Ana García

Effect of cerium dioxide, titanium dioxide, silver, and gold nanoparticles on the activity of microbial communities intended in wastewater treatment

Growth in production and use of nanoparticles (NPs) will result increased concentrations of these in industrial and urban wastewaters and, consequently, in wastewater-treatment facilities. The effect of this increase on the performance of the wastewater-treatment process has not been studied systematically and including all the microbial communities involved in wastewater treatment. The present work investigates, by using respiration tests and biogas-production analysis, the inhibitory effect of four different commonly used metal oxide (CeO(2) and TiO(2)) and zero-valent metal (Ag and Au) nanoparticles on the activity of the most important microbial communities present in a modern wastewater-treatment plant. Specifically, the actions of ordinary heterotrophic organisms, ammonia oxidizing bacteria, and thermophilic and mesophilic anaerobic bacteria were tested in the presence and absence of the nanoparticles. In general, CeO(2) nanoparticles caused the greatest inhibition in biogas production (nearly 100%) and a strong inhibitory action of other biomasses; Ag nanoparticles caused an intermediate inhibition in biogas production (within 33-50%) and a slight inhibition in the action of other biomasses, and Au and TiO(2) nanoparticles caused only slight or no inhibition for all tested biomasses.

Programmed iron oxide nanoparticles disintegration in anaerobic digesters boosts biogas production

A novel concept of dosing iron ions using Fe3O4 engineered nanoparticles is used to improve biogas production in anaerobic digestion processes. Since small nanoparticles are unstable, they can be designed to provide ions in a controlled manner, and the highest ever reported improvement of biogas production is obtained. The nanoparticles evolution during operation is followed by an array of spectroscopic techniques.

Potential use of CeO2, TiO2 and Fe3O4 nanoparticles for the removal of cadmium from water

Abstract Inorganic nanoparticles (NPs) of cerium oxide (CeO2), iron oxide (Fe3O4) and titanium oxide (TiO2) were studied for the removal of dissolved cadmium from water at concentrations ranging from 25 to 350u2009mg/L. Adsorption was the predominant mechanism for sequestration, and particularly efficient cadmium removal was demonstrated for Fe3O4 NPs. Experimental data were fitted to three different adsorption isotherms: Langmuir, Freundlich and Temkin. The best fit was obtained for the Freundlich isotherm (R 2u2009>u20090.96 for all NPs). Adsorption was shown to follow pseudo second-order kinetics (R 2u2009⩾u20090.91 for all NPs). All three NPs showed some removal of cadmium in aqueous solution, but after 72u2009h of process, Fe3O4 NPs showed a higher capacity of cadmium adsorption (101.1u2009mg Cd/g NP) than CeO2 NPs (49.1u2009mg Cd/g NP) or TiO2 NPs (12.2u2009mg Cd/g NP). These results demonstrate the potential use of this NPs to remove dissolved cadmium at high concentrations.

Preliminary study of phosphate adsorption onto cerium oxide nanoparticles for use in water purification; nanoparticles synthesis and characterization.

In this study, the synthesis and characterization of cerium oxide nanoparticles (CeO(2)-NPs) and their adsorption potential for removing phosphate from water was evaluated using a multi-factor experimental design to explore the effect of various factors on adsorption. The objective function selected was the percentage of phosphate removed from water, in which the phosphate concentration and the CeO(2)-NP concentration are quantitative variables (factors in the experimental design). A lineal polynomial fitted the experimental results well (R(2) = 0.9803). The nanostructure was studied by transmission electron microscopy (TEM) and high-resolution TEM techniques before and after the adsorption process. During the adsorption and desorption processes several changes in the morphology and surface chemistry of the CeO(2)-NPs were observed.

The Luminescent Bacteria Test to Determine the Acute Toxicity of Nanoparticle Suspensions

Luminescent bacteria, Vibrio fischeri, is used in an ecotoxicological test to determine toxicity of water samples. In comparison to other ecotoxicological tests, the use of luminescent bacteria reports final toxicity values in a short time (minutes). Luminescent toxicity test can be used to determine toxicity of nanoparticles suspensions.