Most anti-scaling agents currently used are high in phosphorus derivatives, environmental pollutants that can damage aquatic ecosystems. Now, a team of researchers from McGill University, Montreal, have developed a more-effective and phosphorus-free anti-scaling option based on a nanoparticle called hairy nanocellulose.
“The usage of phosphonated additives for water treatment is extremely restricted due to its environmental footprints, such as eutrophication. The hairy nanocellulose anti-scaling technology benefits from carboxylic acid groups, which are known to be green and environmentally friendly,” explains Amir Sheikhi, who led the project, and is now a postdoctoral fellow at the University of California, Los Angeles.
“Cellulose is the most abundant biopolymer in the world. … But it’s probably one of the least attractive options for an anti-scaling agent because it’s neutral, it has no charged functional groups,” he adds.
To address this, the research team nanoengineered negatively charged carboxyl groups onto cellulose nanoparticles. The resulting particles contained charged functional groups capable of controlling the tendency of positively charged calcium ions to form scale. A series of papers published in the Royal Society of Chemistry’s Materials Horizons and the American Chemical Society’s Applied Materials & Interfaces contain more detail.
“Under our harsh electrochemically induced scaling condition, the fully solubilized dicarboxylated cellulose performs better than one of the most efficient industrial scale inhibitors, a phosphonated macromolecule and industrial antiscalant called KemGuard269,” notes Sheikhi.
The researchers have tested the anti-scaling capability of hairy nanocelluloses in a high-temperature, high-ionic strength environment that mimicked industrial conditions. The nanocelluloses effectively prevented scaling at such extreme conditions, thus, the researchers’ next step is to test the nanomaterials in actual plants.
Hairy nanocelluloses can provide new opportunities to prevent a range of industrial scales, say the researchers. “Further improvements may involve conjugating the hairs with a variety of functional groups to address the unmet needs of water-based industries,” notes Sheikhi. He believes the material could significantly enhance the performance of cooling towers, evaporators, heat exchangers and other unit operations. Hairy nanocelluloses also may have a role as catalysts in industrial reactors.
Putting the hairy nanocellulose on metals typically used for industrial piping also seems promising as the material could provide a protective layer against scaling.
Figure 1. Hairy nanocellulose, used as an anti-scaling agent in the container at right, prevents the kind of mineral build-up that is restricting outflow from the container at left. Source: McGill University.
Industrial use does pose one issue, admits Sheikhi. “In synthesizing the hairy nanocelluloses, the reacted metaperiodate must be recycled as much as possible to justify the production costs,” he explains.
Given the chemical versatility of hairy nanocellulose, the research team sees strong potential for applications beyond anti-scaling, including drug delivery, antimicrobial agents and fluorescent dyes for medical imaging. Sheikhi has an extensive research plan to further the applications of hairy nanocelluloses in water treatment, food industry, biomedical platforms, and energy conversion and storage. “The field of hairy nanocelluloses is fairly new, and many unknowns are yet to be discovered and understood,” he says.
“I believe that the next generation ‘green’ materials can significantly improve the performance of chemical plants. These materials, besides having tailored functionality, must be cost-effective, scalable, and preferably produced based on natural resources. As a chemical engineer, my overarching goal is to provide transformative and/or translational solutions based on highly-renewable resources that can set the stage for affordable, widespread technologies with immediate benefits for humans and ecosystems,” concludes Sheikhi.
The team has received a tremendous amount of interest from a wide range of industries for furthering the hairy nanocellulose technology.