Physical and Chemical Characterization of Natural and Modified Nanoclays and their Ecotoxicity on a Freshwater Algae Species (Chlamydomonas reinhardtii)

摘要

Nanoclays represent a class of natural and modified nanomaterials that have received attention from industrial and environmental fields. Studies that assess the physicochemical properties of nanoclays and compare the effects of natural and modified nanoclays are scarce. We assessed the physicochemical characteristics of a natural nanoclay (Na+ montmorillonite) and 2 modified nanoclays (Cloisite (R) 30B and Novaclay) in the dry powder state and in solution, and their potential toxic effects on algal population growth (Chlamydomonas reinhardtii). All 3 nanoclays exhibited properties that are thought to cause toxic effects on organisms, but the properties varied among the nanoclays. Cloisite 30B had a low particle stability and a chemical composition that are thought to induce a greater toxic effect on organisms than either Novaclay or natural nanoclay. In contrast, Novaclay and natural nanoclay had a particle shape (nanoplate) in solution that is thought to induce a greater toxic effect on organisms than the type of particle shape (spherical) that Cloisite 30B has in solution. Cloisite 30B suppressed population growth of C. reinhardtii, an effect that increased with dosage. Neither Novaclay nor natural nanoclay affected algal population growth across a broad array of concentrations. The results show that modified nanoclays differ in their impact on algae, and careful thought must be given to their usage because some will have negative consequences if released into aquatic ecosystems. Environ Toxicol Chem 2018;37:2860-2870. (c) 2018 SETAC