Using a pollen-based sponge to absorb oil from contaminated water – News
From left to right: Shahrudin Ibrahim, Deng Jingyu, Zhao Ze and Cho Nam-Joon
A POLLEN BASED sponge was developed as a more environmentally friendly way to absorb oil and other organic solvents from contaminated water.
Conventional oil spill cleanup methods can be expensive and make damage worse. Now, a research team from Nanyang Technological University in Singapore and Sungkyunkwan University in South Korea have developed a pollen-based sponge that may offer a more durable solution.
Sponges that can be used to clean up marine oil spills are useful in many industries, including health and energy, due to their properties, such as low density, high surface area, and ability to high absorption. However, they are usually made from synthetic polymers, which has raised concerns about their impact on the environment.
Pollen is a renewable raw material which has ideal properties as a material, but until recently it was believed that pollen grains were not pliable due to a hard outer layer which caused them to be called the “diamond of biopolymers”. Previous work by the research team has shown that pollen can be converted into a microgel with a process that adjusts the mechanical properties of the pollen shell layers.
Cho Nam-Joon from the NTU School of Materials Science and Engineering, who led the study, said: “Pollen that is not used for plant pollination is often considered biological waste. Through our work, we try to find new uses for this “waste” and turn it into a renewable, affordable and biodegradable natural resource. Pollen is also biocompatible. It does not cause an immunological, allergic or toxic reaction when exposed to bodily tissues, making it potentially suitable for applications such as dressings, prosthetics and implantable electronics. “
The pollen grains of sunflowers are coated with “pollen cement” which is made from lipid components. The researchers removed it by rinsing the grains with water, acetone, and diethyl ether. The kernels were heated to reflux in an aqueous solution of potassium hydroxide (KOH) to remove the internal part of the kernel, which left only the shell of the pollen kernel. The shells were incubated in KOH and then lyophilized. This created the pollen sponges with 3D porous architectures. The sponge was heated and then incubated in an ethanolic solution containing stearic acid. Coating the sponge with stearic acid – which is a common fatty acid found in nature – causes it to become highly hydrophobic.
The sponges must be squeezed to release the oil before they can be reused. This was tested and it was found that after 100 cycles the sponge retained 92% of its original height with 20% compression and 59% of its original height with 60% compression.
Sponges can absorb oil of different densities and have been tested on a variety of oils, including gasoline, pump oil, and n-hexane. The team tested the sponges for ten cycles to show that they could absorb and release oil multiple times.
The sponge could absorb 9.7-29.3 g / g, which is comparable to commercial polypropylene absorbents which have a capacity range of 8.1 to 24.6 g / g.
“Collectively, these results demonstrate that the pollen sponge can selectively absorb and release contaminants from oil and has performance levels similar to those of commercial oil absorbents while demonstrating compelling properties such as low cost, biocompatibility and sustainable production, ”Cho said.
The sponges designed so far are 5cm in diameter, but the team now plans to increase the size of the sponges to meet industry demands. They are also looking to collaborate with NGOs and international partners to conduct pilot tests in real environments.
“We hope that our innovative pollen materials can one day replace widely used plastics and help reduce the global problem of plastic pollution,” Cho said.
Advanced functional materials https://doi.org/gfkj