The impact of the class of the activating agent (inorganic Vs organic) on the structure and the crystallographic parameters of the activated carbon materials (ACMs) from biomass was studied. The stems of the waste land weed native of India, namely, Calotropis gigantea were used as a representative example for the biomass based sustainable raw material. Likewise, carbonate (K 2 CO 3 ) and oxalate (Na 2 C 2 O 4 ) were chosen as the representative examples of the chemical activators. Irrespective of the class of the activating agent the structure of the activated carbon material remained the same, namely, turbostratic. The interlayer space (d 002 ) values of the ACMs from the carbonate and oxalate activators were 0.411 and 0.385 nm which are higher than the pure graphite (0.3352 nm). The crystallite size along the stacking axis (L c ) and along the a-axis (L a ) of the ACMs from biomass are an order of magnitude higher than that of pure graphite. Moreover, the crystallite sizes (both L c and L a ) of the ACMs from carbonate activation were relatively smaller than that of the material from oxalate activation. The difference in the crystallographic parameters between the ACMs derived from carbonate and oxalate activators is attributed to the slight difference in the mechanistic step (the very first step) of the chemical activation process.

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1. Viswanathan B, Varadarajan TK, Pulidindi IN. A process for the preparation of activated carbon from botanical sources. Indian Patent No. IN200700376-I4, 13/2/2007.
2. Viswanathan B, Indra Neel P, Varadarajan TK. Methods of activation and specific applications of carbon materials. E-book, 2009.
3. Viswanathan B, Indra Neel P, Varadarajan TK. Development of carbon materials for energy and environmental applications. Catalysis Surveys from Asia, 2009; 13:164-83p.
4. Mahalakshmy R, Indra Neel P, Viswanathan B. Surface Functionalities of nitric acid-treated carbon—A density functional theory-based vibrational analysis. Indian Journal of Chemistry, 2009; 48(A):352-56p.
5. Pulidindi IN. Development and exploitation of carbon materials from plant sources. Ph.D. Thesis, IIT Madras, 2009.
6. Pulidindi IN, Varadarajan TK, Viswanathan B. Structure and dynamics of carbon dangling bonds in activated carbon materials from biomass. International Journal of Green Chemistry, 11(1), 2025, 1-16.
7. Pulidindi IN, Varadarajan TK, Viswanathan B. Activating agents control the morphology of activated carbon materials from biomass. International Journal of Analytical and Applied Chemistry, 2025 (Ahead of print).
8. Maryam Kazemipour, Mehdi Ansari, Shabnam Tajrobehkar, Majdeh Majdzadeh, Hamed Reihani Kermani. Removal of lead, cadmium, zinc, and copper from industrial wastewater by carbon developed from walnut, hazelnut, almond, pistachio shell, and apricot stone. Journal of Hazardous Materials, 150 (2008): 322.
9. J. Ganan, J. F. Gonzalez, C. M. Gonzalez-Garcia, A. Ramiro, E. Sabio, S. Roman. Air-activated carbons from almond tree pruning: Preparation and characterization. Applied Surface Science, 252 (2006): 5988.
10. F. Suarez-Garcia, A. Martinez-Alonso, J. M. D. Tascon. Pyrolysis of apple pulp: Chemical activation with phosphoric acid. Journal of Analytical and Applied Pyrolysis, 63 (2002): 283.
11. Mansooreh Soleimani, Tahereh Kaghazchi. Activated hard shell of apricot stones: A promising adsorbent in gold recovery. Chinese Journal of Chemical Engineering, 16(1) (2008): 112.
12. B. H. Hameed, A. T. M. Din, A. L. Ahmed. Adsorption of methylene blue onto bamboo-based activated carbon: Kinetics and equilibrium studies. Journal of Hazardous Materials, 141 (2007): 819.
13. E. C. Bernaro, R. Egashira, J. Kawasaki. Decolorization of molasses wastewater using activated carbon prepared from cane bagasse. Carbon, 35 (1997): 1217.
14. W. T. Tsai, C. Y. Chang, S. L. Lee. Preparation and characterization of activated carbons from corn cob. Carbon, 35 (1997): 1198-1200.
15. Jorge Laine, Alvaro Calafat. Preparation and characterization of activated carbons from coconut shell impregnated with phosphoric acid. Carbon, 29(7) (1991): 949.
