Quality standards for decolorized activated carbon

Quality standards require that manufacturers provide such documents; especially for newly selected manufacturers, they are generally required to submit quality reports for three batches, and these reports must be stamped with a red seal.

First, you need to determine the molecular weight range of the pigments you want to remove, as different pigments have varying molecular weight ranges. Granular activated carbon can be used in decolorization columns and can be regenerated for repeated use. Powdered activated carbon is generally added in a single use and is difficult to regenerate. Different types of activated carbon have **either industry standards or specific specifications; for example, the quality standards for coal-based granular activated carbon used for water purification are given in GB7701.4-87. This type of activated carbon is primarily used for dechlorination and oil removal in industrial water, as well as for the advanced treatment of wastewater. The technical specifications for coal-based granular activated carbon used for water purification should meet the requirements outlined in the table below: Parameter | Specification; Moisture %: ≤5; Strength %: ≥85; Iodine adsorption value, mg/g: ≥800; Methylene blue adsorption value, mg/g: ≥54; Phenol adsorption value, mg/g; Packing density, g/L: to be determined through measurement; Particle size, mm: >2.75, ≤2%; 1.50–2.75: no specification; 1.00–1.5: ≤14%, ≤1.00, ≤1%. Therefore, it is necessary to first determine your requirements based on your objectives.

1. Moisture: It shall be calculated based on the weight of the granular activated carbon contained in the packaging container, or based on the weight of the granular activated carbon shipped in bulk by the supplier; the moisture content must not exceed 8%. Due to environmental conditions that are difficult for suppliers to control, bulk transportation may increase the moisture content of activated carbon, allowing it to exceed 8%. 2. The apparent density must be no less than 0.36 g/cm3. The density of bituminous coal activated carbon after reflux and liquid discharge, in pounds, is calculated by multiplying the apparent density by 62.43 x 0.85. 3. Particle size distribution: The proportion of granular activated carbon remaining on the largest sieve shall not exceed 15%, and the proportion of granular activated carbon that passes through the smallest sieve shall not exceed 5%. The particle size range can be specified separately by the purchaser. 4. The effective particle size must be within the range specified by the purchaser. Granular activated carbon is usually 0.35~1.5 mm in size. (Suppressed activated carbon is not applicable) 5. Uniformity coefficient: The uniformity coefficient is the ratio of the sieve size through which 60% of the representative samples of the filtering material can pass to the sieve size through which 10% of the same samples can pass. Unless otherwise specified by the purchaser, the uniformity coefficient of granular activated carbon after backflow and drainage in the filter shall not exceed 2.1. (Suppressed activated carbon is not applicable.) 6. Wear resistance: It is determined by conducting wear tests using the stirring method or the ball-on-disc method; the average particle size retention rate of granular activated carbon must be no less than 70%. 7. The surface area is determined using the nitrogen BET method; the surface area of granular activated carbon must be no less than 500 m2/g. 8. The pore volume is determined by a combination of mercury displacement and helium displacement methods; the total pore volume of granular activated carbon must be no less than 0.80 cm3/g. 9. Water-soluble ash: Determined by the water extraction method; the water-soluble ash content shall not exceed 4%. 10. Iodine value: Determined according to ASTM 4607 method; the iodine content of granular activated carbon shall be not less than 500 mg/g. 11. General impurities shall not contain any impurities that could have toxic or harmful effects on the health of those who use water treated with activated carbon. 12. Special impurities: It shall not contain special impurities exceeding the specified limit values. Item Indexes: First-class product, Second-class product
Iodine adsorption value, mg/g: ≥ 1000, 900
Methylene blue adsorption rate, <SUP>1)</SUP> mL/0.1g: mg/g ≥ 9.0 (135), 7.0 (105)
Strength, %: ≥ 90.0, 90.0
Apparent density, g/ml: 0.45–0.55, 0.32–0.47
Particle size, <SUP>2)</SUP>: 2.00 mm–0.63 mm, %; ≤ 0.63 mm, %: ≤ 90, 5, 85, 5
Moisture content, %: ≤ 10.0, 10.0
pH value: 5.5–6.5, 5.5–6.5
Ash content, %: ≤ 5.0, 5.0
1) A = 15V, where A is the amount of methylene blue absorbed per gram of activated carbon, in mg/g; V is the volume of methylene blue absorbed by 0.1g of activated carbon, in mL.
2) The particle size range can also be agreed upon by both the supplier and the buyer