Showing 2 results for Kakaei
Hojatolla Kakaei, Mojtaba Beygzadeh, Farideh Golbabaei, Mohammad Reza Ganjali, Mehdi Jahangiri, Sayed Jamaleddin Shahtaheri,
Volume 9, Issue 4 (12-2019)
Abstract
Introduction: Hydrogen sulfide is one of the most important impurities in natural gas. Due to the fact that this gas is hazardous, toxic, corrosive and volatile, therefore, the removal of hydrogen sulfide has been studied using several methods. One of the most known procedures is the adsorption process. In the present study, activated carbon and activated carbon-based composite scaffolds (MOF-5) were used as a cartridge mask to remove hydrogen sulfide from respiratory air.
Methods and Materials: First, activated carbon (AC) was converted to powder form by ball mill, and AC / MOF-5 composite with 10%, 25%, and 40% MOF-5 to AC was synthesized from the MOF-5 metal-organic scaffold. Then, the rates of adsorption and breakthrough time using a designed setup were tested in two ranges of temperatures, humidities and concentrations. XRD, SEM and BET were used to determine the properties of composite absorbents. The Aeroqual S500 Direct-reading sensor with 0.01 ppm accuracy was used to measure the exact amount of hydrogen sulfide gas.
Results: The AC/MOF-5 composite showed higher adsorption and breakthrough time compare to the other adsorbents. The Specific surface area (BET), average pore diameter, and total pore volume of the adsorbent were 814 m2 /g, 1.6795 nm, and 0.342 cm3 /g, respectively. The isotherm diagram showed that, according to IUPAC, most of the pore size of this adsorbent was classified in the micro-porous group. The maximum adsorption (mg/gS) and breakthrough time (min) were related to AC/MOF-5(40 Wt. %) adsorbent with 60.41 mg/gS (SD = 1.08) and 56.26 min (SD =2.38) at a temperature of 15 ° C, a concentration of 9.88 ppm (SD = 0.70), a moisture content of 51.06% (SD = 0.15) and a pressure drop of 51.34 mm water. By adding more than 25% MOF-5 metal-metal scaffold to activated carbon, the amount of adsorption, breakthrough time and pressure drop were increased.
Conclusion: AC / MOF-5 composite adsorbent due to its porous structure, high specific surface area, and most importantly, having Zn-O-C groups increased the adsorption rate as well as the pollutant Breakthrough time. However, it showed a relatively higher pressure drop than commercial activated carbon (AC).
Hossein Ali Rangkooy, Behzad Fouladi Dehaghi, Maedeh Kamalvandi, Hojatollah Kakaei,
Volume 14, Issue 3 (10-2024)
Abstract
Introduction: Exposure to various chemicals can occur in the workplace. Polycyclic aromatic hydrocarbons (PAHs) are among these compounds. The aim of this study was to investigate the relationship between exposure to PAHs and urinary metabolites among built-up roofing installers.
Material and Methods: The current case-control study, conducted in 2021 in Ilam City, involved 35 built-up roofing workers as the case group and 15 non-exposed workers as the control group. In this study, in addition to the workers’ respiratory area, samples were taken from the urine to determine the amount of PAHs metabolites. HPLC was used to analyze the samples. The collected data were analyzed using SPSS software version 22.
Results: The mean concentrations of PAHs including naphthalene, phenanthrene, fluorne, pyrene, benzo(a)pyrene, benzo (ghi)perylene and indeno 1,2,3 cd pyrene were 440.26±80.07, 70.49±24.36, 15.18±5.98, 31.21±10.36, 2.15±1.41, 2.25±0.07 and 1.18±0.06 ng/m3, respectively, in respiratory area of the workers. Also, the average level of compounds 1- naphthol, 2- naphthol, 2-hydroxyfluorene, 3-hydroxyfluorne, 1-hydroxyfenanterol, 2+3-hydroxyfenanterol and 1- hydroxypyrene, present in the urine of the population, was obtained equal to 2±1.02, 6.03±2.5, 0.18±0.15, 0.14±0.1, 0.19±0.08, 0.04±0.02 and 0.34±0.26 μg/g creatinine, respectively. Statistical test showed that the values of these compounds were significantly different in the two groups (p <0.05).
Conclusion: Estimating the concentration of aromatic hydrocarbons in the respiratory area of built-up roofing workers showed the noticeable exposure to these compounds, although lower than the allowable limits. However, due to the high carcinogenic nature of these compounds, it is recommended to use appropriate personal protective equipment such as respirators and appropriate work outfits in addition to the technical strategies to combat the exposure.
