Thiol-Functionalized Membranes for Mercury Capture from Water.

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Pore functionalized membranes are crucial for toxic metal sorption in water treatment.
• Ionic mercury poses significant environmental and health risks, necessitating effective removal strategies.
• Polyvinylidene fluoride-poly(acrylic acid) (PVDF-PAA) membranes offer a versatile platform for functionalization.

Purpose of the Study:

• To explore the sorption capacity of ionic mercury using polyvinylidene fluoride-poly(acrylic acid) (PVDF-PAA) membranes functionalized with cysteamine (MEA).
• To compare two methods for immobilizing cysteamine (MEA) onto PVDF-PAA membranes: ion exchange (IE) and carbodiimide cross-linker chemistry (EDC/NHS coupling).
• To evaluate the efficiency of these functionalized membranes for removing ionic mercury from water.

Main Methods:

• Immobilization of cysteamine (MEA) onto PVDF-PAA membranes via ion exchange (IE) and EDC/NHS coupling.
• Evaluation of mercury(II) sorption capacity using mercury(II) nitrate solutions.
• Assessment of mercury removal efficiency by passing contaminated water through the prepared membranes.

Main Results:

• The MEA immobilized membrane prepared by ion exchange (IE) showed a mercury sorption capacity of 1015 mg/g PAA.
• The MEA immobilized membrane prepared by EDC/NHS coupling exhibited a significantly higher mercury sorption capacity of 2446 mg/g PAA (2.4 times greater than IE).
• Mercury removal efficiencies were 94.1 ± 1.1% for IE and 99.1 ± 0.1% for EDC/NHS coupling.

Conclusions:

• EDC/NHS coupling is a superior method for immobilizing cysteamine (MEA) on PVDF-PAA membranes, leading to enhanced mercury sorption.
• MEA immobilized PVDF-PAA membranes demonstrate high efficiency in removing ionic mercury from water.
• These functionalized membranes hold significant potential for treating industrial wastewater, particularly from the energy and mining sectors, to remove mercury and other toxic metals.