Biochar-C-TETA as a superior adsorbent to acid yellow 17 dye from water: isothermal and kinetic studies

Abstract

Adsorbents from local materials with high adsorption capacity (Qm) are strongly needed. In this study, mandarin peels (MP) as a local waste material were refluxed in 80% sulfuric acid (H2SO4) to produce a novel biochar, which was oxidized by boiling in 50% hydrogen perioxide (H2O2) and then aminated via refluxing in tetraacetic acid (TETA) to produce mandarin biochar-C-TETA (MBCT). Fourier transform infrared (FTIR), Brunauer–Emmett–Teller (BET), Barrett–Joyner–Halenda (BJH), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and thermgravimetric analysis (TGA) studied various characterizations of MBCT. The optimal pH for AY17 dye absorption was discovered to be 1.5 using 0.75 g L−1 MBCT, the maximum absorption capacity predicted for the MBCT was 1250 mg g−1. The high new absorption peaks at 1439.89 and 1362.38 cm−1 in MBCT imply that amino groups were successfully generated onto the surface of MBCT due to TETA treatment. The experimental data were examined using the Langmuir (LNR) and Freundlich (FRH) isotherm models. The FRH best explained the experimental MBCT data. The pseudo-first-order (PFOM) and pseudo-second-order (PSOM) models, intraparticle diffusion (INDM) and film diffusion (FDM) models were applied to calculate the kinetic data. The PFOM rate model ideally defined the absorption of AY17 dye to MBCT with a linear regression coefficient (R2 > 0.99). The key mechanism for absorbing AY17 dye molecules to MBCT was chemisorption, which entails the distribution or exchange of electrons between the absorbent and the dye due to the valency force. According to the findings, the novel MBCT adsorbent had a remarkable adsorption capacity (Qm = 1250 mg g−1) and could be reused without losing its absorption effectiveness. © 2023 Society of Chemical Industry (SCI).