EDTA functionalized ordered SBA-۱۵ mesoporous silica as an effective adsorbent for preconcentration of some heavy metal ions followed by ICP-AES

Heavy metal ions create serious environmental and public concerns at a global scale. Inductively coupled plasma atomic emission spectrometry (ICP-AES) has been reported for determination of metal ions. For determination of trace metal ions in complicated environmental samples, the direct analysis of them by analytical instruments is usually difficult. Therefore, sample pretreatment is necessary and unavoidable. The large pore size (۲-۵۰ nm) of mesoporous silica adsorbents provides high specific surface area for the uptake of pollutants from water samples. The coordination sites of ethylenediaminetetraacetate (EDTA) include two amines and three carboxylate groups, which can be occupied with heavy metal ions to form a stable (۱:۱) complex.The aim of this work was to develop a simple, efficient, and sensitive method to extract and preconcentrate Co۲+, Mn۲+, Cu۲+, Zn۲+, Fe۳+, and Cd۲+ with EDTA functionalized ordered mesoporous silica (EDTA-SBA-۱۵) as a potential adsorbent. The extracted ions were eluted and analyzed by the flow injection ICP-AES.The effect of analytical parameters, such as the sample pH, amounts of the adsorbent, adsorption and desorption times, sample volume, eluent type, eluent volume on the extraction efficiency of the metal ions were investigate. Under optimized conditions, the limits of detection of Co۲+, Mn۲+, Cu۲+, Cd۲+, Zn۲+, and Fe۳+ were found to be ۵۰, ۵, ۱۰, ۵۰, ۱۰, and ۵۰۰ ng L-۱, and the relative standard deviations for determination of ۵۰ μg L-۱ were ۵.۳, ۵.۳, ۴.۶, ۱.۷, ۴.۴, and ۵.۷۸% (n = ۴), respectively. Linear ranges were obtained for the selected metal ions including Co۲+, Cu۲+, Cd۲+, Zn۲+ (۰.۱-۲۵۰ μg L-۱), Fe۳+ (۱-۲۵۰ μg L-۱), and Mn۲+ (۰.۰۱-۲۵ and ۵۰-۵۰۰ μg L-۱) with perfect correlation coefficients (R = ۰.۹۹۵۸-۰.۹۹۹۶, n = ۸). The applicability of the introduced adsorbent was evaluated by the extraction and determination of the heavy metal ions in different environmental water samples.