Graphene oxide(GO) with unique characteristics grasps striking potentials in both academic and industrial applications. After being released into natural waters, the dispersity and stability of GO might be altered by ...Graphene oxide(GO) with unique characteristics grasps striking potentials in both academic and industrial applications. After being released into natural waters, the dispersity and stability of GO might be altered by the chemical conditions in the receiving water bodies. In this review, we summarized that the aggregation of GO in aquatic environments is mostly dependent on properties of nanoparticles(size,structure, and functional groups) and complex water chemistry(p H, temperature, light, ionic strength,and dissolved organic matter). The knowledge about the aggregation/stability of GO is still insufficient due to the variations in GO properties and complex system of natural waters. Although studies about environmental transformation of graphene-related materials can be accessed but a systematic study taking into consideration the various factors of GO and aquatic systems responsible for aggregation of GO is still lacking. Therefore, we summarized that GO homoaggregation or heteroaggregation with other solid particles can affect the distribution in different depths of rivers and toxicity toward plankton or benthic organisms. More studies are needed to investigate the stability of GO in the long term, the effect of other nanomaterial on GO aggregation, the alteration of water constituents at different regions/time and its effect on GO aggregation, to understand the transportation and impact of GO in the environment.展开更多
UV light absorption by aquatic systems affect the physicochemical characteristics of graphene oxide(GO)nanoparticles which ultimately influence its aggregation behavior in water.Regarding this research,various humic a...UV light absorption by aquatic systems affect the physicochemical characteristics of graphene oxide(GO)nanoparticles which ultimately influence its aggregation behavior in water.Regarding this research,various humic and fulvic acids(HA/FA),extracted from China’s different climate zones,were treated with 2 h UV irradiated large(~500 nm)and(~200 nm)GO in 200 mmol/L NaCl.UV irradiated GO particles displayed aggregation even at low humic acid/fulvic acid(HA/FA)concentrations ranging from 0.2 to 1.0 mgC/L,whereas pristine GO particles did not exhibit such behavior.Reduction of functional groups,containing Oxygen(C=O/C–O),via UV irradiation is responsible for this aggregation phenomenon and conversion of GO to reduced graphene oxide(rGO).Consequently,rGO exhibits lower dispersibility,facilitating its agglomeration.Moreover,both small and large-sized GO particles exhibited less aggregation in HAs compared to FAs due to large molecular weight and high polarity of HAs.Aggregation of GO was more obvious with Makou FA and Maqin HA from Plateau and Mountain climate zone and Subtropical Monsoon climate zone,respectively,owing to DOM’s lower molecular weight and aromaticity that reduced their adsorption.The application of the Derjaguin-landau-verwey-overbeek(DLVO)theory did not reveal any significant interaction energy barrier between the 2 h UV irradiated GO particles even in the presence of DOM,indicating that aggregation prevailed despite the addition of DOM.These findings highlight that UV irradiation poses a significant threat to the GO stability in aquatic environments,particularly in the presence of DOM.展开更多
基金financially supported by the National Key R&D Program of China (No. 2021YFC3200401)the National Natural Science Foundation of China (Nos. 21677015, 52170024 and 22006031)the Natural Science Foundation of Hebei Province (No. B2019204315)。
文摘Graphene oxide(GO) with unique characteristics grasps striking potentials in both academic and industrial applications. After being released into natural waters, the dispersity and stability of GO might be altered by the chemical conditions in the receiving water bodies. In this review, we summarized that the aggregation of GO in aquatic environments is mostly dependent on properties of nanoparticles(size,structure, and functional groups) and complex water chemistry(p H, temperature, light, ionic strength,and dissolved organic matter). The knowledge about the aggregation/stability of GO is still insufficient due to the variations in GO properties and complex system of natural waters. Although studies about environmental transformation of graphene-related materials can be accessed but a systematic study taking into consideration the various factors of GO and aquatic systems responsible for aggregation of GO is still lacking. Therefore, we summarized that GO homoaggregation or heteroaggregation with other solid particles can affect the distribution in different depths of rivers and toxicity toward plankton or benthic organisms. More studies are needed to investigate the stability of GO in the long term, the effect of other nanomaterial on GO aggregation, the alteration of water constituents at different regions/time and its effect on GO aggregation, to understand the transportation and impact of GO in the environment.
基金financially supported by the National Natural Science Foundation of China(Nos.42250410319,52170024 and 21677015)the Qingdao Municipal Bureau of Human Resources and Social Security,China(No.QDBSH20220201006).
文摘UV light absorption by aquatic systems affect the physicochemical characteristics of graphene oxide(GO)nanoparticles which ultimately influence its aggregation behavior in water.Regarding this research,various humic and fulvic acids(HA/FA),extracted from China’s different climate zones,were treated with 2 h UV irradiated large(~500 nm)and(~200 nm)GO in 200 mmol/L NaCl.UV irradiated GO particles displayed aggregation even at low humic acid/fulvic acid(HA/FA)concentrations ranging from 0.2 to 1.0 mgC/L,whereas pristine GO particles did not exhibit such behavior.Reduction of functional groups,containing Oxygen(C=O/C–O),via UV irradiation is responsible for this aggregation phenomenon and conversion of GO to reduced graphene oxide(rGO).Consequently,rGO exhibits lower dispersibility,facilitating its agglomeration.Moreover,both small and large-sized GO particles exhibited less aggregation in HAs compared to FAs due to large molecular weight and high polarity of HAs.Aggregation of GO was more obvious with Makou FA and Maqin HA from Plateau and Mountain climate zone and Subtropical Monsoon climate zone,respectively,owing to DOM’s lower molecular weight and aromaticity that reduced their adsorption.The application of the Derjaguin-landau-verwey-overbeek(DLVO)theory did not reveal any significant interaction energy barrier between the 2 h UV irradiated GO particles even in the presence of DOM,indicating that aggregation prevailed despite the addition of DOM.These findings highlight that UV irradiation poses a significant threat to the GO stability in aquatic environments,particularly in the presence of DOM.
