Abstract
In this study, two-step surface modification of sawdust using triethanolamine (at 180 °C) and iodomethane (at 42 °C) was performed to produce a novel quaternized biosorbent, TEA-I-SD. The characterization studies revealed significant morphological changes in the sawdust and successful quaternization with a nitrogen content of 5.75%. The highest vanadium removal (96.2%) was achieved at pH 4 (dosage 1 g/L, initial vanadium concentration 19.1 mg/L). Equilibrium was achieved within 8 h of contact time and the adsorption kinetics were well fitted with the pseudo-second-order model. Both film diffusion and intra-particle diffusion contributed to the adsorption process, while the latter was the rate-limiting step. The maximum vanadium adsorption capacity of TEA-I-SD (35.0 mg/g, pH 4) was close to the theoretical value obtained from the Langmuir model. The best fit was achieved with the Redlich-Peterson model, exhibiting a monolayer adsorption phenomenon. Tests with real mine water containing 11 mg/L of vanadium also confirmed its high removal (91.3%, dosage 1 g/L) using TEA-I-SD at pH 4. The TEA-I-SD could be reused three times without significant capacity loss after regeneration, although the desorption efficiency was rather low (synthetic solution: 38.5–40.5% and mine water: 26.2–43.1%).
Highlights
The chemical modification (TEA-I) method was adapted from previously reported studies (Letaief et al, 2008; Matusik, 2014; Matusik and Bajda, 2013), where TEA was grafted into the interlayer space of clay material, which was quaternized using iodomethane
In the raw and modified sawdust samples, the band at 1630-1650 cmÀ1 might be partly due to the presence of NeH bending (Gogoi et al, 2019; Lim and Hudson, 2004), and its intensity and position changed after TEA modification due to the amination of sawdust (TEA-SD and TEA-I-SD)
The successful quaternization of sawdust with iodomethane was proved by the sharp band at 1471 cmÀ1 in TEA-I-SD due to the presence of quaternary ammonium groups (Pei et al, 2013; Salajkova et al, 2012)
Summary
The chemical modification (TEA-I) method was adapted from previously reported studies (Letaief et al, 2008; Matusik, 2014; Matusik and Bajda, 2013), where TEA was grafted into the interlayer space of clay material, which was quaternized using iodomethane. This is the first study to investigate the application of the TEA-I method for the modification of biomass to produce bio-based anion exchangers. The developed biosorbent was tested on real mine water containing vanadium
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