Porous polyurethane hydrogels incorporated with CMC for eliminating methylene blue from water

Abstract

Here, a series of polyurethane porous hydrogels (PUF-s) loaded with different sodium carboxymethyl cellulose (CMC) were successfully prepared by one-step foaming method. The physio-chemical properties and morphologies were characterized. The effects of CMC content, adsorbent dosage, temperature, pH value and other factors on the adsorption of methylene blue (MB) dye in water by CMC-PUF-s were also investigated through static adsorption experiments. The results showed that CMC-PUF-10 had excellent adsorption performance for MB solution with removal rate of 81.47%, and the maximum adsorption capacity was 27.5 mg/g. In addition, the study of adsorption kinetics and adsorption isotherms showed that the adsorption of MB by CMC-PUF was more consistent with Langmuir isotherm adsorption model and pseudo second-order kinetic model. The adsorption thermodynamics study suggested that the adsorption process of MB by CMC-PUF-10 was spontaneous and exothermic at room temperature. The results of cyclic adsorption experiment demonstrated that the removal rate of MB reached above 70% after five cycles, indicating the foams with excellent recyclability. Finally, a low-cost, environmentally friendly and recyclable MB adsorbent was synthesized in this study. As polyurethane foam was synthesized by one-step foaming method, this adsorbent can be prepared on site in practical application and reduce the transportation cost.