Mesoporous Carbon Derived from Hermetia illucens Pupae Casings and Biogas Slurry for Cadmium Removal from Water by Capacitive Deionization Method
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Date
2025-06
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NM-AIST
Abstract
This study examined capacitive deionization’s effectiveness for recovering Cd2+ from water using novel carbon-based electrodes derived from Hermetia illucens pupae casings (PC) and biogas slurry (BG). Activated carbon (AC) was produced through carbonization at 500°C and chemical activation (KOH) at 700°C. The Brunauer-Emmett-Teller method, Scanning Electron Microscope, X-ray diffractometer, Fourier transform infrared, X-ray photoelectron spectroscopy, Raman spectroscopy, and contact angle measurements were performed on AC. Electrochemical impedance spectroscopy and cyclic voltammetry were used to test the
electrochemical properties of carbons. The PC-derived carbon (PC-2-700) had a specific surface area of 640 m²/g, while the BG-derived carbon (BG-2-700) showed a higher 927 m²/g. PC-2-700 exhibited a higher specific capacitance (271.9 Fg⁻¹) compared to BG-2-700 (105.8 Fg⁻¹), indicating better charge storage performance. The CDI cell containing the working electrodes in 5 and 10 mg/L Cd2+ solution was used for Cd2+ removal. The PC-2-700 electrode achieved 91 % removal efficiency (10.9 mg/g capacity) in 5 mg/L Cd²⁺ solutions, outperforming BG-3-700 electrode (60% efficiency, 2.3 mg/g). Moreover, PC-2-700 also demonstrated better charge and energy efficiency, consuming only 0.65 and 0.07 kWhm-3versus BG-2-700’s 0.24 and 0.93 kWhm-3at 5 mg/L concentration, respectively. The enhanced performance of PC-2-700 was due to its better capacitance, specific surface area, and porous structure on the surface. This study showed potential electrodes can be designed from pupae casings to remove heavy metals from water.
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