The efficiency of activated carbon in adsorbing pollutants from contaminated water is influenced by several factors, including the concentration and pore size of the activated carbon. To understand how these factors affect the adsorption process, let's first briefly discuss the properties of activated carbon and the adsorption mechanism.Activated carbon is a highly porous material made from carbonaceous materials, such as wood, coal, or coconut shells. It is produced through a series of processes, including carbonization and activation, which create a large surface area and a network of pores within the material. These pores can be classified into three categories based on their size: micropores <2 nm , mesopores 2-50 nm , and macropores >50 nm .Adsorption is the process by which pollutants adsorbates are attracted and bound to the surface of activated carbon adsorbent through various forces, such as van der Waals forces, electrostatic interactions, and hydrogen bonding. The efficiency of adsorption depends on the physical and chemical properties of both the activated carbon and the pollutants, as well as the conditions of the system e.g., temperature, pH, and presence of other substances .Now, let's examine how the concentration and pore size of activated carbon affect its efficiency in adsorbing pollutants from contaminated water:1. Concentration of activated carbon: The concentration of activated carbon in the system plays a crucial role in determining the adsorption capacity and rate. A higher concentration of activated carbon provides a larger surface area and more adsorption sites, which can lead to increased adsorption capacity and faster adsorption rates. However, there is a limit to the improvement in adsorption efficiency, as increasing the concentration beyond a certain point may cause the activated carbon particles to aggregate and block the pores, reducing the available surface area for adsorption.2. Pore size of activated carbon: The pore size distribution of activated carbon affects its adsorption efficiency by determining the accessibility of pollutants to the adsorption sites. In general, micropores are responsible for the majority of the adsorption capacity due to their large surface area, while mesopores and macropores contribute to the transport of pollutants within the activated carbon structure.- For small pollutants, micropores provide a high adsorption capacity due to their large surface area and strong interactions with the pollutants. However, the adsorption rate may be limited by the slow diffusion of pollutants into the micropores.- For larger pollutants, mesopores and macropores play a more significant role in adsorption, as they provide better accessibility and faster diffusion rates. However, the adsorption capacity may be lower due to the smaller surface area and weaker interactions with the pollutants.In summary, the concentration and pore size of activated carbon are important factors that influence its efficiency in adsorbing pollutants from contaminated water. Optimizing these factors, along with other properties of the activated carbon and the system conditions, can help improve the adsorption performance and achieve the desired level of pollutant removal.