Activated carbon generally come with a huge internal surface area of about 1,000m² per gram. They perform selective absorption through capillary actions which makes it perform multi-functions such as absorption, desorption, deodorisation, discolouration, purification, recovery, catalyst, etc.

The activated carbon for water purification filters is an absorbent made from processing coconut peels at a high temperature of over 1500°C. Due to the high temperature steam, molecular size cavities are formed, and plenty of passages are developed. Such structure has remarkable effects in removing and absorbing organic compounds, smell and gaseous substances.

It can remove the organic compounds like formaldehyde, trihalomethane, ABS (Sodium Alkylbenzene Sulfonate), taste, smell, phenol-type, and organophosphosphates of petrochemical materials (e.g. benzene, toluene). The inorganic compounds such as arsenic (As), cadmium (Cd), chromium (Cr) can be partially removed, yet chlorine (Cl₂), copper (Cu), lead (Pb), mercury (Hg), and hydrogen sulfide (H₂S) can be removed effectively.

BionTech adopts Kurary GW-H grade activated carbon & T-S grade silver-coated activated carbon. Those are top-class iodine absorption capacity (high-class absorption on organic molecules). With silver-coating, it can prevent the generation of general bacteria in a water purifiers.

Dechlorination by calcium sulphite is a vital water purification process applied especially in drinking water to eliminate the free residual chlorine, as chlorine is adopted for water sterilization in HK water supply. The sum of chlorine (Cl₂), NaOCl, Ca(OCl)₂, hypochlorous (HClO), and OCl^- is referred to as free available chlorine (FAC) or free residual chlorine (FRC). In addition, the reaction of chlorine with ammonia compounds present in the water forms chloramines (NH₂Cl). These chlorine-ammonia compounds are referred to as combined available chlorine (CAC) or combined residual chlorine (CRC). The sum of free and combined available/residual chlorine is called the total residual chlorine (TRC). TRC can be found in the sterilized tap water and are harmful to human.

Calcium sulphite can turn the harmful hypochlorous acid (HClO) into harmless hydrogen chloride (HCl) as dechlorination effect. In addition to the chlorine removal ability of activated carbon, 99.9% of total residual chlorine (TRC) can be removed by BioTech’s UF filter. The purified water is safe to drink without harmful substances.