Heavy Metal Removal from Aqueous Effluents by TiO2 and ZnO Nanomaterials

SOSA LISARRAGUE, MATÍAS; SAMEER ALSHEHRI; ABDULLAH ALSALHI; LASSALLE, VERONICA L.; LÓPEZ-CORRAL, IGNACIO

ADSORPTION SCIENCE & TECHNOLOGY

MULTI SCIENCE PUBL CO LTD

Lugar: Brentwood, UK; Año: 2023

0263-6174

The presence of heavy metals in wastewater, such as Ni, Pb, Cd, V, Cr, and Cu, is a serious environmental problem. This kind ofinorganic pollutant is not biodegradable for several years, and its harmful effect is cumulative. Recently, semiconductornanomaterials based on metal oxides have gained interest due to their efficiency in the removal of heavy metals fromcontaminated water, by inducing photocatalytic ion reduction when they absorb light of the appropriate wavelength. The mostcommonly applied semiconductor oxides for these purposes are titanium oxide (TiO2), zinc oxide (ZnO), and binarynanomaterials composed of both types of oxides. The main purpose of this work is to critically analyse the existent literatureconcerning this topic focusing specially in the most important factors affecting the adsorption or photocatalytic capacities ofthis type of nanomaterials. In particular, photocatalytic activity is altered by various factors, such as proportion of polymorphs,synthesis method, surface area, concentration of defects and particle size, among others. After a survey of the actual literature,it was found that, although these metal oxides have low absorption capacity for visible light, it is possible to obtain anacceptable heavy metal reduction performance by sensitization with dyes, doping with metallic or nonmetallic atoms,introduction of defects, or the coupling of two or more semiconductors.