Rice scientists lead production of superhydrophilic membrane to clean fluids for reuse
A new filter produced by Rice University scientists has proven able to remove more than 90 percent of hydrocarbons, bacteria and particulates from contaminated water produced by hydraulic fracturing (fracking) operations at shale oil and gas wells.
The work by Rice chemist Andrew Barron and his colleagues turns a ceramic membrane with microscale pores into a superhydrophilic filter that “essentially eliminates” the common problem of fouling.
The researchers determined one pass through the membrane should clean contaminated water enough for reuse at a well, significantly cutting the amount that has to be stored or transported.
The work is reported in Nature’s open-access Scientific Reports.
The filters keep emulsified hydrocarbons from passing through the material’s ionically charged pores, which are about one-fifth of a micron wide, small enough that other contaminants cannot pass through. The charge attracts a thin layer of water that adheres to the entire surface of the filter to repel globules of oil and other hydrocarbons and keep it from clogging.
A hydraulically fractured well uses more than 5 million gallons of water on average, of which only 10 to 15 percent is recovered during the flowback stage. “This makes it very important to be able to re-use this water,” Barron said.
Not every type of filter reliably removes every type of contaminant, he said.
Solubilized hydrocarbon molecules slip right through microfilters designed to remove bacteria. Natural organic matter, like sugars from guar gum used to make fracking fluids more viscous, require ultra– or nanofiltration, but those foul easily, especially from hydrocarbons that emulsify into globules. A multistage filter that could remove all the contaminants isn’t practical due to cost and the energy it would consume.
“Frac water and produced waters represent a significant challenge on a technical level,” Barron said. “If you use a membrane with pores small enough to separate, they foul, and this renders the membrane useless.
“In our case, the superhydrophilic treatment results in an increased flux (flow) of water through the membrane and inhibits any hydrophobic material – such as oil – from passing through. The difference in solubility of the contaminants thus works to allow for separation of molecules that should in theory pass through the membrane.”
Barron and his colleagues used cysteic acid to modify the surface of an alumina-based ceramic membrane, making it superhydrophilic, or extremely attracted to water. The superhydrophilic surface has a contact angle of 5 degrees. (A contact angle of 0 degrees would be a puddle.)
The acid covered not only the surface but also the inside of the pores, and that kept particulates from sticking to them and fouling the filter.
In tests with fracking flowback or produced water that contained guar gum, the alumna membrane showed a slow initial decrease in flux — a measure of the flow of mass through a material — but it stabilized for the duration of lab tests. Untreated membranes showed a dramatic decrease within 18 hours.
The researchers theorized the initial decrease in flow through the ceramics was due to purging of air from the pores, after which the superhydrophilic pores trapped the thin layer of water that prevented fouling.
“This membrane doesn’t foul, so it lasts,” Barron said. “It requires lower operating pressures, so you need a smaller pump that consumes less electricity. And that’s all better for the environment.”
Learn more: Filter may be a match for fracking water
The Latest on: Fracking
- Both Sides of California Fracking Debate Await Newsom's Next Move on April 18, 2019 at 8:32 am
California has been deeply involved with the oil and gas business since the first wooden derricks were erected in sleepy Kern County in the 19th century. But these days California is flush with laws, ... […]
- Schlumberger's profit falls on shale drilling, fracking slowdown on April 18, 2019 at 6:31 am
Schlumberger, the world's leading energy services company, said Thursday that its first quarter profit fell 20 percent from a year ago as a slowdown in North American shale plays crimped revenues. ... […]
- Environmentalists Call On Governor To Ban All Types of Fracking, Not Just Some on April 18, 2019 at 5:38 am
To mark Ron DeSantis's 100th day in the Governor's office, environmentalist groups gathered across several cities in Florida on Wednesday for a day of action to ban all forms of fracking, the ... […]
- Environmentalists Say Bill Being Considered by Texas Senate Would Let Companies Dump Fracking Waste Into Waterways on April 17, 2019 at 11:37 pm
Environmental groups are warning that a bill passed by the Texas House and now awaiting discussion in the Texas Senate would give fracking companies a license to pollute the state's waterways. House ... […]
- Faith Leaders, Youth Advocates and Sarasota Elected Officials Call on Governor DeSantis to Speak Out On Flawed Ban Fracking Bills on April 17, 2019 at 3:34 pm
SARASOTA, FL -- On Wednesday, local elected, faith leaders, youth climate advocates, and dozens of residents came together to rally in Sarasota and call on Governor Ron DeSantis to clarify his ... […]
- Anti-Fracking Advocates Gather To Call Attention to Governor’s Silence On Link Between Oil & Gas Operations and Earthquakes In Panhandle on April 17, 2019 at 10:29 am
Pensacola, FL — On Wednesday, environmental and water advocacy groups gathered at the Escambia government complex to call on Governor DeSantis to fully investigate the 12 recent earthquakes near the ... […]
- Environmentalists cite report on Florida oil spills as bid to ban fracking stalls on April 17, 2019 at 9:07 am
A set of bills that would ban some forms of fracking in Florida have likely stalled out in the Legislature, leaving environmentalists discouraged and petroleum industry representatives hopeful. People ... […]
- How Do New Fracking Laws Compare to Polis’s 2014 Initiatives? on April 17, 2019 at 8:58 am
Just before he signed Senate Bill 181, Democrats’ sweeping package of oil and gas reforms, into law at the State Capitol on Tuesday, April 16, Governor Jared Polis told a roomful of reporters and ... […]
- Fracking Giants May Offer Signs of Recovery During Earnings on April 17, 2019 at 8:53 am
It’s been a tough few years for Schlumberger Ltd. and Halliburton Co., but the oilfield services giants may finally be on an upward curve, thanks to a recovery in international drilling activity and ... […]
- Dockery: Florida legislators should pass a real fracking ban. on April 12, 2019 at 2:09 pm
The history of fracking bills in the Florida Legislature offers a better understanding of what’s happening this legislative session. Since at least 2013, the Legislature has proposed ways with dealing ... […]
via Google News and Bing News