Black Soldier Fly Pupal ExuviExperimentae as a Biomaterial for Cadmium Adsorption: Characterization, Efficiency and Pot

Abstract

Chitin-chitosan, derived from black soldier fly (BSF) pupal exuviae (BSF-PE), has emerged as a promising adsorbent due to its abundance from the food waste management and biodegradability. This study investigated the Cd (II) ion adsorption capacity of different BSF-PE-derived adsorbents prepared through demineralization, deproteinization, and deacetylation. Ground BSF-PE and BSF-chitin exhibited the highest Cd adsorption efficiencies (91.23% and 97.33%, respectively) under the condition of pH 7, temperature 328 K, and shaking rate of 150 rpm for 24 h. The Langmuir isotherm confirmed monolayer adsorption, with Cd binding to calcium carbonate in ground BSF-PE which can precipitate as a solid from SEM observation (q_m = 31.48 mg/g and K_L = 0.54 L/mg), and to the acetyl and hydroxyl groups in chitin (q_m = 37.85 mg/g and K_L = 0.55 L/mg). The phytotoxicity of BSF-chitin and ground BSF-PE leaching demonstrated a significantly high germination index (~ 50–66%) in Bok choy. Whereas, ground BSF-PE and BSE-PE leaching showed a comparable percentage in germination index in rice (31–42%). A pot experiment using 10 mg/kg-spiked Cd contaminated soil and ground BSF-PE revealed that a mixture not exceeding 10 g/kg optimizes Bok choy growth while minimizing Cd leaching and plant uptake (3.95 mg /kg) compared to soil control (87.56 mg/kg). This study highlights the potential of BSF-PE as sustainable and effective adsorbent for Cd removal from soil contamination, consequently contributing in environmental protection and remediation.