Heavy metals are potentially toxic to living organisms. Heavy metals and metalloids that are not necessary for metabolic activities, may be toxic to the cells even at quite low concentrations. Environmental exposure to heavy metal ions is a well-known risk factor for the health of human, plants, and animals. Therefore, effective separation of heavy metals from different matrices and their consequent preconcentration for sensitive determination is an important issue. Direct determination of heavy metal ions which are present in real matrices such as natural water, wastewater, plant, soil, and sediment are not possible with general analytical techniques such as atomic absorption spectrometry (AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES), due to the matrix effect of foreign ions and low concentration of the analytes. Therefore, it is necessary to separate/extract and preconcentrate the trace elements, before their analysis, to remove interferes and to enhance the concentration.
Solid-phase extraction (SPE) is one of the most powerful techniques for separation and enrichment of various inorganic and organic analytes that has been used for separation of heavy metals. The most important factor of SPE is the use of a stable phase, including features such as porosity and high contact surface, reversible absorption, high purity, good chemical stability, and high recovery rates. Moreover, high selectivity and cost-efficiency are two important challenges for an adsorbing medium that may be used in a SPE process. In addition, SPE technique should be applicable for high rates of fluids and samples to be processed; thereby, making SPE usable widely in different industries.
Hence, considering the widespread application of the SPE method, there is a need for development of efficient, cost-effective, flexible, and green usable phases for heavy metal ions in SPE field. Additionally, there is a need for a SPE method that may be used continuously to separate heavy metals from fluids with high flow rates and volumes with high sorption efficiencies. Moreover, there is a need for a SPE method and apparatus with high selectivity for different metals.