Journal
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
Volume 142, Issue -, Pages 230-236Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ecoenv.2017.04.017
Keywords
Multi-walled carbon nanotubes; Phosphorus; Sediments; Adsorption behavior
Categories
Funding
- National Key Plan for Research and Development of China [2016YFC0401703, 2016YFC0502203]
- National Natural Science Foundation of China [51379062]
- National Science Funds for Creative Research Groups of China [51421006]
- Key Program of National Natural Science Foundation of China [91647206]
- Fundamental Research Funds for the Central Universities [2015B25314]
- Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
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Aquatic sediments are believed to be an important sink for carbon nanotubes (CNTs). With novel properties, CNTs can potentially disturb the fate and mobility of the co-existing contaminants in the sediments. Only toxic pollutants have been investigated previously, and to the best of our knowledge, no data has been published on how CNTs influence phosphorus (P) adsorption on aquatic sediments. In this study, multi-walled carbon nanotubes (MWCNTs) were selected as model CNTs. Experimental results indicated that compared to pseudo first order and intraparticle diffusion models, the pseudo-second-order model is better for describing the adsorption kinetics of sediments and MWCNT-contaminated sediments. Adsorption isotherm studies suggested that the Langmuir model fits the isotherm data well. With the increase in the MWCNT-to-sediment ratio from 0.0% to 5.0%, the theoretical maximum monolayer adsorption capacity (Q(max)) for P increased from 0.664 to 0.996 mg/g. However, the Langmuir isotherm coefficient (K-L,) significantly decreased from 4.231 L/mg to 2.874 L/mg, indicating the decrease in the adsorption free energy of P adsorbed on the sediments after MWCNT contamination. It was suggested that P was released more easily to the overlying water after the re-suspension of sediments. Moreover, the adsorption of sediments and sediment-MWCNT mixture was endothermic and physical in nature. Results obtained herein suggested that the change in the specific surface area and zeta potential of sediments is related to MWCNT contamination, and the large adsorption capacity of MWCNTs is probably the main factor responsible for the variation in the adsorption of P on aquatic sediments.
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