Publication: Development of empty fruit bunch-derived biochar and its modification via sonication, mgo deposition and amine functionalization for carbon dioxide capture
Loading...
Date
2023-12-01
Authors
Anis Natasha Bt Shafawi
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Physical and chemical modifications could improve the porosity, surface area and surface alkalinity of pristine biochar for a higher CO2 capture. In this study, the optimized pristine biochar was prepared by pyrolysis treatment of an empty fruit bunch (EFB) at 700 oC (PB700); the CO2 uptake capacity of PB700 was determined to be 35.10 mg/g. Subsequently, PB700 was treated by sonication (amplitudes of 20, 40, 60, and 80% and different treatment durations of 1, 2, and 3 min), MgO deposition (wet impregnation processes with 5, 10, and 15 wt% MgO/biochar) and amine functionalization treatments with different ratios of biochar to melamine (5:0.5, 5:1, 5:2, 5:3), activation temperature (500, 700 and 900 C) and activation ramp (5, 10, 15 and 20 C/min). CO2 uptake capacities using thermogravimetric analyzer (TGA) revealed that the optimized ultrasonicated biochar (UB), MgO-deposited biochar (MB) and ultrasonicated MgO-deposited biochar (UMB) were determined to be 45.24, 59.52 and 60.62 mg/g, respectively. Meanwhile, the CO2 uptake capacities of amine-functionalized biochar (AB), ultrasonicated amine-functionalized biochar (UAB) and ultrasonicated amine-functionalized MgO-deposited biochar (UAMB) were determined to be 71.42, 75.33 and 84.95 mg/g, respectively. Comprehensive characterizations such as SEM-EDX, FTIR, BET, XRD, Raman, TEM and XPS, were used to study the physical and chemical properties of the modified biochar. The results showed that sonication, MgO deposition and amine functionalization successfully improved the surface area, porosity and surface basicity (due to the presence of MgO and N-functional groups) of the biochar. However, the successive treatments with sonication prior to MgO- deposition were not synergistic, as MgO particles accumulated in the pores created by sonication. The modified biochar samples (UMB and UAMB) exhibited the highest affinity for CO2 adsorption over air, methane, and nitrogen, and demonstrated high stability in the CO2 uptake capacity for 12 cycles of CO2 adsorption-desorption. Avrami kinetic model was the best model to describe the CO2 adsorption on PB700 and modified biochar samples, shows that physisorption is the main mechanism. Finally, the best operating parameters using fixed-bed reactor were determined to be 30 mL/min, 15 % of the initial CO2 concentration, and an adsorption temperature of 30 ℃.