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Title (Primary) Turbulent mixing accelerates PAH desorption due to fragmentation of sediment particle aggregates
Author Rakowska, M.I.; Smit, M.P.J.; Kupryianchyk, D.; Qin, J.; Koelmans, A.A.; Rijnaarts, H.H.M.; Grotenhuis, T.;
Journal Journal of Soils and Sediments
Year 2017
Department UMB;
Volume 17
Issue 1
Language englisch;
POF III (all) T41;
Supplements https://static-content.springer.com/esm/art%3A10.1007%2Fs11368-016-1556-5/MediaObjects/11368_2016_1556_MOESM1_ESM.pdf
Keywords Desorptio;n Mixing Particles; Polycyclic aromatic hydrocarbons; Sediment
UFZ wide themes RU3;
Abstract

Purpose

Stripping contaminants from sediments with granular activated carbon (GAC) is a promising remediation technique in which the effectiveness depends on the rate of contaminant extraction from the sediment by the GAC. The purpose of the present study was to investigate the effect of mixing intensity on the short-term extraction rate of polycyclic aromatic hydrocarbons (PAHs) from contaminated sediment.

Materials and methods

PAH desorption from sediment at a wide range of rotational speeds (min−1; rotations per minute (rpm)) was monitored by uptake in Tenax polymeric resins using a completely mixed batch reactor. Desorption data were interpreted using a radial diffusion model. Desorption parameters obtained with the radial diffusion model were correlated with particle size measurements and interpreted mechanistically.

Results and discussion

Fast desorption rate constants, De/r2, with De the effective diffusion coefficient and r the particle radius, ranged from 3.7 × 10−3 to 1.1 × 10−1 day−1 (PHE) and 6 × 10−6 to 1.9 × 10−4 day−1 (CHR), respectively, and increased with the intensity of mixing. The De/r2 values would correspond to De ranges of 1.8 × 10−14–1.2 × 10−16 m2 × day−1 and 1.8 × 10−12–3.7 × 10−15 m2 × day−1, assuming fast desorption from the measured smallest particle size (9 μm) classes at 200 and 600 rpm, respectively.

Conclusions

Desorption of PAHs was significantly accelerated by a reduction of particle aggregate size caused by shear forces that were induced by mixing. The effective intra-particle diffusion coefficients, De, were larger at higher mixing rates.

ID 18604
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=18604
Rakowska, M.I., Smit, M.P.J., Kupryianchyk, D., Qin, J., Koelmans, A.A., Rijnaarts, H.H.M., Grotenhuis, T. (2017):
Turbulent mixing accelerates PAH desorption due to fragmentation of sediment particle aggregates
J. Soils Sediments 17 (1), 277 - 285