An official website of the United States government
A novel rhodamine-6G derivative, RdN, was synthesized by condensing rhodamine glyoxal and 3-hydroxy-2-naphthoic hydrazide using a microwave irradiation-assisted reaction. Colorimetric and photophysical studies have demonstrated that the molecule produced can selectively sense Pb2+ and Cu2+ ions in a solution of CH3CN/H2O (9:1, v/v). The spirolactam ring of RdN opens upon complexation with the cations, forming a highly fluorescent complex and a visible color change in the solution. The compound RdN was further studied with the help of computational methods such as the Density Functional Theory (DFT) method and time-dependent density functional theory (TD-DFT) calculations to study the binding interactions and properties of the molecule. DFT calculations and job plot data supported the 2:1 complex formation between RdN and Pb2+/Cu2+. The limit of detection for Pb2+ was determined to be 0.112 µM and 0.130 µM for Cu2+. The probe RdN was applied to the image of Pb2+ and Cu2+ ions in living cells and is safe for biomedical applications. It is used to monitor Pb2+ in environmental water samples.
more »
« less
This content will become publicly available on February 1, 2026
Efficient Sequestration of Heavy Metal Cations by [Mo2S12]2− Intercalated Cobalt Aluminum-Layered Double Hydroxide
Heavy metal cations such as Ag+, Pb2+, and Hg2+ can accumulate in living organisms, posing severe risks to biological systems, including humans. Therefore, removing heavy metal cations from wastewater is crucial before discharging them to the environment. However, trace levels and high-capacity removal of the heavy metals remain a critical challenge. This work demonstrates the synthesis and characterization of [Mo2S12]2− intercalated cobalt aluminum-layered double hydroxide, CoAl―Mo2S12―LDH (CoAl―Mo2S12), and its remarkable sorption properties for heavy metals. This material shows high efficiency for removing over 99.9% of Ag+, Cu2+, Hg2+, and Pb2+ from 10 ppm aqueous solutions with a distribution constant, Kd, as high as 107 mL/g. The selectivity order for removing these ions, determined from the mixed ion state experiment, was Pb2+ < Cu2+ ≪ Hg2+ < Ag+. This study also suggests that CoAl―Mo2S12 is not selective for Ni2+, Cd2+, and Zn2+ cations. CoAl―Mo2S12 is an efficient sorbent for Ag+, Cu2+, Hg2+, and Pb2+ ions at pH~12, with the removal performance of both Ag+ and Hg2+ cations retaining > 99.7% across the pH range of ~2 to 12. Our study also shows that the CoAl―Mo2S12 is a highly competent silver cation adsorbent exhibiting removal capacity (qm) as high as ~918 mg/g compared with the reported data. A detailed mechanistic analysis of the post-treated solid samples with Ag+, Hg2+, and Pb2+ reveals the formation of Ag2S, HgS, and PbMoO4, respectively, suggesting the precipitation reaction mechanism.
more »
« less
- Award ID(s):
- 2100797
- PAR ID:
- 10639145
- Publisher / Repository:
- MDP
- Date Published:
- Journal Name:
- Inorganics
- Volume:
- 13
- Issue:
- 2
- ISSN:
- 2304-6740
- Page Range / eLocation ID:
- 50
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
null (Ed.)A highly porous adsorbent based on a metal–organic framework was successfully designed and applied as an innovative adsorbent in the solid phase for the heavy metal removal. MIL-125 was densely decorated by 2-imino-4-thiobiuret functional groups, which generated a green, rapid, and efficacious adsorbent for the uptake of Hg( ii ) and Pb( ii ) from aqueous solutions. ITB-MIL-125 showed a high adsorption affinity toward mercury( ii ) ions of 946.0 mg g −1 due to covalent bond formation with accessible sulfur-based functionality. Different factors were studied, such as the initial concentration, pH, contact time, and competitive ions, under same circumstances at the room temperature. Moreover, the experimental adsorption data were in excellent agreement with the Langmuir adsorption isotherm and pseudo-second order kinetics. At a high concentration of 100 ppm mixture of six metals, ITB-MIL-125 exhibited a high adsorption capacity, reaching more than 82% of Hg( ii ) compared to 62%, 30%, 2%, 1.9%, and 1.6% for Pb( ii ), Cu( ii ), Cd( ii ), Ni( ii ), and Zn( ii ), respectively.more » « less
-
