Chitosan graft poly(acrylic acid-co-2-acrylamide-2-methyl propane sulfonic acid) (CTS-g-P(AA-co-AMPS)) hydrogel is prepared and used to remove methylene blue (MB) and rhodamine B (RB) mixed dyes from aqueous solutions. The effect of adsorption conditions, including the initial concentrations of dye solutions, contact time, initial pH values, ionic strength, and the adsorbent dosage, on the adsorption capacities is investigated. The maximal adsorption capacity for MB and RB is 936.0 and 556.9 mg/g, respectively. The adsorption isotherms of the mixed dyes are discussed using the extended Langmuir (EL) and the extended Freundlich (EF) isotherm equations. It indicates that the adsorption of both dyes is in good agreement with the extended Freundlich isotherm. Meanwhile, the adsorption processes of both dyes are spontaneous. Adsorption kinetics is in accordance with the pseudo-secondorder kinetic equation. It is concluded that the available adsorption sites are shared by both kinds of the dye molecules. The difference of the maximal adsorption capacities of the two dyes is due to their different affinity to the adsorbent. K E Y W O R D S adsorption, hydrogel, mixed dyes How to cite this article: Tang Y, He T, Liu Y, Zhou B, Yang R, Zhu L. Sorption behavior of methylene blue and rhodamine B mixed dyes onto chitosan graft poly (acrylic acid-co-2-acrylamide-2-methyl propane sulfonic acid) hydrogel. Adv

Sodium alginate graft poly (acrylic acid‐co‐2‐acrylamide‐2‐methyl propane sulfonic acid)/graphene oxide (SA‐g‐P(AA‐co‐AMPS)/GO) hydrogel composite is prepared. The composite is characterized by infrared (IR) spectroscopy, X‐ray diffraction (XRD), high‐resolution scanning electron microscope (HRSEM), and differential scanning calorimetry (DSC). The swelling properties of the composite are investigated. GO acts as part of the cross‐linking points, which improves the swelling property of the composite. Maximal amount of absorption capacity in water and 0.9% NaCl is 862.3 and 164.7 g/g, respectively, with a GO content of 5 wt% of total mass of monomers. However, the absorption of water and 0.9% NaCl is only 390.3 and 52.5 g/g, respectively, without the incorporation of GO. Water retention properties of the composite are also tested.

With the unique advantages in structure and property, covalent organic frameworks have been widely employed for separation and enrichment. In this work, the thiosemicarbazide‐linked covalent organic framework (TpTc) was prepared by using 1,3,5‐triformylphloroglucinol and non‐rigid thiosemicarbazide as building blocks for the first time. The as‐prepared TpTc COF was fully characterized, presenting an agaric‐like structure, large specific surface area (63.5 m2 g−1), uniform pore size distribution (1.36 nm), inherent porosity and ordered crystallinity. The potential of TpTc as adsorbent for metal ions capture was investigated by static batch adsorption experiment using the one‐factor procedure. The maximum adsorption capacities of 73.50, 56.53 and 94.13 mg g−1 were obtained for Cu (II), Pb (II) and Cd (II) at natural pH, respectively. The anchoring of three metal ions onto TpTc is a multi‐layer sorption involving chemical adsorption, and obeys the Freundlich and pseudo‐second‐order model. According to XPS analysis, the adsorption mechanism may be attributed to the coordination and electrostatic interaction between metal ions and N, O and S atoms on TpTc COF. This work not only provides a candidate for the application of COFs in metal ions capture, but also a reference for exploring functional design of COFs.

With the unique advantages in structure and property, covalent organic frameworks have been widely employed for separation and enrichment. In this work, the thiosemicarbazide-linked covalent organic framework (TpTc) was prepared by using 1,3,5-triformylphloroglucinol and non-rigid thiosemicarbazide as building blocks for the first time. The as-prepared TpTc COF was fully characterized, presenting an agaric-like structure, large specific surface area (63.5 m2 g-1), uniform pore size distribution (1.36 nm), inherent porosity and ordered crystallinity. The potential of TpTc as adsorbent for metal ions capture was investigated by static batch adsorption experiment using the one-factor procedure. The maximum adsorption capacities of 73.50, 56.53 and 94.13 mg g-1 were obtained for Cu (II), Pb (II) and Cd (II) at natural pH, respectively. The anchoring of three metal ions onto TpTc is a multi-layer sorption involving chemical adsorption, and obeys the Freundlich and pseudo-second-order model. According to XPS analysis, the adsorption mechanism may be attributed to the coordination and electrostatic interaction between metal ions and N, O and S atoms on TpTc COF. This work not only provides a candidate for the application of COFs in metal ions capture, but also a reference for exploring functional design of COFs .