Effect mechanism of H₃PO₄ on the formation and transformation of persistent free radicals in biochar

Abstract

Persistent free radicals (PFRs) in biochar have attracted wide attention due to their multifaceted roles in the environment. The regulation of PFRs in biochar is not only beneficial to broaden its application potential, but also eliminates its environmental risks. However, as a common biochar modification reagent, phosphoric acid (H₃PO₄) has not been studied in the field of PFRs regulation. Herein, this study systematically investigated the effect of H₃PO₄ on PFRs in biochar under various conditions. The results indicated that H₃PO₄ promoted the formation of PFRs in biochar at low pyrolysis temperature (< 500 °C), owing to the positive effect of catalytic cross-linking on the degradation of biomass precursor. Yet, H₃PO₄ reduced PFRs in biochar at high pyrolysis temperature (≥ 500 °C), since the capture of H∙ or HO∙ by PO∙ and the steric hindrance changed by H₃PO₄, which caused the rearrangement and polycondensation of carbon structure. H₃PO₄ also favored carbon-centered PFRs as the dominant type. The ingredients of biomass precursor, including cellulose, Fe, Ti, protein, etc., contributed to different effects on PFRs under H₃PO₄ modification. This study provided new insights into the roles of H₃PO₄ on the formation and transformation of PFRs in biochar, coupled with regulation strategies in the practical application.

Graphical Abstract

References

[1] Alfei S, Pandoli OG. Biochar-derived persistent free radicals: a plethora of environmental applications in a light and shadows scenario. Toxics, 2024, 12 245.

[2] Budinova T, Ekinci E, Yardim F, Grimm A, Björnbom E, Minkova V, Goranova M. Characterization and application of activated carbon produced by H₃PO₄ and water vapor activation. Fuel Process Technol, 2006, 87 899-905.

[3] Chen G, Zhang Z, Zhang Z, Zhang R. Redox-active reactions in denitrification provided by biochars pyrolyzed at different temperatures. Sci Total Environ, 2018, 615 1547-1556.

[4] Chen D, Xu J, Ling P, Fang Z, Ren Q, Xu K, Jiang L, Wang Y, Su S, Hu S, Xiang J. Formation and evolution mechanism of persistent free radicals in biochar during biomass pyrolysis: insights from biochar’s element composition and chemical structure. Fuel, 2024, 357. 129910

[5] Chu G, Zhao J, Huang Y, Zhou D, Liu Y, Wu M, Peng H, Zhao Q, Pan B, Steinberg CEW. Phosphoric acid pretreatment enhances the specific surface areas of biochars by generation of micropores. Environ Pollut, 2018, 240 1-09.

[6] Chu G, Wang W, Zhao J, Zhou D. Transformation of phosphorus species during phosphoric acid-assisted pyrolysis of lignocellulose. Sci Total Environ, 2023, 866. 161010

[7] Duquesne S, Lefebvre J, Seeley G, Camino G, Delobel R, Le Bras M. Vinyl acetate/butyl acrylate copolymers. Polym Degrad Stab, 2004, 85 883-892.

[8] Fang G, Liu C, Gao J, Dionysiou DD, Zhou D. Manipulation of persistent free radicals in biochar to activate persulfate for contaminant degradation. Environ Sci Technol, 2015, 49 5645-5653.

[9] Fang G, Liu C, Wang Y, Dionysiou DD, Zhou D. Photogeneration of reactive oxygen species from biochar suspension for diethyl phthalate degradation. Appl Catal B Environ, 2017, 214 34-45.

[10] Fernandez ME, Ledesma B, Román S, Bonelli PR, Cukierman AL. Development and characterization of activated hydrochars from orange peels as potential adsorbents for emerging organic contaminants. Bioresour Technol, 2015, 183 221-228.

[11] Gao Y, Yue Q, Gao B, Li A. Insight into activated carbon from different kinds of chemical activating agents: a review. Sci Total Environ, 2020, 746. 141094

[12] Gehling W, Dellinger B. Environmentally persistent free radicals and their lifetimes in PM_2.5. Environ Sci Technol, 2013, 47 8172-8178.

[13] Hu Y, Tong K, Guo Q, Zhang B, Jiao L, Li M, Zhang Z. Effect of controlled temperature and biomass addition on the formed environmental persistent free radicals (EPFRs) in sewage sludge-based biochar from pyrolysis treatment. J Anal Appl Pyrolysis, 2022, 162. 105460

[14] Huang D, Luo H, Zhang C, Zeng G, Lai C, Cheng M, Wang R, Deng R, Xue W, Gong X, Guo X, Li T. Nonnegligible role of biomass types and its compositions on the formation of persistent free radicals in biochar: insight into the influences on Fenton-like process. Chem Eng J, 2019, 361 353-363.

[15] Huang C, Zhang C, Huang D, Wang D, Tian S, Wang R, Yang Y, Wang W, Qin F. Influence of surface functionalities of pyrogenic carbonaceous materials on the generation of reactive species towards organic contaminants: a review. Chem Eng J, 2021, 404. 127066

[16] Jagtoyen M, Derbyshire F. Activated carbons from yellow poplar and white oak by H₃PO₄ activation. Carbon, 1998, 36(7–8): 1085-1097.

