ABSTRACT
This study aimed to assess the effectiveness of urban derived biochars such as Sugarcane bagasse (SB), Brinjal Stem (BS), and Citrus Peel (CP) produced at two different pyrolysis conditions (450 and 600 °C for 60 min) for soil heavy metal bioremediation potential. An ex-situ study was conducted to remediate single heavy metal-contaminated SoilRite with lead (Pb), copper (Cu), chromium (Cr) and cadmium (Cd), with biochars applied at different rates. Heavy metal status in soilrite was evaluated using various extraction methods (water-soluble, exchangeable, TCLP (Toxicity Characteristic Leaching Procedure), and PBET (Physiologically Based Extraction Tests)) to determine the biochar treatments' efficacy. The findings show that SB biochar at 450-60 are more effective in immobilizing heavy metals in water-soluble (Cd-100% Pb and Cu-70%), exchangeable (Pb:91%, Cd and Cu by 70-80%) and PBET-extracted forms (Cd-91%, Pb-80%, and Cu-75%), whereas biochar derived from BS (84%) and CP (90%) at 600-60 are more effective in immobilizing TCLP-extracted form of Pb and Cu. Urban derived biochars significantly reduced the toxicity of Pb, Cu, and Cd in various extractable forms and can stabilize and convert them into less accessible forms except for Cr. These extraction methods aid in evaluating environmental risks and influencing remediation strategies for soil heavy metal pollution. Urban biochar, as a cost-effective and eco-friendly solution, significantly solves this issue, facilitating sustainable waste management.
Subject(s)
Charcoal , Environmental Restoration and Remediation , Metals, Heavy , Pyrolysis , Soil Pollutants , Charcoal/chemistry , Soil Pollutants/chemistry , Soil Pollutants/analysis , Metals, Heavy/chemistry , Metals, Heavy/analysis , Environmental Restoration and Remediation/methods , Citrus/chemistry , Saccharum/chemistry , Soil/chemistry , Biodegradation, EnvironmentalABSTRACT
This study investigated the adsorption performance of biochar produced from different types of urban biowaste material viz., sugarcane bagasse (SB), brinjal stem (BS), and citrus peel (CP) for removal of heavy metal ions (Pb, Cu, Cr, and Cd) from aqueous solution. The effects of biowaste material, dosage of biochar, solution pH, and initial concentration of heavy metal ions and isotherm models were performed to understand the possible adsorption mechanisms. The results showed that the biochar derived from BS and SB removes Cu (99.94%), Cr (99.57%), and Cd (99.77%) whereas biochar derived from CP removes Pb (99.59%) and Cu (99.90%) more efficiently from the aqueous solution. Biochar derived from BS showed maximum adsorption capacity for Cu (246.31 mg g-1), Pb (183.15 mg g-1), and Cr (71.89 mg g-1) while the biochar derived from CP showed highest for Cd (15.46 mg g-1). Moreover, biochar derived from BS and SB has more polar functional groups and less hydrophobicity than the biochar derived from CP. This study reveals that solution pH and biochar doses play a major role in removal of heavy metal ions from aqueous solution. The results of Langmuir model fitted well for Pb and Cu while the Freundlich model for Cr and Cd. Our study concludes that the biochar derived from different biowaste materials adsorbs heavy metal ions majorly through surface complexation and precipitation processes. The results of this study will be very useful in selecting the effective urban biowaste material for making biochar for heavy metal removal from the aqueous environment.
