As(III) removal from aqueous solution by katoite (Ca₃Al₂(OH)₁₂)

Area of Science:

• Environmental Chemistry
• Materials Science

Background:

• Arsenic(III) is a prevalent and challenging contaminant in groundwater.
• Efficient removal of arsenic(III) is crucial for safe drinking water and irrigation.

Purpose of the Study:

• To develop a cost-effective method for removing arsenic(III) from groundwater.
• To synthesize and characterize katoite for arsenic(III) remediation.

Main Methods:

• Co-grinding calcium hydroxide with aluminum hydroxide to produce katoite.
• Utilizing X-ray diffraction (XRD), FT-IR, TG, and XPS to analyze the adsorption mechanism.
• Conducting one-step agitation experiments for arsenic(III) removal.

Main Results:

• Katoite effectively removes arsenic(III) to concentrations below the WHO drinking water standard (<10 ppb).
• Arsenic(III) is intercalated into katoite, forming arsenite-pillared Ca-Al layered double hydroxide (LDH).
• Coexisting anions (Cl-, SO42-, NO3-) showed minimal impact on arsenic(III) removal efficiency.

Conclusions:

• Katoite is a promising material for the one-step removal of arsenic(III) from contaminated groundwater.
• The synthesis and application of katoite are techno-economically feasible for large-scale groundwater purification.
• This method offers a practical solution for arsenic(III) remediation, particularly in developing regions.