Effects of Multi-Walled Carbon Nanotubes on Mineralization and Mobility of Nonylphenol and Sodium Dodecyl Sulfate in Agricultural Soils.

It is known that carbon based nanoparticles (CNPs) are interacting with organic pollutants (OPs) in wastewater. With respect to wastewater irrigation the fate of OPs in presence of CNPs have to be studied in agricultural soils.

Thus mineralization and sorption experiments were conducted to provide information about the mineralization potential of organic pollutants in presence of MWNTs in different agricultural soils. For that nonylphenol (NP) and sodium dodecyl sulfate (SDS) were selected as model pollutants since they occur frequently in aqueous systems and also reveal different chemical and physical parameter. Moreover, two different multi-walled carbon nanotubes (MWNT) with varying in length and diameter were used. To identify mineralization processes also peroxidase activity, microbial biomass as well as the pollutant extractability was monitored over time.

The results show that the interaction of MWNTs and pollutants increases the pollutant adsorption to the soil solid phase. Thus, in presence of MWNTs the NP and SDS mineralization decreased, respectively, which could be explained by a reduced pollutant bioavailability. It could be demonstrated that the MWNT BET surface area has significant influence on the NP and SDS adsorption and thus also on pollutant degradation in the soil environment. Whereas peroxidase activity as well as the microbial biomass could not directly be related to the NP and SDS degradation, the pollutant extractability seems to influence the pollutant mineralization. However, due to the lower degradation of NP and SDS in the presence of MWNT a longer retention of the substances in the soils and potential toxic effects for humans and animals, as a result of plant uptake may be taken into account.