Ambient gas and particle phase samples were collected during two sampling periods from a residential area of an industrialized city, Kocaeli, Turkey. The sampling occurred during winter months when structures were being heated, and summer months when structures were not being heated. Σ(13)PAH (gas + particle) concentrations ranged between 6.2 ng m(-3) (DahA) and 98.6 ng m(-3) (Phe) in the heating (winter) period and 3.0 ng m(-3) (BaA) and 35.1 ng m(-3) (Phe) in the non-heating (summer) period. Phe, Flt and Pyr were found to be at high concentrations in both sampling periods. Winter time to summer time concentration ratios for individual ambient PAH concentration ratios ranged between 1.2 (DahA) and 17.5 (Flu), indicating the effect of the emissions from residential heating on measured concentrations of PAHs, but great industrial plants and the only incinerator facility of Turkey are other important pollution sources around the city. Temperature dependence of gas phase PAHs was investigated using the Clausius-Clapeyron equation. A high slope obtained (5069.7) indicated the effect of the local sources on measured gas phase PAHs. Correlation of the supercooled vapor pressure (P) with the gas particle partitioning coefficient (K(p)) and particle phase fraction was also evaluated. The relationship between the meteorological parameters and individual PAH (gas + particle) concentrations was investigated further by multiple linear regression analysis. It was found that the temperature had a significant effect on all of the measured PAH concentrations, while the effects of the wind speed and direction were not significant on the individual PAHs. On the other hand, PAH concentrations showed a strong linear relationship with the ventilation coefficient (VC) which showed the influence of local sources on measured PAHs. Benzo[a]pyrene toxic equivalent (BaP(eq.)) concentrations were used for health risk assessment purposes. The winter period risk level (2.92 × 10(-3)) due to the respiratory exposure to PAHs was found to be almost 3 times higher than in the summer period (1.15 × 10(-3)).

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In this work, activities of modified dolomite catalysts using calcium acetate in the heterogeneously catalyzed transesterification of microalgae oil with methanol were investigated. Modified catalysts were prepared via wet impregnation method and calcined 850°C for 2 h. Reaction conditions were examined as the catalyst type, amount of catalyst, methanol/microalgae oil molar ratio, and reusability of the catalyst using the dolomite and modified dolomite catalysts. When investigated reusability of the modified dolomite catalyst in the transesterification of microalgae oil with methanol, catalyst was reused three times with a small loss of activity. After fourth run, reused catalyst was calcined again and got similar activity to the first run. The highest fatty acid methyl esters (FAME) yield of 90% was obtained when the reaction was performed with methanol/microalgae oil molar ratio of 6:1, catalyst amount of 3%, and reaction temperature at 65°C for 3 h by using the 30% CaO/dolomite catalyst.

Demand on energy from alternative fuels are growing rapidly due to depletion of fossil fuels and global warming crises. Biodiesel instead of conventional petroleum diesel, is a non toxic, biodegradable and renewable fuels. Therefore, biodiesel can be considered as a promising liquid fuel for transport sector. Among the routes of biodiesel synthesis, the most commonly used are transesterification of oil feedstocks and esterification of free fatty acids, in which these are carried forward in the presence of a catalyst. In transesterification process, a large majority of feedstocks come from vegetable/edible oil, as the first generation biodiesel feedstocks, in many regions of the world. The use of edible oils is not convenient in production of biodiesel due to insufficient amount of edible oil feedstocks and demand for food materials in the world. When it is thought that over 70% of price of biodiesel includes cost of feedstocks, use of cheaper and more sustainable resources have become inevitable. Waste cooking oil and algae oil, which have not been used as food sources, are termed as second generation feedstocks and seem more attractive and promising for biodiesel production. In addition to raw material source, the type of alcohol and catalyst also affects to price and quailty of biodiesel. Since biodiesel is a process includes sustainable technology, all inputs are investigated in terms of usability, sustainability and eco-friendly. The aim of this study to give an overwive on the biodiesel production in that select of the most effective and available feedstocks and summarize the recent development and innovation in the production process.