Paper Title
Aggregation Of Graphene Oxide In Aquatic Environment Under Uv Light Irradiation: Role Of Different Climate Zone’s Humic And Fulvic Acid

Abstract
UV light’s significant role in physicochemical characteristics of dissolved organic matter (DOM) in river sediments may influence the stability of Graphene oxide (GO) in aquatic environment. In this study, humic and fulvic acid (HA/FA) extracted from various climate zones of China were subjected to small (around 200 nm) and large (around 500 nm) GO in NaCl under 120 h UV irradiation. HA/FA promoted GO aggregation under UV light that is more obvious for small GO than large GO. More aggregation of GO was observed with Makou’s HA from Subtropical Monsoon climate zone and Maqin’s FA from Plateau and Mountain climate zone via high molecular weight and aromaticity that facilitated penetration of UV light. UV Irradiation Converted GO to RGO with less C-O functional groups and lower dispersibility that promoted aggregation. GO generated electron-hole pair under UV light degraded C-O and C=O groups of GO and HA/FA to lower molecular weights that ultimately promoted aggregation. The holes consumption by HA/FA degradation reaction prolonged electrons lifetime that can be transferred to GO and reduced GO to rGO. GO aggregation was C=C/C-C and C-O functional groups dependent in HA/FA under UV light. The results reveal that DOM’s climate zone and UV irradiation might be serious concern for the stability of GO in aquatic systems. Keywords - Graphene Oxide, Aggregation, UV Irradiation, Humic and Fulvic Acid, Climate Zone