Work

Waste-Derived Porous Geopolymers for Pb(II) Removal: Kinetics, Thermodynamics, and Regeneration

Year: 2025

Type: article

Abstract: Lead (Pb) is a highly toxic heavy metal frequently found in industrial wastewater, posing serious risks to both human health and the environment. In this study, a porous geopolymer synthesized from fly ash, metakaolin, and red mud was evaluated for Pb(II) removal via batch adsorption experiments under varying pH, dosage, contact time, temperature, and initial concentration. The synthesized material exhibited a favorable mesoporous structure, with a BET surface area of 42.05 m2 g−1 and an average pore width of 6.26 nm, making it suitable for heavy metal uptake. Adsorption kinetics followed the pseudo-second-order model (R2 = 0.9993), while the Langmuir isotherm (R2 ≈ 0.999) best described the equilibrium data, indicating monolayer chemical adsorption as the dominant mechanism, with a maximum capacity of 74.26 mg g−1 at 318 K. Thermodynamic analyses confirmed that the adsorption was spontaneous (ΔG° < 0), endothermic (ΔH° > 0), and accompanied by increased entropy (ΔS° > 0). Desorption and regeneration tests revealed EDTA to be a more effective agent than HNO3, maintaining a reuse efficiency of 81.35% after four cycles. These results highlight the potential of waste-derived porous geopolymers as regenerable, low-cost, and efficient adsorbents for lead removal.

Source: Sustainability

DOI: 10.3390/su17229940

Authors: İlker Acar, Serkant Aykul

Institution: Atatürk University

Language: English

Topic: Adsorption and biosorption for pollutant removal

Subfield: Water Science and Technology

Field: Environmental Science

Domain: Physical Sciences

SDGs: Responsible consumption and production, Clean water and sanitation

Open Access status: gold

Estimated APC paid: $2,896