Sustainable approach of modified biochar based adsorbents towards enhanced phosphorus removal from wastewater

Increasing dependence on non-renewable phosphate rocks has led towards search for new alternative methodologies for recovering it from waste reserves. Natural adsorbents from carbonaceous-rich biochar have gained attention for nutrient recovery and utilization due to their distinctive surface properties and reusability. However, often native biochar lacks appropriate functional groups or porous properties for efficient phosphorus adsorption which emphasizes the need to revisit research field to identify lacunae. Thus, an initial systematic scientometric analysis was conducted to evaluate research gaps, recent advancements, and hot spots associated with biochar-based phosphorus (P) adsorption. Boolean logic model was utilized to retrieve 1694 documents for the period 2011-2023 from web-of-science database. A rapid surge in publications was evident from 2017 onwards. China (61.7 %), USA (15.76 %), South Korea (5.88%), Australia (5.0 %), and India (4.82 %) are the top countries contributing to research domain. Major research hotspots were found to be different activation strategies for performance enhancement, interpretation of complex mechanisms using analytical techniques, and real-time end applications in water and soil. The present review also comprehensively summarizes the effects of biochar production/ modification and adsorption parameters on the P-adsorption efficiency. The underlying mechanisms include ligand/ion exchange, electrostatic interaction, surface precipitation, surface complexation. P-adsorption using biochar mostly follows Langmuir isotherm model suggesting the monolayer chemical process. Assessment of optimization parameters on adsorption process, and underlying environmental and economic impacts of biochar-based adsorbents need to be focussed. Overall, comprehensive summary delineates practicality of scaling-up biochar-based P-adsorption processes to achieve sustainable development goals (SDGs) combined with circular bio-economy perspectives.