16. Dinesh Mohan, Kunwar P. Singh, Vinod K. Singh. Trivalent chromium removal from wastewater using low-cost activated carbon derived from agricultural waste material and activated carbon fabric cloth. Journal of Hazardous Materials, 135 (2006): 280.
17. Jeremias S. Macedo, Larissa Otubo, Odair Pastor Ferreira, Iara de Fatima Gimenez, Italo Odone Mazali, Ledjane Silva Barreto. Biomorphic activated porous carbons with complex microstructures from lignocellulosic residues. Microporous and Mesoporous Materials, 107 (2007): 276.
18. Feng Zhang, Hua Ma, Jun Chen, Guo-Dong Li, Yu Zhang, Jie-Sheng Chen. Preparation and gas storage of high surface area microporous carbon derived from biomass source cornstalks. Bioresource Technology, 99 (2008): 4803.
19. Badie S. Girgis, Abdel-Nasser A. El-Hendawy. Porosity development in activated carbons obtained from date pits under chemical activation with phosphoric acid. Microporous and Mesoporous Materials, 52 (2002): 105.
20. J. D. Rocha, A. R. Coutinho, C. A. Luengo. Biopitch produced from Eucalyptus wood pyrolysis liquids as a renewable binder for carbon electrode manufacture. Brazilian Journal of Chemical Engineering, 19 (2002): 127-132.
21. I. A. Rahman, B. Saad. Utilization of guava seeds as a source of activated carbon for removal of methylene blue from aqueous solution. Malaysian Journal of Chemistry, 5 (2003): 8.
22. Margaret Iley, H. Marsh, F. Rodriguez Reinoso. The adsorptive properties of carbonized olive stones. Carbon, 11 (1973): 633.
23. J. de D. Lopez-Gonzalez, F. Martinez-Vilchez, F. Rodriguez-Reinoso. Preparation and characterization of active carbons from olive stones. Carbon, 18 (1980): 413-418.
24. Badie S. Girgis, Samya S. Yunis, Ashraf M. Soliman. Characteristics of activated carbon from peanut hulls in relation to conditions of preparation. Materials Letters, 57 (2002): 164.
25. Badie S. Girgis, Amina A. Attia, Nady A. Fathy. Modification in adsorption characteristics of activated carbon produced by H3PO4 under flowing gases. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 299 (2007): 79.
26. Sayed A. Dastgheib, David A. Rockstraw. Pecan shell activated carbon: Synthesis, characterization, and application for the removal of copper from aqueous solution. Carbon, 39 (2001): 1849.
27. Nevin Yalcin, Vahdettin Sevinc. Studies of the surface area and porosity of activated carbons prepared from rice husks. Carbon, 38 (2000): 1943.
28. Chang Hun Yun, Yun Heum Park, Chong Rae Park. Effects of pre-carbonization on porosity development of activated carbons from rice straw. Carbon, 39 (2001): 559.
29. V. Gomez-Serrano, J. Pastor-Villegas, C. J. Duran-Valle, C. Valenzuela-Calahorro. Heat treatment of rockrose char in air: Effect of surface chemistry and porous texture. Carbon, 34 (1996): 533-538.
30. P. K. Malik. Dye removal from wastewater using activated carbon developed from sawdust: Adsorption equilibrium and kinetics. Journal of Hazardous Materials, B113 (2004): 81.
31. Ru-Ling Tseng, Szu-Kung Tseng. Characterization and use of high surface area activated carbons prepared from cane pith for liquid-phase adsorption. Journal of Hazardous Materials, B136 (2006): 671-680.
32. Vicente Gomez-Serrano, Eduardo M. Cuerda-Correa, Maria Carmen Fernandez-Gonzalez, Maria F. Alexandre-Franco, Antonio Macias-Garcia. Preparation of activated carbons from walnut wood: A study of microporosity and fractal dimension. Smart Materials and Structures, 14 (2005): 363.
33. Anupama Sahu, Abhishek Kumar, Love Dashairya, Partha Saha, Subrat Kumar Bhuyan, Sudipta Sen, Subash Chandra Mishra. Performance of wasteland biomass Calotropis gigantea-derived activated carbon as Lithium-ion battery anode. Diamond & Related Materials, 136 (2023): 110053.
34. Anupama Sahu, Sudipta Sen, Subash Chandra Mishra. Economical way of processing activated carbon from Calotropis gigantea and its suitability for application in Lithium/Sodium-ion batteries. Diamond & Related Materials, 108 (2020): 107931.
