Cornell University chemists have developed a means to upcycle polystyrene, a form of plastic present in many everyday things, into benzoic acid, a chemical often found in college and high school chemistry laboratories and utilized in scents, food preservatives, and other products.

Benzoic acid has long been used as an antibacterial ingredient in foods, usually in the form of its sodium counterpart, sodium benzoate.

Use of oxygen and light to disintegrate plastics

(Photo : NARINDER NANU/AFP via Getty Images)

Polystyrene is found in styrofoam egg cartons, rigid plastic compact disc cases, red drinking cups, and many other everyday items, and it accounts for one-third of all landfill debris globally.

The reaction may even happen under a sunlit window, according to a Cornell team led by Erin Stache, associate professor of chemistry and chemical biology.

Their research was published in the Journal of the American Chemical Society as "Chemical Upcycling of Commercial Polystyrene through Catalyst-Controlled Photooxidation," as cited by ScienceDaily.

The new technique is gentle, climate-friendly, and expandable to industrial waste streams, according to Stache, which is in keeping with her lab's objective to address environmental challenges via chemistry.

Furthermore, the technique is resistant to additives found in consumer trash, such as dirt, colors, and other forms of plastics.

The advantage of employing light is that you can have controllability over the biological process, thanks to some of the white light-harnessing catalysts scientists have created.

It's a win-win if humans can utilize sunshine to power the process, Stache said, noting that current polymer recycling necessitates melting and processing a polymer, which often necessitates the use of fossil fuels.

The researchers employed a variety of goods, spanning from product packaging to coffee cup lids, to evaluate the technique's tolerance to other materials blended with PS plastic.

The researchers developed a system with two infusion pumps and two LED lights in a 3D-printed photoreactor to demonstrate scalability and possible commercial applicability.

The degradation process was as efficient on a big scale as it was in small amounts.

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Benefits of Benzoic Acid

Benzoic acid (BA) is a frequent antimicrobial preservative in snacks and drinks, particularly carbonated beverages since its antibacterial action is highest at pH 2.5-4.0, as per Preservatives in Beverages: Perception and Needs

BA inhibits the growth of bacteria and yeasts, which is a primary cause of food deterioration.

Although adding BA to beverages might increase their shelf life and reduce nutritional losses, too much of it can induce diarrhea, stomach discomfort, and other symptoms, as well as interfere with the body's intermediary metabolic reactions.

As a result, the maximum permitted amounts of BA in all types of food are regulated.

Benzoic acid is commonly paired with salicylic acid, as per Apollo Pharmacy.

Salicylic acid is a keratolytic medication that breaks down clumps of keratin, eliminates dead skin cells, and softens the skin.

It softens, separates, and produces desquamation (peeling) of the cornified epithelium or horny layer of skin.

Salicylic acid is also a topical antibacterial and anti-inflammatory agent. It eliminates corns, calluses, and warts as well as treats acne and seborrhea (scaly areas and red skin primarily on the scalp).

Benzoic acid is a fungistatic/antiseptic chemical that prevents fungi from growing.

It's also utilized as a lubricant for tablets and capsules, as well as an antibacterial preservative.

Related article: Recycled Plastics Harm Environment by Leaking Hazardous Chemicals, According to Experts