Kinetic, Thermodynamic, and Adsorption Behavior of Cationic and Anionic Dyes onto Corn Stigmata: Nonlinear and Stochastic Analyses

The potential to remove methylene blue (MB) basic dye and indigo carmine (IC) acidic dye, from wastewater treatment systems using corn stigmata through biosorption was investigated in batch experiments. The effects of contact time, solution pH, biosorbent dosage, initial dye concentration, salts, and temperature were sought. Results showed that the maximal uptakes of MB were 106.3 mg g⁻¹ at pH = 7 and 63.7 mg g⁻¹ for IC at pH = 2. In order to determine the properties and surface structure of the biomass physicochemical properties (pH_pzc, elemental analysis, Boehm's titration, and chemical composition), spectral (FTIR analysis) and morphological characteristics (SEM) were investigated. Random distribution of the active sites was described by the new biosorption fractal model of Brouers–Sotolongo. The thermodynamic study demonstrated the favorable character of the biosorption of MB and of IC, which was inhibited by the presence of salts. The elucidation of the biosorption mechanism showed that the biosorption of MB onto corn stigmata was mainly controlled by chemisorption and the biosorption of IC was described by physisorption.