Adsorption behaviors and mechanisms of porous polyvinyl alcohol/xanthan gum hydrogel for methylene blue and Pb2+

Faced with extensive water pollution caused by dyes and heavy metals, it is imperative to create cost-effective adsorbents that can effectively eliminate residual pollutants in wastewater. The synthesis of polyvinyl alcohol/xanthan gum (PVA/XG) hydrogels involved a combination of freeze-thaw cycling technique and the adsorption characteristics and mechanisms of methylene blue (MB) and heavy metal ions Pb2+ were investigated. In comparison to pure PVA hydrogels, the swelling behavior of PVA/XG3 hydrogel exhibited a 185 % increase in swelling rate. The adsorption test results suggested that PVA/XG3 hydrogel was effective in absorbing MB (27.39 mg/g) and Pb2+ (17.07 mg/g) from a 50 mg/L pollutant solution. The adsorption process of MB and Pb2+ by PVA/XG3 hydrogel followed Langmuir adsorption isotherm and the QFO models, indicating a preference for homogeneous physical adsorption. Specifically, the Langmuir isothermal model predicted that the qmax of MB and Pb2+ by PVA/XG3 hydrogel were 94.47 and 58.50 mg/g, respectively. Therefore, this essay has created a cost-effective and environmentally friendly method for producing versatile PVA/XG hydrogels specifically intended for water treatment purposes.