INFLUENCING FACTORS OF STABILITY OF GRAPHENE OXIDE IN WATER
Based on the analysis of the physicochemical properties of graphene oxide(GO),the effects of electrolyte,natural organic matter(NOM),and stable solution concentration on its aggregation and sedimentation in water were studied.The results showed that the concentration of GO stable solution had little effect on its physicochemical properties and stability in water.Electrolytes induced the GO aggregation by reducing Zeta potential in water.The aggregation process presented two stages:reaction limited and diffusion limited.The critical condensation concentrations(CCC)of each electrolyte were 180 mmol/L of Na+,4.5 mmol/L of Mg2+and 1.8 mmol/L of Ca2+,respectively.Compared with Mg2+,Ca2+could strengthen the aggregation process by adsorption bridging.The sedimentation process of GO was also divided into two stages:rapid sedimentation and slow sedimentation,and aggregation was the main factor affecting GO sedimentation.The presence of natural organic matter could effectively inhibit coagulation and enhance the stability of GO in water.However,HA has a complex correlation with GO and Ca2+,which further accelerates the aggregation process.With the increase of GO concentration in water,the aggregation and sedimentation rate were accelerated.In the presence of a lower concentration,GO had higher stability in the water environment.
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