A Performance Comparison of Selected Commercially Available Sorbents
Authors: Marinello S.A. , Fucik K.W. 
Published: October 2008

Selected sorbent materials were studied to determine real world applicability in treating hydrocarbon spills on water. These commercially available products were evaluated in the laboratory to determine potential performance parameters in the field. The initial focus was to compare four different oleophilic/hydrophobic absorbent technologies with the standard Absorbent, polypropylene, with respect to the ability to retain and hold acVabsorbed oil. All of the four absorbent technologies were found to be far superior to polypropylene in this area. This is particularly significant in light of disposal and incineration problems and restrictions associated with polypropylene products. However, in analyzing for water soluble fractions from 24 hour stir tests of the absorbents saturated with crude oil, it was found that their ability to strongly attract the oil phase resulted, under specific conditions, in an apparent shift of partitioning coefficients causing the release of significant levels of toxic fractions.

INTRODUCTION

With the recent and continuing media attention paid to large and small releases of oil onto water, much discussion has focused on finding new and better ways to handle the spills. Some of these discussions have addressed the inefficiencies and shortcomings of the use of the "standard" polypropylene Absorbent in its' various forms. And other, not necessarily related talks have focused on the use of "new" oleophilic and hydrophobic absorbents of varying technologies to contain the spilled hydrocarbons and retain it at the surface of the water for subsequent recovery and disposal or reuse. The Absorbents of this focus would not incur the disposal quandary associated with polypropylene Absorbents, nor subject the environment to the toxicities associated with effective applications of dispersant. And these absorbents would not, as they held the absorbed oil on the surface and did not transfer it into the water column, allow wildlife to be further impacted by contact. The problem would be isolated.

As it turns out, the dynamics of these systems are not necessarily that simple. This study began intending to address simple physical performance characteristics of commercially available absorbents with respect to polypropylene absorbent. Such a comparison is provided with the results of agitation testing to determine Absorbent ability to retain ah/adsorbed oil. What became of critical concern in this study are the chemical dynamics taking place after crude oil is strongly absorbed which can result in potentially increased toxicity in the water column. This appears to be due to the partitioning and transfer into the water phase of some less strongly attracted hydrocarbon components of significant toxicity.

In addition to the base polypropylene Absorbent tested, four "new" absorbents were evaluated. Absorbent 1 is a thermally altered product derived from wood waste. Absorbent 2 is one of a number of peat derived absorbents. Absorbent 3 is essentially an incomplete petrochemical fertilizer produced in the form of microscopic capillary tubes. The final subject of these tests, Absorbent 4, is manufactured from chemically treated woodpulp waste. Absorbents 1 and 4, therefore, have an added advantage of being derived from recycled waste materials.