Cellulose is an interesting biopolymer offering numerous functionalization possibilities for various applications. Yet, cellulose functionalization usually involves expensive chemicals and complex processes. Here, we aim to utilize inexpensive fertilizer-grade phosphate for cellulose functionalization. Cellulose microfibers (CMF) were isolated from Giant Reed (GR) and were then phosphorylated using either a reagent-grade or a fertilizer-grade diammonium hydrogen phosphate (DAP) in the presence of urea following a water-based protocol. The effect of DAP on the phosphorylation reaction was mainly studied by conductometric titration, ICP-OES and FTIR, while further characterization was performed by SEM/EDX, TGA and XRD to investigate the morphology, composition, charge content, structure, and thermal degradation of the phosphorylated materials. It was found that cellulose phosphorylation using DAP fertilizer gave materials with the same charge content as that registered when using the reagent-grade DAP. Optimizing the reaction conditions with respect to the amount of fertilizer-grade DAP used for the phosphorylation gave high charge content (7000 mmol·g⁻¹). The corresponding phosphorylated CMF (P-CMF) were processed into a paper and used as sorbent for methylene blue (MB) removal from aqueous solutions with different concentrations. The findings indicated that the pseudo-second-order model could be useful to assess the adsorption kinetics while the Langmuir isotherm model can suitably describe the adsorption isotherms. With fast adsorption kinetics (2–6 h), high adsorption efficiency (92–99 %) and a MB adsorption capacity of ~1200 mg·g⁻¹ surpassing what has been reported so far for cellulose-based sorbents, the P-CMF paper holds great promises for the effective remediation of dye-contaminated wastewater effluents. Adsorption/desorption tests confirmed the reusability and regeneration of the paper with a recovery of 100 % for MB in the second cycle.

纤维素是一种有趣的生物聚合物，可为各种应用提供多种功能化可能性。然而，纤维素功能化通常涉及昂贵的化学品和复杂的过程。在这里，我们的目标是利用廉价的肥料级磷酸盐进行纤维素功能化。纤维素微纤维 (CMF) 从 Giant Reed (GR) 中分离出来，然后在尿素存在下按照水基方案使用试剂级或肥料级磷酸氢二铵 (DAP) 进行磷酸化。主要通过电导滴定法、ICP-OES和FTIR研究DAP对磷酸化反应的影响，进一步通过SEM/EDX、TGA和XRD进行表征，研究其形貌、组成、电荷含量、结构和热降解情况。磷酸化物质。发现使用 DAP 肥料进行纤维素磷酸化产生的材料与使用试剂级 DAP 时所记录的电荷含量相同。根据用于磷酸化的肥料级 DAP 的量优化反应条件，得到高电荷含量（7000 mmol·g^-1 )。将相应的磷酸化 CMF (P-CMF) 加工成纸，用作吸附剂，从不同浓度的水溶液中去除亚甲基蓝 (MB)。研究结果表明，准二级模型可用于评估吸附动力学，而 Langmuir 等温线模型可以适当地描述吸附等温线。具有快速吸附动力学（2-6 小时）、高吸附效率（92-99 %）和约 1200 mg·g ^{-1的 MB 吸附容量}P-CMF 纸超越了迄今为止关于纤维素基吸附剂的报道，为有效修复染料污染的废水排放物提供了广阔的前景。吸附/解吸测试证实了纸张的可重复使用性和再生性，MB 在第二个循环中的回收率为 100%。