null (Ed.)Heavy metal ions are highly toxic and widely spread as environmental pollutants. This work reports the development of two novel chelating adsorbents, based on the chemical modifications of graphene oxide and zirconium phosphate by functionalization with melamine-based chelating ligands for the effective and selective extraction of Hg( ii ) and Pb( ii ) from contaminated water sources. The first adsorbent melamine, thiourea-partially reduced graphene oxide (MT-PRGO) combines the heavier donor atom sulfur with the amine and triazine nitrogen's functional groups attached to the partially reduced GO nanosheets to effectively capture Hg( ii ) ions from water. The MT-PRGO adsorbent shows high efficiency for the extraction of Hg( ii ) with a capacity of 651 mg g −1 and very fast kinetics resulting in a 100% removal of Hg( ii ) from 500 ppb and 50 ppm concentrations in 15 second and 30 min, respectively. The second adsorbent, melamine zirconium phosphate (M-ZrP), is designed to combine the amine and triazine nitrogen's functional groups of melamine with the hydroxyl active sites of zirconium phosphate to effectively capture Pb( ii ) ions from water. The M-ZrP adsorbent shows exceptionally high adsorption affinity for Pb( ii ) with a capacity of 681 mg g −1 and 1000 mg g −1 using an adsorbent dose of 1 g L −1 and 2 g L −1 , respectively. The high adsorption capacity is also coupled with fast kinetics where the equilibrium time required for the 100% removal of Pb( ii ) from 1 ppm, 100 ppm and 1000 ppm concentrations is 40 seconds, 5 min and 30 min, respectively using an adsorbent dose of 1 g L −1 . In a mixture of six heavy metal ions at a concentration of 10 ppm, the removal efficiency is 100% for Pb( ii ), 99% for Hg( ii ), Cd( ii ) and Zn( ii ), 94% for Cu( ii ), and 90% for Ni( ii ) while at a higher concentration of 250 ppm the removal efficiency for Pb( ii ) is 95% compared to 23% for Hg( ii ) and less than 10% for the other ions. Because of the fast adsorption kinetics, high removal capacity, excellent regeneration, stability and reusability, the MT-PRGO and M-ZrP are proposed as top performing remediation adsorbents for the solid phase extraction of Hg( ii ) and Pb( ii ), respectively from contaminated water.more » « less
-
null (Ed.)Rice husks are an agricultural residue of great annual production and have a high cellulose content. In this study, we have prepared highly charged carboxyl cellulose nanofibers (CNFs) from rice husks using the TEMPO-oxidation method and the extracted CNFs were evaluated as an adsorbent for the removal of lead( ii ) and lanthanum( iii ) (Pb( ii ) and La( iii )) ions from contaminated water. Three different forms of nanocellulose adsorbents were prepared: suspension, freeze-dried, and nanocomposite containing magnetic nanoparticles, where their adsorption performance was tested against the removal of the two chosen heavy metal ions. The maximum adsorption capacity of rice husk based CNFs was found to be the highest in the nanocellulose suspension, i.e. , 193.2 mg g −1 for Pb( ii ) and 100.7 mg g −1 for La( iii ). The separation of the used adsorbent in the suspension was further facilitated by the gelation of the CNFs and metal cations, where the resulting floc could be removed by gravity-driven filtration. The absorption mechanism of the investigated CNF system is mainly due to electrostatic interactions between negatively charged carboxylate groups and multivalent metal ions. It was found that 90% lanthanum content in the form of lanthanum oxychloride (determined by X-ray powder diffraction) could be obtained by incinerating the CNF/LaCl 3 gel. This study demonstrates a viable and sustainable solution to upcycle agricultural residues into remediation nanomaterials for the removal and recovery of toxic heavy metal ions from contaminated water.more » « less
-
Many natural water sources and industrial wastewaters contain low concentrations of metals and other contaminants. Therefore, an efficient and economical method for low-level contaminant removal and recovery is needed. The purpose of the research is to improve and modify a newly developed continuous flow ion exchange process for expansion to a variety of non-industrial applications, including removal of metal ions from the Upper Clark Fork River Watershed. The process involves a dual column reactor designed to capture metal ions using 90–105 μm spherical, functionalized silica gel coated magnetite particles, targeting copper ions with future expansion to additional metals, such as manganese and zinc. The optimization of nanoparticle synthesis and dispersion is ongoing with variables that include pH, metal ion concentration, nanoparticle concentration, and temperature. Additional focus involves maximizing contaminant capture, with current values of 0.19 mmol Cu/g Fe3O4 for magnetite and 0.25 mmol Cu/g Fe3O4 for silica-coated magnetite.more » « less
