Do You Really Know KDF-55 and KDF-85?

What exactly is KDF?

KDF is a copper-zinc alloy. In simple terms, it’s made by combining copper and zinc.  In our products, we mainly use two types of KDF: KDF-55 and KDF-85.  KDF-55 contains about 50% copper and 50%      zinc, while KDF-85 contains about 85% copper and 15% zinc.

How is KDF actually made?

First, we start with high-purity metallic copper and zinc. These two metals are melted together under controlled conditions. During the melting process, copper and zinc combine to form a specific copper-      zinc alloy. After that, the alloy goes through a controlled granulation process, which turns it into the small particles that we know as KDF media.

So, basically, the process is: Pure copper + pure zinc → melting and alloying → granulation → KDF particles. But here's the interesting part: Why does this copper-zinc alloy actually work in water? The          answer has to do with an electrochemical reaction. When copper and zinc come into contact with water, they can form what is essentially a small galvanic cell.

Think of it like a tiny battery. Copper and zinc act differently in this electrochemical system. Zinc tends to lose electrons, while those electrons can move toward the copper side. And this movement of            electrons is what creates an electrical current at the microscopic level.

This electrochemical behavior is actually the key to understanding what KDF can do in water.

As we mentioned before, copper and zinc can create an electrochemical reaction when they come into contact with water. In this process, zinc tends to lose electrons. In simple terms, zinc in its metallic        state, or zero-valent zinc, can be oxidized and become zinc ions, Zn²⁺.

At the same time, the electrons that are released can move toward the copper side. So, you can think of KDF as creating a tiny electrochemical system on the surface of the media. And this is where              things  get interesting. Those electrons can participate in reactions with certain oxidizing substances in water, including residual chlorine. For example, chlorine and hypochlorous acid can be reduced through      these electrochemical reactions, which helps lower the level of residual chlorine in the water. KDF can also interact with certain heavy metal ions.

Through electrochemical reactions and surface reactions, some heavy metals can be reduced or deposited onto the media surface. However, there’s an important point here: The removal efficiency is not        always the same. It can depend on many factors, including the initial concentration, water flow rate, contact time, and especially the conductivity and chemistry of the water. For example, if the concentration      is relatively low and the flow rate is slower, you may get better removal performance. A soaking or batch test may also show different results compared with a high-flow, continuous filtration test.