Adsorption Behaviour of Selected Biochar for Cadmium in Black Soldier Fly (Hermetia Illucens) Larvae Fed On Contaminated Organic Waste

Abstract

The efficiency of rice husk biochar (RHB) and coconut shell biochar (CSB) in adsorbing Cadmium (Cd), as one of the prevalent heavy metals reported to bioaccumulate highly at the larval stage of the black soldier fly (BSF) was investigated. The synthesized biochars were activated using sulphuric acid and surface morphology investigated using SEM. The surfaces of CS biochar had well defined pores while RH had irregular pores of different sizes. Batch adsorption studies were done to optimize the effect of different adsorption parameters in three replicates. The equilibrium data was then used to design adsorption isotherms where Freundlich isotherm model best fitted both RHB and CSB data with R2 values of 0.9967 and 0.9877 respectively while kinetic data was best described by pseudo second order model suggesting chemisorption process took place for both the adsorbents. The adsorption capacity of CSB and RHB were reported as 0.8484 mg×g-1 and 0.8399 mg×g-1 respectively. The efficiency of Cd removal by RHB and CSB was found to be 97% and 96% respectively. These results confirmed the suitability of RHB and CSB as adsorbents for effective removal of Cd in organic wastes.