کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5746972 | 1618802 | 2017 | 9 صفحه PDF | دانلود رایگان |
- The aggregation/retention of nTiO2 is stronger in single NH4+ than that in Na+.
- The enhanced transportability of nTiO2 in binary system of Na++NH4+.
- Two-site kinetic retention model provides good simulation for transport in NH4+.
- The reversible retention of nTiO2 in NH4+ is related to K2 on Site 2 from model.
The widely used artificial nanoparticles (NPs) and the excess of ammonium (NH4+) fertilizers are easily released into the natural environment. So, clarifying the mobility of NPs in the presence of NH4+ is therefore of great urgency and high priority. Currently, few studies focus on the transport and deposition of nanoparticle titanium dioxide (nTiO2) in single and binary systems containing NH4+, especially describing this process by a mathematical model. In this work, the comparison between the transport and retention of rutile nTiO2 in single and binary electrolyte solutions of NH4Cl and/or NaCl (0.5-50Â mM) were conducted at pH 6.0 and 8.0 through running the column experiments. Experimental results show that the aggregation and retention of nTiO2 in solution containing mono-valence cations obeys the order as follows: NH4+Â >Â Na+Â >Â Na+Â +Â NH4+ at the same ion strength (IS). It is attributed to the lower critical coagulation concentration (CCC) of rutile nTiO2 in NH4+ than that in Na+ solution. In particular, the simultaneous presence of NH4+ and Na+ favors the transportability of nTiO2 due to the strong competitive adsorption on the surface of NPs. The two-site kinetic retention model provides the good simulation for their transport behavior. The likely mechanism is that the secondary energy minimum of nTiO2 in NH4+ system associated with the greater K2 at surface Site 2 (from model) on sand can be explained for the more reversible deposition. Ammonium leachate associated with NPs can thus be considered a serious concern.
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Journal: Chemosphere - Volume 169, February 2017, Pages 9-17