Batch studies of phosphonate adsorption on granular ferric hydroxides

Area of Science:

• Environmental Science
• Water Treatment Technologies
• Adsorption Science

Background:

• Phosphonates are prevalent in industrial applications.
• Effective removal of phosphonates from wastewater is crucial before discharge.
• Existing treatment methods may require optimization for phosphonate removal.

Purpose of the Study:

• To evaluate granular ferric hydroxide (GFH) as an adsorbent for phosphonate removal.
• To determine the optimal GFH material and conditions for phosphonate adsorption.
• To assess the performance and reusability of GFH in treating phosphonate-containing wastewater.

Main Methods:

• Batch adsorption experiments were conducted using four types of GFH.
• Adsorption isotherms were determined for nitrilotrimethylphosphonic acid (NTMP) at various pH and temperatures.
• The adsorption of six different phosphonates was studied as a function of pH.
• Adsorption-desorption cycles were performed to assess GFH reusability.

Main Results:

• A maximum NTMP loading of approximately 12 mg P/g was achieved under specific conditions.
• GFH demonstrated efficacy in removing all six investigated phosphonates.
• Adsorption capacity decreased with increasing pH for all phosphonates studied.
• GFH maintained good performance after five adsorption-desorption cycles.

Conclusions:

• Granular ferric hydroxide is a highly effective adsorbent for a range of phosphonates.
• GFH exhibits good reusability, indicating its potential for sustainable wastewater treatment.
• Optimizing pH is key to maximizing GFH adsorption capacity for phosphonates.