Preparation of carboxymethyl chitosan/phytic acid composite hydrogels for rapid dye adsorption in wastewater treatment

In recent years, chitosan has been used as a common raw material to prepare hydrogels for wastewater treatment. In this work, a series of carboxymethyl chitosan/phytic acid (CMCS-PA) composite hydrogels with various amounts of PA were prepared to remove methyl orange (MO) and Congo red (CR) dyes from aqueous solution. The composite hydrogels with well-defined structure were characterized by different techniques. The experimental results revealed that the hydrogel possessed stable porous structure with more wrinkles on the surface due to the formation of intermolecular hydrogen bonding between CMCS and PA during the in-situ polymerization process. More importantly, the optimal adsorption conditions of CMCS-PA were obtained by changing different adsorption factors: ratio of two molecules and pH. And the CMCS-PA (3:1) composite hydrogel presented great adsorption capacity for MO (13.62 mg/g) and CR (8.49 mg/g) at pH = 7 at room temperature. In addition, the hydrogel also showed great adsorption reusability and stability. This work promotes further development in composite hydrogels design and their applications of wastewater treatment.