The adsorption of paraquat was examined in the presence of renewable nanomaterials of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxidized cellulose nanofibers (TOCNs) with different oxidation time (i.e. TOCN-1h, TOCN-4h, TOCN-8h, and TOCN-24h). First, we monitored the relationships among TEMPO-mediated oxidation times, cellulose surface functional groups, and fiber diameters. We observed the oxidation and the carboxylate contents of cellulose were promptly increased in an hour, leading to the formation of nano-sized cellulose fibers (ca. 20 nm). These cellulose nanofibers were characterized by Fourier-transform infrared (FT-IR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) method, and wide angle X-ray diffraction (WAXRD). Accordingly, the TOCNs with enlarged specific surface area (ca. 180 m²/g) performed high adsorption efficiency for paraquat (>90%), contributing from the strong attraction force between carboxylate anion on TOCNs and parquet cation. The adsorption behaviors were revealed by intra-particle diffusion (IPD) model. For TOCN-24 h, IPD of adsorbate from the surface to the active sites within the hemicellulose or disorder region was observed, resulting in the increase of the adsorption equilibrium time. We then comprehended the absorption performance was sensitive under different pH environments. The adsorption capacity over 100 mg/g can be reached at a pH value greater or equal to 7. Furthermore, Langmuir isotherm model was fitted to the adsorption behaviors at various temperatures, indicating a single layer adsorption mechanism.

在存在具有不同氧化时间（即，TOCN-1h，TOCN-4h，TOCN- 8h和TOCN-24h）。首先，我们监测了TEMPO介导的氧化时间，纤维素表面官能团和纤维直径之间的关系。我们观察到，纤维素的氧化和羧酸盐含量在一小时内迅速增加，导致形成纳米级纤维素纤维（约20 nm）。这些纤维素纳米纤维的特征在于傅立叶变换红外（FT-IR），扫描电子显微镜（SEM），Brunauer-Emmett-Teller（BET）方法和广角X射线衍射（WAXRD）。因此，具有较大比表面积（约180 m ²/ g）对百草枯具有较高的吸附效率（> 90％），这归因于TOCN上的羧酸根阴离子与镶木地板阳离子之间的强大吸引力。通过颗粒内扩散（IPD）模型揭示了吸附行为。在TOCN-24小时内，观察到了从表面到半纤维素或无序区域内活性部位的被吸附物的IPD，从而导致了吸附平衡时间的增加。然后，我们了解到吸收性能在不同的pH环境下是敏感的。在大于或等于7的pH值下，吸附容量可达到100 mg / g以上。此外，将Langmuir等温模型拟合到各种温度下的吸附行为，表明了单层吸附机理。