Recent advances of biochar materials for typical potentially toxic elements management in aquatic environments: A review

Pristine biochar, a low-cost, sustainable and environmentally friendly material, has been regarded as an effective potentially toxic elements scavenger for many years. However, with the development of urbanization and industrialization, more types and quantities of potentially toxic elements are discharged into the environment indiscriminately, which has already exceeded the limit of pristine biochar as potentially toxic elements scavenger. Therefore, designed biochar with higher surface area, more functional groups, and higher potentially toxic elements scavenging efficiency has been concerned by researchers. Herein, the review begins with the fundamental aspects of pristine biochar fabrication, including pyrolysis, hydrothermal carbonization and some other strategies. Then the synthetic methods of designed biochar were presented to develop to control the surface morphology, functional groups and some other phy-chemical properties based on some physical and chemical design, which were more beneficial for potentially toxic elements scavenging compared with pristine biochar. Most importantly, the latest advances in biochar materials for typical contaminated potentially toxic elements (lead, cadmium, chromium, arsenic, mercury, copper, and zinc) in aquatic environments have been specifically and comprehensively performed to deeply investigate their involved mechanisms. Finally, future directions and potential challenges for this emerging frontier are discussed. It is believed that this review can afford powerful influences on the development of biochar technologies for potentially toxic elements scavenging in both experiment research and large-scale practical applications. (C) 2019 Elsevier Ltd. All rights reserved.