Utilising calcined eggshell waste as a multifunctional sustainable agent as a nano-adsorbent, photocatalyst and priming elicitor.

Abstract

Since waste-to-value approach and having potential benefits in several applications, eggshell-derived calcium oxide (ECaO) produced from eggshells is attracting attention in the recent research. ECaO nanoparticles (NPs) were investigated here for its dual purpose in cleaning wastewater and as a nanopriming agent, since catalysts have an impact on seedlings even after being dumped in the soil. The initial comparison was between the adsorption capacities of naturally occurring ECaO and chemically synthesised CaO (CCaO), demonstrating that ECaO NPs had a higher adsorption capacity due to its greater porosity. Congo Red utilises ECaO NPs for both adsorption and photodegradation. Adsorption equilibrium was achieved with 93.4% in just 6min, but photocatalysis requires 120min to break down 95% of Congo Red, which is reduced to 45min in sono-photocatalysis. Second, the priming impact of ECaO NPs on germination was investigated using monocot and dicot seeds. In contrast to phytotoxic effects at higher loadings, 50mg/l of ECaO NPs demonstrated quicker floral development, stronger seedling growth and higher chlorophyll content.