[17] Jia H, Zhao S, Shi Y, Zhu L, Wang C, Sharma VK. Transformation of polycyclic aromatic hydrocarbons and formation of environmentally persistent free radicals on modified montmorillonite: the role of surface metal ions and polycyclic aromatic hydrocarbon molecular properties. Environ Sci Technol, 2018, 52 5725-5733.

[18] Jia H, Zhao S, Shi Y, Zhu K, Gao P, Zhu L. Mechanisms for light-driven evolution of environmentally persistent free radicals and photolytic degradation of PAHs on Fe(III)-montmorillonite surface. J Hazard Mater, 2019, 362 92-98.

[19] Kotake T, Kawamoto H, Saka S. Mechanisms for the formation of monomers and oligomers during the pyrolysis of a softwood lignin. J Anal Appl Pyrolysis, 2014, 105 309-316.

[20] Lian F, Xing B. Black Carbon (Biochar) In water/soil environments: molecular structure, sorption, stability, and potential risk. Environ Sci Technol, 2017, 51 13517-13532.

[21] Lian F, Yu W, Zhou Q, Gu S, Wang Z, Xing B. Size matters: nano-biochar triggers decomposition and transformation inhibition of antibiotic resistance genes in aqueous environments. Environ Sci Technol, 2020, 54 8821-8829.

[22] Liao S, Pan B, Li H, Zhang D, Xing B. Detecting free radicals in biochars and determining their ability to inhibit the germination and growth of corn, wheat and rice seedlings. Environ Sci Technol, 2014, 48 8581-8587.

[23] Liu X, Zheng Y, Liu Z, Ding H, Huang X, Zheng C. Study on the evolution of the char structure during hydrogasification process using Raman spectroscopy. Fuel, 2015, 157 97-106.

[24] Liu H, Cheng C, Wu H. Sustainable utilization of wetland biomass for activated carbon production: a review on recent advances in modification and activation methods. Sci Total Environ, 2021, 790. 148214

[25] Liu Y, Wang R, He L, Li C, Wang Y, Lu H, Yang S. Microbial resistance stability of rice straw biochar with vermiculite modification: a novel insight into persistent free radicals and pore structure. J Environ Chem Eng, 2023, 11. 110572

[26] Liu X, Chen Z, Lu S, Shi X, Qu F, Cheng D, Wei W, Shon HK, Ni B. Persistent free radicals on biochar for its catalytic capability: a review. Water Res, 2024, 250. 120999

[27] Lomnicki S, Truong H, Vejerano E, Dellinger B. Copper oxide-based model of persistent free radical formation on combustion-derived particulate matter. Environ Sci Technol, 2008, 42 4982-4988.

[28] Lord K, Moll D, Lindsey JK, Mahne S, Raman G, Dugas T, Cormier S, Troxlair D, Lomnicki S, Dellinger B, Varner K. Environmentally persistent free radicals decrease cardiac function before and after ischemia/reperfusion injury in vivo. J Recept Signal Transduct Res, 2011, 31 157-167.

[29] Neme I, Gonfa G, Masi C. Activated carbon from biomass precursors using phosphoric acid: a review. Heliyon, 2022, 8. e11940

[30] Nguyen T, Nguyen T, Chen W, Chen C, Kumar Patel A, Bui X, Chen L, Singhania RR, Dong C. Phosphoric acid-activated biochar derived from sunflower seed husk: selective antibiotic adsorption behavior and mechanism. Bioresour Technol, 2023, 371. 128593

[31] Nowakowski DJ, Woodbridge CR, Jones JM. Phosphorus catalysis in the pyrolysis behavior of biomass. J Anal Appl Pyrolysis, 2008, 83 197-204.

[32] Odinga ES, Waigi MG, Gudda FO, Wang J, Yang B, Hu X, Li S, Gao Y. Occurrence, formation, environmental fate and risks of environmentally persistent free radicals in biochars. Environ Int, 2020, 134. 105172

[33] Osman AI, Fawzy S, Farghali M, El-Azazy M, Elgarahy AM, Fahim RA, Maksoud M, Ajlan AA, Yousry M, Saleem Y, Rooney DW. Biochar for agronomy, animal farming, anaerobic digestion, composting, water treatment, soil remediation, construction, energy storage, and carbon sequestration: a review. Environ Chem Lett, 2022, 20 2385-2485.

[34] Peng H, Gao P, Chu G, Pan B, Peng J, Xing B. Enhanced adsorption of Cu(II) and Cd(II) by phosphoric acid-modified biochars. Environ Pollut, 2017, 229 846-853.

[35] Qin Y, Li G, Gao Y, Zhang L, Ok YS, An T. Persistent free radicals in carbon-based materials on transformation of refractory organic contaminants (ROCs) in water: a critical review. Water Res, 2018, 137 130-143.

