Adsorption of Some Heavy Metals and Dyes in Aquatic Environment by Using Sludge Biochars Obtained at Different Pyrolysis Temperatures

The complex mixture of organic matter, metals, and potentially harmful substances found in sewage sludge, a wastewater treatment byproduct, presents risks to human health and can foster antibiotic resistance. Numerous studies have investigated the influence of pyrolysis temperature on biochar characteristics and performance. Investigating the effects of pyrolysis temperature on sludge-derived biochar's properties and the fate of heavy metals and azodyes throughout the process is the specific aim of this study. This reduction primarily stems from the volatilization of carbon, the major constituent, at temperatures around 600°C. In experiments evaluating contaminant removal, biochar produced at 500°C (Biochar 500) was used at a concentration of 5g/ L, with a contact time of 30 minutes, an average solution temperature of 23.4°C, and an average pH of 7.94. Under these conditions, the average removal percentage of trace metals ranged from 80.0% for selenium (Se) and arsenic (As) to 99.79% for cobalt (Co). The removal efficiency for methylene blue (MB) ranged from 99.69 to 99.96%. Optimal removal of the harmful substances was achieved with a specific adsorbent dosage (5mg/ L), a controlled solution pH, and a 30-minute contact time. The study demonstrates that even small amounts of the adsorbent are highly effective in removing MB from water. The Langmuir adsorption model predicted a maximum MB adsorption capacity of 965mg/ g, which aligns with experimental results obtained from using MB to treat wastewater contaminated with methylene blue.