35. Qi-Qi Yang, Lin-Feng Gao, Zhi-Yuan Zhu, Chen-Xia Hu, Zhi-Peng Huang, Rui-Tong Liu, Qiang Wang, Fei Gao, Hao-Li Zhang. Confinement effect of natural hollow fibers enhances flexible supercapacitor electrode performance. Electrochimica Acta, 260 (2018): 204-211.
36. Wenzhen Duan, Minghan Li, Weilong Xiao, Ningfen Wang, Bihui Niu, Lei Zhou, Yian Zheng. Enhanced adsorption of three fluoroquinolone antibiotics using polypyrrole functionalized Calotropis gigantea fiber. Colloids and Surfaces A, 574 (2019): 178-187.
37. Lamouroux C, Delhaes P. Conductivity and structure of carbonized cellulose fibers. Carbon, 35(8) (1997): 1127.
38. Kinoshita K. Carbon materials for electrochemical capacitors. Carbon, 27(5) (1989): 647.
39. Tang L, Liu F. Dye adsorption by activated carbon prepared from sugarcane bagasse. Adsorption Science & Technology, 17(8) (1999): 607-616.
40. Mochidzuki K, Soutric F, Mabic S, Rouzaud JN, Bonnamy S, Beguin F. Microstructure of cellulose-carbonized composite materials. Carbon, 32(1) (1994): 163.
41.  Inagaki M, Ohashi F, Toyoda M. Characterization and adsorption capacity of mesoporous carbons prepared from furfuryl alcohol. Carbon, 32(2) (1994): 269.
42. Yoneyama Y, Ohta T. Adsorption and ion-exchange on activated carbon. Surface Science, 350 (1996): 62-68.
43. Ramesh D, Rangasamy A, Subramaniyan J, et al. High-energy electrode material for supercapacitors based on biomass derived activated carbon materials from Calotropis gigantea. Sustainable Energy & Fuels, 3 (2019): 209.
44. Wenli Yao , Fenghui Qin , Ziwei Zhao, Zhijun Ma, Chunyang Hu, Lei Zhou, Yian Zheng, Calotropis gigantea fiber confined ZIF-67 derived Co, N in-situ assembled hollow carbon fiber to activate peroxymonosulfate for degradation of perfluorooctanoic acid. Industrial Crops & Products 206 (2023) 117687.
45. Sharma A, Pulidindi IN, Viswanathan B. Adsorption of phenolic compounds on modified activated carbons. Indian Journal of Chemical Technology, 2010; 17: 346-52.
46. Singh S, Bhardwaj P. Thermo-chemical characterization of raw and chemically treated agricultural residue. Bioresource Technology, 102 (2011): 1207-1214.
47. Laxmi D, Ramachandran C. Production and characterization of biochar from agricultural residues. International Journal of Analytical and Applied Chemistry, 2023 (Ahead of Print).
48. Li Y, Feng J. Preparation of porous biochar from pistachio shell by microwave heating. Microporous Mesoporous Materials, 248 (2017): 88-96.
49. Smith J. Adsorption equilibrium studies for methylene blue. Journal of Environmental Science, 32 (2012): 452.
50. E. A. Correa. The role of porosity in adsorption phenomena. Surface Interface Analysis, 38 (2006): 323.
51. Jiang Q, Zhang H. Chemical activation of bio-waste for carbonization. Microporous Mesoporous Materials, 271 (2022): 23-30.
52. Singh N. Carbon-based materials as adsorbents. Chemical Reviews, 117(5) (2017): 2848-2925.
53. Bhatia VK, Bhardwaj R. Study on physicochemical properties of biochar derived from rice husks. Indian Journal of Environmental Research, 12 (2018): 98-108.
54. Pulidindi IN. Enhancing activated carbon properties for water remediation. Indian Journal of Green Chemistry, 8 (2023): 75-81.
55. Zhang L, Li D. Metal-free adsorbents in water treatment. Materials Chemistry, 56(3) (2018): 246-254.
56. Arvind S, Kapoor K. Preparation of porous materials via hydrothermal routes. Chemistry Letters, 48(6) (2019): 554-561.
57. Kumar J, Rao V. Energy storage materials derived from carbon sources. Journal of Advanced Materials Research, 55 (2020): 310-320.
