The concentration of adsorbate in water plays a significant role in determining the efficiency of activated carbon in removing pollutants. Activated carbon is a highly porous material with a large surface area, which allows it to adsorb a wide range of pollutants from water, such as organic compounds, heavy metals, and other contaminants. The adsorption process is influenced by several factors, including the concentration of the adsorbate, the properties of the activated carbon, and the environmental conditions e.g., temperature, pH .When the concentration of adsorbate in water is low, the activated carbon can efficiently remove pollutants because there are plenty of available adsorption sites on its surface. In this case, the adsorption process is mainly governed by the chemical interactions between the adsorbate molecules and the activated carbon surface, such as van der Waals forces, hydrogen bonding, and electrostatic interactions.As the concentration of adsorbate increases, the available adsorption sites on the activated carbon surface become occupied, leading to a decrease in the overall adsorption efficiency. This is because the adsorption process becomes more competitive, with multiple adsorbate molecules competing for the limited number of available sites. In this situation, the adsorption process is influenced by both the chemical interactions between the adsorbate molecules and the activated carbon surface, as well as the mass transfer of the adsorbate molecules from the bulk solution to the activated carbon surface.At very high adsorbate concentrations, the activated carbon may become saturated, meaning that all available adsorption sites are occupied, and no further adsorption can occur. In this case, the efficiency of the activated carbon in removing pollutants from water is significantly reduced.In summary, the concentration of adsorbate in water affects the efficiency of activated carbon in removing pollutants through the availability of adsorption sites, the competition between adsorbate molecules for these sites, and the potential saturation of the activated carbon. To optimize the efficiency of activated carbon in water treatment, it is essential to consider the concentration of the adsorbate and select the appropriate activated carbon material and operating conditions.