Cigarette butts transforming into carbon dots

From Trash to Treasure: Turning Cigarette Butts into Valuable Resources

Rhea Morgan in Climate & Environment August 2025 • 4 min read.

"Discover how scientists are converting toxic cigarette waste into fluorescent carbon dots for various high-tech applications."

Cigarette butts (CBs) are one of the most pervasive forms of litter globally, posing a significant environmental challenge. Washed into drains, these butts make their way to lakes, rivers, and oceans and are primarily composed of cellulose acetate, which degrades very slowly, leading to persistent pollution and toxic leachates that harm aquatic life.

Recognizing the urgent need for effective waste management, researchers are exploring innovative ways to transform CBs into valuable resources. Instead of conventional disposal methods like landfilling or incineration, which are unsustainable and costly, scientists are developing methods to convert cigarette waste into high-demand products.

One of the recent studies focuses on converting toxic cigarette butts into highly fluorescent N,S-codoped carbon dots (CBCDs) using a simple hydrothermal approach. These carbon dots exhibit bright and stable fluorescence and can be used in various applications such as fluorescent films, security inks, bioimaging, sensing, and logic gate operations, offering a promising solution to mitigate pollution while creating valuable materials.

The Science Behind the Transformation: How Cigarette Butts Become Carbon Dots

Cigarette butts transforming into carbon dots

The key to this transformation lies in a hydrothermal method that converts the cellulose acetate fibers of cigarette butts into water-soluble carbon dots. Concentrated sulfuric acid plays a crucial role in this process, acting as a strong acid to hydrolyze cellulose acetate into cellulose and further convert it into hydrophilic cellulose nanoparticles.

Sulfuric acid also serves as a dehydrating agent, creating unsaturated C=C bonds from saturated C-C bonds, and as an oxidizing agent, generating hydrophilic C-O-H and O=C-O-H groups from hydrophobic C-H. The presence of nicotine, polycyclic aromatic hydrocarbons (PAHs), and aromatic amines further enhances the formation of carbon dots, with sulfuric acid acting as a sulfur dopant to improve the quantum yield (QY) of the resulting CBCDs.

Key steps in the conversion process include:

Cutting cigarette butts into small pieces and sonicating them in sulfuric acid.
Heating the dispersion in a Teflon-lined stainless-steel autoclave at 180°C for 6 hours.
Centrifuging the solution to remove large particles and neutralizing it with Na2CO3.
Purifying the solution by dialysis and obtaining CBCDs powder through freeze-drying.

The resulting CBCDs are spherical nanoparticles with a mean diameter of 3.7 ± 1.4 nm, composed of a graphitic core and amorphous surface functionalities. These carbon dots exhibit bright and stable fluorescence with a quantum yield of 26%, making them suitable for various high-tech applications. The systematic characterization of CBCDs involves techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) to confirm their structure and properties.

The Future is Bright: Endless Possibilities for Carbon Dots

By converting toxic cigarette butts into valuable resources, this research provides a sustainable approach to waste management and pollution reduction. The resulting carbon dots offer versatile applications in various fields, paving the way for a cleaner, more sustainable future. As research continues, these innovative solutions hold the potential to transform waste into valuable assets, contributing to a circular economy and a healthier planet.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1021/acsomega.8b01743, Alternate LINK

Title: Facile Conversion Of Toxic Cigarette Butts To N,S-Codoped Carbon Dots And Their Application In Fluorescent Film, Security Ink, Bioimaging, Sensing And Logic Gate Operation

Subject: General Chemical Engineering

Journal: ACS Omega

Publisher: American Chemical Society (ACS)

Authors: Rajkumar Bandi, Neela Priya Devulapalli, Ramakrishna Dadigala, Bhagavanth Reddy Gangapuram, Veerabhadram Guttena

Published: 2018-10-18

Everything You Need To Know

What are N,S-codoped carbon dots (CBCDs) and how are they made from cigarette butts?

CBCDs are highly fluorescent nanoparticles created from cigarette butts (CBs) using a hydrothermal method. This process involves cutting CBs into small pieces and sonicating them in sulfuric acid. The mixture is then heated in a Teflon-lined stainless-steel autoclave at 180°C for 6 hours. The resulting solution undergoes centrifugation to remove large particles, neutralization with Na2CO3, dialysis for purification, and finally, freeze-drying to obtain the CBCDs powder. The sulfuric acid plays a crucial role by hydrolyzing cellulose acetate, the main component of CBs, and acting as a dehydrating and oxidizing agent, which facilitates the formation of carbon dots.

What is the role of sulfuric acid in converting cigarette butts into CBCDs?

Sulfuric acid is central to the transformation of cigarette butts into CBCDs. It acts as a strong acid, hydrolyzing the cellulose acetate in cigarette butts into cellulose and converting it into hydrophilic cellulose nanoparticles. It also serves as a dehydrating agent, which creates unsaturated C=C bonds, and as an oxidizing agent, which generates hydrophilic C-O-H and O=C-O-H groups. Furthermore, it acts as a sulfur dopant, improving the quantum yield of the resulting CBCDs. Without the presence of sulfuric acid, the process would not be successful.

How do CBCDs contribute to environmental sustainability and what are their potential applications?

CBCDs contribute to environmental sustainability by converting a major pollutant, cigarette butts (CBs), into a valuable resource. This reduces the environmental burden caused by CBs, which are a pervasive form of litter. The CBCDs, with their bright and stable fluorescence, have potential applications in various high-tech areas such as fluorescent films, security inks, bioimaging, sensing, and logic gate operations. This provides a circular economy approach, where waste is transformed into useful materials, promoting a cleaner and more sustainable future.

What are the key steps in the conversion process of cigarette butts into CBCDs?

The key steps in the conversion process include: cutting cigarette butts into small pieces and sonicating them in sulfuric acid. The dispersion is then heated in a Teflon-lined stainless-steel autoclave at 180°C for 6 hours. Afterward, the solution is centrifuged to remove large particles. It is then neutralized with Na2CO3, purified by dialysis, and the CBCDs powder is obtained through freeze-drying. These steps are crucial for breaking down the cellulose acetate and creating the desired carbon dot structure.

What characteristics and properties make CBCDs suitable for various high-tech applications?

CBCDs are suitable for various high-tech applications due to their unique characteristics. They are spherical nanoparticles with a mean diameter of 3.7 ± 1.4 nm, featuring a graphitic core and amorphous surface functionalities. The most important feature is their bright and stable fluorescence, with a quantum yield of 26%. This fluorescence makes them ideal for use in fluorescent films, security inks, bioimaging, sensing, and logic gate operations. The systematic characterization using techniques like transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) further confirms their structure and properties, ensuring their suitability for the mentioned applications.