Toxicology of Graphene Oxide Nanosheets Against Paecilomyces catenlannulatus.

Graphene oxide (GO) nanosheets have been extensively investigated to fabricate the graphene in recent years. The migration of GO nanosheets into the environment could lead to the instability of biological system. In this study, the GO nanosheets were synthesized and were characterized by SEM, high resolution TEM, XRD, Raman, FTIR and XPS techniques. Toxicology testing of GO nanosheets against Paecilomyces catenlannulatus (P. catenlannulatus) was performed by measuring the efflux of cytoplasmic materials of P. catenlannulatus. Approximate 35 % of the bacteria could survive on the surface of GO nanosheets compared to the control sample (~92 %) within 3 h, indicating that GO nanosheets presented significantly antibacterial activities. It was observed that the concentration of RNA in the solution was obviously higher than that of control sample, which could be due to direct contact of the bacterial cell. The results showed that the damage of cell membrane of P. catenlannulatus was attributed to the direct contact of the P. catenlannulatus with the extremely sharp edges of GO nanosheets, which resulted in the P. catenlannulatus inactivation. The less resistant to the damage of cell membrane was observed with increasing of GO concentration and contact time.

The effect of Paecilomyces catenlannulatus on removal of U(VI) by illite.

The effect of Paecilomyces catenlannulatus (P. catenlannulatus) on removal of U(VI) onto illite as a function of contact time, pH, ionic strength, and solution concentration was conducted by batch techniques. The adsorption kinetics indicated that the removal of U(VI) on illite and illite coated P. catenlannulatus can be fitted by pseudo-second order kinetic model very well. The removal of U(VI) on illite and illite coated P. catenlannulatus increased with increasing pH from 1.0 to 7.0, whereas the decrease of U(VI) adsorption on illite and illite coated P. catenlannulatus was observed at pH > 7.5. The adsorption behavior of U(VI) on illite and illite coated P. catenlannulatus can be simulated by the double diffuse model under various pH conditions. The ionic strength-dependent experiments showed that the removal of U(VI) on illite was outer-sphere surface complexation, whereas the inner-sphere surface complexation predominated the U(VI) adsorption onto illite coated P. catenlannulatus at pH 5.0-7.0. The maximum adsorption capacity of U(VI) on illite and illite coated P. catenlannulatus calculated from Langmuir model at pH 5.0 and T = 298 K was 46.729 and 54.347 mg/g, respectively, revealing enhanced adsorption of U(VI) on illite coated P. catenlannulatus. This paper highlights the effect of microorganism on the removal of radionuclides from aqueous solutions in environmental pollution management.