Magnetic zeolitic imidazolate frameworks composite as an efficient adsorbent for arsenic removal from aqueous...

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Arsenic contamination in water poses significant health risks.
• Conventional adsorbents often lack efficiency or reusability for arsenic removal.
• Zeolitic imidazolate frameworks (ZIFs) offer tunable properties for adsorption applications.

Purpose of the Study:

• To synthesize magnetic zeolitic imidazolate frameworks (magnetic ZIF-8) using a facile one-step method.
• To evaluate the adsorption performance of magnetic ZIF-8 for arsenite (As(III)) and arsenate (As(V)) removal.
• To investigate the adsorption mechanism and practical applicability of the developed adsorbent.

Main Methods:

• One-step synthesis of magnetic ZIF-8 involving coprecipitation and self-assembly.
• Structural characterization using techniques to determine morphology, surface area, and magnetization.
• Adsorption experiments to assess the capacity for As(III) and As(V) under various conditions.
• Kinetic and isotherm modeling (pseudo-second-order and Langmuir models) to understand adsorption behavior.
• Spectroscopy analysis to elucidate the adsorption mechanism.

Main Results:

• Magnetic ZIF-8 was successfully synthesized with a large specific surface area (696.5 m²/g) and saturation magnetization (4.31 emu/g).
• The adsorbent demonstrated enhanced adsorption of As(III) and As(V) compared to bare Fe₃O₄.
• Adsorption kinetics followed the pseudo-second-order model, and isotherms fitted the Langmuir model, indicating chemisorption.
• Maximum adsorption capacities were 30.87 mg/g for As(III) and 17.51 mg/g for As(V).
• Adsorption was sensitive to pH for As(V) but not significantly affected by ionic strength or coexisting ions.

Conclusions:

• The synthesized magnetic ZIF-8 is an effective adsorbent for both As(III) and As(V).
• The adsorbent's magnetic separability facilitates easy recovery and reuse.
• This material shows significant potential for practical applications in arsenic remediation from contaminated water.