The Fine Art of Toxic Waste
An engineer and an artist are transforming pollution from coal mines into pigments used to tint paint.
To the unacquainted eye, southeastern Ohio is a picturesque vision of rolling, grass-covered hills dotted with trees. But for Guy Riefler, an associate professor of civil engineering specializing in environmental remediation, this pastoral landscape is deceptive. It hides abandoned, underground coal mines that leach iron and acid waste into nearby streams, filling them with an orange sludge that kills fish and destroys habitat.
Bent on restoring these streams, Riefler has devised an unorthodox strategy: He’s mining the polluted seeps for the ingredients to make pigments—the kind used to tint paint. Not only does Riefler’s process remove pollutants from stream waters, but the pigments he produces can be sold to fund the streams’ cleanup.
Riefler’s focus on coal mines began about 12 years ago when he learned that they were a major source of local pollution. He realized early on that his biggest hurdle wasn’t figuring out how to clean up the contaminated streams, however—it was overcoming the lack of state funds to pay for restoration.
Inspiration struck when Riefler discovered that the acidic, iron-rich conditions of Ohio’s streams were strikingly similar to the starting materials used to produce commercial pigments. “In my reading, I came across a description of how synthetic pigments are manufactured using ‘pickle liquor,’ a waste product of the steel industry containing iron dissolved in sulfuric acid,” he says. “[That’s] basically the same thing coming out of these mines.”
When the region’s underground coal mines were abandoned, many were improperly sealed, allowing them to fill with water. Over time, as that water has been exposed to the mines’ natural deposits of iron and sulfur, it has turned into a kind of accidental “pickle liquor.”
Riefler’s process begins when he collects water in plastic jugs from a mine while the liquid is still clear. While underground, the water has an acidic pH that keeps the iron in a dissolved form. It’s not until the water is exposed to air at the surface that the iron oxidizes and precipitates as an orange sludge that taints the riverbeds.
Back in the lab, Riefler simulates that natural oxidation process by raising the pH of the water and bubbling air through it. The iron separates from the water and falls as sludge to the bottom where it can be collected. A series of de-watering and drying steps transforms the sludge into a non-toxic iron oxide powder that can then be used as a pigment to tint paint. Meanwhile, the leftover water is now iron-free, and after Riefler neutralizes its pH, he can return it to the stream.
Theoretically, from a starting point of dissolved iron, variations on three main colors are possible: yellow, red, and black. But in practice, which color actually develops is dependent on the crystal structure of the iron oxide that Riefler precipitates. There are about 10 to 15 different iron crystals that can form, he says, but they all consist of iron, oxygen, and hydrogen. Through trial and error, Riefler has learned how to control, to an extent, the crystal structure—and hence the resulting color—by manipulating conditions such as pH and temperature.
But creating consistent colors is just one part of the pigment-concocting challenge. “I could produce a pigment with a known composition,” Riefler explains, “but paint companies are looking for different qualities such as ‘hiding power,’ ‘tinting strength,’ and ‘hue,’ that don’t translate well into chemistry.” Riefler realized that to create a pigment people would use, he needed someone with an artist’s eye to help him.
That’s where Riefler’s colleague, Ohio University fine arts professor John Sabraw, came in. Sabraw is a painter, known for his vibrant depictions of life forms and natural landscapes. Coincidentally, he’s also well versed in creating his own paints. By examining Riefler’s pigments for qualities such as opacity, texture, purity, and, of course, color, Sabraw could judge whether the results of the pigment-making process would translate into a viable product. “We’ve made a lot of bad paint together, but now we’re able to get something that is basically identical to what’s commercially available,” says Sabraw.
Sabraw adds that Riefler’s pigments have a scent reminiscent of where they came from. “They have just a little tiny fraction of a percent of extra stuff in there from the source stream, and this gives them a certain deep and pleasant earthy aroma,” he says. “I am loving working with them.”
Sabraw now uses Riefler’s pigments in all of his art (though not exclusively). His “Chroma” series (shown in the slideshow above) reveals the beauty that can be derived from polluted streams. Each Chroma painting begins with Sabraw dropping a precariously large water bubble on an aluminum composite panel. He then carefully places a mixture of various paints onto the droplet’s surface and leaves the panel to dry for four to six weeks, or longer. As the water evaporates, ambient factors such as temperature, humidity, and airflow take over, affecting how the paints spread and dry. “Once I make the initial selection of colors, I have no control,” says Sabraw. “This series is about me as an artist letting go and letting the environment have a say in what happens.”
While Riefler hopes to one day make his pigments available for artists to purchase, his focus now is on the big picture: He’d like to build an on-site treatment plant at a stream in Truetown, Ohio, that would treat one million gallons of polluted water and produce up to two tons of pigment daily. With such a large volume of pigment to sell, he’s looking towards products with bigger markets than artistic media, such as concrete colorants and paints for bridges or other infrastructure. “The main reason I got into this was to clean up the streams,” says Riefler. “Creating pigment is a way I can do this is in an affordable way.”