Sustainable paper production using lignin and ascorbic acid to protect cellulose fibers.

Paper's New Armor: How Lignin and Ascorbic Acid Could Revolutionize Pulp Production

Mira Elwood in Climate & Environment August 2025 • 4 min read.

"Discover how adding natural antioxidants to pulp refining enhances paper durability and reduces environmental impact, making sustainable paper production a reality."

In an era where sustainability is not just a buzzword but a necessity, the paper industry is under increasing pressure to adopt eco-friendly practices. The conventional pulp refining process, crucial for paper production, often involves harsh mechanical treatments that can degrade cellulose, the very backbone of paper. This degradation leads to weaker paper products, necessitating further chemical treatments that are harmful to the environment. But what if there was a way to naturally shield paper from this damage, enhancing its strength and longevity while minimizing environmental impact?

Enter lignin and ascorbic acid—two naturally occurring compounds with potent antioxidant properties. Lignin, a complex polymer found in plant cell walls, and ascorbic acid, commonly known as Vitamin C, have shown promise in protecting cellulose from degradation during the pulp refining process. Recent research has delved into how these compounds can be integrated into pulp refining to improve the chemical characteristics, handsheet properties, and thermal stability of paper.

This article explores the findings of a study that investigates the impact of pretreating pulp with ascorbic acid (AA) and purified kraft lignin (KL) before refining. By examining the effects on chemical characteristics, handsheet properties, and thermal stability, this research sheds light on a potential revolution in paper production—one that champions sustainability without compromising quality.

The Science Behind the Shield: Lignin and Ascorbic Acid in Pulp Refining

Sustainable paper production using lignin and ascorbic acid to protect cellulose fibers.

The study focused on two pretreatment methods: impregnation with ascorbic acid (AA) and purified kraft lignin (KL). These methods were applied to bleached pulp, and the resulting handsheets were rigorously tested to assess the impact on their properties. The core idea was to leverage the antioxidant capabilities of AA and KL to counteract the degradation typically induced by mechanical refining processes.

Ascorbic acid, known for its ability to donate hydrogen radicals, was hypothesized to suppress the recombination reactions of hydrocarbon radicals formed during refining. Kraft lignin, with its phenolic groups, was expected to stabilize radical species, offering a natural shield against degradation. The effects of these pretreatments were evaluated through a series of tests, including measurements of intrinsic viscosity, UV resonance Raman (UVRR) spectroscopy, and X-ray photoelectron spectroscopy (XPS).

Here are some key observations from the study:

Ascorbic Acid (AA): Amplified cellulose depolymerization and impaired strength properties, especially when combined with intensive refining.
Kraft Lignin (KL): Improved burst index stability after humid thermal treatment and reduced total color difference compared to AA-treated and reference handsheets.
Thermal Treatments: Enhanced cellulose depolymerization and color changes in AA-impregnated handsheets more than in KL-impregnated ones.

The results indicated that while ascorbic acid amplified cellulose depolymerization and impaired strength properties, kraft lignin offered a protective effect, enhancing burst index stability and minimizing color changes after thermal treatment. This protective action of lignin could pave the way for more durable and stable paper products, reducing the need for additional chemical treatments.

The Future of Paper: Sustainable, Durable, and Environmentally Friendly

The integration of lignin and ascorbic acid into pulp refining represents a significant step forward in creating sustainable, durable, and environmentally friendly paper products. While ascorbic acid may not be the ideal shield due to its tendency to promote cellulose depolymerization, kraft lignin shows considerable promise in protecting pulp from degradation. By leveraging the natural antioxidant properties of lignin, the paper industry can reduce its reliance on harmful chemicals and create products that are both stronger and more sustainable. Further research and development in this area could unlock new possibilities for the industrial utilization of kraft lignin, paving the way for a greener future in paper production.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.15376/biores.11.1.1808-1827, Alternate LINK

Title: Addition Of Ascorbic Acid Or Purified Kraft Lignin In Pulp Refining: Effects On Chemical Characteristics, Handsheet Properties, And Thermal Stability

Subject: Waste Management and Disposal

Journal: BioResources

Publisher: BioResources

Authors: Emilia Vänskä, Tuomas Vihelä, Leena-Sisko Johansson, Tapani Vuorinen

Published: 2016-01-06

Everything You Need To Know

How does kraft lignin contribute to enhancing paper durability and sustainability during pulp refining?

In pulp refining, kraft lignin demonstrates the potential to protect pulp from degradation. It enhances burst index stability after humid thermal treatment and reduces total color difference compared to ascorbic acid-treated and reference handsheets. This protective action could lead to more durable and stable paper products, decreasing the need for additional chemical treatments. Further research could unlock new possibilities for the industrial utilization of kraft lignin, promoting a greener future in paper production.

What roles do ascorbic acid and lignin play in protecting cellulose during the pulp refining process?

Ascorbic acid, also known as Vitamin C, and lignin are natural compounds with antioxidant properties. Research suggests they can protect cellulose from degradation during pulp refining, potentially enhancing paper strength and longevity while reducing environmental impact. Ascorbic acid donates hydrogen radicals to suppress hydrocarbon radical recombination during refining, while kraft lignin stabilizes radical species, acting as a natural shield against degradation.

What specific methods were used to evaluate the impact of ascorbic acid and kraft lignin on pulp properties?

The study investigated pretreating pulp with ascorbic acid and purified kraft lignin before refining. It examined the effects on chemical characteristics, handsheet properties, and thermal stability. Measurements included intrinsic viscosity, UV resonance Raman spectroscopy, and X-ray photoelectron spectroscopy. These tests were crucial in evaluating the impact of ascorbic acid and kraft lignin on cellulose degradation and paper quality.

Are there any drawbacks or limitations to using ascorbic acid in pulp refining, compared to kraft lignin?

While kraft lignin shows promise, ascorbic acid was found to amplify cellulose depolymerization and impair strength properties, especially when combined with intensive refining. Thermal treatments also enhanced cellulose depolymerization and color changes more in ascorbic acid-impregnated handsheets than in kraft lignin-impregnated ones. Therefore, while ascorbic acid has antioxidant properties, its application in pulp refining may not be as beneficial as kraft lignin, requiring careful consideration of refining intensity and desired paper properties.

What are the broader implications of using kraft lignin in pulp refining for the environment and the paper industry?

The integration of kraft lignin into pulp refining can reduce reliance on harmful chemicals, creating stronger and more sustainable paper products. By acting as a natural antioxidant, kraft lignin protects pulp from degradation during the refining process, minimizing the need for additional chemical treatments to enhance paper durability. This shift not only benefits the environment but also aligns with the increasing demand for eco-friendly practices in the paper industry.