In the pharmaceutical, natural product extraction, and polymer synthesis industries, mixed solvent systems composed of chloroform, ethanol, and water are widely used. However, the recovery and purification of such systems have long been recognized as a major technical bottleneck. These solvent mixtures readily form azeotropes, and when dichloromethane is present as an impurity, the separation difficulty increases exponentially. Conventional single distillation or simple water-washing methods are ineffective, resulting in substandard solvent purity, high recovery costs, and even adverse impacts on final product quality.

Leveraging a deep understanding of complex solvent systems and extensive industrial application experience, Zhengzhou Tiei Extraction Technology Co., Ltd. has innovatively proposed a distillation–centrifugal extraction coupled process. With its core CWL-M series centrifugal extractor as the key equipment, this approach provides an efficient, stable, and cost-effective solution to this highly challenging separation task.

Technical Challenge: When Multiple Azeotropes Meet Similar Impurities

The chloroform/ethanol/water mixture is itself a typical azeotropic system, making separation inherently difficult. Moreover, the target impurity—dichloromethane—exhibits physicochemical properties (such as boiling point, density, and polarity) that are extremely similar to those of the main solvent, chloroform, rendering them virtual “molecular twins.” This results in the following challenges:

1.Extremely low distillation efficiency: The relative volatility of dichloromethane to chloroform is close to unity. As a result, conventional distillation would require an excessively high number of theoretical stages, leading to enormous energy consumption and still failing to achieve the required level of deep removal.
2.Poor performance of traditional water washing: Within the complex chloroform–ethanol–water matrix, simple stirred water washing readily causes emulsification and phase separation difficulties. The selective removal efficiency for dichloromethane is low, and significant entrainment losses of the main solvent may occur.
3.Overly complex process routes: To obtain high-purity chloroform, multiple distillation and post-treatment steps are typically required, resulting in long process flows, high capital investment, and elevated operating costs.

Tiei Extraction’s Innovative Process: Coupling the Advantages of Distillation and High-Efficiency Extraction

For this complex system, our company Tiei Extraction recommends and has verified the following efficient process route, the core of which lies in combining the preliminary separation of distillation with the selective deep purification of centrifugal extraction:

1.Preliminary Distillation (Pre-separation)
The chloroform/ethanol/water mixed waste solvent is first pretreated and subjected to preliminary distillation. The objective is to remove the majority of ethanol and water, yielding a chloroform-rich distillate that still contains the target impurity, dichloromethane. This step effectively mitigates the azeotrope issue and creates favorable conditions for subsequent deep impurity removal.

2.Deep Extraction (Core Purification Step)
The chloroform-rich distillate is then fed into the CWL-M series centrifugal extractor, where it undergoes multistage counter-current contact with a washing agent at a specific ratio (typically water or a customized aqueous solution).
Key mechanism: By exploiting the subtle differences in solubility of dichloromethane and chloroform in the washing agent, and leveraging the extremely high mass-transfer efficiency generated within the centrifugal extractor, dichloromethane is selectively and maximally transferred into the aqueous phase, while chloroform losses are kept to an absolute minimum.

3.Instantaneous and Precise Phase Separation
Under a centrifugal field thousands of times greater than gravity, the mixture achieves a complete and clear separation of the organic phase (high-purity chloroform) and the aqueous phase (washing solution containing dichloromethane) within 2-5 seconds, completely avoiding emulsification and ensuring high yield and high quality of the main product.

Why Choose Tiei Extraction Centrifugal Extractor?

In this coupled process, the centrifugal extractor is the core element that determines both the effectiveness of deep purification and the overall economic performance:

1.High-efficiency removal of trace impurities: Specifically optimized for the separation of closely similar components, the system achieves exceptionally high removal efficiency even when dichloromethane is present at very low concentrations.
2.High processing capacity: A single unit offers large throughput and supports continuous operation, meeting processing demands from laboratory scale to full industrial production.
3.Green and environmentally friendly operation: The entire system operates in a fully enclosed manner, eliminating solvent volatilization. The washing agent can be recycled, and the volume of the dichloromethane-containing aqueous phase is small with a high impurity concentration, significantly reducing downstream waste treatment costs.
4.Automation and safety: With a high level of system integration, fully automated control can be implemented, minimizing manual intervention and enhancing the safety and operational stability of the overall solvent recovery unit.

Core Value Delivered to Customers

1.Breakthrough in product purity: Dichloromethane impurities in chloroform can be consistently reduced to 10 ppm or even lower, meeting the most stringent process and product quality standards.
2.Significant cost reduction: Compared with solutions relying solely on energy-intensive high-precision distillation, the coupled process reduces total energy consumption by 30–50%, while achieving a chloroform recovery rate of over 99%.
3.Simplified process flow: Tiei provides an integrated process package and equipment support, transforming a highly complex separation challenge into a stable, reliable, and continuous production operation.
4.Enhanced core competitiveness: By ensuring high quality and stable supply of critical solvents, the solution improves downstream product consistency and helps customers maintain a leading position in high-end markets.

When confronted with the challenge of removing dichloromethane from complex chloroform/ethanol/water systems, Zhengzhou Tiei Extraction delivers not merely a single piece of equipment, but a comprehensive, end-to-end solution encompassing process design, core equipment, and full system integration. We are committed to transforming complex separation challenges into tangible gains for our customers—in the form of higher product purity and clear cost advantages.
Email: sales@tieiextraction.com
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