Removal of Methylene Blue dye from aqueous solution using Fenton-modified submerged aquatic plant Schoenoplectus species (Bulrush).

Abstract

When dumping coloured effluent into the ecosystem, methylene blue dye contributes significantly to environmental health problems. In this investigation, Schoenoplectus species, commonly known as Bulrush, underwent modification using a Fenton reagent to enhance its effectiveness in adsorbing methylene blue (MB) from effluent. The Fenton-treated Bulrush was analysed using SEM, FTIR, BET, and TGA techniques, while various operational parameters were systematically explored to optimise the adsorbent. The FTIR results revealed an increase in the intensity of chemical compounds (-OH, C=C, and C-O, etc.). The FTIR data showed an increase in the intensity of chemical compounds (-OH, C=C, and C-O, among others) and aromatic structures on the exterior of the adsorbent, which aided in MB removal. The results exhibited conformity with the Langmuir model, with an R² value of 0.9904 with an optimal adsorption capacity of 41.23 mg/g achieved for the Fenton-treated Bulrush. Kinetic analysis indicated adherence to the pseudo-second-order model (R² = 1), with chemical bonding adsorption primarily governing the adsorption rate. Optimal adsorption conditions were determined to be 26 °C, pH 8, a reaction time of 60 min, a dosing amount of 2 g, and a preliminary concentration of 100 mg/L. Enhanced pH and increased dosing of Fenton-treated Bulrush led to improved adsorption capacity. Crystal structural characteristics and surface functional groupings of Fenton-treated Bulrush emerged as crucial factors influencing adsorption, describing the three main processes that control MB absorption by the adsorbent: physical adsorption, electrostatic attraction, and π-π interaction. These processes demonstrated the economical, efficient, and environmentally friendly attributes of Fenton-treated Bulrush, which shows promise for eliminating dye contaminants from aquatic environments.