Adsorption properties of β-cyclodextrin modified hydrogel for methylene blue.

With the development of dye and printing, production wastewater has become one of the most primary pollution sources of water and soil pollution. Most of the dyes are toxic substances, which have the "three-way" effect of carcinogenic, teratogenic and mutagenic. Therefore, it is a very difficult but significant issue to deal with the dye in the wastewater. Here, we report a study on low-cost, high-capacity hydrogels that remove water-soluble dyes. The hydrogel is prepared by crosslinking the β-cyclodextrin and functional monomer: acrylamido and 2-acrylamide-2-methylpropane sulfonic acid by aqueous solution polymerization, meanwhile, alkaline hydrolysis is also an important step for adsorption performance. After alkaline hydrolysis, the amide and sulfonic groups in the hydrogel were converted into carboxylate and sulfonate, which was beneficial to the adsorption of cationic dyes. This polymer could remove 96.58% methylene blue (400 mg/L) and only requires 0.02 wt%. Its maximum adsorption capacity for methylene blue could reach 2638.22 mg/g under equilibrium condition. It is the most powerful adsorbent used to treat dye wastewater, according to the report. It also provides some references for hydrogel treatment of dye wastewater.