Iranian Journal of

Background and Objective: Transportation sector generates the largest share of greenhouse gas emissions (CO₂ and CH₄) which causes global warming. “Stop-and-go” driving and congested traffic flow results in a decrease in average car speeds, an increase in traffic incidents, and finally escalates GHGs emissions. Hence, congestion is directly related to carbon emissions. The objective of this study was to estimate the GHGs emissions of urban transportation sector using the congestion index.
Materials and Methods: The traffic flow in the main street of Hamadan city was continuously monitored in 8 time periods from 8 am to 12 pm in August 2018. Then, a traffic congestion map was prepared. Subsequently the surface area and weight coefficient of each road were obtained based on the traffic assignment model. Finally, the amount of GHGs emissions from transportation sector, CO₂ emission per capita, and annual amount of CO₂ and CH₄ release in each street were calculated and estimated.
Results: Results showed that the total CO₂ and CH₄ emissions from the transportation sector of Hamadan city are 776000 and 396 ton/year, respectively. Imam Khomeini Highway (29166 ton CO₂/year) and Mirzadeh Eshghi Street (24453 ton CO₂/year) recorded the highest level of carbon emission due to the highespeed and more width “stop and go” driving conditions.
Conclusion: The conformity of the congestion index with the traffic assignment model can be used to estimate the amount of urban traffic pollution. Finally, because of the high growth rate of CO₂ and CH₄ and the role of forests in maximizing carbon sequestration, it is imperative to manage and increase green spaces to reduce CO₂.

Background and Objective: Among greenhouse gases, CO₂ has a crucial role; thus, its impact on health indicators such as life expectancy is of great importance. Hence, one of the most important challenges in the health sector has been the impact of the environmental pollutants emission, namely CO₂, on life expectancy of men and women.
Materials and Methods: This is a descriptive-analytical and applied design with the health economics approach. The present paper examined the impact of pollutant emissions, namely CO₂, per capita income, death rate and birth rate, separately on Iranians’ life expectancy. This analysis was conducted using Quantile regression with EViews10 software during the period 1960 - 2019. In this study, first, the impact of pollutant emissions on life expectancy of all Iranians was calculated. Then, the impact of CO₂ on life expectancy of Iranian men and women in different quantiles was estimated.
Results: The results confirm the impact of carbon dioxide emissions per capita on total life expectancy was -0.133 and the impact of this pollutant emission on life expectancy obtained -0.170 and -0.127 for men and women, respectively. Both effects were estimated as negative and significant. This effect on life expectancy of men was 0.43% higher than that of women. Furthermore, the impact of death on life expectancy was negative, while the effect of per capita income on life expectancy was positive. Also, birth rate had a positive impact on women's life expectancy, whereas, it showed a negative impact on men.
Conclusion: The study revealed that CO₂ emissions had a negative impact on total life expectancy of both men and women. Thus, in order to increase life expectancy in Iran, pollutants emission, namely CO₂, should be controlled. These results can be a good guide to decision makers and macro-policy makers in Iran to control environmental pollutants to increase life expectancy.
 

Background and Objective: One of the major challenges in the calcium looping process is the loss of CO₂ capture capacity of calcium-based sorbents during consecutive cycles due to increased sintering mechanism. This article aims to improve the performance of carbonation conversion in different cycles by employing hydration and acidification methods.
Materials and Methods: Following the preparation of both  CaO-based and modified sorbents, scanning electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller analyses were employed to verify the proper preparation of the sorbents and examine their structures. Subsequently, the adsorption performance of different samples was assessed using a thermogravimetric analyzer device .
Results: The results of the carbonation reaction showed that the effective conversion rates for the raw and modified sorbents, employing acidification and hydration methods, at the end of the first cycle were 75%, 86%, and 73%, respectively. By the twentieth cycle, these rates decreased to 24%, 38%, and 26%, respectively. This decline indicates an improvement in the sorbent's capture capacity, attributed to the formation of calcium acetate, resulting in a more stable and porous structure. The findings from utilizing raw limestone sorbents and their modified versions through acidification and hydration techniques demonstrated a decrease in sorbent capture capacity by 69, 58, and 67% across twenty cycles. This highlights the enhanced sorbent stability achieved with the acidification method.
Conclusion: Based on obtained results, acidification method can be considered as one of the most efficient approaches for improving the performance of calcium oxide sorbents.
 

Background and Objective: The global increase in energy consumption has led to a rise in carbon dioxide emissions, causing significant and often irreparable damages such as global warming. This study investigates the adsorption capacity of hairy nanocrystalline cellulose as a novel adsorbent and seeks to enhance its performance in carbon dioxide capture by modifying it with two types of amines: monoethanolamine and diethanolamine.
Materials and Methods: Hairy nanocrystalline cellulose was synthesized through oxidation and amine modification. The formation of chemical groups and sample morphology was analyzed using Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Additionally, thermogravimetric analysis was performed at two temperatures (25 and 50 °C) and two concentrations (10% and 90% carbon dioxide in nitrogen) to evaluate the adsorption capacity of the samples.
Results: The results showed that at 25 °C and a carbon dioxide concentration of 90%, the adsorption capacities of hairy nanocrystalline cellulose, cellulose modified with 20% by weight of monoethanolamine, and cellulose modified with 20% by weight of diethanolamine were 1.74, 2.5, and 1.96 mmol/g, respectively. These findings indicate that modifying the adsorbent with monoethanolamine increased its carbon dioxide adsorption capacity by approximately 44%, while modification with diethanolamine resulted in a 13% improvement.
Conclusion: The findings suggest that hairy nanocrystalline cellulose, particularly in its modified forms, holds significant promise as a novel and effective adsorbent for carbon dioxide capture.