggregate. The SAXS crystallinity and the mechanical properties of the composites showed similar trends as a function of MWNT content. This suggested that the improvement of the interfacial strength between polymer and carbon nanotubes was a result of synergistic effects of better dispersion of the filler, better stress transfer, due to the grafting of polymer and MWNT, and the nucleation of a crystalline phase around MWNT. The latter effect was confirmed by measurements of kinetics of non-isothermal crystallization.     

Life cycle assessment of power generation alternatives for a stand-alone mobile house

This paper presents comparative life cycle assessment of nine different hybrid power generation solutions that meet the energy demand of a prototypical mobile home. In these nine solutions, photovoltaic panels and a wind turbine are used as the main energy source. Fuel cell and diesel generator are utilized as backup systems. Batteries, compressed H₂, and H₂ in metal hydrides are employed as backup energy storage. The findings of the study shows that renewable energy sources, although they are carbon-free, are not as environmentally friendly as may generally be thought. The comparative findings of this study indicate that a hybrid system with a wind turbine as a main power source and a diesel engine as backup power system is the most environmentally sound solution among the alternatives.     

Equilibrium and kinetic adsorption study of Basic Yellow 28 and Basic Red 46 by a boron industry waste

In this study, the adsorption characteristics of Basic Yellow 28 (BY 28) and Basic Red 46 (BR 46) onto boron waste (BW), a waste produced from boron processing plant were investigated. The equilibrium adsorption isotherms and kinetics were investigated. The adsorption equilibrium data were analyzed by using various adsorption isotherm models and the results have shown that adsorption behavior of two dyes could be described reasonably well by a generalized isotherm. Kinetic studies indicated that the kinetics of the adsorption of BY 28 and BR 46 onto BW follows a pseudo-second-order model. The result showed that the BW exhibited high-adsorption capacity for basic dyes and the capacity slightly decreased with increasing temperature. The maximum adsorption capacities of BY 28 and BR 46 are reported at 75.00 and 74.73mgg(-1), respectively. The dye adsorption depended on the initial pH of the solution with maximum uptake occurring at about pH 9 and electrokinetic behavior of BW. Activation energy of 15.23kJ/mol for BY 28 and 18.15kJ/mol for BR 46 were determined confirming the nature of the physisorption onto BW. These results indicate that BW could be employed as low-cost material for the removal of the textile dyes from effluents.     

A mobile renewable house using PV/wind/fuel cell hybrid power system

A photovoltaic/wind/fuel cell hybrid power system for stand-alone applications is proposed and demonstrated with a mobile house. This concept shows that different renewable sources can be used simultaneously to power off-grid applications. The presented mobile house can produce sufficient power to cover the peak load. Photovoltaic and wind energy are used as primary sources and a fuel cell as backup power for the system. The power budgeting of the system is designed based on the local data of solar radiation and wind availability. Further research will focus on the development of the data acquisition system and the implementation of automatic controls for power management.     

Production and characterization of pyrolytic oils by pyrolysis of waste machinery oil

The main objective of this work is to propose an alternative method for evaluation of the waste machinery oil which is an environmental problem in Turkey. For this purpose, pyrolysis of waste machinery oil was conducted in a tubular reactor. Effect of the experimental conditions (various temperatures, catalyst type) on the formation of pyrolytic oil, gas, and char was investigated. Nickel supported on silica and zeolite (HZSM-5) were used as catalysts. Properties of the pyrolytic oils were characterized by gas chromatograph equipped with a mass selective detector (GC–MS), gas chromatography with flame ionization detector (GC–FID for boiling point range distribution), nuclear magnetic resonance (¹H NMR) spectroscopy, higher heating value measurement, and elemental analysis. The behavior of the metals in the waste machinery oil and the pyrolytic oil samples was also quantitatively detected by inductively coupled plasma (ICP) analysis. As, Cd and Cr contents of the all pyrolytic oils were found as <0.05 ppm, while Cu content of the pyrolytic oils varied between 0.3 ppm and 0.61 ppm. Only Vanadium contents of the pyrolytic oils obtained at 800 °C (0.342 ppm) and in the presence of HZSM5 (0.57 ppm) increased compared to that obtained by waste machinery oil (0.1 ppm). Lower metal contents of the pyrolytic oils reveal that pyrolysis of the waste machinery oils leads to the formation of environmental friendly pyrolytic oils with higher heating values.     

