Efficient Removal of Pb(II) from Aqueous Medium Using Chemically Modified Silica Monolith

Area of Science:

• Environmental Chemistry
• Materials Science
• Nanotechnology

Background:

• Lead (II) contamination in aqueous environments poses significant environmental and health risks.
• Development of efficient and cost-effective adsorbents is crucial for heavy metal removal from wastewater.
• Silica monoliths offer a promising scaffold for adsorbent development due to their porous structure and surface area.

Purpose of the Study:

• To synthesize and characterize a novel inorganic-organic hybrid adsorbent based on chemically modified silica monolith particles.
• To evaluate the adsorptive performance of the modified silica monolith for lead (II) removal from aqueous solutions.
• To investigate the adsorption mechanism, kinetics, thermodynamics, and reusability of the developed adsorbent.

Main Methods:

• Porous silica monolith particles were synthesized using the sol-gel method.
• Surface modification was performed using trimethoxy silyl propyl urea (TSPU) to create the inorganic-organic hybrid adsorbent.
• Adsorption experiments were conducted to determine the effects of pH, adsorbent dose, initial concentration, and contact time. Characterization included SEM, BET/BJH, and TGA. Isotherm, kinetic, and thermodynamic studies were performed.

Main Results:

• The chemically modified silica monolith (SM) achieved 98% removal of Pb(II) ions under optimal conditions (pH 5, 0.4 g/L dose, 500 mg/L concentration, 1 h contact time).
• Adsorption followed pseudo-second-order kinetics and fitted well with both Freundlich and Langmuir isotherm models.
• The adsorbent exhibited a high adsorption capacity of 792 mg/g, with only a 7% drop in capacity after three regeneration cycles.

Conclusions:

• Chemically modified silica monolith particles are highly effective adsorbents for lead (II) removal from aqueous media.
• The adsorbent's high capacity, efficiency, and reusability make it a viable candidate for industrial wastewater treatment.
• The spontaneous and exothermic nature of the adsorption process, coupled with favorable isotherm and kinetic models, highlights its potential for heavy metal remediation.