Effective response of multiple kinetic models and DFT calculations to the ultrafast adsorption behaviors of cellulose-titanium dioxide composites
2022
Zhou, Qianya | Zhang, Tao | Su, Yaoming | Zheng, Liuchun | Zeng, Hao | Ren, Jingjing | Yu, Huajian | Meng, Peipei
A cellulose-polyacrylic acid-TiO₂ composite (CAT) with multiple carboxyl groups in the network structure and that could undergo ultrafast adsorption was successfully synthesized, and the adsorption capacity for cadmium(II) (Cd(II)) under optimal conditions was as high as 105 mg/g within 5 min. Additionally, CAT maintained the advantages of fast and efficient adsorption even when the concentrations of potentially interfering ions (NaCl, MgSO₄, HA) were high. Importantly, 13 nonlinear kinetic models, including 6 empirical models and 7 diffusional models with their 5 error functions, were used to evaluate the adsorbent performance and mass transfer mechanism. As a result, regardless of whether interfering ions were present, the PNO model and Langmuir kinetics model were perceived as the best fit for the adsorption reaction and empirical model and mass transfer model, respectively. Adsorption at active centers was the rate limiting step for CAT. Moreover, the micromechanisms were also quantitatively explained with multiple DFT calculations, which illustrated ion exchange and electrostatic interactions with the oxygen atom on the introduced carboxyl group.
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