58. Neelam S, Vikas K. Development of activated carbons for gas adsorption. International Journal of Applied Chemistry, 32 (2023): 402-410

The impact of the class of the activating agent (inorganic Vs organic) on the structure and the crystallographic parameters of the activated carbon materials (ACMs) from biomass was studied. The stems of the waste land weed native of India, namely, Calotropis gigantea were used as a representative example for the biomass based sustainable raw material. Likewise, carbonate (K 2 CO 3 ) and oxalate (Na 2 C 2 O 4 ) were chosen as the representative examples of the chemical activators. Irrespective of the class of the activating agent the structure of the activated carbon material remained the same, namely, turbostratic. The interlayer space (d 002 ) values of the ACMs from the carbonate and oxalate activators were 0.411 and 0.385 nm which are higher than the pure graphite (0.3352 nm). The crystallite size along the stacking axis (L c ) and along the a-axis (L a ) of the ACMs from biomass are an order of magnitude higher than that of pure graphite. Moreover, the crystallite sizes (both L c and L a ) of the ACMs from carbonate activation were relatively smaller than that of the material from oxalate activation. The difference in the crystallographic parameters between the ACMs derived from carbonate and oxalate activators is attributed to the slight difference in the mechanistic step (the very first step) of the chemical activation process.

🔒 This is a subscription article

Full text is available to subscribers and institutional members. Please choose an option below to access it.

1. Viswanathan B, Varadarajan TK, Pulidindi IN. A process for the preparation of activated carbon from botanical sources. Indian Patent No. IN200700376-I4, 13/2/2007.
2. Viswanathan B, Indra Neel P, Varadarajan TK. Methods of activation and specific applications of carbon materials. E-book, 2009.
3. Viswanathan B, Indra Neel P, Varadarajan TK. Development of carbon materials for energy and environmental applications. Catalysis Surveys from Asia, 2009; 13:164-83p.
4. Mahalakshmy R, Indra Neel P, Viswanathan B. Surface Functionalities of nitric acid-treated carbon—A density functional theory-based vibrational analysis. Indian Journal of Chemistry, 2009; 48(A):352-56p.
5. Pulidindi IN. Development and exploitation of carbon materials from plant sources. Ph.D. Thesis, IIT Madras, 2009.
6. Pulidindi IN, Varadarajan TK, Viswanathan B. Structure and dynamics of carbon dangling bonds in activated carbon materials from biomass. International Journal of Green Chemistry, 11(1), 2025, 1-16.
7. Pulidindi IN, Varadarajan TK, Viswanathan B. Activating agents control the morphology of activated carbon materials from biomass. International Journal of Analytical and Applied Chemistry, 2025 (Ahead of print).
8. Maryam Kazemipour, Mehdi Ansari, Shabnam Tajrobehkar, Majdeh Majdzadeh, Hamed Reihani Kermani. Removal of lead, cadmium, zinc, and copper from industrial wastewater by carbon developed from walnut, hazelnut, almond, pistachio shell, and apricot stone. Journal of Hazardous Materials, 150 (2008): 322.
9. J. Ganan, J. F. Gonzalez, C. M. Gonzalez-Garcia, A. Ramiro, E. Sabio, S. Roman. Air-activated carbons from almond tree pruning: Preparation and characterization. Applied Surface Science, 252 (2006): 5988.
10. F. Suarez-Garcia, A. Martinez-Alonso, J. M. D. Tascon. Pyrolysis of apple pulp: Chemical activation with phosphoric acid. Journal of Analytical and Applied Pyrolysis, 63 (2002): 283.
11. Mansooreh Soleimani, Tahereh Kaghazchi. Activated hard shell of apricot stones: A promising adsorbent in gold recovery. Chinese Journal of Chemical Engineering, 16(1) (2008): 112.
12. B. H. Hameed, A. T. M. Din, A. L. Ahmed. Adsorption of methylene blue onto bamboo-based activated carbon: Kinetics and equilibrium studies. Journal of Hazardous Materials, 141 (2007): 819.
13. E. C. Bernaro, R. Egashira, J. Kawasaki. Decolorization of molasses wastewater using activated carbon prepared from cane bagasse. Carbon, 35 (1997): 1217.
14. W. T. Tsai, C. Y. Chang, S. L. Lee. Preparation and characterization of activated carbons from corn cob. Carbon, 35 (1997): 1198-1200.
15. Jorge Laine, Alvaro Calafat. Preparation and characterization of activated carbons from coconut shell impregnated with phosphoric acid. Carbon, 29(7) (1991): 949.
