水环境中不同浓度铝离子对氧化石墨烯团聚行为的影响OA

In this study,the impacts of Na+,Mg2+,Ca2+and Al3+on the aggregation kinetics of graphene oxide(GO)were investigated and compared using dynamic light scattering at pH 5.0 in an aquatic environment.The aggregation behavior of GO in the presence of Na+,Mg2+and Ca2+complied with the classical Derjaguin-Landau-Verwey-Overbeek(DLVO)theory and the Schulze-Hardy rule.At pH 5.0,the monomeric form Ala accounted for more than 80％of Al(Ⅲ),while the polymeric form Alb and solid form Alc accounted for much less.Double-layer compression and e-lectrostatic neutralization induced by Ala reduced the electrostatic repulsion between GO,causing the attachment efficiency(α)of GO to increase and plateau at 1 as the concentration of Al(Ⅲ)increased from 0 to 0.04 mmol·L-1.With a further increase in Al(Ⅲ)concentration(0.04～0.2 mmol·L-1),the negative surface charge of GO reversed to positive,and its absolute value in-creased,resulting in stronger electrostatic repulsion and a decrease in α to 0.In the presence of Al(Ⅲ)concentrations of 0.2～10 mmol·L-1,in addition to the contribution of Ala to GO stability,the formed Alc colloids interacted with GO to form new aggregates,which remained stable in water.These results indicate that the stability of GO is closely related to the type and concentration of cat-ions in aqueous environments.