Ji Hongliang, Liu Zhenzhong, Jiang Wen
School of Resources and Environment, Nanchang University, No. 999 Xuefu Avenue, Honggutan District, Nanchang, 330031, Jiangxi, China.
Environ Sci Pollut Res Int. 2023 Feb;30(10):26256-26269. doi: 10.1007/s11356-022-24056-8. Epub 2022 Nov 10.
Nanoplastics can be produced directly from some artificial products, such as cosmetics, or indirectly from the breakup of large pieces of plastic waste. They have a small particle size, large specific surface area, and stable structure and can concentrate toxic compounds in water. The discharge of nanoplastics into the water environment through urban piping systems or surface runoff may lead to the contamination of surface water resources, which poses a great threat to the safety of drinking water. As a common adsorbent, granular activated carbon (GAC) is widely used in the advanced treatment of drinking water. However, most of the studies focused on the transport ability of nanoplastics in quartz sand, and there is a lack of research on the migration behavior of nanoplastics in activated carbon media. In this study, the stability and pore characteristics of GAC were studied, and its regeneration efficiency was investigated. The transport curves of PSNPs, which have a particle size of 98 ± 9 nm and specific surface area of about 67 m/g, were compared under different ionic strengths, ionic species, flow rates, pH, and humic acid (HA) concentrations. And DLVO theory was used to analyze the transport behavior of nanoplastics in activated carbon column. All experiments were performed at room temperature to make the results generalizable. The results showed that GAC had stable pore structure and excellent adsorption capacity. The surface area and pore volume of GAC are 759 m/g and 0.357 cm/g, respectively. And the regeneration rate of GAC can reach 90% and 83.3% after the first two regeneration cycles. On the other hand, at high ionic strength and low pH, the repulsive barrier between PSNPs and activated carbon gradually disappeared; then, more PSNPs were deposited in the activated carbon media, and the concentration of PSNPs in the effluent water was lower. Both the flow rate and HA promoted the transport of PSNPs, but the breakthrough curves of PSNPs did not change significantly when the HA concentration was further increased. At the same ion concentration, PSNPs tend to deposit on the surface of activated carbon in the background solution of Ca compared with Na. This study reveals the migration mechanism of PSNPs in the activated carbon filter column, which is of great importance to ensure the safety of drinking water and human health.
纳米塑料可以直接由一些人工制品产生，比如化妆品，或者由大块塑料垃圾的分解间接产生。它们粒径小、比表面积大、结构稳定，并且能够在水中富集有毒化合物。纳米塑料通过城市管道系统或地表径流排放到水环境中可能会导致地表水资源受到污染，这对饮用水安全构成了巨大威胁。作为一种常见的吸附剂，颗粒活性炭（GAC）被广泛应用于饮用水的深度处理。然而，大多数研究集中在纳米塑料在石英砂中的传输能力，而缺乏对纳米塑料在活性炭介质中迁移行为的研究。在本研究中，对GAC的稳定性和孔隙特性进行了研究，并考察了其再生效率。比较了粒径为98±9 nm、比表面积约为67 m/g的聚苯乙烯纳米塑料（PSNPs）在不同离子强度、离子种类、流速、pH值和腐殖酸（HA）浓度下的传输曲线。并利用DLVO理论分析了纳米塑料在活性炭柱中的传输行为。所有实验均在室温下进行，以使结果具有普遍性。结果表明，GAC具有稳定的孔隙结构和优异的吸附能力。GAC的表面积和孔容分别为759 m/g和0.357 cm/g。在前两个再生循环后，GAC的再生率可达90%和83.3%。另一方面，在高离子强度和低pH值下，PSNPs与活性炭之间的排斥屏障逐渐消失；然后，更多的PSNPs沉积在活性炭介质中，出水水中PSNPs的浓度较低。流速和HA都促进了PSNPs的传输，但当HA浓度进一步增加时，PSNPs的穿透曲线没有显著变化。在相同离子浓度下，与Na相比，PSNPs在Ca背景溶液中更容易沉积在活性炭表面。本研究揭示了PSNPs在活性炭过滤柱中的迁移机制，这对于确保饮用水安全和人类健康具有重要意义。
