Isotherm nonlinearity and nonlinear partitioning of organic compounds into resin XAD-7: Insight from displacement experiments.
Environ Pollut
; 267: 115563, 2020 Dec.
Article
in En
| MEDLINE
| ID: mdl-33254628
ABSTRACT
Nonlinear sorption and isotherm nonlinearity of organic compounds by widely used porous resins such as XAD-7 are commonly interpreted as adsorption due to their large surface area. However, through displacement experiments using saturated 4-nitrophenol as the displacer, we observed that the nonlinear sorption and isotherm nonlinearity of selected organic compounds (i.e., naphthalene, nitrobenzenes, phenols and anilines) by XAD-7 was captured by a nonlinear partition mechanism rather than the adsorption mechanism. Nonlinear sorption of organic compounds by XAD-7 includes a nonlinear/displaced fraction and a linear/non-displaced fraction. A dual-mode (DM) model, including a nonlinear Dubinin-Ashtakhov (DA) model component and a linear model component, was developed to describe the nonlinear/displaced fraction and the linear/non-displaced fraction, respectively. The capacity of these two fractions are dependent on their solubility in water or octanol with positively linear relationships but not their molecular size, supporting the nonlinear partitioning mechanism. Besides van-der-waals force, hydrogen-bonding is primarily responsible for the nonlinear partitioning of phenols and anilines into XAD-7, while π-π interaction is responsible for the nonlinear partitioning of naphthalene and nitrobenzenes. The explored nonlinear partitioning mechanism for XAD-7 implies that the nonlinear sorption of organic compounds by porous resins should be recognized for their recovery and applications as sorbents.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Organic Chemicals
/
Polystyrenes
Language:
En
Journal:
Environ Pollut
Journal subject:
SAUDE AMBIENTAL
Year:
2020
Document type:
Article
Affiliation country: