New photocatalytic approach to cleaning wastewater from oil sands

With oil sands in the title, this story had to mention the Canadian province of Alberta, which has been widely castigated and applauded for its oil extraction efforts in their massive oil sands field. A Nov. 24, 2015 news item on Nanotechnology Now describes a new technology for cleaning the wastewater from oil sands extraction processes,

Researchers have developed a process to remove contaminants from oil sands wastewater using only sunlight and nanoparticles that is more effective and inexpensive than conventional treatment methods.

Frank Gu, a professor in the Faculty of Engineering at the University of Waterloo [in the province of Ontario] and Canada Research Chair in Nanotechnology Engineering, is the senior researcher on the team that was the first to find that photocatalysis — a chemical reaction that involves the absorption of light by nanoparticles — can completely eliminate naphthenic acids in oil sands wastewater, and within hours. Naphthenic acids pose a threat to ecology and human health. Water in tailing ponds left to biodegrade naturally in the environment still contains these contaminants decades later.

A Nov. 23, 2015 University of Waterloo news release, which originated the news item, expands on the theme but doesn’t provide much in the way of technical detail,

“With about a billion tonnes of water stored in ponds in Alberta, removing naphthenic acids is one of the largest environmental challenges in Canada,” said Tim Leshuk, a PhD candidate in chemical engineering at Waterloo. He is the lead author of this paper and a recipient of the prestigious Vanier Canada Graduate Scholarship. “Conventional treatments people have tried either haven’t worked, or if they have worked, they’ve been far too impractical or expensive to solve the size of the problem.  Waterloo’s technology is the first step of what looks like a very practical and green treatment method.”

Unlike treating polluted water with chlorine or membrane filtering, the Waterloo technology is energy-efficient and relatively inexpensive. Nanoparticles become extremely reactive when exposed to sunlight and break down the persistent pollutants in their individual atoms, completely removing them from the water. This treatment depends on only sunlight for energy, and the nanoparticles can be recovered and reused indefinitely.

Next steps for the Waterloo research include ensuring that the treated water meets all of the objectives Canadian environmental legislation and regulations required to ensure it can be safely discharged from sources larger than the samples, such as tailing ponds.

Here’s a link to and a citation for the paper,

Solar photocatalytic degradation of naphthenic acids in oil sands process-affected water by Tim Leshuk, Timothy Wong, Stuart Linley, Kerry M. Peru, John V. Headley, Frank Gu. Chemosphere Volume 144, February 2016, Pages 1854–1861 doi:10.1016/j.chemosphere.2015.10.073

This paper is behind a paywall.

Leave a Reply

Your email address will not be published. Required fields are marked *