300,000 Disposable Diapers Could be Broken Down By UV Light Instead of Being Dumped in Landfills

According to recent research, disposable diapers could be broken down by UV light during disposal rather than having 300,000 of them burned or disposed of in landfills every minute.

300,000 Disposable Diapers Every Minute

Disposable diapers stand as a colossal contributor to global waste due to their intricate composition that hinders easy recycling. However, a novel approach offers hope by salvaging the 'superabsorber' polymer found in diaper liners, even when soiled. These liners predominantly consist of sodium polyacrylate, transforming into a hydrogel upon liquid absorption.

Crafted from wood pulp, cotton, viscose rayon, polyester, polyethylene, and polypropylene, disposable nappies, as per a 2021 United Nations Environment Programme report, pose extensive environmental impacts throughout their life cycle. They strain on local authorities tasked with their disposal.

The challenge lies in recycling superabsorbers based on crosslinked sodium polyacrylate, resulting in 2 million tons ending up in landfills or incinerated yearly. An efficient strategy is crucial to alleviate this environmental burden. Enter a rapid recycling method leveraging UV degradation in crosslinked sodium polyacrylate hydrogels without additional chemicals besides water. This revolutionary technique achieves swift conversion to soluble sodium polyacrylate within minutes, a significant advancement over slower de-esterification methods by almost 200 times.

The resultant soluble sodium polyacrylate holds versatile applications, from thickening aqueous dyes to serving as a base for pressure-sensitive adhesives. This process, featuring fast, scalable, safe, and cost-effective UV photodegradation and esterification, yields polymers with adjustable molecular weights (100-400 kg/mol), surpassing prior de-crosslinking methods.

Compounded with the plastic content, disposing of diapers with baby waste further complicates recycling. Shockingly, the US$71 billion disposable diaper market stands among the largest contributors to global public waste, with over 300,000 diapers incinerated, landfilled, or polluting the environment every minute.

Diverting Disposable Diapers From Landfills Using UV Light

Disposable nappies offer unparalleled ease and convenience, prompting their widespread use. The reluctance to adopt reusable alternatives often stems from parents feeling overwhelmed by the extra effort involved, a lack of proper washing and drying facilities, or the deterrent of initial costs. Consequently, disposable diaper sales have surged in regions like Southeast Asia, notably in countries such as Indonesia, buoyed by a growing middle class and an expanding population.

Traditionally, recycling these nappies involved immersing them in a potent heated acid for roughly 16 hours, a process that breaks down the crosslinked polymer chains in the gel for potential recycling. However, due to its substantial time and energy demands, this method remains infrequently used.

Also Read: Recycled Plastic Pellets From 13 Countries Across the Globe Detected With Highly Toxic Chemicals 

In pursuit of a more efficient approach, scientists at Germany's Karlsruhe Institute of Technology devised a groundbreaking method. They soaked sodium polyacrylate diaper liners with water and exposed them to ultraviolet light from a 1,000-watt lamp at room temperature. Astonishingly, within a mere five minutes, the polymer gel dissolved into a liquid, which was collected. Leveraging existing techniques, the researchers transformed the liquified sodium polyacrylate into both an adhesive and a dye-thickening agent.

Professor Pavel Levkin from Karlsruhe Institute elucidated that the light breaks the chains linking the polymers, causing them to transform into loose, water-soluble liquid fibers. This UV light method proved 200 times faster than the conventional acid treatment. Although clean diaper liners were used in the experiments, the scientists remain confident in the method's efficacy for used ones.

Levkin highlighted his team's discovery as a promising strategy for recycling superabsorbers, emphasizing its potential to significantly diminish environmental pollution and foster a more sustainable utilization of polymers.

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