16. Dinesh Mohan, Kunwar P. Singh, Vinod K. Singh. Trivalent chromium removal from wastewater using low-cost activated carbon derived from agricultural waste material and activated carbon fabric cloth. Journal of Hazardous Materials, 135 (2006): 280.
17. Jeremias S. Macedo, Larissa Otubo, Odair Pastor Ferreira, Iara de Fatima Gimenez, Italo Odone Mazali, Ledjane Silva Barreto. Biomorphic activated porous carbons with complex microstructures from lignocellulosic residues. Microporous and Mesoporous Materials, 107 (2007): 276.
18. Feng Zhang, Hua Ma, Jun Chen, Guo-Dong Li, Yu Zhang, Jie-Sheng Chen. Preparation and gas storage of high surface area microporous carbon derived from biomass source cornstalks. Bioresource Technology, 99 (2008): 4803.
19. Badie S. Girgis, Abdel-Nasser A. El-Hendawy. Porosity development in activated carbons obtained from date pits under chemical activation with phosphoric acid. Microporous and Mesoporous Materials, 52 (2002): 105.
20. J. D. Rocha, A. R. Coutinho, C. A. Luengo. Biopitch produced from Eucalyptus wood pyrolysis liquids as a renewable binder for carbon electrode manufacture. Brazilian Journal of Chemical Engineering, 19 (2002): 127-132.
21. I. A. Rahman, B. Saad. Utilization of guava seeds as a source of activated carbon for removal of methylene blue from aqueous solution. Malaysian Journal of Chemistry, 5 (2003): 8.
22. Margaret Iley, H. Marsh, F. Rodriguez Reinoso. The adsorptive properties of carbonized olive stones. Carbon, 11 (1973): 633.
23. J. de D. Lopez-Gonzalez, F. Martinez-Vilchez, F. Rodriguez-Reinoso. Preparation and characterization of active carbons from olive stones. Carbon, 18 (1980): 413-418.
24. Badie S. Girgis, Samya S. Yunis, Ashraf M. Soliman. Characteristics of activated carbon from peanut hulls in relation to conditions of preparation. Materials Letters, 57 (2002): 164.
25. Badie S. Girgis, Amina A. Attia, Nady A. Fathy. Modification in adsorption characteristics of activated carbon produced by H3PO4 under flowing gases. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 299 (2007): 79.
26. Sayed A. Dastgheib, David A. Rockstraw. Pecan shell activated carbon: Synthesis, characterization, and application for the removal of copper from aqueous solution. Carbon, 39 (2001): 1849.
27. Nevin Yalcin, Vahdettin Sevinc. Studies of the surface area and porosity of activated carbons prepared from rice husks. Carbon, 38 (2000): 1943.
28. Chang Hun Yun, Yun Heum Park, Chong Rae Park. Effects of pre-carbonization on porosity development of activated carbons from rice straw. Carbon, 39 (2001): 559.
29. V. Gomez-Serrano, J. Pastor-Villegas, C. J. Duran-Valle, C. Valenzuela-Calahorro. Heat treatment of rockrose char in air: Effect of surface chemistry and porous texture. Carbon, 34 (1996): 533-538.
30. P. K. Malik. Dye removal from wastewater using activated carbon developed from sawdust: Adsorption equilibrium and kinetics. Journal of Hazardous Materials, B113 (2004): 81.
31. Ru-Ling Tseng, Szu-Kung Tseng. Characterization and use of high surface area activated carbons prepared from cane pith for liquid-phase adsorption. Journal of Hazardous Materials, B136 (2006): 671-680.
32. Vicente Gomez-Serrano, Eduardo M. Cuerda-Correa, Maria Carmen Fernandez-Gonzalez, Maria F. Alexandre-Franco, Antonio Macias-Garcia. Preparation of activated carbons from walnut wood: A study of microporosity and fractal dimension. Smart Materials and Structures, 14 (2005): 363.
33. Anupama Sahu, Abhishek Kumar, Love Dashairya, Partha Saha, Subrat Kumar Bhuyan, Sudipta Sen, Subash Chandra Mishra. Performance of wasteland biomass Calotropis gigantea-derived activated carbon as Lithium-ion battery anode. Diamond & Related Materials, 136 (2023): 110053.
34. Anupama Sahu, Sudipta Sen, Subash Chandra Mishra. Economical way of processing activated carbon from Calotropis gigantea and its suitability for application in Lithium/Sodium-ion batteries. Diamond & Related Materials, 108 (2020): 107931.
