Glycolic acid, also known as hydroxyacetic acid, is widely used in skincare products, biodegradable materials such as PLGA, and fine chemical intermediates. With the explosive growth of the biodegradable plastics and medical aesthetics industries, market demand for high-purity glycolic acid continues to rise. However, the production process of glycolic acid is often accompanied by a large number of by-products and impurities. How to purify glycolic acid efficiently and cost-effectively has become a major technical challenge for many manufacturers.

This article discusses how glycolic acid can be purified, with a particular focus on the application of liquid–liquid extraction technology and its core equipment—the CWL-M centrifugal extractor—to achieve clean production and high-efficiency purification.

Challenges in Glycolic Acid Purification

• Complex impurity composition: The reaction solution typically contains unreacted raw materials, by-product salts, colored impurities, and other carboxylic acids.
• High thermal sensitivity: Glycolic acid is prone to self-polymerization or decomposition at elevated temperatures, making traditional distillation unsuitable for purification.
• Strong affinity with water: Glycolic acid is highly soluble in water. Effectively extracting it from the aqueous phase and separating it from other impurities requires highly efficient separation technology.

Core Advantages of the CWL-M Centrifugal Extractor in Glycolic Acid Purification

The liquid–liquid extraction method utilizes the difference in solubility of glycolic acid between specific extractants (such as organophosphorus compounds, amine extractants, or ketone solvents) and water. Glycolic acid is transferred from the fermentation broth or reaction solution into the organic phase, and then recovered as a purified glycolic acid solution through stripping. Due to its continuous operation, low energy consumption, high separation efficiency, and ease of scale-up, liquid–liquid extraction has become a mainstream solution for upgrading glycolic acid purification processes.

The CWL-M series centrifugal extractor, independently developed by Zhengzhou Tiei Extraction Technology Co., Ltd., is advanced equipment specifically designed to address complex liquid–liquid separation challenges. In glycolic acid purification processes, it demonstrates the following distinct advantages:

1.High Mass Transfer Efficiency and Enhanced Extraction Rate
The CWL-M centrifugal extractor generates strong centrifugal force through high-speed rotation, enabling instantaneous and thorough mixing of the light and heavy liquid phases, resulting in extremely high mass transfer efficiency. In glycolic acid extraction processes, this allows the extractant to rapidly capture glycolic acid molecules from the aqueous phase. The single-stage extraction efficiency is significantly higher than that of traditional mixer-settlers or extraction columns, thereby reducing solvent consumption and minimizing the number of extraction stages required.

2.Rapid Phase Separation and Effective Emulsion Control
Glycolic acid systems often contain trace amounts of proteins or surfactants, which can easily cause emulsification in conventional extraction equipment, preventing proper phase separation. By utilizing a high-intensity centrifugal field, the CWL-M centrifugal extractor rapidly breaks droplets and eliminates emulsions, achieving clear and stable phase separation. This ensures minimal organic phase entrainment in the raffinate (wastewater) and effectively prevents solvent loss.

3.Automated Continuous Operation with Compact Footprint
For glycolic acid systems that require multistage countercurrent extraction, the CWL-M centrifugal extractor can be easily configured in multistage series operation, enabling stable 24-hour continuous production. The equipment features fast start-up, convenient shutdown, and a compact structural design. Each unit integrates both mixing and separation functions, significantly reducing plant space requirements.

4.Fully Enclosed Design and Environmental Friendliness
Volatile organic solvents (VOCs) may be involved in the glycolic acid extraction process. The CWL-M centrifugal extractor adopts a fully enclosed structure with no leakage points, ensuring a clean and safe production environment. This design minimizes solvent evaporation losses and complies with increasingly stringent environmental regulations.

Glycolic Acid Extraction Process

1.Pretreatment: The fermentation broth or reaction solution is first filtered to remove biomass or solid impurities. The pH is then adjusted to an appropriate level. Depending on the extractant used, the solution is typically adjusted to acidic conditions to ensure glycolic acid remains in its molecular form.

2.Extraction Stage: The pretreated feed solution and the organic extractant are introduced into the CWL-M centrifugal extractor at a specified phase ratio. After high-speed mixing, glycolic acid is transferred into the organic phase, while most sugars, inorganic salts, and other impurities remain in the aqueous phase (raffinate) and are discharged.

3.Washing Stage:The organic phase loaded with glycolic acid enters the washing stage, where it is contacted with a small amount of acid or water to remove entrained trace impurities, further improving product purity.

4.Stripping Stage: The washed organic phase is then contacted with a stripping agent (such as dilute alkaline solution or pure water). Glycolic acid is transferred from the organic phase into the stripping phase, yielding a purified glycolate solution or aqueous glycolic acid solution. The regenerated organic phase can be recycled back into the extraction system for reuse.

With the continuous expansion of glycolic acid application fields—particularly the growing demand for medical-grade and electronic-grade high-purity glycolic acid—selecting an efficient and stable purification equipment has become increasingly critical. Leveraging years of expertise in liquid–liquid extraction technology and the outstanding performance of the CWL-M centrifugal extractor, Zhengzhou Tiei Extraction Technology Co., Ltd. provides glycolic acid producers with comprehensive solutions covering laboratory testing, pilot-scale validation, and full-scale industrial production.

If you are interested in the liquid–liquid extraction purification process for glycolic acid or in the CWL-M centrifugal extractor, please feel free to contact Tiei Extraction for further information.
Email: sales@tieiextraction.com
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