氧化石墨烯在不同盐度水体中的聚沉行为研究

Study on sedimentation of graphene oxide in aqueous matrices with different salinity

研究氧化石墨烯(GO)的水环境行为对于阐明其生态风险具有重要意义。本文将GO分散于不同盐度的水体中,研究了GO在水环境中的分散稳定性及聚沉行为。结果表明,GO能够均匀分散于去离子水中,且降低溶液的pH。随着静置时间的延长,GO产生缓慢聚沉。随分散水体盐度增加,GO溶液的聚沉速率快速增加,聚沉颗粒粒径明显增加;当水体盐度达到8～10后,GO溶液的聚沉速率趋于理想状态下的快速聚沉速率。GO在不同盐度海水中的聚沉服从经典的胶体稳定性理论,其聚集效率随盐度的增加呈现两阶段过程。由此计算出2～100 mg/L的GO溶液的临界团聚盐度为6. 79～11. 84。由此可见,较稳定分散于淡水水体的GO可能对淡水生物产生较高的生态风险,而在海水中易于聚沉的GO可能对近海底栖生物存在较高的生态风险。

The study on the behavior of graphene oxide(GO)in the aqueous environment is very significant for its ecological risk assessment.In the present study,GO was dispersed in water with different salinity in order to investigate its dispersion stability and sedimentation.The results indicated that GO could be uniformly dispersed in deionized water that caused the decrease of the pH of the solution.With the extension of the settling time,GO still deposited slowly.With the increasing salinity of water,the sedimentation of GO became more serious and the size of aggregates increased obviously.When the salinity of water was higher than 8~10,the sedimentation rate of GO approached the fastest sedimentation rate at the favorable conditions.The sedimentation of GO in water with different salinity exhibited two processes,which was consistent with the classic Derjaguin-Landau-Verwey-Overbeek theory of colloidal stability.The calculated Critical Coagulation Salinity values were 6.79~11.84 for GO solutions with the concentration range of 2 to 100 mg/L.Therefore,GO stably dispersed in the freshwater might have a higher exposure risk to aquatic organisms living in the upper water column,whereas GO easily deposited in seawater might pose a higher exposure risk to benthic organisms.