Application of a terephthalate and pyrazine-based MOF in Cr adsorption

Metal-organic frameworks (MOFs) are a group of high-porosity materials that had been studying for enormous applications. Today, with increasing the human population and the growth of technology and industry, the entry of various chemical and microbial contaminants such as toxic substances, heavy metals and hospital wastewater into the ecosystem creates new health problems and important health hazards for human and other creatures.[1]

Several methods have been used to remove heavy metals from water, including ion exchange, membrane filtration, chemical deposition, and adsorption in the past two decades. Due to the effectiveness, economic value, flexibility of design and reversibility, absorption techniques are currently one of the technologies used to remove heavy metals. According to the literature, one of the most important features of a good absorbent is its selectivity. Many factors such as electrostatic interactions, covalent interactions, pore size and shape can affect the absorption selectivity.[2]

In order to achieve the purpose of designing MOFs with the ability to absorb metallic contaminants, a metal-organic framework with the formula of [CoNi(µ₃-tp)₂(µ₂-pyz)₂[ containing nickel and cobalt ions and two types of ligands including terephthalic acid (H₂tp) and pyrazine (pyz) was prepared.

In this paper, the adsorption behavior of the named framework was investigated for removal of heavy metal ions and, according to ICP data, it was shown that the Cr ions, as a serious metallic pollutant have a high uptake.