The researchers modified biochars to improve the removal of a harmful chemical called pentachlorophenol (PCP) from soil. They found that biochars with high redox capacity were most effective at reducing PCP levels. Biochar treated with FeCl3 and KMnO4 showed the best results, especially in anaerobic conditions. Biochar with high redox capacity and conductivity was the most successful at removing PCP quickly. Overall, the key to successful PCP remediation in soil lies in the biochar's ability to both conduct electricity and have a high redox capacity.