College of Agricultural Science and Engineering, Hohai University, Nanjing, 210098, China.
College of Agricultural Science and Engineering, Hohai University, Nanjing, 210098, China.
Chemosphere. 2020 Oct;256:127100. doi: 10.1016/j.chemosphere.2020.127100. Epub 2020 May 20.
The environmental behaviors of graphitic carbon nitride (g-CN) have drawn increasing attention in recent. Understanding the fate and transport of g-CN in porous media is necessary for evaluating its environmental risks. Column experiments were used in this study to investigate the combined effect of ionic strength (IS) and other common physicochemical factors (i.e. sand grain size, solution pH, and humic acid concentration) on g-CN transport. The one-site kinetic models were applied to simulate the retention and transport of g-CN in porous media, which fitted the breakthrough curves very well. Experimental and model results showed that g-CN had a weak mobility with the transport mass recovery (TMR) less than 39.6% at pH 6.0 in absence of humic acid (HA). The mobility of g-CN was inhibited with decreasing sand grain size, and the inhibited efficiency was enhanced with IS. However, g-CN transport was significantly enhanced with increasing pH and HA concentration, and the enhanced efficiency was more obviously at high IS. The maximum TMR (78.3%) of g-CN was observed with the presence of 5 mg L HA. These results indicated that physicochemical factors played an important and combined role in controlling g-CN transport in porous media, which would lead to the more complex evaluation on the environmental behaviors of g-CN.
近年来，石墨相氮化碳（g-CN）的环境行为引起了越来越多的关注。了解 g-CN 在多孔介质中的归宿和迁移行为对于评估其环境风险是必要的。本研究采用柱实验研究了离子强度（IS）和其他常见物理化学因素（如沙粒大小、溶液 pH 值和腐殖酸浓度）对 g-CN 迁移的联合影响。应用单一位点动力学模型模拟了 g-CN 在多孔介质中的保留和迁移，该模型很好地拟合了穿透曲线。实验和模型结果表明，在 pH 值为 6.0 且不存在腐殖酸（HA）的情况下，g-CN 的迁移能力较弱，迁移质量回收率（TMR）小于 39.6%。g-CN 的迁移能力随沙粒粒径的减小而受到抑制，且随着 IS 的增加，抑制效率增强。然而，g-CN 的迁移能力随着 pH 值和 HA 浓度的增加而显著增强，在高 IS 下增强效果更为明显。当存在 5mg/L 的 HA 时，g-CN 的最大 TMR（78.3%）。这些结果表明，物理化学因素在控制 g-CN 在多孔介质中的迁移行为方面发挥了重要的综合作用，这将导致对 g-CN 的环境行为进行更复杂的评估。
