Walnut Bloom Powder as a novel green sorbent for cationic dyes removal:Equilibrium, Kinetic, and Thermodynamic Studies

3,7-bis(Dimethylamino)-phenothiazin-5-ium chloride or Methylene Blue (MB) is a heterocyclic aromatic compound, widely used in a range of different fields,especially in textile industry [1]. Most of the dyes like MB or their metabolites are toxic and some of them are considered carcinogenic for human health [2]. Therefore, it is important to treat the dye wastewater before releasing it into the groundwater [3]. In this study for the first time, Walnut Bloom (WNB) powder was used as a natural and economic sorbent for the removal of MB from aqueous solutions. This new biosorbent was characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and elemental EDX. The influence of various parameters such as initial dye concentration, contact time, pH temperature, and dosage of biosorbent on the remove efficiency was investigated in batch experiments. Under the optimum condition, the removal percentages achieved ∼92%. In addition to Kinetics, equilibrium, and thermodynamics studies was investigated and equilibrium data and adsorption isotherms fitted well with the Langmuir model with maximum monolayer adsorption capacity of 46 mg/g. Kinetic data can be well fitted by the pseudo-second-order model, indicating a chemical adsorption. Thermodynamic data indicated that theadsorption was spontaneous, exothermic, and favorable at room temperature.