Activated Carbon For Phosphoric Acid Decolorization
Why is activated carbon needed to decolorize phosphoric acid?
Phosphoric acid (especially wet-process phosphoric acid) often contains:
- Organic impurities (such as humic acid, lignin, and residual surfactants)
- Inorganic impurities (such as iron, aluminum, and magnesium ions)
These impurities cause phosphoric acid to turn dark brown or yellowish-brown, affecting its purity and applications (especially in food or electronics).
The purpose of activated carbon decolorization is to remove these organic coloring impurities, making the phosphoric acid lighter in color or colorless and transparent.
Activated Carbon for Phosphoric Acid Decolorization Principle
Activated carbon possesses a highly developed specific surface area (500–1500 m²/g) and abundant microporous structure, and its decolorization of phosphoric acid is primarily based on physical adsorption.
1. Large Specific Surface Area and Pore Structure
Activated carbon has a highly developed pore structure (micropores, mesopores, macropores), providing it with a large specific surface area (typically reaching 500-1500 m²/g or even higher). This provides numerous “sites” for impurity adsorption.
2. Adsorption of Colored Impurities
Colored impurities in phosphoric acid are mainly large organic molecules, such as:
- Decomposition products of humic substances and hydrocarbons introduced from the raw phosphate rock.
- Organic byproducts generated during the production process.
The molecular size of these large molecules precisely matches the mesoporous structure (2-50 nm) of activated carbon, thus allowing them to be effectively adsorbed into the pores of the activated carbon, thereby removing them from the phosphoric acid and achieving decolorization.
3. Removal of other impurities
In addition to using wood powder activated carbon for decolorization, if customers also need to remove impurities from phosphoric acid solutions, nutshell or coconut shell activated carbon can be used to adsorb residual organic matter, odors, and bubbles in phosphoric acid, further improving the purity and appearance quality of the product.
Activated Carbon for Phosphoric Acid Decolorization H3PO4 Process Flow
Next, we will demonstrate a method for decolorizing industrial phosphoric acid:
The phosphoric acid concentration after wet extraction is 40%-45%.
After one concentration, 75% phosphoric acid is obtained; this is pumped to a desulfurizer.
Barium carbonate is added for desulfurization, and after passing desulfurization, the solution enters a settling tank for precipitation.
The supernatant after precipitation is filtered and pumped to a decolorizing tank; when heated to 90-95℃, 1‰-5‰ of wood powdered activated carbon (by volume of the decolorizing tank solution) is added, and the mixture is stirred for 20-45 minutes.
The decolorized solution is filtered, and the resulting clear acid is the qualified finished product – 85% industrial phosphoric acid.
Powdered wood-based activated carbon can be used for phosphoric acid decolorization. If customers require further fine filtration, nutshell or coconut shell granular activated carbon can be used (depending on customer needs).
Advantages:
This industrial phosphoric acid decolorization method can obtain 85% qualified industrial phosphoric acid in one decolorization, which simplifies the process and reduces equipment investment. At the same time, this method can also produce 75% industrial phosphoric acid according to production needs.
Activated Carbon for H3PO4 Decolorization Affecting Factors
Activated Carbon Dosage
The optimal dosage should be determined through small-scale laboratory tests. Typically, the dosage of activated carbon is between 0.1% and 0.5% of the phosphoric acid weight, depending on the initial color and impurity content of the phosphoric acid.
Phosphoric acid H3PO4 concentration
Concentration affects viscosity and the solubility of impurities. Generally, a moderate concentration is beneficial for adsorption. Too high a concentration leads to increased viscosity, affecting diffusion and adsorption rates; too low a concentration may increase energy consumption for subsequent evaporation and concentration. Optimization is necessary based on specific circumstances.
pH Value
Activated carbon generally exhibits better adsorption performance under acidic conditions. Phosphoric acid itself is a strong acid, and its pH environment is highly suitable for the effective functioning of activated carbon.
Iron ion contamination
This is one of the most common problems in phosphoric acid decolorization. Some activated carbons themselves have a high iron content, or production equipment (such as reaction vessels, pipelines, and filters) may introduce iron ions due to corrosion, causing the phosphoric acid to turn yellow instead.
It is necessary to use low-iron activated carbon and corrosion-resistant equipment (such as enamel, graphite, or 316L stainless steel).
