Overcoming biochar limitations to remediate pentachlorophenol in soil by modifying its electrochemical properties

• Published in: Journal of hazardous materials 2022-03, Vol.426, p.127805-127805, Article 127805
• Main Authors: Chacón, Francisco J., Cayuela, Maria L., Cederlund, Harald, Sánchez-Monedero, Miguel A.
• Format: Article
• Language: English
• Subjects: biochar; biomass; Charcoal; Conductivity; Designer biochar; electrochemistry; Environmental Restoration and Remediation; Markvetenskap; oxidation; Pentachlorophenol; Redox properties; remediation; Soil; Soil Pollutants - analysis; Soil remediation; Soil Science
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.127805

In this study, we produced modified biochars with enhanced electrochemical properties to increase PCP remediation in soil. Although all biochars enhanced PCP remediation in aerobic conditions, only a few did in anaerobic soil. The most successful modifications were (i) the preloading of biomass with 10% w/w FeCl3, to obtain a biochar rich in redox-active metals (B-Fe); (ii) the oxidation of a conductive biochar pyrolyzed at 1000 ºC with 0.025 M KMnO4, to produce a biochar with both moderate conductivity and redox capacity (B-1000-KMnO4); and (iii) KMnO4 oxidation of an amorphous biochar pyrolyzed at 400 ºC to obtain a biochar with very high redox capacity (B-KMnO4). B-Fe reduced extractable PCP to almost zero after 50 days in both incubations, but showed slow kinetics of remediation in aerobic soil. B-1000-KMnO4 had the highest rate of remediation under aerobic conditions, but no significant effect under anaerobic conditions. B-KMnO4, however, presented high rates of remediation and high removal of extractable PCP under both conditions, which made it the recommended modification strategy for increased PCP remediation. We found that the degree of remediation primarily depends on the redox capacity, while the rate of remediation was determined by both the conductivity and redox capacity of biochar. [Display omitted] •Raw biochar inhibited PCP remediation in anaerobic soil.•Biochar modification enhanced PCP remediation in both aerobic and anaerobic soil.•Biochar redox capacity determines both the rate and extent of PCP remediation.•Biochar conductivity mainly influences the rate of PCP remediation