The efficiency of activated carbon in removing a specific pollutant from water depends on various factors, including the type of pollutant, temperature, pH, and contact time. It is difficult to provide a specific value for the efficiency without knowing the exact pollutant and experimental conditions. However, I can provide a general overview of how these factors can influence the efficiency of activated carbon in removing pollutants from water.1. Type of pollutant: Activated carbon is more effective in removing organic pollutants, such as pesticides, volatile organic compounds VOCs , and pharmaceuticals, compared to inorganic pollutants like heavy metals. The adsorption capacity of activated carbon depends on the molecular size, polarity, and solubility of the pollutant.2. Temperature: The efficiency of activated carbon in removing pollutants generally increases with increasing temperature. Higher temperatures can enhance the diffusion rate of pollutants into the pores of the activated carbon, leading to better adsorption. However, excessively high temperatures may cause the desorption of some pollutants, reducing the overall efficiency.3. pH: The pH of the water can significantly affect the adsorption capacity of activated carbon. For instance, the removal of heavy metals is generally more efficient at lower pH values, as the metals are present in their cationic forms, which can be adsorbed more easily. On the other hand, the removal of organic pollutants may be more efficient at higher pH values, as the deprotonated forms of these pollutants can interact more effectively with the activated carbon surface.4. Contact time: The efficiency of activated carbon in removing pollutants from water increases with contact time, as more time allows for better adsorption of the pollutants onto the activated carbon surface. However, there is a limit to the adsorption capacity of activated carbon, and once it becomes saturated, the efficiency will no longer increase with additional contact time.In summary, the efficiency of activated carbon in removing a specific pollutant from water depends on various factors, and it is essential to optimize these conditions to achieve the best possible removal efficiency. To determine the efficiency for a specific pollutant and set of conditions, experimental studies and data analysis are required.