Functionalized microcrystalline cellulose (MCC) and its composites have a wide range of applications. In this research, bio-based phytic acid (PA) rich in phosphorus and condensed tannins (CT) were incorporated into MCC, and a product PA/CT/MCC with excellent flame retardant and cationic dye adsorption properties was prepared. The FT-IR and ICP-MS analyses confirmed the phosphorylation of MCC. The thermal stability, charring ability, heat release capability, and combustibility of PA/CT/MCC were investigated. PA/CT/MCC was susceptible to degradation and charring at low temperature primarily resulting from the pyrolysis products of PA, and yielded char layers at high temperature. Furthermore, PA/CT/MCC had a very low heat release capability in the microscale combustion, and displayed excellent flame retardancy in the vertical combustion, thereby being a potential FR material. Additionally, PA/CT/MCC exhibited a strong capability of adsorbing cationic dye from water, thereby being a potential adsorbent for removing cationic dye. The adsorption of cationic dye on PA/CT/MCC followed the pseudo-second-order kinetic model and the Langmuir–Nernst dual isotherm model. The Langmuir adsorption played a major role in total adsorption. This research suggests the novel approaches of constructing flame retardant and adsorptive MCC materials, which have potential application prospects in the fire protection and water treatment fields, respectively.

功能化微晶纤维素（MCC）及其复合材料具有广泛的应用。在这项研究中，富含磷的生物基植酸（PA）和将缩合单宁（CT）掺入MCC中，制备出具有优异阻燃和阳离子染料吸附性能的产品PA/CT/MCC。FT-IR 和 ICP-MS 分析证实了 MCC 的磷酸化。研究了 PA/CT/MCC 的热稳定性、炭化能力、放热能力和可燃性。PA/CT/MCC主要由PA的热解产物在低温下易降解和炭化，并在高温下产生炭层。此外，PA/CT/MCC在微尺度燃烧中具有非常低的放热能力，在垂直燃烧中表现出优异的阻燃性，是一种潜在的阻燃材料。此外，PA/CT/MCC 表现出很强的吸附水中阳离子染料的能力，从而成为去除阳离子染料的潜在吸附剂。PA/CT/MCC对阳离子染料的吸附遵循准二级动力学模型和Langmuir-Nernst双等温线模型。Langmuir吸附在总吸附中起主要作用。该研究提出了构建阻燃和吸附MCC材料的新方法，分别在消防和水处理领域具有潜在的应用前景。