Activated Carbon for Phosphoric Acid H3PO4 Decolorization Product
Coconut Shell/Nut shell GAC Activated Carbon For Phosphoric Acid
Heycarbons uses carefully selected fruit shells or coconut shells for the production of granular activated carbon, which can be used to remove impurities from phosphoric acid solutions.
- Iodine value: 900-1100 mg/g
- Ash content: 1% max. 2% max
- pH: 4-7 (after acid washing)
- Hardness: 98% min
- Bulk density: 450-550 kg/m³
Wood Powdered Activated Carbon For Phosphoric Acid Decolorization
Heycarbsorb-WPAC activated carbon uses high-quality wood chips as raw material and is produced using advanced activation technology. The product has advantages such as large specific surface area, strong adsorption capacity, and fast filtration speed. It is suitable for phosphoric acid decolorization.
Wood powdered activated carbon specification:
- 200 mesh passing rate 90% min.
- Methylene blue: 210-300mg/g min.
- Moisture: 10% max.
- AS: 3ppm max.
- Chloride: 0.2% max.
- Heavy metal: 5ppm max.
Heycarbsorb-WPAC wood powdered activated carbon has well-developed micropores, which are suitable for adsorbing organic macromolecules in the liquid phase, thereby achieving phosphoric acid decolorization.
Different fields and applications have different quality requirements for phosphoric acid. Heycarbons can customize activated carbon products with different parameters according to customers’ actual needs.
Activated Carbon Usage Methods
Nut Shell Activated Carbon Filtration Method
- Recommended Empty Bed Contact Time (EBCT): 8–25 minutes
- Recommended Flow Rate: 5–10 BV/h
- Number of Regenerations: 2–4 times (depending on operating conditions and cleaning cycle)
Wood Powdered Activated Carbon Dosage Method
- Dosage: 0.1%–0.5% of phosphoric acid weight
- Stirring Time: 20–45 minutes
- Filtration Method: Plate and frame filter press or fine filter cloth filtration
Activated Carbon for Phosphoric Acid Decolorization H3PO4 Customer Case
Activated Carbon for Phosphoric Acid H3PO4 Customer Case-1
A customer wanted to use activated carbon to filter a phosphoric acid solution, removing impurities and decolorizing it to make the yellow solution transparent.
Heycarbons recommended wood powdered activated carbon.
The customer ultimately chose powdered wood-based activated carbon with a methylene blue value of 14ml/0.1g or higher.
Activated Carbon for Phosphoric Acid H3PO4 Customer Case-2
Another customer wants to use activated carbon to decolorize 85% phosphoric acid H3PO4.
The decolorization effect of wood powdered activated carbon using the phosphoric acid method is relatively good.
Methylene blue ≥ 14ml/0.1g, recommended temperature > 30℃.
Activated Carbon for Phosphoric Acid Decolorization FAQs
Q1: Why is decolorization incomplete?
A: This is mostly due to high original acid color / insufficient dosage / insufficient contact time / char surface blockage.
Q2: Will activated carbon affect the purity of phosphoric acid?
A: Choosing acid-washed, low-ash, low-metallic activated carbon will not have an impact.
Q3: Can I test a sample first?
A: It is recommended to conduct a small-scale test of 1–5 kg first to confirm the decolorization rate.
Custom Heycarbons Activated Carbon Solution For H3PO4 Decolorization
Heycarbons provides a full range of activated solutions at competitive prices.
What Clients Say on Our Activated Carbon
Customize Heycarbons Activated Carbon for Phosphoric Acid Decolorization
Heycarbons has proudly served the activated charcoal industry with high-quality products since 2005, Heycarbons can customize activated carbon for your phosphoric acid decolorization project.
- Customize different raw materials according to different applications.
- Customized size, iodine value, methylene blue, moisture, PH, ash, etc.
- Cost-effective solutions customized according to customer applications.
- China leading and professional supplier of activated carbon.
Steps to Custom Activated Carbon For Phosphoric Acid Decolorization
Consultation
By understanding your needs and requirements, our salesmen work with you to submit the appropriate activated carbon solution.
Quotation
Heycarbons expert customer service will provide you with a free quote based on your requirements as well as product specifications and quantities.
Production
Heycarbons has sufficient inventory and strong production capacity, and will report production progress to you from time to time.
Shipping
Heycarbons know you need to receive the product as soon as possible, after rigorous quality checks and protective packaging, by fedex shipping.
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