Effect of KOH activation on the biocarbon materials derived from Polyalthia longifolia seeds towards the germination and seedling growth of mung bean

Polyalthia longifolia (PL) seed biomass was effectively converted into pristine and activated biocarbon using KOH mediated chemical activation process at 800°C under N 2 atmosphere for 1 h. Both the synthesized pristine and activated biocarbon materials were characterized by PXRD, FT-IR, RAMAN, SEM, TG and BET surface analyses in order to understand their physicochemical, structural, morphological and thermal properties. The obtained biocarbon materials showed the turbostratic structure possessing both the graphitic and amorphous features. Activation process greatly enhanced the specific surface area of the biocarbon material and it is found to be 688 m 2 /g, whereas their pristine form showed as low as 1 m 2 /g. Under the studied conditions, mung bean seeds treated with the activated biocarbon (PL-AC) exhibited the superior germination efficiency with enhanced shoot and leaf growth compared to their pristine counterpart (PL-PC) and control. Mung bean seed treated with 1000 mg PL-AC exhibited enhanced plant growth (total length/weight of plant ∼24.4 cm/0.482 g; leaf length/weight/width of plant 5.08 cm/0.068 g/1.84 cm) than mung bean seed treated with 1000 mg PL-PC (total length/weight of plant ∼20.3 cm/0.480 g; leaf length/weight/width of plant 5.2 cm/0.078 g/1.64 cm). The statistical analysis of the obtained plant parameters indicate the P value of < 0.05 (P = 0.010 for PL-PC and P = 0.006 for PL-AC), which suggests a strong statistical confidence of the results. • Polyalthia longifolia (PL) seeds converted into activated biocarbon by KOH-activation process. • Activated biocarbon (PL- AC) exhibited higher surface area than pristine biocarbon (PL-PC). • These materials showed the turbostratic structure possessing both graphitic and amorphous features. • Both the biocarbon materials utilized for the germination and seedling growth of mung bean. • PL-AC showed the enhanced plant growth than PL-PC and control treatments.