Particle-phase dry deposition and air-soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in Izmir, Turkey

Ambient air and dry deposition samples were collected at suburban and urban sites in Izmir, Turkey. Atmospheric total (particle+gas) ∑(14)PAHs concentrations were 36±39 and 144±163 ng m(-3) for suburban and urban sites, respectively. Phenanthrene was the most abundant compound at all sites, and all samples were dominated by low molecular weight PAHs. Average particulate ∑(14)PAH dry deposition fluxes were 8160±5024 and 4286±2782 ng m(-2) day(-1) and overall average particulate dry deposition velocities were 1.5±2.4 and 1.0±2.3 cm s(-1) for suburban and urban sites, respectively. Soil samples were collected at suburban site. Average soil concentration for ∑(14)PAH was 55.9±14.4 ng g(-1) dry weight. Calculated gas-phase air-soil exchange fluxes indicated that fluorene, phenanthrene, anthracene, and carbazole were deposited to soil in winter while they were volatilized in summer. Other compounds (fluoranthene-benzo[g,h,i]perylene) were deposited to soil in both periods. Annual average fluxes of PAHs representing soil to air (i.e., gas volatilization) and air to soil transfer (i.e., gas absorption, dry deposition, and wet deposition) processes were also compared. All processes were comparable for Σ(14)PAHs however their input was dominated by gas absorption. Gas absorption dominated for lower molecular weight PAHs, however dry deposition dominated for higher molecular weight PAHs. The results have suggested that for fluorene, soil and air may be approaching a steady state condition. For the remaining compounds, there was a net accumulation into the soil.     

Steam pyrolysis of an industrial waste for bio-oil production

Potato skin, a food industry waste, was pyrolysed under three different atmospheres namely static, nitrogen, and steam to produce bio-oil and its derivatives. The oil yield obtained at 550 °C was 24.77% in static atmosphere, whereas it reached to 27.11% in nitrogen atmosphere. Moreover, the use of steam caused a sharp increase of oil yields up to 41.09% with a steam velocity of 1.3 cm s^− 1. TG-DTA analyses were applied on the raw material to investigate the thermal degradation. Liquid products obtained under the most suitable conditions were characterized by elemental analyses, FT-IR and ¹H NMR. In addition, column chromatography was employed to separate the bio-oil into its derivatives. Asphaltene fraction of bio-oil is decreased under steam atmosphere. Gas chromatography was also used to investigate the C distributions. The characterization has shown that the bio-oil obtained under steam atmosphere was more beneficial than those obtained under both static and inert atmospheres. Further comparison of H/C ratios of pyrolysis oils with conventional fuels indicates that the H/C ratios of the oils obtained in this study lie between those of light and heavy petroleum products. It can be concluded that potato skin could be evaluated as a promising biomass candidate of bio-oil production.     

Magnetic chitosan microspheres: preparation and characterization

In this study, magnetic chitosan microspheres were prepared in a well shaped spherical form with a size range of 100 to 250 μm (size distribution ±15 to ±40 μm, respectively) by the suspension cross-linking technique for use in the application of magnetic carrier technology. The magnetic material (i.e. Fe₃O₄) used in the preparation of the magnetic chitosan microspheres was prepared by precipitation from FeSO₄ and Fe₂(SO₄)₃ solutions in basic medium and then ground to the desired size (i.e. 1–5 μm). The morphological and magnetic properties of the microspheres were characterized by different techniques (i.e. SEM, optical microscopy, magnetometry). The results demonstrated that the stirring rate of the suspension medium and the Fe₃O₄/chitosan ratio are the most effective parameters for the size/size distribution and the magnetic quality of the microspheres, while the chitosan molecular weight (MW) has no significant effect on these properties for the given MW range (i.e. 150 to 650 kDa). The best magnetic quality of the magnetic chitosan microspheres is around 9.1 emu/g microsphere at 10 kG magnetic field intensity.     

