Novel palm peat lignocellulosic adsorbent derived from agricultural residues for efficient methylene blue dye removal from textile wastewater

Abstract Palm Peat (PP), the world’s first rich lignocellulosic medium derived from date palm agricultural residues, has not been previously explored for environmental purification. This study evaluates PP's performance in adsorbing methylene blue (MB) dye. PP is characterized by a spongy, porous structure with a surface area of 16 m 2 /g. It possesses a significant carbon and oxygen composition and features active surface functional groups. Under conditions of 30 mg/L initial MB concentration, 1 g/L PP dose, T = 30 °C, pH 7, and 900 rpm stirring speed, PP achieved a 68.26% MB removal efficiency within 90 min. Although higher temperatures enhanced MB removal efficiencies, room temperature (30 °C) was chosen for subsequent experiments to assess adsorption performance under ambient conditions and minimize energy consumption. Stirring speeds exceeding 900 rpm reduce MB removal efficiency, likely due to shear forces disrupting the interaction between MB molecules and PP or causing desorption of previously adsorbed dye molecules. Response surface methodology combined with a central composite design was employed to optimize the initial MB concentration, PP dosage, and solution pH. Under the optimum conditions, PP achieved 97.89% MB removal. PP exhibited strong stability over five adsorption cycles. Adsorption occurs via π-π stacking, hydrogen bonding, hydrophobic-hydrophobic interactions, and electrostatic interaction with the process being endothermic and following the Langmuir isotherm model and pseudo-second-order kinetic model. The adsorption efficiency studies across different water matrices revealed the lowest degradation rate in the drain water matrix. PP achieved 71.5% MB removal and 48.16% TOC removal from real textile wastewater.