Bio-inspired, 3D-printed solar steam generators to desalinate, purify water

To separate salt from water, scientists devised bioinspired 3D-printed solar steam generators at Nanyang Technological University (NTU) in Singapore.

The machine called solar steam generator (SSG) shows promise for a more affordable, less energy-intensive device that effectively desalinates seawater.

Yanbei Hou, co-author of the study told Interesting Engineering that the team of scientists also employed a novel metal-organic framework (MOF) derived fusing agent in a multi-jet fusion (MJF) printer – 3D printing.

Preparing solar steam generator

This technique helped prepare the solar steam generator (SSG) with a capillary pore structure.

The generator works when iron oxide particles (Fe3O4) are encapsulated in a carbon layer (C@Fe3O4 hybrids) derived from MOF has excellent capabilities for absorbing sunlight and converting it into heat, Hou explained to IE .

“When exposed to sunlight, the SSG’s temperature increases, facilitating water evaporation.”

Hou further noted that the capillary pore structure ensures efficient wicking of water and uniform spreading across the surface of the SSG. This facilitated effective heat transfer to promote continuous heat absorption and subsequent water evaporation.

The MJF printing technology paved the way for devising intricate structures with a highly specific surface area, increasing the specific surface area of the SSG, and the contact area between water and air, further enhancing water evaporation.

SSG absorbs sunlight, transfers to water

In simple terms, Hou says that the SSG absorbs sunlight and converts it into thermal energy which is then uniformly transferred to water, resulting in its absorption of heat and subsequent evaporation.

Not only does the new machine tackle the challenges faced with the traditional desalination process but it also aims to champion sustainability by employing renewable energy sources like solar power to reduce carbon footprint.

According to a statement by the American Institute of Physics, the desalinated water from SSG met drinking water standards consistently, proving the system’s effectiveness over prolonged periods.

Alluding to prolonged testing, Hou told IE that the water evaporation rate of the MJF-printed SSGs remained relatively stable and reached as high as 1.55 kilograms of water per square meter per hour.

“These results not only compare favorably to reported polymeric SSGs but also outperform the majority of data,” he says. “The fabricated evaporator demonstrates significant improvements in the evaporation rate and energy utilization.”

The design was inspired by plant transpiration and therefore its crafted with miniature tree-shaped microstructures.

Kun Zhou, a professor of mechanical engineering at Nanyang Technological University explained in the statement that the bioinspired design increases the SSG’s efficiency. The tree-like arrangement enhances water transport and boosts evaporation efficiency.

Beyond desalination, the SSG technology can also be used as a heating device. Hou told IE that the porous structure theoretically possesses good thermal insulation and sound absorption properties, making it suitable for applications in insulation and noise reduction.

Also, the capillary structure’s rapid water absorption abilities can be employed for directional and quick transport of water.

“These applications are theoretically feasible and hold significant potential for practical use,” Hou said.

The study was published in the journal – Applied Physics Reviews .