Effect of Phosphate on the Particle Size of Ferric Oxyhydroxides Anchored onto Activated Carbon: As(V) Removal from Water

• Published in: Environmental science & technology 2012-09, Vol.46 (17), p.9577-9583
• Main Authors: Arcibar-Orozco, Javier A, Avalos-Borja, Miguel, Rangel-Mendez, J. Rene
• Format: Article
• Language: English
• Subjects: Activated carbon; Adsorption; Applied sciences; Arsenic - isolation & purification; Biological and physicochemical phenomena; Charcoal - chemistry; Chemical synthesis; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Ferric Compounds - chemistry; Iron compounds; Nanoparticles; Nanoparticles - chemistry; Nanoparticles - ultrastructure; Natural water pollution; Particle Size; Phosphates; Phosphates - chemistry; Pollution; Pollution, environment geology; Surface Properties; Water Pollutants, Chemical - isolation & purification; Water Purification - methods; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es204696u

The surface area of iron oxyhydroxides is a key factor when removing As from water. However, research related to this matter shows that this issue has not been explored in detail. The use of capping agents is a viable method to synthesize ferric oxyhydroxide nanoparticles; however, this method to our knowledge has not been applied for the anchorage of iron oxyhydroxide nanoparticles on activated carbon (AC). In the present work, the addition of PO4 (as a capping agent) in forced hydrolysis of FeCl3 in AC was investigated. Results revealed that the surface area of modified materials reached a maximum of about 900 m2/g with a molar ratio PO4/Fe of 0.1. Moreover, microscopy studies indicate a size range of iron nanoparticles from 2 to 300 nm, where the smallest particles are attained with the highest concentration of PO4. The surface charge distribution of modified samples became less positive; however, the As removal increased, indicating that electrostatic interaction is not the controlling sorption mechanism. Modified samples showed a 40% increase on As(V) adsorption capacity when using a molar ratio PO4/Fe of 1.5. The proposed method allowed anchoring of iron oxyhydroxides nanoparticles on AC, which have a high As(V) adsorption capacity (5 mg/g).