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

Abstract

Polyalthia longifolia (PL) seed biomass was effectively converted into pristine and activated biocarbon using KOH mediated chemical activation process at 800°C under N₂ 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 m²/g, whereas their pristine form showed as low as 1 m²/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.