Grape pomace as a biosorbent for fluoride removal from groundwater

Area of Science:

• Environmental Science
• Materials Science
• Water Treatment

Background:

• Fluoride contamination in water poses significant health risks.
• Development of cost-effective and efficient defluoridation materials is crucial.
• Agricultural waste, like grape pomace, presents an opportunity for sustainable material development.

Purpose of the Study:

• To synthesize and characterize a novel biosorbent for fluoride removal from water.
• To evaluate the defluoridation efficiency and adsorption capacity of zirconium-loaded grape pomace (Zr(iv)-GP).
• To investigate the performance of Zr(iv)-GP under various conditions, including pH, coexisting anions, and in real groundwater.

Main Methods:

• Grape pomace was loaded with tetravalent zirconium ions (Zr(iv)) to create the Zr(iv)-GP biosorbent.
• Batch adsorption experiments were conducted to determine the optimal pH, maximum adsorption capacity, and the effect of coexisting anions.
• Continuous column adsorption tests were performed using real groundwater samples to assess practical applicability.

Main Results:

• Zr(iv)-GP achieved a defluoridation efficiency of 96.13% at an optimal pH of 3.0.
• The biosorbent demonstrated excellent performance (>90% removal) even at pH near 10 due to self-acidification.
• The maximum adsorption capacity of Zr(iv)-GP was 7.54 mg g⁻¹, outperforming commercial ion exchange resins.
• CO₃²⁻ and HPO₄²⁻ significantly inhibited defluoridation, while Cl⁻, NO₃⁻, and SO₄²⁻ had minimal impact.
• In continuous flow, pre-adjusting groundwater pH to 3.0 extended the breakthrough time by approximately 8 times.
• The Zr(iv)-GP adsorbent maintained good capacity after three adsorption-desorption cycles.

Conclusions:

• Zr(iv)-GP is a highly effective and promising biosorbent for removing fluoride from water.
• Its ability to function effectively across a wide pH range and its reusability make it a sustainable and economical option.
• This material holds significant potential for groundwater purification and addressing fluoride contamination issues.