Novel MOF Grown on Ni foam as a Ex Situ Absorptive Medium for the Remediation of Hg Polluted Water in Surface Water

Abstract

A novel metal organic framework (MOF) was fabricated on the surface of an open cell nickel foam and employed as a selective sorbent for Hg²⁺ dissolved in surface water. Two organic ligands (2-amino-teraphthalate and 4,4-dipyridyl) were combined with Ni(NO₃)₂ and grown on a Ni foam (95% porosity) to generate a P41 symmetric MOF with an internal 2.487 Å pore size and an active amino moiety serving as a binding site for Hg²⁺ and other heavy metals, characterized by XRD, and a lenticular crystal habit producing relatively well distributed spherical crystals, characterized by SEM-EDX. Adsorption experiments were conducted in both deionized water and mercury spiked into river water at concentrations typical for polluted areas ([Hg²⁺] ~ 4, 40, and 400 ppb). The adsorption effect was characterized by Au-stabilized ICP-MS, finding highly favorable adsorptive efficacy, exhibiting adsorption capacities of 201.31 mg/g, 25.68 mg/g, and 3.017 mg/g, at initial concentrations of 400 ppb, 40 ppb, and 4 ppb, respectively. The coating of the MOF on the metal foam modulated the adsorption behavior of the MOF, maximizing the effective surface area of the adsorbent and thereby reversing the otherwise inverse relationship of % adsorbed with respect to increasing Ci.