What is Steam Activation?

In order for Charcoal to be most effective it goes through an activation process. This process increases the many small low-volume pores in each grain of carbon, vastly increasing the surface area available for the adsorption of toxins and chemicals.

Steam activation is one of the best ways of activating charcoal. In this process, the carbon (e.g. from coconut husks) is heated in a furnace at very high temperatures in the absence of oxygen. All volatile compounds are removed and at the same time many layers of carbon atoms are peeled off, which expands the internal pores, leaving behind a carbon skeleton. 

Typically 3 kg of raw charcoal will produce 1 kg of activated charcoal. In other words, "Less is More", as the internal porous space expands.

Due to its high degree of microporosity, just one gram of activated carbon has a surface area in excess of 3,000 m2 (32,000 sq ft) [1]

After activation the charcoal is cooled and washed to remove any ash content.

Because of the very high temperatures required for steam activation (600 - 1,200 °C), these results are difficult to achieve outside of industrial technology.

[1] (Dillon, Edward C; Wilton, John H; Barlow, Jared C; Watson, William A (1989-05-01). "Large surface area activated charcoal and the inhibition of aspirin absorption". Annals of Emergency Medicine. 18 (5): 547–552. doi:10.1016/S0196-0644(89)80841-8.)