Polanyi-Based Models for the Competitive Sorption of Low-Polarity Organic Contaminants on a Natural Sorbent

Abstract

The development of appropriate equilibrium sorption relationships for anthropogenic organic contaminants with soils and sediments is essential to predicting the extents and rates of solid-water interactions in the environment. In this context, we previously reported results that showed how nonlinear sorption isotherms with nine lowpolarity organic chemicals on a silty aquitard material could be modeled as a combined adsorption-partitioning process. The adsorption component was ascribed to presumed traces of a carbonaceous adsorbent, for which adsorption was well described by a Polanyi-based isotherm. In this work, we report competitive sorption behavior on the same material, as observed from batch experiments in binary solute systems that contain combinations of the previously studied sorbates (chorinated benzenes and polyaromatic hydrocarbons) over wide ranges of concentration. The results confirmed our expectation that partitioning is an increasingly dominating contribution to overall sorption when cosorbates are present. Moreover, the competitive effects could be very well predicted on the basis of Polanyi-Manes adsorption theory and the prior single solute results. Overall, the results further validate the applicability of a Polanyi-based modeling approach and lend additional support to the hypothesis that this sorbent contains trace quantities of high surface area carbonaceous material.

AFM study on the adsorption and aggregation behavior of dissolved humic substances on mica

“…Therefore, earlier investigations [10,11,[42][43][44][45] showed that sorption of hydrophobic organic contaminants (HOCs) by soils and sediments is dominated by partitioning into relatively homogeneous, lipophilic, gel-like humic matrices, which can be recognized as a partition or dissolution process and has the linear adsorption features. A number of more recent studies [12][13][14][15][46][47][48][49][50][51][52][53][54][55] , however, have indicated that such sorption often manifests substantial deviations from a linear partition model, provided that very low concentrations of HOCs are studied. In that case, a presumed adsorption process is often observed, as evidenced by the nonlinear, slow, hysteretic and competitive sorption behaviors.…”

Incorporating nonlinear isotherms into robust multilayer sorptive barrier design

“…However, recent research has explored the use of more complicated three-and four-parameter expressions [4,35,56,[58][59][60]. Table 2 summarizes the isotherm expressions considered in this study, including the linear isotherm, several common nonlinear isotherms, and some dual mode formulations (e.g.…”

Influence of the coexisting contaminants on bisphenol A sorption and desorption in soil

“…It is commonly accepted that sorption of organic compounds to soils/sediments consists of adsorption in glassy domain and partition in rubbery domain. Adsorption is characteristic of nonlinearity while partition is linear [23][24][25]. BPA is a weak acid with a pK a of 10.23 and exists in molecular form in the solution with pH of 7.34 used in this study.…”