Activated biochar derived from Ricinus communis outer shell: Influence of KOH impregnation ratio on physicochemical properties and EMI shielding effectiveness
Raja Sekar Perumal, B. Muralidharan
Abstract
• The novel RCOS-based activated carbons are prepared using KOH at 800 °C with various impregnation ratios. • The impregnation ratio at 1:3 enhances biochar surface area of 554.13 m²/g. • ACRS3 prepared at 800 °C had a superior electrical conductivity of 150 S/m. • The 40 wt% ACRS3 in the epoxy composite obtained SE TL of 41.5 dB in the 8–12 GHz. Recently, there has been much interest in high-performance electromagnetic wave (EMW) absorption materials made from sustainable biomass sources. The research focuses on producing activated biochar at 800 °C from Ricinus communis outer shell (RCOS) with high carbon content through a two-step activation process with varying KOH impregnation ratios (1:2, 1:3, and 1:4). Many studies have focused on direct usage of the produced biochar, but a process like activation can improve the properties of RCOS, which were not yet carried out for RCOS. The activated biochar's physicochemical properties were analysed using field emission scanning electron microscope (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Electrical conductivity for potential use in electromagnetic (EM) shielding applications. The biochar activated at a 1:3 ratio exhibited the highest carbon content (89.81 %), surface area (554.13 m²/g) and electrical conductivity (155 S/m). The vector network analyser (VNA) recorded a maximum shielding efficiency of 41.5 dB in the 8–12 GHz frequency for 40 wt% activated biochar/epoxy composite. The results suggest that RCOS-activated biochar/epoxy composites are potential EMI shielding materials in the X-band frequency owing to their strong electromagnetic wave absorption capabilities.