An Evaluation of Various Carbonaceous and Synthetic Adsorbents for the Treatment of Sulfolane

Abstract

Sulfolane (2,3,4,5-tetrahydrothiophene-1,1-dioxide) is an industrial solvent used in a variety of applications including in synthetic chemistry, electric and electrical circuit processing, and in the oil and gas industry. The most popular application of sulfolane is for the extraction of aromatic hydrocarbons and sweetening of natural gas in which sulfolane is mixed with alkanolamines (such as diisopropanolamine) as well as other organic substances. Improper handling, storage, and disposal of pure sulfolane solvent and sulfolane-containing wastes have created contaminated sites where the concentration of sulfolane can be hundreds of mg/L. Sulfolane is miscible with water, non-volatile, does not adsorb to mineral surfaces to an appreciable extent, and does not biodegrade quickly under conditions where nutrients and oxygen are limited. As such, once sulfolane is released into the subsurface it will travel long distances and create large contamination plumes that can be difficult to contain and mitigate. Sulfolane in groundwater systems and private wells have been detected in Canada, the US, Australia, and other countries. While sulfolane's toxicity and the risk that it can pose to human health are not thoroughly understood, residences whose drinking water wells containing detectable levels of sulfolane (0.01 mg/L-1 mg/L) have been put under water advisories. Therefore, there is an urgent need to develop treatment technologies capable of cleaning up sulfolane-contaminated sites and removing sulfolane from drinking water to protect water resources and human health. The overall objective of this research was to investigate the adsorption of sulfolane on a wide variety of natural and synthetic adsorbents, including sand, iron oxide, aluminum oxide, eight types of granular activated carbons (GAC), Ambersorb 560, Optipore L493, silica gel, zeolite, and silica gel. The removal of sulfolane by these materials were xii