December 9, 2023

We use 5 trillion plastic bags every year and they are in the top five of all plastics found in the natural environment.However, paper did not fare much better, with many studies including 2020 environment agency The report cites the environmental cost of the energy and resource-intensive process of producing less durable plastic alternatives.

Part of the problem with paper bags is that they have a relatively short life cycle, they are not compatible with moisture, and lack real utility as flimsy containers for short periods of time.

Researchers at Penn State decided to meet these challenges and created a product that has the potential to benefit consumers and the environment. Through some cheap heat and chemical manipulation, the scientists created a paper product that is strong enough to be reused many times, resistant to water contact, and could eventually be used as a good source of end-of-line biofuel.

“Reuse depends primarily on the strength of the bag, and because typical paper bags have low durability when wet, it’s unlikely to be reused as many times as needed,” said lead researcher Jaya Tripathi, formerly of Penn State and now with the joint lab. explain. California Bioenergy Institute. “Using expensive chemical processes to improve wet strength reduces the environmental and cost-effective properties of paper for commercial applications, so non-chemical techniques need to be explored to improve wet strength of paper bags.”

The technique Tripathi pioneered was toasting, in which the paper’s cellulose is slowly heated in an oxygen-deprived space to increase its tensile strength when wet. After 40 minutes of baking, the paper’s wet tensile strength peaked at 1,533 percent at 392°F (200°C) and steadily decreased with increasing heat.

“I’m working on something else, looking at how torrefaction affects glucose production from cellulose as a biofuel substrate,” she said. “But I noticed that as we baked the cellulose, the strength of the paper was increasing. That made me think it might be good for packaging, which is a whole different application.”

This stronger product could see the paper bag durable after use, wet or dry, however, baking reduces its usefulness as a biofuel product and significantly reduces the glucose yield of the product. To get around this, the researchers treated the paper with an alkaline sodium hydroxide solution. Paper changed from 690 mg/g of biomass substrate (baked at 392 °F) to 933 mg/g with 10% alkali treatment.

“By switching to stronger, reusable paper shopping bags, we can eliminate most of the waste,” Tripathi said. “A technique like the one we demonstrated in this study – if it can be perfected – involves using worn-out bags as a substrate for biofuel production, the implications would be huge.”

While this laboratory study shows the promise of the filter paper model, it is clearly still a long way from practical application. However, extending the life cycle of paper, making it stronger, and finding a use for it after processing could greatly offset the environmental costs of its production and make it a viable alternative to plastic.

“When the primary use of these paper products ends, putting them to a secondary use makes them more sustainable,” said researcher Daniel Ciolkosz, associate research professor of agricultural and biological engineering at Penn State. “It’s a concept we think society should think about.”

The study was published in the journal Resources, Conservation and Recycling.

source: Pennsylvania State University