Powdered Activated Carbon (PAC): Uses & Selection

Powdered activated carbon works on a completely different rhythm from every other carbon format. There is no bed and no cartridge. PAC is weighed out, dosed into a liquid, stirred for a defined contact time, and then removed by settling or filtration, taking its captured contaminants with it. That cycle, dose, mix, separate, is the whole product, and most PAC problems trace to one of those three steps rather than to the powder itself.

This guide covers where PAC is the right format, the specs that matter when selecting a grade, and how to get dosing and separation right. The figures quoted reflect the PAC grades Carbeva stocks and batch-tests.

What PAC Is

PAC is activated carbon milled to a fine powder, typically 100 to 325 mesh, roughly 44 to 149 microns. The fine particle size is the point: small particles mean short diffusion paths into the pore network, so adsorption that takes a granule minutes happens in a powder in seconds to a couple of minutes. That speed is what makes batch treatment practical. The trade-off is that PAC is single-use: once mixed into a process, it can only leave as spent filter cake, so there is no reactivation and no reuse.

Where PAC Is the Right Format

PAC dominates four application families. In decolorization, it strips color bodies from sugar syrups, glucose, glycerin, and edible oils during processing. In municipal water treatment, it is dosed seasonally to knock down taste and odor compounds like geosmin and MIB during algae events, precisely because dosing can be turned on and off with the problem. In food and pharmaceutical purification, it removes trace organics and color from intermediates and final products, using certified food or pharma grades. In cosmetics, ultra-fine grades provide both function and the characteristic black color in masks and cleansers, where texture depends directly on particle fineness.

"PAC is the format you reach for when the problem is temporary, the process is a batch, or the contact time available is measured in minutes."

Carbeva Technical Notes

Selecting a PAC Grade

Particle Size Distribution

Finer powder adsorbs faster and, in cosmetics, feels smoother, but it is also harder to settle and filter out, and dustier to handle. A 200 mesh grade is the general-purpose middle ground for most liquid processing; 325 mesh suits cosmetic formulations and processes with fast filtration equipment. What matters as much as the nominal mesh is the distribution around it: a wide distribution with a coarse tail feels gritty in a formulation, while a fine tail slips through filters into the product.

Adsorption Capacity

Iodine number carries over from other formats: 500 to 900 mg/g covers general decolorization duty, 900 mg/g and above suits demanding purification. For decolorization specifically, ask for the methylene blue value as well, since it reflects capacity for the larger molecules that color removal actually targets, which iodine number alone understates. A wood-based PAC with a moderate iodine number will frequently out-decolorize a coconut PAC with a higher one, because its mesopores fit the molecules in question.

Purity and Certification

Because PAC ends up mixed directly into the product stream, purity specs carry more weight than they do for a carbon that water merely flows past. For food, beverage, and pharma work, the grade must be batch-certified against FCC or USP limits for heavy metals and microbials; an industrial decolorizing grade is not a substitute at any price. Ash and acid-soluble content matter for sensitive formulations even outside food applications.

Dosing, Contact Time and Separation

PAC performance in practice is set by three process numbers. Dose is determined by jar testing, not by rule of thumb: treat samples of your actual liquid at a ladder of doses, measure the result, and read the required grams per liter off the curve. Typical working doses run from tens of milligrams per liter in municipal taste and odor work to several grams per liter in heavy decolorization. Contact time of 15 to 30 minutes with good mixing captures most of PAC's usable capacity; extending far beyond that buys little. Separation has to be designed before the first dose goes in: settling basins, filter presses, or polishing filters must be able to remove the powder completely, because any carbon that escapes separation is now in your product, carrying everything it adsorbed.

PAC vs. GAC in One Minute

Common Mistakes When Using PAC

• Skipping the jar test. Doses copied from another plant or a supplier brochure routinely miss by a factor of two in either direction.
• Dosing without a separation plan. PAC that cannot be settled or filtered out ends up in the product, along with everything it adsorbed.
• Selecting on iodine number alone for decolorization. Methylene blue value and pore structure predict color removal better than iodine number does.
• Using industrial PAC in a food or pharma stream. The powder mixes into the product, so certification is not optional.
• Ignoring dust handling. Fine carbon dust is an inhalation nuisance and a housekeeping problem; closed transfer and proper extraction pay for themselves.

Ordering a PAC Sample for Jar Testing

The jar test is the whole selection process compressed into an afternoon, and it needs the real product. Tell us your liquid, your target (color, taste and odor, or a specific contaminant), and your separation equipment, and we will recommend one or two candidate grades and ship samples with each batch's certificate, so your dosing curve is built on the exact material you would be buying.

Frequently Asked Questions

What is powdered activated carbon used for?

PAC is dosed into liquids for batch purification: decolorizing sugar, glycerin, and edible oils, treating seasonal taste and odor in municipal water, purification steps in food and pharmaceutical production, and as a functional ingredient in cosmetics.

What is the difference between PAC and GAC?

PAC is fine powder dosed directly into a liquid and removed after treatment; GAC is coarse granules packed into a bed that liquid or air flows through. PAC suits batch and intermittent problems, GAC suits continuous loads.

How much PAC should I dose?

Determine dose by jar testing your actual liquid at a range of doses and measuring the result. Working doses vary enormously by application, from tens of milligrams per liter for taste and odor to several grams per liter for heavy decolorization.

Can powdered activated carbon be reused?

No. PAC is a single-use format: after treatment it is removed by settling or filtration and disposed of as spent cake. Only bulk granular formats are realistically reactivated and reused.