abstract
This work reports a simple and safe, but powerful, route to depollute lead-containing aqueous solutions. Inorganic polymer foams (cm-size) were used as bulk-type adsorbents. The influence of the specimens' porosity and activator molarity on the foams' physical properties and on their lead extraction ability was studied. Then, the best performing samples were deeply evaluated as lead adsorbents by studying the impact of pH, lead concentration, contact time, ionic strength and solution volume. Lead sorption kinetics is strongly affected by the pollutant concentration, pH and the solution ionic strength. Under the most favourable conditions the foams showed an impressive removal capacity (105.9 mg/g at pH 5, 23 degrees C, C-0 = 800 ppm, deionised water), surpassing all other reported values on the use of bulk-type inorganic polymers. The foams' lead uptake is 2.3 times higher than the previous best performing bulk-type specimens (mm-size spheres), and sorption is 12.5-15 times faster. The foams can be easily regenerated using mild acidic conditions, and then reused as adsorbent, suggesting that the main adsorption mechanism is ion exchange.
keywords
HEAVY-METAL ADSORPTION; WASTE-WATER; GEOPOLYMER; REMOVAL; IMMOBILIZATION; ADSORBENT; MICROSTRUCTURE; STRENGTH; SPHERES; GREEN
subject category
Environmental Sciences & Ecology
authors
Novais, RM; Carvalheiras, J; Seabra, MP; Pullar, RC; Labrincha, JA
our authors
João António Labrincha Baptista
Full professor
Rob Pullar
Collaborator
Rui Miguel Novais
Assistant Professoracknowledgements
Novais (CEECIND/00335/2017), Carvalheiras (SFRH/BD/144562/2019) and Pullar (IF/00681/2015) wish to thank FCT for supporting their work. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Foundation for Science and Technology/MCTES.