Superselective Hg(II) Removal from Water Using a Thiol-Laced MOF-Based Sponge Monolith: Performance and Mechanism

Abstract

Point-of-use (POU) devices with satisfying mercury (Hg) removal performance are urgently needed for public health and yet are scarcely reported. In this study, a thiol-laced metal–organic framework (MOF)-based sponge monolith (TLMSM) has been investigated for Hg­(II) removal as the POU device for its benchmark application. The resulting TLMSM was characterized by remarkable chemical resistance, mechanical stability, and hydroscopicity (>2100 wt %). Importantly, the TLMSM has exhibited high adsorption capacity (∼954.7 mg g–1), fast kinetics (k f ∼ 1.76 × 10–5 ms–1), broad working pH range (1–10), high selectivity (K d > 5.0 × 107 mL g–1), and excellent regeneration capability (removal efficiency >90% after 25 cycles). The high applicability of TLMSM in real-world scenarios was verified by its excellent Hg­(II) removal performance in various real water matrices (e.g., surface waters and industrial effluents). Moreover, a fixed-bed column test demonstrated that ∼1485 bed volumes of the feeding streams (∼500 μg L–1) can be effectively treated with an enrichment factor of 12.6, suggesting the great potential of TLMSM as POU devices. Furthermore, the principal adsorption complexes (e.g., single-layer -S-Hg-Cl and double-layer -S-Hg-O-Hg-Cl and -S-Hg-O-Hg-OH) formed during the adsorption process under a wide range of pH were synergistically and systematically unveiled using advanced tools. Overall, this work presents an applicable approach by tailoring MOF into a sponge substrate to achieve its real application in heavy metal removal from water, especially for Hg­(II).

Proton Self-Enhanced Hydroxyl-Enriched Cerium Oxide for Effective Arsenic Extraction from Strongly Acidic Wastewater

“…The parameters (i.e., rate constants) obtained from the pseudo-kinetic models typically depend on the adsorbent dose and are not appropriate for engineering design. , Therefore, the mass flow rate equation was employed to describe the adsorption kinetics of As­(III) or As­(V) on CeO 2 –OH-1, CeO 2 –OH-2, and CeO 2 –OH-3. Thus, the experimental parameters can be used for engineering analysis and design . The mass flow rate equation is expressed as eqs and . where C is the concentration of As­(III) or As­(V) (mg/L) in bulk solution at time t and C s is the concentration of As­(III) or As­(V) at the interface (mg/L).…”

“…Thus, the experimental parameters can be used for engineering analysis and design. 34 The mass flow rate equation is expressed as eqs 1 and 2.…”

Coordination/cation exchangeable dual sites intercalated multilayered T3C2Tx MXene for selective and ultrafast removal of thallium(i) from water

“…The adsorption capacity and removal percentage of Tl + was calculated by using the following equations:where q e (mg g −1 ) refers to the adsorption capacity of KOH@Ti 3 C 2 T x NSs; C 0 (mg L −1 ) represents the initial concentration of Tl + ; C e (mg L −1 ) indicates the equilibrium concentration of Tl + ; V (L) is the working volume, and m (g) is the mass of adsorbent. 2,33–39 The data from the isothermal experiments were analyzed by Langmuir, Freundlich, Dubinin–Radushkevich models and thermodynamics calculations. Kinetic adsorption data fitted by pseudo-first-order and pseudo-second-order models were used to reveal the adsorption process.…”

Customization of functional MOFs by a modular design strategy for target applications

“…As shown in Figure 2C, FM-MOF-6 displayed extremely high Hg 2+ uptake. By fitting with Langmuir model, the saturated adsorption capacity of FM-MOF-6 for Hg 2+ was determined to be 1077 mg g -1 , which is about 1.4 times higher than that of FM-MOF-1, surpassing various MOF adsorbents Supplementary Table 2 [38][39][40][41][42][43][44][45][46][47][48] . In addition, we also investigated the adsorption kinetics of FM-MOF-6 toward Hg 2+ .…”