Chloride Ion Adsorption by Modified Pisha Sandstone-Based Cementitious Materials

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Pisha sandstone (PS) is an abundant, low-cost material with potential for adsorption.
• Chloride ion contamination in wastewater poses environmental and infrastructure challenges.
• Existing adsorbents may be costly or inefficient for widespread chloride removal.

Purpose of the Study:

• To enhance the chloride ion adsorption performance of Pisha sandstone.
• To optimize modification methods for efficient resource utilization of PS.
• To investigate the mechanisms behind improved chloride adsorption.

Main Methods:

• Raw Pisha sandstone was modified using mechanical grinding (15 min) and high-temperature calcination.
• Adsorption kinetics experiments were conducted to determine equilibrium time and model.
• Material characterization was performed using XRD, FTIR, and SEM-EDS.

Main Results:

• The modified PS (PSM15) achieved optimal chloride adsorption, reaching equilibrium in 240 min.
• Adsorption followed a pseudo-second-order kinetic model, indicating chemisorption.
• PSM15 demonstrated a maximum chloride removal efficiency of 33.3%, outperforming calcined (30.1%) and raw PS (23.6%).

Conclusions:

• Mechanochemical activation refines crystallite size and exposes active sites, enhancing adsorption.
• In situ formation of C-S-H gel aids chloride immobilization through encapsulation and electrostatic attraction.
• Modified PS offers a low-cost, eco-friendly solution for chloride-containing wastewater purification.