Evaluating the combined influence of microwave-enhanced alkali pretreatment and copyrolysis on characteristics of biochars produced by thermal and microwave pyrolysis

• Published in: Journal of thermal analysis and calorimetry 2024, Vol.149 (21), p.12011-12023
• Main Authors: Neelancherry, Remya, Binnal, Prakash, Kumar, N. Keerthi, Misra, Ranjeet Kumar, Banapurmath, N. R., Sajjan, Ashok M., Badruddin, Irfan Anjum, Kamangar, Sarfaraz, Alqahtani, Mohammed
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Carbon content; Chemistry; Chemistry and Materials Science; Graphene; Inorganic Chemistry; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences; Pretreatment; Pyrolysis; Rice
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-024-13587-6

In the present study, a two-step process involving microwave-enhanced alkali pretreatment (MEAP) of rice husk followed by the copyrolysis of pretreated rice husk with LDPE was adopted to produce biochars in conventional electrically heated pyrolyzer (CPR) and microwave pyrolyzer (MWPR). Proximate and ultimate analysis revealed that biochar produced in MWPR exhibited higher fixed carbon (73.36%), lower volatile matter (8.45%), lower ash yield (17.41%), higher-carbon content (73.57%) and lower H/C and O/C ratios (0.19 and 0.12, respectively), as compared to biochar produced in CPR. BET analysis indicated that the surface area and total pore volume were significantly higher for biochar produced under microwave irradiation (1280.31 m 2 g −1 and 0.41 cc g −1 ), as compared to biochar produced in CPR (470.25 m 2 g −1 and 0.12 cc g −1 ). The XRD analysis showed that the biochar produced in MWPR exhibited two peaks at 26° (JCPDS No. 41-1487) and 43° (JCPDS Card No. 75-1621), thus closely resembling the reduced graphene oxide. Furthermore, uniform and cleaner pores were observed for MWPR chars in contrast with heterogeneous surface and blocked pores for CPR chars.