[36] Ruan X, Sun Y, Du W, Tang Y, Liu Q, Zhang Z, Doherty W, Frost RL, Qian G, Tsang DCW. Formation, characteristics, and applications of environmentally persistent free radicals in biochars: a review. Bioresour Technol, 2019, 281 457-468.

[37] Sakaguchi M, Ohura T, Iwata T, Takahashi S, Akai S, Kan T, Murai H, Fujiwara M, Watanabe O, Narita M. Diblock copolymer of bacterial cellulose and poly (methyl methacrylate) initiated by chain-end-type radicals produced by mechanical scission of glycosidic linkages of bacterial cellulose. Biomacromol, 2010, 11 3059-3066.

[38] Sevilla M, Fuertes AB. Chemical and structural properties of carbonaceous products obtained by hydrothermal carbonization of saccharides. Chemistry, 2009, 15 4195-4203.

[39] Shao M, Ding ZC, Yang YZ, Zhang ZP, Wan YS. Phosphoric acid-modified biochar enhances electrokinetic in situ leaching technology to remediate Pb²⁺ contaminated soil. Int J Environ Sci Technol, 2024.

[40] Solum MS, Pugmire RJ, Jagtoycn M, Derbyshire F. Evolution of carbon structure in chemically activated wood. Carbon, 1995, 33(9): 1247-1254.

[41] Suuberg EM, Peters WA, Howard JB. Product compositions in rapid hydropyrolysis of coal. Fuel, 1980, 59(6): 405-412.

[42] Tao W, Duan W, Liu C, Zhu D, Si X, Zhu R, Oleszczuk P, Pan B. Formation of persistent free radicals in biochar derived from rice straw based on a detailed analysis of pyrolysis kinetics. Sci Total Environ, 2020, 715. 136575

[43] Vejerano E, Lomnicki S, Dellinger B. Formation and stabilization of combustion-generated environmentally persistent free radicals on an Fe(III)₂O₃/Silica surface. Environ Sci Technol, 2011, 45 589-594.

[44] Volpe R, Bermudez Menendez JM, Ramirez Reina T, Volpe M, Messineo A, Millan M, Titirici M. Free radicals formation on thermally decomposed biomass. Fuel, 2019, 255. 115802

[45] Wang Y, Gu X, Huang Y, Ding Z, Chen Y, Hu X. Insight into biomass feedstock on formation of biochar-bound environmentally persistent free radicals under different pyrolysis temperatures. RSC Adv, 2022, 12 19318-19326.

[46] Wu W, Zhu S, Huang X, Wei W, Jin C, Ni B. Determination of instinct components of biomass on the generation of persistent free radicals (PFRs) as critical redox sites in pyrogenic chars for persulfate activation. Environ Sci Technol, 2021, 55 7690-7701.

[47] Xiang C, Liu Q, Shi L, Liu Z. A study on the new type of radicals in corncob derived biochars. Fuel, 2020, 277. 118163

[48] Xie J, Latif J, Yang K, Wang Z, Zhu L, Yang H, Qin J, Ni Z, Jia H, Xin W, Li X. A state-of-art review on the redox activity of persistent free radicals in biochar. Water Res, 2024, 255. 121516

[49] Zhang R, Zhang R, Zimmerman AR, Wang H, Gao B. Applications, impacts, and management of biochar persistent free radicals: a review. Environ Pollut, 2023, 327. 121543

[50] Zhang J, Chen Z, Liu Y, Wei W, Ni B. Removal of emerging contaminants (ECs) from aqueous solutions by modified biochar: a review. Chem Eng J, 2024, 479. 147615

[51] Zheng D, Wang Y, Zhang W, Xu H, Zheng E, Wang T, Shi Y, Wu M. Mechanisms of biochar-mediated promotion of acidogenic fermentation in waste activated sludge and propionic acid production pathways. Chem Eng J, 2023, 470. 144230

[52] Zhong D, Jiang Y, Zhao Z, Wang L, Chen J, Ren S, Liu Z, Zhang Y, Tsang DCW, Crittenden JC. pH dependence of arsenic oxidation by rice-husk-derived biochar: roles of redox-active moieties. Environ Sci Technol, 2019, 53 9034-9044.

[53] Zhou B, Liu Q, Shi L, Liu Z. Electron spin resonance studies of coals and coal conversion processes: a review. Fuel Process Technol, 2019, 188 212-227.

[54] Zuo S, Yang J, Liu J, Cai X. Significance of the carbonization of volatile pyrolytic products on the properties of activated carbons from phosphoric acid activation of lignocellulosic material. Fuel Process Technol, 2009, 90 994-1001.

[55] Zuo S, Xiao Z, Yang J. Evolution of gaseous products from biomass pyrolysis in the presence of phosphoric acid. J Anal Appl Pyrolysis, 2012, 95 236-240.

Funding

National Natural Science Foundation of China(52270059)

National Key Research and Development Program of China(2020YFC1807800)

Natural Science Foundation of Liaoning Province of China(2023-MS-095)

RIGHTS & PERMISSIONS

The Author(s)