Once inevitably released into the aquatic environment,polystyrene nanoplastics(PS-NPs)will present complicated environmental behaviors,of which the aggregation is a key process determining their environmental fate and...Once inevitably released into the aquatic environment,polystyrene nanoplastics(PS-NPs)will present complicated environmental behaviors,of which the aggregation is a key process determining their environmental fate and impact.In this study,the aggregation kinetics of different sizes(30 nm and 100 nm)of PS-NPs with metal cations(Na^(+),K^(+),Ca^(2+),Mg^(2+)and Pb^(2+))at different solution pH(3,6 and 8)were investigated.The results showed that the aggregation of PS-NPs increased with cation concentration.Taking Pb^(2+)as an example,the adsorption behavior of cations onto PS-NPs was determined by transmission electron microscopy(TEM)and energy dispersive X-ray(EDX)spectroscopy,which demonstrated Pb^(2+)could be adhered onto the surface of PS-NPs with the effect of charge neutralization.The critical coagulation concentrations(CCC)of smaller PS-NPs were higher than that of larger PS-NPs for monovalent cations,whereas a different pattern is observed for divalent cations.It was suggested that there were other factors that DLVO theory does not consider affect the stability of NPs with different particle sizes.In addition,it should be noted that PS-NPs had the capacity of adsorbing large amounts of heavy metal cations and carried them transport to a long distance,and the corresponding ecological risks need to further elucidate.展开更多
Specific ion effects(Hofmeister effects)have recently attracted the attention of soil scientists,and it has been found that ionic non-classic polarization plays an important role in the specific ion effect in soil.How...Specific ion effects(Hofmeister effects)have recently attracted the attention of soil scientists,and it has been found that ionic non-classic polarization plays an important role in the specific ion effect in soil.However,this explanation cannot be applied to H+.The aim of this work was to characterize the specific ion effect of H+on variably charged soil(yellow soil)colloid aggregation.The total average aggregation(TAA)rate,critical coagulation concentration(CCC),activation energy,and zeta potential were used to characterize and compare the specific ion effects of H+,K+,and Na+.Results showed that strong specific ion effects of H+,K+,and Na+existed in variably charged soil colloid aggregation.The TAA rate,CCC,and activation energy were sensitive to H+,and the addition of a small amount of H+changed the TAA rate,CCC,and activation energy markedly.The zeta potential results indicated that the specific ion effects of H+,K+,and Na+on soil colloid aggregation were caused by the specific ion effects of H+,K+,and Na+on the soil electric field strength.In addition,the origin of the specific ion effect for H+was its chemical adsorption onto surfaces,while those for alkali cations were non-classic polarization.This study indicated that H+,which occurs naturally in variably charged soils,will dominate variably charged soil colloid aggregation.展开更多
基金supported by Scientific Research Project of Guangzhou University(No.YK2020017)the Program Foundation of Institute for Scientific Research of Karst Area of NSFC-GZGOV(No.U1612442)+2 种基金Research Grants Council of the Hong Kong Special Administrative Region,China(No.UGC/IDS(R)16/19)IndustryUniversity Cooperation and Collaborative Education Project of the Ministry of Education of the People's Republic of China(No.202101134012)Innovative training program for College Students of Guangzhou University(No.S202111078039).
文摘Once inevitably released into the aquatic environment,polystyrene nanoplastics(PS-NPs)will present complicated environmental behaviors,of which the aggregation is a key process determining their environmental fate and impact.In this study,the aggregation kinetics of different sizes(30 nm and 100 nm)of PS-NPs with metal cations(Na^(+),K^(+),Ca^(2+),Mg^(2+)and Pb^(2+))at different solution pH(3,6 and 8)were investigated.The results showed that the aggregation of PS-NPs increased with cation concentration.Taking Pb^(2+)as an example,the adsorption behavior of cations onto PS-NPs was determined by transmission electron microscopy(TEM)and energy dispersive X-ray(EDX)spectroscopy,which demonstrated Pb^(2+)could be adhered onto the surface of PS-NPs with the effect of charge neutralization.The critical coagulation concentrations(CCC)of smaller PS-NPs were higher than that of larger PS-NPs for monovalent cations,whereas a different pattern is observed for divalent cations.It was suggested that there were other factors that DLVO theory does not consider affect the stability of NPs with different particle sizes.In addition,it should be noted that PS-NPs had the capacity of adsorbing large amounts of heavy metal cations and carried them transport to a long distance,and the corresponding ecological risks need to further elucidate.
基金the National Natural Science Foundation of China(Nos.41501241 and 41530855)the Natural Science Foundation of Chongqing,China(No.cstc2015jcyj A00036)the Fundamental Research Funds for the Central Universities of China(No.XDJK2017D199)for supporting this research
文摘Specific ion effects(Hofmeister effects)have recently attracted the attention of soil scientists,and it has been found that ionic non-classic polarization plays an important role in the specific ion effect in soil.However,this explanation cannot be applied to H+.The aim of this work was to characterize the specific ion effect of H+on variably charged soil(yellow soil)colloid aggregation.The total average aggregation(TAA)rate,critical coagulation concentration(CCC),activation energy,and zeta potential were used to characterize and compare the specific ion effects of H+,K+,and Na+.Results showed that strong specific ion effects of H+,K+,and Na+existed in variably charged soil colloid aggregation.The TAA rate,CCC,and activation energy were sensitive to H+,and the addition of a small amount of H+changed the TAA rate,CCC,and activation energy markedly.The zeta potential results indicated that the specific ion effects of H+,K+,and Na+on soil colloid aggregation were caused by the specific ion effects of H+,K+,and Na+on the soil electric field strength.In addition,the origin of the specific ion effect for H+was its chemical adsorption onto surfaces,while those for alkali cations were non-classic polarization.This study indicated that H+,which occurs naturally in variably charged soils,will dominate variably charged soil colloid aggregation.
