Activated carbon for water filtration: How does it work?


activated carbon water filter

In the quest for cleaner, safer drinking water, activated carbon has emerged as a hero in the world of water filtration. From simple jugs to complex reverse osmosis systems, activated carbon plays a crucial role in removing impurities and enhancing the taste and purity of our water supply.

But what exactly is it about activated carbon that makes it crucial to the water purification process? 

We recently covered everything you need to know about activated carbon and its many applications, but for the purpose of this blog, we’ll focus on how it works its magic in water filtration.

The origination of activated carbon

Activated carbon isn’t a product of modern science; its roots delve deep into ancient civilisations’ practices. Dating back to ancient Egypt where charcoal was used to filter impurities from water, activated carbon’s efficacy has been recognised for centuries. 

However, it wasn’t until the 20th century that scientists unlocked the secrets of enhancing charcoal’s purifying capabilities through the process of activation.

Understanding activation

Activated carbon undergoes a process called activation, which involves exposing carbon-rich materials, such as wood, coal, coconut shells, or peat, to high temperatures in the presence of gases like oxygen or steam. 

This process creates a highly porous structure with a vast internal surface area, often measured in square metres per gram. It’s this sponge-like structure that gives activated carbon its extraordinary adsorption capacity, making it the perfect material for processes such as water purification.

How it works in water filtration

Post-activation, activated carbon is shaped into water filters which can be used across various applications, from household water filtration systems to industrial water treatment processes and everything in between. But, what makes activated carbon so good at purifying water and how does it work?

Let’s take a look at the intricate workings of activated carbon’s structure and its role in purifying water:

1. Porous architecture

Activated carbon has a high quantity of small, low-volume pores that are created during the activation process and come in different sizes. This gives it the unique structure needed to trap contaminants and chemicals as water passes through the filter.

So, the more pores, the more places for impurities to get caught and the higher the chance of effective adsorption.

2. Expanded surface area

Activated carbon can be likened to a sponge. Even though it’s relatively small in volume it has a huge surface area, providing plenty of room for contaminants to stick to, ensuring that the water passing through gets thoroughly cleaned.

This large surface area can facilitate the adsorption of a wide range of impurities, including chlorine, volatile organic compounds (VOCs), pesticides, herbicides, and even certain heavy metals like lead and mercury.

3. How contaminants are trapped

As water flows through the filter, contaminants are drawn to the porous surface of the carbon particles. They stick to the surface and are retained there, essentially getting trapped.

This process occurs through physical and chemical interactions, such as van der Waals forces, hydrophobic interactions, and hydrogen bonding. Activated carbon’s surface may also undergo chemical reactions with certain contaminants, leading to their transformation or degradation.

carbon used in water filter

4. Selected removal of contaminants

One of the many remarkable attributes of activated carbon is its selectivity towards different types of contaminants. 

It can be tailored to address specific water quality concerns, whether it’s removing chlorine from tap water, eliminating volatile organic compounds (VOCs) from well water, or reducing the taste of certain chemicals, activated carbon filters offer customisable solutions to meet diverse filtration needs.

The activated carbon range offered by RBH is tailored for selective adsorption, so it can effectively remove the target pollutants in the application whilst leaving all other substances untouched.

5. Regeneration and lifespan

Over time, activated carbon may become saturated with adsorbed contaminants, diminishing its filtration efficiency. However, unlike some filtration media, activated carbon can often be regenerated through processes like thermal reactivation or chemical washing, extending its lifespan and reducing waste. 

Regular maintenance and replacement of activated carbon filters are essential to ensure continued efficacy in water purification.

Benefits of activated carbon in water filtration

Using activated carbon as a water filter isn’t a new thing, in fact, it’s been used across many different industries in varied applications for decades. Some of the key benefits that make it a popular choice include:

  • Ability to adsorb a wide range of impurities: We mentioned this earlier, but by being able to capture many different contaminants, activated carbon helps to improve the taste, odour, and overall quality of drinking water.
  • Water preservation: Unlike some filtration methods that strip water of beneficial minerals or alter its pH balance, activated carbon filters preserve the natural composition of water. By selectively removing harmful substances while allowing essential minerals to pass through, activated carbon helps maintain the water’s nutritional integrity and taste.
  • Sustainability: Activated carbon is a sustainable and eco-friendly filtration medium. It’s commonly derived from natural sources like coconut shells or wood, making it a renewable resource that can easily be replenished.
  • Cost-effective & low maintenance: Water filters equipped with activated carbon are generally affordable, and replacing the carbon filter is a simple task that can be done at regular intervals to ensure optimal performance. Filters can be regenerated and put to use again, enhancing their sustainability credentials.

As we continue to face water contamination challenges worldwide, the role of activated carbon in water filters becomes increasingly significant. Whether you’re looking to enhance the taste of drinking water or reduce harmful chemicals, activated carbon-based water filters stand out as a reliable solution.

activated carbon

Which activated carbon is best?

When integrated into water filters, activated carbon can be found in various forms such as granular activated carbon (GAC), powdered activated carbon (PAC), extruded activated carbon (EAC), or carbon block filters. 

Each form offers unique advantages in terms of filtration efficiency and lifespan, catering to different filtration needs and preferences. Therefore, it’s important that the chosen form is one that’s tailored to the application at hand to guarantee the highest rate of effectiveness.

The RBH Group is partnered with Donau Carbon to supply powdered, granular and extruded grades of activated carbon to the UK, Ireland and Benelux. The extensive range covers activated carbon for water filtration amongst other applications such as air & gas treatment, liquid & chemical purification, and more.

To ensure that the type of activated carbon chosen meets the needs of your application, speak to one of our expert Market Managers. We specialise in providing advanced technical support and advice to businesses on material selection that enhances their product performance and efficiency.

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