How to apply activated carbon for sugar purification and decolorization?

Sugar is a staple in food production and daily life, and its quality directly affects product taste and market acceptance. Sugar purification and decolorization are critical steps in sugar processing, as raw sugar contains impurities, pigments and colloids that need to be removed. Activated carbon, with its strong adsorption capacity, is an indispensable material for this process. Having worked in the activated carbon industry for over 25 years, I’ve helped numerous sugar mills optimize their purification and decolorization processes. From small scale refineries to large sugar production enterprises exporting globally, the correct application of activated carbon can significantly improve sugar quality while reducing production costs. In this article, I’ll share practical methods, key considerations and real world cases to help you master the use of activated carbon for sugar purification and decolorization.

The first step to successful sugar purification and decolorization is choosing the appropriate activated carbon. As a general rule, gas treatment typically uses honeycomb activated carbon and pellets activated carbon, while decolorization and purification mainly rely on powder activated carbon. For sugar processing, powder activated carbon is the ideal choice due to its large specific surface area, fast adsorption rate and ability to fully mix with sugar syrup. A few years ago, a sugar mill in southern China was struggling with inconsistent color and purity of their refined sugar. After analyzing their production process and sugar syrup samples, we recommended a food grade coconut shell based powder activated carbon with a specific surface area of over 1100 m²/g. This choice not only effectively removed pigments and impurities but also preserved the natural sweetness of the sugar. It’s important to avoid using granular or pellets activated carbon for this task, as they have slower adsorption rates and may not mix well with the syrup, leading to incomplete purification and decolorization. Industry experts from the sugar processing association emphasize that food grade activated carbon must meet strict safety standards, with no heavy metal residues or harmful substances.

The dosage of activated carbon directly impacts the effect of sugar purification and decolorization as well as production costs. Using too little will result in insufficient removal of pigments and impurities, while too much can cause unnecessary waste and may affect the sugar’s taste. Based on our experience, the optimal dosage of powder activated carbon for sugar purification and decolorization ranges from 0.2% to 1.5% of the sugar syrup weight. For example, in a project for a large sugar mill in Southeast Asia, we conducted small scale tests and determined a dosage of 0.5% powder activated carbon. This dosage successfully reduced the color value of the sugar syrup from 800 ICUMSA to 150 ICUMSA, meeting international quality standards. Before use, powder activated carbon should be properly prepared. It’s best to mix it with a small amount of warm water (around 40-50°C) to form a uniform slurry. This step helps to disperse the carbon particles fully in the sugar syrup, ensuring maximum contact with pigments and impurities. In our technical guidance, we always remind clients to stir the slurry gently to avoid damaging the carbon’s adsorption structure.

Temperature, pH value and contact time are three critical process parameters that influence the effect of activated carbon in sugar purification and decolorization. Different types of sugar (such as cane sugar, beet sugar) require different parameter settings. Generally, the adsorption effect improves with moderate temperature increase, but excessively high temperatures may cause sugar degradation. For most sugar purification and decolorization processes, the temperature should be controlled between 60°C and 80°C. A sugar mill in northern China once ignored temperature control and processed the syrup at 90°C, resulting in reduced sugar yield and poor color. The pH value also plays an important role. The optimal pH range for sugar purification and decolorization is 7.0-8.5, as this environment enhances the adsorption capacity of activated carbon for acidic pigments. The contact time between activated carbon and sugar syrup should be at least 30-45 minutes to ensure sufficient adsorption. In a project for a beet sugar factory in Europe, we extended the contact time from 20 to 40 minutes, which increased the decolorization rate by 30% and improved the sugar’s clarity. According to research data from sugar processing laboratories, proper control of these three parameters can improve the efficiency of activated carbon in sugar purification and decolorization by 40-60%.

Uniform mixing is essential to ensure that every particle of activated carbon comes into contact with pigments and impurities in the sugar syrup. During the mixing process, use a low speed stirrer to avoid generating excessive bubbles, which may affect the subsequent separation. In a case involving a small sugar refinery in Africa, the client initially used a high speed stirrer, leading to poor mixing and incomplete adsorption. After switching to low speed stirring, the sugar’s color and purity improved significantly. Once the adsorption is complete, it’s crucial to separate the activated carbon from the sugar syrup thoroughly. Common separation methods include filtration, centrifugation and sedimentation. For large scale sugar production, a combination of plate and frame filtration and vacuum filtration is recommended to ensure the final sugar syrup is free of carbon residues. In a project we undertook for a sugar mill in Brazil, this separation method resulted in clear, pure syrup with no visible impurities. It’s important to note that the separation equipment should be cleaned regularly to prevent cross contamination and maintain filtration efficiency.

Food safety is paramount when applying activated carbon for sugar purification and decolorization. All activated carbon used must be food grade, with certificates of analysis and safety testing reports. Our company’s powder activated carbon undergoes strict quality control, with a dedicated inspection department testing every batch for heavy metals, ash content and adsorption capacity. In addition, it’s necessary to monitor the sugar purification and decolorization process continuously. Regularly test the color value (ICUMSA), purity and impurity content of the sugar syrup before and after treatment to ensure consistent quality. For example, a sugar company we cooperate with conducts ICUMSA tests every two hours during production, adjusting the dosage of activated carbon in real time based on the results. It’s also important to store powder activated carbon properly – keep it in a dry, well ventilated place away from moisture and odorous substances. Remember that gas treatment generally uses honeycomb activated carbon and pellets activated carbon, while decolorization and purification mainly use powder activated carbon. This clear division helps to avoid material misuse and ensures optimal results for sugar purification and decolorization.

Applying activated carbon for sugar purification and decolorization requires a combination of proper product selection, accurate dosage control, optimized process parameters and strict quality management. By following the methods and precautions shared in this article, you can achieve efficient and safe sugar purification and decolorization, improving the quality and market competitiveness of your sugar products. Each type of sugar has its unique characteristics, so it’s essential to conduct small scale tests before large scale application to determine the best conditions. With over 25 years of experience in the activated carbon industry, we’ve helped 856 clients in 78 countries achieve successful sugar purification and decolorization. Whether you’re processing cane sugar, beet sugar or other types of sugar, the correct application of activated carbon will bring tangible benefits to your production, including improved product quality, reduced costs and enhanced customer satisfaction.