Hetero-aggregation And Interfacial Dynamic Assembly Of NC₆₀ With Kaolinite And Tannic Acid

Increasing application and production of C60 fullerene increased their imminent environmental incorporation.Previous studies have elicited the role of natural organic matter(NOM)on fullerene transport.But the hetero-associations involving engineered nanoparticles(ENPs)and natural mineral colloids can reinforce the existing paradigm on formers environmental transport,considering the ubiquity of mineral particulates colloidal hetero-associations._Several studies have underscored the importance of naturally abundant mineral colloids on ENPs environmental mobility including fullerene.Clay is a naturally abundant phyllosilicate mineral and major constituent of the soils and sediments.Therefore,colloidal transport of fullerene can be significantly affected by their interactions through environmental media.Aquatic mobility of C60 fullerene as affected by kaolinite(Na-Kl)in the absence and presence of ? electron-rich tannic acid(TA)was discussed.Unlike high isomorphous substituted 2:1 montmorillonite,1:1 thick lamella kaolinite differs significantly in terms of surface charge heterogeneity in various facets that may led to more complex inter and intra particle association.Fast hetero-aggregation kinetics of nC60 fullerene(FWS)with Na-Kl elicited enhanced stabilization in the presence of NaCl but diminished minutely to Na-Kl alone in the presence of CaC12.However,critical coagulation concentration(CCC)increased significantly for both Na-Kl and Na-Kl/FWS mixture in the presence of 2 mg/L tannic acid(TA)at both pH 4 and 7.In situ AFM observations revealed that hydrophobicity driven by non-specific adhesion of fullerene to Na-Kl is strongly prevented by TA upon specific interactions such as ?-? interaction.From the perceived understanding,lack of carboxylate in TA in contrast to humic/fulvic acid and weaker complexation ability with hydrated Ca2+led to such enhancement in stabilization.In addition,time-dependent interfacial dynamic growth of the binary assembly,formed upon such hetero-association was monitored with in situ AFM imaging.In near diffusion limited aggregation(DLA)CaCl2 concentration,the ternary mixture of Na-Kl,FWS and TA at pH 7 elicited honeycomb-like and hexagonal assembly instead of irregular aggregates.Weak complexation ability of TA with Ca2+,asymmetric intra and inter particle electrostatic repulsions,and Ca2+induced Ostwald ripening and growth are the notable features leading to such assembly formation.Thus,structural incorporation of fullerenes can substantially impede their interfacial movement and bioavailability and may produce hierarchical hybrid material with unique properties.