Cd2+ toxicity as affected by bare TiO2 nanoparticles and their bulk counterpart

Area of Science:

• Environmental Science
• Nanotechnology
• Ecotoxicology

Background:

• Engineered nanoparticles (NPs) coexist with pollutants, yet their interactions are poorly understood.
• The influence of these interactions on environmental fate and effects requires investigation.

Purpose of the Study:

• To investigate the effects of titanium dioxide engineered nanoparticles (TiO(2)-NP) and bulk (TiO(2)-BC) on cadmium (Cd(2+)) bioavailability and toxicity.
• To examine Cd(2+) adsorption kinetics and isotherms on TiO(2) particles in algal culture medium.

Main Methods:

• Studied Cd(2+) adsorption kinetics and equilibrium isotherms on TiO(2)-NP and TiO(2)-BC.
• Assessed the impact of TiO(2) particles on Cd(2+) toxicity and bioaccumulation in Chlamydomonas reinhardtii.

Main Results:

• Cd(2+) adsorption followed pseudo-first-order kinetics and Langmuir isotherm on both TiO(2) forms.
• TiO(2)-BC showed higher surface-area-based Cd(2+) adsorption than TiO(2)-NP.
• Both TiO(2) forms reduced Cd(2+) toxicity by decreasing free Cd(2+) ion concentration, with no intracellular TiO(2) observed.

Conclusions:

• TiO(2) particles mitigate Cd(2+) toxicity and bioaccumulation by reducing ambient free Cd(2+) ion concentrations.
• Particle size is not the sole determinant of adsorption differences; surface area plays a role.
• Cd(2+) adsorption by TiO(2) is the primary mechanism reducing its bioavailability and toxicity to algae.