Effects of pH and natural organic matter (NOM) on the adsorptive removal of CuO nanoparticles by periphyton.

The presence of nanoparticles (NPs) in natural aquatic environment is a potential risk to aquatic and human life. Periphyton, ubiquitous in aquatic environment, has been used to remove pollutants from aquatic systems. Understanding the interaction between NPs and periphyton will help to better predict the behavior and fate of NPs in aquatic media. This study was aimed to investigate the CuO NP biosorption mechanism by periphyton at acidic, neutral, and alkaline pH and with varying natural organic matter (NOM) concentrations. The rate of adsorption and removal of CuO NPs was decreased with increase in initial pH and NOM concentration. The zeta potential study suggests that the biosorption of CuO NPs by periphyton was related to electrostatic force of attraction. The particle size distribution of CuO NPs in solution with different NOM concentrations played an important role in CuO NP removal. The well fit between pseudo-first-order kinetics and adsorption process indicated that physical sorption appears to be the dominating process. These results show that periphyton can be employed for an environmentally benign and effective solution for NP removal.