چكيده به لاتين
Abstract
Heavy metals are a kind of pollutant in the environment which is increasing gradually due to the industrial growth of the societies and increase in number of factories all around the world. These heavy metals have devastating effects on the quality of agricultural products, the health of aquatic animals and human beings. In this work, solid phase extraction (SPE) method was applied in order to preconcentrate and evaluates the trace amounts of heavy metal ions (lead, mercury) by using modified magnetic adsorbent.
In the first research for preconcentration and determination of mercury ions with initial concentration of 10µg/L, the magnetic graphene oxide modified by 2-pyridinecarboxaldehyde thiosemicarbazone groups was used as sorbent. The optimum conditions obtained: pH:5, absorption time 4 minute, desorption time by Vortex 4 minute, the volume of eluent (HCl, 0.1 M) 0.5 ml and dosage of adsorbent 8 mg. Finally the maximum preconcentration factor of 190 and the extraction percentage of 99.6% was achieved the. Values of RSD and detection limit were less than 2% and 0.0079 µg/L, respectively.
In the second research program, Magnetic graphene oxide functionalized with amine ligands dipyridyl amine was utilized as an adsorbent. Initial concentration of lead was kept at the constant concentration of 30 µg/L.
. The optimum conditions were: pH: 5, the absorption time 4 minute, desorption time using ultrasonic bath 2 minute, the volume of eluent (HNO3, 1 M) 0.5 ml and dosage of adsorbent 12 mg. In this work, maximum preconcentration factor of 483.6, the extraction percentage of 98.21%, RSD of less than 3% and the detection limit of 0.05 µg/L were obtained.
To carry out the project, Chemometrics and Experimental Design methods was used to investigate the effect of important factors on extraction efficiency, simultaneously as well as to perform the experimental runs and to determine the optimum condition of preconcentration and determination.
The real samples studied in the current project were water samples (mineral water, well water, and plating) and food samples (fish, milk, rice and tea). Extraction percentage of mercury ions in fish, rice, tea, milk, mineral water and tap water were 92.9, 93.4, 98.2, 93.8, 100 and 98.6%, respectively. The values of this parameter for lead ions in mineral water, well water and plating water were 98.2, 90.6 and 74.5%, respectively.
Keywords: Solid phase extraction, Ultrasound bath, Preconcentration factor, Lead, Mercury, Experimental design
