Design of l-Cysteine Functionalized UiO-66 MOFs for Selective Adsorption of Hg(II) in Aqueous Medium

Mercury ions can cause a series of hazards to humans and the environment, even in trace amounts. Here, we designed a novel adsorbent (Cys-UiO-66) by functionalizing NH₂-UiO-66 with l-cysteine for selective removal of Hg(II) from solution. The Cys-UiO-66 was characterized by different instruments. The adsorption property of Cys-UiO-66 was evaluated by batch methods. The maximum adsorption capacity was 350.14 mg/g at pH 5.0. Furthermore, the adsorption isotherm and kinetics models were in accord with the Langmuir and pseudo-second-order models, respectively, evidencing that the adsorption behavior was dominated by monolayer chemisorption. The Cys-UiO-66 had better affinity for Hg(II) than other coexisting ions in wastewater and could be regenerated for at least five cycles. The results prove that Cys-UiO-66 is a talented and efficient sorbent for mercury ions.