Key Laboratory of Recycling and Eco-treatment of Waste Biomass of Zhejiang Province, Zhejiang University of Science and Tìhnology, Hangzhou 310023, China.
Liaoning Key Laboratory of Lignocellulose Chemistry and Biomaterials, Dalian Polytechnic University, Dalian 116034, China.
Int J Biol Macromol. 2024 Nov;280(Pt 4):135950. doi: 10.1016/j.ijbiomac.2024.135950. Epub 2024 Sep 27.
Lignin-based adsorbents for the removal of Cr(VI) ions have attracted intensive attention due to the advantages of renewability, biodegradablity, low cost and environmental friendliness. However, there are still a lot of challenges such as poor adsorption capacity, low lignin content in adsorbents, and harsh preparation conditions. Here, a tandem hydroxymethylation-demethylation method is proposed for preparing an excellent lignin-based Cr(VI) adsorbent (DHKL), which features with high lignin content (>85 wt%) and high hydroxyl content (up to 6.26 mmol/g) under milder conditions. The prepared DHKL exhibits an adsorption capacity reaching up to 1040.9 mg/g and can maintain this capacity even in the presence of other metal ions in the solution. Model analyses indicate that chemisorption occurring in a monolayer is the main process, which is spontaneous and endothermic. Structural changes of DHKL before and after adsorption indicated that Cr(VI) ions are mainly reduced to Cr(III) ions by hydroxyl groups with some of the absorbed Cr ions dispersed into the inner part of DHKL. Based on these results, the detailed possible adsorption mechanism is deduced, providing guidance for designing, producing and utilizing lignin-based adsorbents.
基于木质素的吸附剂由于可再生性、可生物降解性、低成本和环境友好性等优点，已成为去除 Cr(VI)离子的研究热点。然而，仍存在吸附容量差、吸附剂中木质素含量低、制备条件苛刻等诸多挑战。本研究提出了一种串联羟甲基化-脱甲基化方法，用于制备一种性能优异的基于木质素的 Cr(VI)吸附剂（DHKL）。该吸附剂在温和条件下具有高木质素含量（>85wt%）和高羟基含量（高达 6.26mmol/g）。所制备的 DHKL 具有高达 1040.9mg/g 的吸附容量，即使在溶液中存在其他金属离子时也能保持这种容量。模型分析表明，单层发生的化学吸附是主要过程，该过程是自发的和吸热的。吸附前后 DHKL 的结构变化表明，Cr(VI)离子主要被羟基还原为 Cr(III)离子，部分吸附的 Cr 离子分散到 DHKL 的内部。基于这些结果，推导出了详细的可能吸附机制，为设计、生产和利用基于木质素的吸附剂提供了指导。
