Abstract
M.Tech. (Chemistry)
The main objective of this study is to develop simple, sensitive and fast solid phased based microextraction methods for selective removal of arsenic in environmental samples. Different nanoadsorbents (CoFe2O4@SiO2, Co1+xZrxFe2-2xO4 (x=0.3) and Ni0.5Zn0.5Fe2O4 ) were synthesized and characterized using scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM–EDS), BET transmission electron microscopy (TEM) and x-ray diffractometer (XRD). The nanoadsorbents were used to develop three microextraction methods and the findings are summarized in the subsequent paragraphs.
A separation/preconcentration of trace arsenic in environmental samples using micro solid-phase extraction (μ-SPE) using CoFe2O4@SiO2 magnetic nanoparticles (MNP) prior to ICP-OES determination was developed. Optimal experimental conditions including pH, adsorbent mass, and eluent acid concentration were found to be 3, 100 mg and 5 mol L-1 HCl, respectively. The adsorption capacity of the MNPs of As was found to be 8.5 mg g-1. Under optimum conditions, the analytical limits of detection (LOD) and limits of quantification (LOQ) were found to be 2.8 and 9.2 μg L-1, respectively. The accuracy of the method was tested by analyzing certified waste water (CWW-TM-D) and the recoveries were found to be greater than 90%. The method was successfully applied to the determination of trace amounts of As in river and tap water samples.
The adsorption characteristics of Co1+xZrxFe2-2xO4 as a active material for separation and preconcentration of total arsenic from aqueous solution was investigated. Under optimized experimental conditions, the LOD, LOQ, dynamic linear range, and precision were 0.57 μg L-1, 1.9 μg L-1, 2.0- 70 μg L-1, and 1.5%, respectively. The accuracy of the method was tested by analyzing certified reference material and the μ-SPE procedure was successfully applied for the preconcentration of As in river water.
A preconcentration technique based on stir bar sorptive-dispersive microextraction (SBSDμE) has been developed. Depending on the stirring rate, the magnetic nanoparticles act as either a coating material to the stir bar thus following SBSE system, or as a dispersed nanoadsorbent for separation of the analyte thus corresponding to the DμSPE technique. The optimization of the SBSDμE procedure was carried out by using a two level fractional factorial design with three central points. The adsorption capacity of the magnetic nano-sorbent was found to be 22.51 mg g-1. Under optimized experimental conditions, the method showed good analytical features in terms of linearity (0.350-142.1 μg L-1), limit of...