Globally, more than 2 billion people live in countries with severe water deficits, largely due to contamination of water supplies, insufficient management and a lack of adequate infrastructure. Frequently, many fall ill to oftentimes fatal water-transmitted diseases such as diarrhea, dysentery and Hepatitis A. Population growth increases water insecurity, and climate change disrupts weather patterns, causing an increase in unpredictable water availability. Fortunately, researchers have developed a porous, loofah-inspired hydrogel that could sustainably purify water in a cost-effective way.

Initial Development

Previously developed thermoresponsive hydrogels absorbed and then released purified water. However, they had a slow response rate and were not effective in cloudy weather, providing an insufficient volume of water for a person’s daily needs. With increased release rates, the newly innovated loofah-inspired hydrogel improves on this. Researchers used a mixture of water and a chemical called ethylene glycol to induce polymerization, creating a ‘PNIPAm hydrogel’ with interconnected pores inspired by the porous structure of a loofah. They coated the inner pores of the hydrogel with the chemicals polydopamine (PDA) and poly(sulfobetaine methacrylate) (PSMBA), which provide the hydrogel with the ability to remove pollutants. The porous structure filters out microplastics, and the polydopamine traps contaminants such as dyes and metals. Furthermore, PSMBA creates a hydration layer that stops oils and microorganisms from being absorbed along with the water. When the hydrogel is cool, it can absorb water, but when warmed, it becomes hydrophobic and releases water. The hydrogel will only absorb water, not contaminants such as oil; therefore, it releases purified water.

Testing and Results

The porous, loofah-inspired hydrogel’s efficiency was tested with artificial light to replicate the solar energy of the sun. When heated, it “released 70% of its stored water in 10 minutes.” This improvement in response rate, four times faster than the closed-pore thermoresponsive hydrogels, means that this development could potentially meet a person’s daily water demand. Furthermore, it can work effectively even when a source of solar energy is not available. This is essential, as weather patterns may be unpredictable in areas of water deficit. Researchers proved the hydrogel’s effectiveness by testing under artificial light conditions, which replicated cloudy weather. It took about 20 minutes for the hydrogel to emit a similar amount of water to the volume released in sunny conditions. The hydrogel has also been tested on polluted samples containing “organic dyes, heavy metals, oil and microplastics.” These tests returned positive results, as the hydrogel successfully purified the water, removing contaminants.

Looking Forward

The hydrogel technology looks to be a vital step toward providing access to clean water in areas experiencing water insecurity. Although still in development, it has enormous potential. Research continues to create new and improved versions, such as hydrogel that could kill waterborne bacteria by utilizing its antibacterial properties. This provides hope for a brighter future for those without the financial ability to access clean water.

Isla Wright

Photo: Flickr