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Background: Dental clinics are known to be one of the largest users of Toxic inorganic mercury. It is well documented that dentists and dental assistants who work with amalgam are chronically exposed to mercury vapor. This study investigates exposure to mercury vapor in a dental clinic. Methods: GBC cold vapor atomic absorption spectrometry (AAS), using sodium borohydride as the reducing agent, was employed to determine mercury concentrations. The determination of mercury in urine and air was carried out using a flow injection system after sample treatment according to the standard procedure. Result: In this study mercury exposure in some dentist and dental office personnel was examined. We studied 495 persons (280 dentists and 215 dental personnel) occupationally exposed to mercury while working at 58 dental clinics in Tehran. In addition 305 samples from dental office’s air were taken and their mercury was measured with HG-AAS. Conclusion: In this study, mercury levels in dentists urine and dental office atmosphere were lower than occupational safety and health administration (OSHA). Results acquired from this study show that the amount of mercury were in normal range and it is lower than to the potential for adverse exposure to elemental mercury vapor concentration in a dental office.

Hassan Zavvar Mousavi, Ahmad Rouhollah, Hamid Shirkhanloo

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the aim of this study was to investigate the removal of toluene from air through Nano-graphene modified by ionic liquid (NG-IL). The batch adsorption experiments in glass bottle of gas chromatography equipped with flame ionization detector (GC-FID) were used. Graphene ultrahigh-quality synthesized by substrate-free gas-phase method in a single step and graphene sheets were deposited with ionic- liquid by thermal adsorption in acetone blank solution. Various conditions including contact time, amount of adsorbent, adsorbate concentration, humidity, and temperature were studied and optimized. NG-IL adsorbent was used for the adsorption of toluene vapor from gaseous media and the effect of different conditions such as; toluene concentration, humidity, and temperature on the adsorption were investigated. The Langmuir adsorption isotherms were employed for toluene by NG-IL adsorbent. The adsorption capacity was decreased by raising the sorbent humidity above of 50 percent. The toluene capture capacity for NG-IL was 126 mg/g. The results of SEM, XRD and TEM showed that the NG-IL have beneficial surfaces for toluene removal. NG-IL as a novel adsorbent has not previously been used for the adsorption of pollutants.

HAMID SHIRKHANLOO, MAHMOOD OSANLOO, and ORKIDEH QURBAN DADRAS