Fabrication of hydrophobic PLA filaments for additive manufacturing

Journal of Materials Science - There is an ever-greater need for self-cleaning and water-repelling properties of hydrophobic materials at this time in history, mainly due to the coronavirus disease...     

A facile route to end-functionalized poly(N-isopropylacrylamide) brushes synthesized by surface-initiated SET-LRP

In this study, the facile synthesis of well defined, end-functionalized poly(N-isopropylacrylamide) [poly(NIPAM)] brushes was achieved by surface-initiated single-electron transfer living radical polymerization (SET-LRP). Surface-initiated SET-LRP of N-isopropylacrylamide in the presence of cysteamine chain transfer agent was conducted via Cu(0) generated in situ by the disproportionation of Cu(I) to Cu(0) and Cu(II) in N,N-dimethylformamide at 90 °C. Initially, silicon surfaces were modified with 2-bromopropionyl bromide (2-BPB). [Poly(NIPAM)] brushes with amine end-group were then synthesized via surface-initiated SET-LRP from the immobilized 2-BPB. Various characterization techniques including ellipsometry, grazing angle-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and water contact-angle measurements were used to characterize the immobilization of 2-BPB on the silicon wafer and the subsequent polymer with amine end-group formation. The addition of free 2-BPB initiator was required for the formation of free polymer chains in solution. The free polymer chains were isolated and used to estimate the molecular weights and polydispersity index of chains attached to the surface. Although there are several chemicals methods for post-polymerization transformation of the halide chain end to amine groups, this study mainly provides a method for in situ functionalization of poly(NIPAM) brushes.     

Application of O3/UV/H2O2 oxidation and process optimization for treatment of potato chips manufacturing wastewater

Effluents coming from potato chips manufacturing have high organic loads and require adequate treatment before discharge to environment. In this study, O₃/UV/H₂O₂ advanced oxidation process was applied to treat these wastewaters. With this aim, batch experiments were conducted in a reaction tank equipped with ozone injection and UV irradiation. Process variables were determined to be pH, ozone concentration, reaction time, H₂O₂ dosage and efficiency of the system was evaluated considering total organic carbon (TOC) removal. Central composite design technique was applied to examine the individual and synergetic effects of the experimental factors. A quadratic model was developed to maximize the TOC removal. Furthermore, operation costs were calculated for different experimental conditions and interactions between process variables and costs were analysed.     

Multi-Tier Cellular Network Dimensioning

Wireless communications systems enable the end users to be mobile. The majority of the wireless communications networks are cellular networks. Several methods are developed to increase the performance of the cellular networks, which depends on the correct determination of the design parameters as well as the architecture of the system and the traffic requirements. In this study, we introduce a Simulated Annealing (SA) based method to determine the design parameters of a multi-tier cellular network, for which the implementation cost is minimized. The cellular system employs guard channels and allows calls to overflow to upper tiers. We conducted experiments with the SA-based technique on different example problems in two-tier cellular networks and obtained promising results.     

Wet and dry deposition of formaldehyde in Izmir, Turkey

Samples were collected between May 2003 and May 2004 in Izmir, Turkey to measure dry and wet deposition of formaldehyde (HCHO). Particle-phase HCHO fluxes measured with dry deposition plates ranged between 2 and 56 microg m(-2) day(-1) (average+/-SD, 17+/-12 microg m(-2) day(-1)). Particulate phase dry deposition velocities calculated using the particulate fluxes measured and ambient particulate concentrations ranged from 0.1 to 9.6 cm s(-1) (1.4+/-1.4 cm s(-1)). The particulate overall dry deposition velocity agreed well with those measured previously for other pollutants using the same method. Formaldehyde concentration measured in 27 rain samples collected at the sampling site ranged between 10 and 304 microg l(-1). The annual formaldehyde wet deposition was calculated as 31.4 mg m(-2) year(-1). The annual HCHO total deposition (wet+dry) was dominated by wet deposition (83.7%).