Transformer oils as a potential source of environmental exposure to polychlorinated biphenyls (PCBs): an assessment in three central provinces of Iran

Environmental Science and Pollution Research - Polychlorinated biphenyl (PCB) contamination of oils from all transformers of the national electrical grid in Tehran, Qom, and Alborz, three central...     

Harvesting of microalgae biomass from the phycoremediation process of greywater

The wide application of microalgae in the field of wastewater treatment and bioenergy source has improved research studies in the past years. Microalgae represent a good source of biomass and bio-products which are used in different medical and industrial activities, among them the production of high-valued products and biofuels. The present review focused on greywater treatment through the application of phycoremediation technique with microalgae and presented recent advances in technologies used for harvesting the microalgae biomass. The advantages and disadvantages of each method are discussed. The microbiological aspects of production, harvesting and utilization of microalgae biomass are viewed.     

Room temperature synthesis of 2H-1,4-benzoxazine derivatives using a recoverable ionic liquid medium

2H-1,4-Benzoxazines are major heterocyclic compounds with interesting biological and synthetic applications. Therefore, it would be very interesting to develop new efficient methods for their synthesis. Here, we synthesized 2H-1,4-benzoxazines in one pot using K₂CO₃/H₂O in the ionic liquid of choice, [omim][BF₄]. After reactions, products are extracted from [omim][BF₄] by Et₂O and the ionic liquid is recovered and successfully reused over several recycles. Results show that high yields of 3-aryl-2H-1,4-benzoxazine derivatives are obtained chemoselectively at room temperature from their corresponding o-aminophenols and phenacyl bromides. To our knowledge, our method represents the most efficient and straightforward route for the synthesis of 3-aryl-2H-1,4-benzoxazine derivatives in short times and under environmentally benign conditions.     

Effect of water and temperature on ammonia volatilization of maize straw returning

ABSTRACT

Ammonia volatilization is an important nitrogen (N) loss pathway in agricultural production and consequent significant atmospheric pollutant. The primary objective of this study was to (1) examine effects of environmental factors such as temperature and soil water capacity, as well as crop residue (CR) addition as fertilizer, on ammonia (NH₃) volatilization, and (2) search for a comprehensive management strategy to reduce accumulative ammonia volatilization (AAV). A bench-scale cultivated experiment was conducted at two environment temperatures (15 or 25 °C), three forms of soil water capacity (30%, 50%, or 70% soil field moisture capacity), and two treatments of fertilizers (conventional fertilizer urea and straw returning – 10% of total N application arising from maize straw and remainder from conventional urea). Results showed that AAV was markedly decreased by adjusting soil water capacity, temperature, and CR addition. Significant quantified exponential correlation between AAV and soil moisture was observed. More than 70% AAV was reduced in intermediate 50% and high 70% soil moisture compared to low 30%. AAV was less sensitive to temperature than soil moisture using black soils. Only in low soil moisture, AAV rose with increasing of temperature. Straw restoration addition decreased significantly the AAV loss.     

A detailed kinetic investigation on the effects of hydrogen enrichment on the performance of gas-fueled SI engine

This study investigates the effects of hydrogen enrichment on formation of pollutants and greenhouse gases in gas-fueled spark ignition engines. To this end, a previously validated detailed mechanism is embedded with a comprehensive one-dimensional engine model and the results are verified with experimental observations at different compression ratios and engine loads. The simulations are then performed for different mixtures of hydrogen and natural gas. The results indicate that adding hydrogen increases the cylinder peak pressure at different loads and compression ratios, despite the fact that reduces the amount of carbon monoxide, carbon dioxide, and methane in all the conditions.