Enhanced removal of methylene blue by 2-(2,4,5-tricarboxybenzyloxy)-1,2,3-propanetricarboxylic acid modified cellulose

A new type of polycarboxylic acid crosslinking agent 2-(2,4,5-tricarboxybenzyloxy)-1,2,3-propanetricarboxylic acid (TBPTA) with the morphology similar to the regular arrangement of the foliar morphology of Araucaria was synthesized by dissolving carboxylic acid system of 1, 2, 3, 4-butane tetracarboxylic acid (PMDA) and citric acid (CA) in the molar ratio of 1: 1 in tetrahydrofuran (THF) at 68 °C. On this basis, a novel adsorbent TEMPO-derived nanocellulose (CNF)/TBPTA with excellent adsorption properties for methylene blue (MB) was prepared by mixing CNF, TBPTA as raw materials and sodium hypophosphite (SHP) as catalyst in various proportions. The X-ray diffraction (XRD) spectra showed that the cross-linking effect of TBPTA transformed the crystal structure of CNF from type I to type II. The MB adsorption results suggested that the maximum adsorption capacity of CNF/TBPTA was 1152 mg g−1, which was 321.58 % higher than that of CNF without TBPTA esterification crosslinking modification. The adsorption process can be described by Langmuir isothermal adsorption model and pseudo-second-order kinetic model, involving electrostatic force, hydrogen bond and π-π conjugation effect. CNF/TBPTA demonstrates a strong potential for reuse, maintaining 92 % of its initial MB adsorption efficiency after undergoing 7 successive adsorption-desorption cycles.