School of environment, Northeast Normal University, Changchun 130117, China.
Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, China.
Sci Total Environ. 2016 Apr 15;550:717-726. doi: 10.1016/j.scitotenv.2016.01.141. Epub 2016 Feb 2.
This study examines the cotransport of graphene oxide (GO) and Cu in porous media. The impacts of GO concentration and ion strength (IS) on Cu transport in laboratory packed columns were investigated. The results indicated that GO had fairly high mobility at a IS of 1mM, and could serve as an effective carrier of Cu(II). The facilitated transport was found to increase with increasing concentration of GO (CGO). The peak effluent concentration (C/C0)max of Cu was 0.57 at CGO of 120mg/L and IS=1mM and 0.13 at 40mg/L and IS=1mM. The Cu appears to be irreversibly adsorbed by the sand because no Cu appeared in the effluent in the absence of GO. However, the GO-facilitated Cu transport was reduced as the IS increased from 1 to 1000mM. In fact, the facilitated transport was zero percent at an IS of 1000mM. Particle size analysis, Zeta potential measurements and DLVO calculations demonstrated that higher IS values made the GO became unstable and it flocculated and attached to the sand. We also fed GO into the column pre-equilibrated by Cu as sequential elution experiments and found that the later introduced GO can complex the pre-adsorbed Cu from the sand surface because GO has a higher adsorption affinity for Cu. An advection-dispersion-retention numerical model was able to describe the Cu and GO transport in the column. Our work provides useful insights into fate, transport and risk assessment of heavy metal contaminants in the presence of engineered nanoparticles.
本研究考察了氧化石墨烯（GO）和 Cu 在多孔介质中的共运移。研究了 GO 浓度和离子强度（IS）对实验室填充柱中 Cu 迁移的影响。结果表明，在 IS 为 1mM 时，GO 的迁移率相当高，可作为 Cu（II）的有效载体。发现促进迁移随 GO 浓度（CGO）的增加而增加。在 CGO 为 120mg/L 和 IS=1mM 时，Cu 的峰值流出浓度（C/C0）max 为 0.57，在 CGO 为 40mg/L 和 IS=1mM 时为 0.13。由于没有 GO，Cu 似乎被沙子不可逆地吸附，因此在没有 GO 的情况下，流出物中没有 Cu 出现。然而，随着 IS 从 1 增加到 1000mM，GO 促进的 Cu 迁移减少。事实上，在 IS 为 1000mM 时，促进迁移为零。颗粒大小分析、Zeta 电位测量和 DLVO 计算表明，较高的 IS 值使 GO 变得不稳定，发生絮凝并附着在沙子上。我们还在通过 Cu 预先平衡的柱子中注入 GO，进行连续洗脱实验，发现随后引入的 GO 可以从沙子表面络合预先吸附的 Cu，因为 GO 对 Cu 具有更高的吸附亲和力。运移-弥散-滞留数值模型能够描述 Cu 和 GO 在柱子中的迁移。我们的工作为在工程纳米颗粒存在的情况下，重金属污染物的归宿、迁移和风险评估提供了有用的见解。
