Frequently Asked Questions
Answers to the questions we are asked most often about activated carbon and our other products.
General
What is activated carbon?
Activated carbon is a carbon material processed to develop an extensive network of internal pores. That pore structure gives it a very large internal surface, where dissolved organic compounds and other impurities are held by adsorption. It is made from carbon-rich raw materials such as coconut shell, coal or wood.
What is the difference between GAC and PAC?
Granular activated carbon (GAC) is sized into granules and used in filter beds that liquid or gas flows through, which suits continuous treatment. Powdered activated carbon (PAC) is a fine powder dosed directly into a liquid and removed afterwards by settling or filtration, which suits batch or intermittent treatment.
Where is activated carbon used?
Common uses include drinking water and effluent treatment, decolourisation and purification in pharmaceutical and bulk drug manufacture, purification in food, sugar and edible oil processing, and air and gas purification.
Which activated carbon is suitable for water treatment?
It depends on what you need to remove and how your plant is set up. GAC is typically used in filter vessels for continuous treatment; PAC is dosed when needed, for example during seasonal taste and odour problems. Share your water quality and system details and we will suggest suitable grades.
What industries use activated carbon?
Water treatment, pharmaceuticals, bulk drugs, food and agro processing, dairy, chemicals, and air and gas purification are among the main users.
How do I choose the right grade?
Start with what needs removing, whether the process is continuous or batch, and the equipment you use. Grades are then compared on parameters such as particle size, iodine value, methylene blue value, ash, moisture and pH. We can help narrow the options for your application.
What packaging options are available?
Packaging depends on the product and quantity, and is confirmed with each quote.
How can I request technical information?
Send an enquiry with the product and your application. Technical data for the relevant grade is shared on request.
Granular Activated Carbon
How is GAC different from PAC?
The carbon is the same kind of material. GAC is granular and sits in a filter bed that the liquid passes through; PAC is a fine powder dosed into the liquid and then removed by settling or filtration. GAC suits continuous treatment; PAC suits batch or intermittent treatment.
Which mesh size should I choose?
It depends on your filter vessel, flow rate and pressure drop, and on what you need to remove. Share your system details with us and we will suggest suitable grades.
Can spent GAC be reused?
In many applications spent granular carbon can be reactivated rather than discarded. Whether that suits you depends on what the carbon has adsorbed.
Powdered Activated Carbon
What is the difference between washed and unwashed PAC?
Washed PAC is treated with acid and water after activation to remove soluble ash and impurities. It is used where purity matters, such as pharmaceutical processing. Unwashed PAC suits applications where standard purity is sufficient.
How is PAC removed after treatment?
Usually by filtration, often with a filter aid to keep fine carbon out of the filtrate and maintain flow, or by settling in water treatment.
How much PAC should I dose?
Dose depends on the liquid, the impurity and the result you need, and is usually confirmed by trials. We can share grade information to support your trials.
Filter Aid Powder
What is the difference between precoat and body feed?
Precoat is a layer of filter aid laid on the filter medium before filtration starts. Body feed is filter aid dosed into the liquid during filtration so the growing cake stays porous. Many processes use both.
Why use filter aid after a carbon treatment?
Powdered carbon particles are very fine and can pass through or blind a filter cloth. A filter aid layer traps them while keeping the flow rate steady.
Which grade do I need?
Finer grades give higher clarity at a lower flow rate; coarser grades filter faster. Tell us your filter type and the clarity you need, and we will suggest a grade.
Hydrated Lime
What is hydrated lime used for in water treatment?
Mainly to raise pH, reduce corrosiveness, soften water by precipitating hardness, and neutralise acidic effluent.
How is hydrated lime dosed?
It is usually mixed with water into a slurry or saturated solution, then dosed into the stream with suitable mixing.
Is hydrated lime the same as quicklime?
No. Quicklime is calcium oxide. Hydrated lime is calcium hydroxide, made by reacting quicklime with water, and is easier to handle and dose.
Activated Alumina
What is the difference between activated alumina and activated carbon?
Activated alumina is aluminium oxide and attracts water and some polar compounds and ions such as fluoride. Activated carbon is carbon and is best at adsorbing organic compounds. They solve different problems.
Can activated alumina be regenerated?
Yes. In drying applications it is regenerated by heating or purging with dry air. In defluoridation, beds are commonly regenerated chemically.
Which ball size should I use?
It depends on the vessel and flow. Smaller balls offer faster uptake; larger balls give lower pressure drop. We will suggest a size once we know your system.
Silica Gel
How does silica gel remove moisture?
Water vapour is adsorbed onto the very large internal surface of the porous silica. The beads stay dry to the touch while holding the moisture.
Can silica gel be reused?
Yes. Heating drives off the adsorbed moisture so the gel can be used again, within the temperature range suitable for its type.
Is silica gel the same as activated alumina?
Both are desiccants, but they differ in material and in how they perform at different humidity and temperature conditions. The better choice depends on the application.
Have a question we have not answered?
Tell us about your application and requirements. Our team will help you identify the appropriate product for your needs.