Scientists at New York University Abu Dhabi (NYUAD) have developed a new technique to remove toxic contaminants from water. CalP, as it has been named, is calixarene-based superhydrophobic porous material that acts as a water purifier by repelling water and attracting toxins like oil and dye.
“CalP is a light brown powdered material which can absorb up to seven times its weight of oil from an oil and water mixture,” said Dinesh Shetty, lead researcher and chemist at NYUAD.
“While the basic material itself has been around for decades, this is the first porous organic calixarene-based polymer synthesized in the lab for the purpose of purifying water,” he explained.
CalP has the ability to remove oil from water efficiently and quickly. Ali Trabolsi, assistant professor of chemistry at NYUAD said: “CalP floats, has high surface area, and low density. It also has pores both from calixarene cavity and hyper-crosslinked 3D structure that collects toxins. The material is superhydrophobic, which means it repels water, while also containing the ability to absorb a range of pollutants.”
The researchers tested CalP in the lab using both engine oil and commercial grade crude oil.
“After being placed on top of an oil-water mixture, the light brown powder quickly absorbed the oil and turned dark brown,” said Shetty. “Complete absorption of the oil happened in about five minutes.”
Further experiments were conducted replacing oil with different types of dyes and yielded the same impressive results. In one experiment, toxic dye was poured into a glass of water and within five minutes of its interaction with CalP, 80 percent of the dye was absorbed by the material and all of it was separated from the water after 15 minutes. This, in spite of dyes being chemically designed to withstand degradation.
In addition to acting as a quick and efficient solution to absorbing pollutants from water, one of CalP’s most useful properties is that it is re-useable, making it a potentially cost-effective solution to cleaning oil spills. “This was an important part of our discovery,” added Ilma Jahovic, student researcher and chemistry major at NYUAD.
She said: “We found it was very easy to regenerate the material even after it was soaked in oil or dye. We did multiple cycles and its efficiency was maintained. Other similar materials can be re-used but require cleaning at high temperatures which makes the process expensive,” she explains. CalP on the other hand requires mild washing with diethyl ether, ethanol or a light acidic solution.”
Currently, CalP is not developed enough to use on large oil spills, as it is being worked on at gram scale in the lab environment. The research will now focus on further improving its absorption efficiency of oil products, and to find ways to make its production cheaper.
“Once developed further, CalP could potentially also be used to further other areas of petroleum research such as gas separation, to make cleaner fuel,” added Jahovic.