Transport, retention, and long-term release behavior of polymer-coated silver nanoparticles in saturated quartz sand: The impact of natural organic matters and electrolyte

• Published in: Environmental pollution (1987) 2017-10, Vol.229, p.49-59
• Main Authors: Hou, Jun, Zhang, Mingzhi, Wang, Peifang, Wang, Chao, Miao, Lingzhan, Xu, Yi, You, Guoxiang, Lv, Bowen, Yang, Yangyang, Liu, Zhilin
• Format: Article
• Language: English
• Subjects: DLVO thoery and hydrophobicity; Electrolytes; Humic Substances; Hydrogels; Long-term release; Metal Nanoparticles - analysis; Metal Nanoparticles - chemistry; Models, Chemical; Natural organic matters and electrolyte; Osmolar Concentration; Polymers - analysis; Polymers - chemistry; Povidone; Quartz; Saturated quartz sand; Silicon Dioxide; Silver - analysis; Silver - chemistry; Silver Compounds; Silver nanoparticles; Transport; Water
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2017.05.059

This study investigated the transport and long-term release of stabilized silver nanoparticles (AgNPs), including polyvinylpyrrolidone-coated AgNPs (PVP–AgNPs) and bare AgNPs (Bare–AgNPs), in the presence of natural organic matters (NOMs; both humic acids (HA) and alginate (Alg)) and an electrolyte (Ca2+) in a sand-packed column. Very low breakthrough rate (C/C0) of AgNPs (below 0.04) occurred in the absence of NOM and the electrolyte. Increasing the concentration of NOM and decreasing the influent NOM solution's ionic strength (IS) reduced the retention of AgNPs. The reduced NP retention at high NOM and low IS was mainly attributed to the increased energy barrier between the AgNPs and the sand grain surface. Notably, the retention of PVP–AgNPs was enhanced at high Alg concentration and low IS, which mainly resulted from the improved hydrophobicity that could increase the interaction between the PVP-AgNPs and the collector. The total release amount of PVP–AgNPs (10.03%, 9.50%, 28.42%, 6.37%) and Bare–AgNPs (3.28%, 2.58%, 10.36%, 1.54%) were gained when exposed to four kinds of NOM solutions, including deionized water, an electrolyte solution (1 mM Ca2+), HA with an electrolyte (1 mM Ca2+), and a Alg (40 mg/L) solution with an electrolyte (1 mM Ca2+). The long-term release of retained silver nanoparticles in the quartz sand was mostly through the form of released Ag NPs. The factors that increased the mobility of AgNPs in quartz sand could improve the release of the AgNPs. The release of AgNPs had no significant change in the presence Ca2+ but were increased in the presence of HA. The Alg slightly decreased the release of AgNPs by increasing the hydrophobicity of AgNPs. The results of the study indicated that all the tested NOM and Ca2+ have prominent influence on the transport and long-term release behavior of silver nanoparticles in saturated quartz sand. [Display omitted] •Transport and long-term release of AgNPs in a sand-packed column was investigated.•All tested NOM can increase the transport of AgNPs except Alg on PVP-AgNPs.•Hydrophobicity play important roles on AgNPs transportation in saturated quartz sand.•The long-term release of retained AgNPs were mostly by the form of released Ag NPs. Increasing the concentration of NOM and decreasing the influent NOM solution's IS increased the transport and long-term release of AgNPs in quartz sand.