Potential role of biochar in water treatment
Piyush Gupta, N. P. Gupta
Abstract
ABSTRACT Since the past decades, the water dearth has turned attention of researchers towards its restoration along with the remediation of contaminated water in lieu of rejuvenating valuable resources. Through the treatment of wastewater, it is possible to decrease the exploitation of natural water resources as well as alleviating the problem of water shortage. As a circular or closed loop economy solution, the organic waste such as biomass can be renewed in biochar, a carbon rich product by means of thermochemical conversion methods. Biochar demonstrates an incredible potential in water treatment for removing different pollutants considering low-cost, widely accessible feed-stock, and easy surface modifications for enhancing contamination remediating properties as well. Hence, this manuscript focuses on an overview of remediating toxic pollutants employing biochar. The biochar production methods and different feedstocks have been discussed. Process parameters like selection of biomass as a raw material, pyrolyzing temperature, residence time, pre-treatment of biomass, and post treatment methods, etc. are the determining factors of carbonaceous biochar yields in a thermochemical conversion method. The key mechanisms like pore-filling, precipitation, complexation, ion-exchange, diffusion, partitioning, π–π electron-donor-acceptor interactions, H-bonding, and electrostatic attraction, etc. drive the specific type of contaminant to be phased out from polluted environments whether organic/inorganic in nature. Activation/modification (physical/chemical) of biochar is another aspect for its rising utilization in the field of expelling specific contaminations. The application of biochar in water treatment has many limitations. In order to meet the challenges, biochar-based materials may be developed with improved physicochemical properties and efficiency of biochar, along with combined advantages of biochar and other materials. This manuscript covers different perspectives of biochar viz. biochar and production techniques, mechanisms involved in removal of toxic contaminants from aqueous medium using bio-char, modification/activation methods used to improve the characteristics of biochar, biochars and different biochar-based materials for remediating aqueous environments, associated challenges and future directions. This compilation of evidences focused on biochar technology in water treatment will assist new researchers in their studies through developing a thorough understanding of the research and development of eco-friendly biochar-based environmental remediation.