Sodium alginate/poly(vinyl alcohol) alloy membranes for the pervaporation, vapour permeation and vapour permeation with temperature difference separation of dimethylformamide/water mixtures: A comparative study

In this study, sodium alginate (NaAlg)/poly(vinyl alcohol) (PVA) membranes were prepared for the separation of dimethylformamide (DMF)/water mixtures. The two polymer components were independently crosslinked chemically with glutaraldehyde. The crosslinked membranes were characterized by fourier transform infrared spectrometry (FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). The permeation and separation characteristics of water/DMF mixtures were investigated using the vacuum processes pervaporation (PV), vapour permeation (VP) and vapour permeation with temperature difference (TDVP) methods. The effects of NaAlg/PVA ratio, membrane thickness, operating temperature and temperature of the membrane surroundings, feed concentration on the transmembrane permeation rate and separation factor were investigated. Optimum NaAlg/PVA ratio was determined as 80/20 (w/w) for the separation. The permeation rate in VP was lower than those in PV, whereas the separation factors were higher. The activation energies of permeation in PV and VP were calculated to be 5.070 and 2.229 kcal/mol, respectively, for a 20 wt% of DMF solution.     

Actual and Reference Evaporative Losses and Surface Coefficients of a Maize Field during Nongrowing (Dormant) Periods

Effective water resources planning, allocation, management, and use in agroecosystems require accurate quantification of actual evapotranspiration (ETc) during growing and nongrowing (dormant) periods. Prediction of ETc for a variety of vegetation surfaces during the growing season has been researched extensively, but relatively little information exists on evaporative losses during nongrowing periods for different surfaces. The objectives of this research were to evaluate ETc in relation to available energy, precipitation, and grass and alfalfa-reference ET (ETo and ETr) for a maize (Zea mays. L) field and to analyze the dynamics of surface coefficients (Kc) during the nongrowing period (October 15–April 30). The evaporative losses were measured using a Bowen ratio energy balance system (BREBS) on an hourly basis and averaged over 24?h for three consecutive nongrowing periods: 2004–2005 (Season I), 2005–2006 (Season II), and 2006–2007 (Season III). BREBS-measured ETc was approximately 50% of available energy (Rn?G; Rn is net radiation and G is soil heat flux density) during normal and wet seasons (Seasons I and III) and 41% of available energy during a dry season (Season II). Cumulative ETc ranged from 133?mm in Season II to 167?mm in Season III and exceeded precipitation by 21% during the dry season. The ratio of ETc to precipitation was 0.85 in Season I, 1.21 in Season II, and 0.41 in Season III. ETc was approximately 50% of ETo and 36% of ETr in both Seasons I and III, whereas in Season II, ETc was 32% of ETo and 23% of ETr. Overall, measured ETc during the dormant season was generally most strongly correlated with radiation terms, particularly Rn, albedo, incoming shortwave radiation, and outgoing longwave radiation. Average surface coefficients over the three seasons were 0.44 and 0.33 for grass and alfalfa-reference surfaces, respectively. Using geometric mean Kc values to calculate ETc using a KcETref approach over the entire nongrowing season yielded adequate predictions with overall root mean square deviations of 0.64 and 0.67?mm?day?1 for ETo and ETr, respectively. Estimates of ETc using a dual crop coefficient approach were good on a seasonal basis, but performed less well on a daily basis. Regression equations that were developed (accounting for serial autocorrelation in the ETc and ETref time series) yielded good estimates of ETc. Considering nongrowing period evaporative losses in water budget calculations would enable water regulatory agencies to better account for water use in hydrologic balance calculations over the entire year rather than only for the growing season and to better assess the progression and availability of water resources for the next growing season.     

Melamine‐based microporous polymer for highly efficient removal of copper(II) from aqueous solution

In this study, we investigated the ability of a melamine‐based microporous polymer network as an adsorbent for removal of copper(II) species from aqueous solutions. A designed Schiff based network (SNW) with high specific surface area was synthesized using melamine and terephthalaldehyde monomers at 180 °C for 3 days followed by a freeze‐drying process. The porous structure of the material was confirmed by SEM analysis and CO₂ adsorption/desorption studies at 77.3 K. The adsorption character of the SNW polymer for various metal salts, namely Pb(II), Fe(II), Hg(II), Zn(II), Ni(II) and Cd(II), was investigated and a specific sorption behaviour against Cu(II) salts was observed. The role of pH and contact time was examined and the highest adsorption capacity for Cu(II) was found as 92% with pH 3.5 at the end of 300 min. As evidenced by XRD and Fourier transform infrared spectral analysis, the sorption mechanism is attributed to the coordination system formed between amino groups in the porous structure and Cu(II) ions. Reusability of the system was also demonstrated by applying four cycles without any significant loss of activity. © 2016 Society of Chemical Industry