35. Qi-Qi Yang, Lin-Feng Gao, Zhi-Yuan Zhu, Chen-Xia Hu, Zhi-Peng Huang, Rui-Tong Liu, Qiang Wang, Fei Gao, Hao-Li Zhang. Confinement effect of natural hollow fibers enhances flexible supercapacitor electrode performance. Electrochimica Acta, 260 (2018): 204-211.
36. Wenzhen Duan, Minghan Li, Weilong Xiao, Ningfen Wang, Bihui Niu, Lei Zhou, Yian Zheng. Enhanced adsorption of three fluoroquinolone antibiotics using polypyrrole functionalized Calotropis gigantea fiber. Colloids and Surfaces A, 574 (2019): 178-187.
37. Lamouroux C, Delhaes P. Conductivity and structure of carbonized cellulose fibers. Carbon, 35(8) (1997): 1127.
38. Kinoshita K. Carbon materials for electrochemical capacitors. Carbon, 27(5) (1989): 647.
39. Tang L, Liu F. Dye adsorption by activated carbon prepared from sugarcane bagasse. Adsorption Science & Technology, 17(8) (1999): 607-616.
40. Mochidzuki K, Soutric F, Mabic S, Rouzaud JN, Bonnamy S, Beguin F. Microstructure of cellulose-carbonized composite materials. Carbon, 32(1) (1994): 163.
41.  Inagaki M, Ohashi F, Toyoda M. Characterization and adsorption capacity of mesoporous carbons prepared from furfuryl alcohol. Carbon, 32(2) (1994): 269.
42. Yoneyama Y, Ohta T. Adsorption and ion-exchange on activated carbon. Surface Science, 350 (1996): 62-68.
43. Ramesh D, Rangasamy A, Subramaniyan J, et al. High-energy electrode material for supercapacitors based on biomass derived activated carbon materials from Calotropis gigantea. Sustainable Energy & Fuels, 3 (2019): 209.
44. Wenli Yao , Fenghui Qin , Ziwei Zhao, Zhijun Ma, Chunyang Hu, Lei Zhou, Yian Zheng, Calotropis gigantea fiber confined ZIF-67 derived Co, N in-situ assembled hollow carbon fiber to activate peroxymonosulfate for degradation of perfluorooctanoic acid. Industrial Crops & Products 206 (2023) 117687.
45. Sharma A, Pulidindi IN, Viswanathan B. Adsorption of phenolic compounds on modified activated carbons. Indian Journal of Chemical Technology, 2010; 17: 346-52.
46. Singh S, Bhardwaj P. Thermo-chemical characterization of raw and chemically treated agricultural residue. Bioresource Technology, 102 (2011): 1207-1214.
47. Laxmi D, Ramachandran C. Production and characterization of biochar from agricultural residues. International Journal of Analytical and Applied Chemistry, 2023 (Ahead of Print).
48. Li Y, Feng J. Preparation of porous biochar from pistachio shell by microwave heating. Microporous Mesoporous Materials, 248 (2017): 88-96.
49. Smith J. Adsorption equilibrium studies for methylene blue. Journal of Environmental Science, 32 (2012): 452.
50. E. A. Correa. The role of porosity in adsorption phenomena. Surface Interface Analysis, 38 (2006): 323.
51. Jiang Q, Zhang H. Chemical activation of bio-waste for carbonization. Microporous Mesoporous Materials, 271 (2022): 23-30.
52. Singh N. Carbon-based materials as adsorbents. Chemical Reviews, 117(5) (2017): 2848-2925.
53. Bhatia VK, Bhardwaj R. Study on physicochemical properties of biochar derived from rice husks. Indian Journal of Environmental Research, 12 (2018): 98-108.
54. Pulidindi IN. Enhancing activated carbon properties for water remediation. Indian Journal of Green Chemistry, 8 (2023): 75-81.
55. Zhang L, Li D. Metal-free adsorbents in water treatment. Materials Chemistry, 56(3) (2018): 246-254.
56. Arvind S, Kapoor K. Preparation of porous materials via hydrothermal routes. Chemistry Letters, 48(6) (2019): 554-561.
57. Kumar J, Rao V. Energy storage materials derived from carbon sources. Journal of Advanced Materials Research, 55 (2020): 310-320.
58. Neelam S, Vikas K. Development of activated carbons for gas adsorption. International Journal of Applied Chemistry, 32 (2023): 402-410