Congo red dye adsorption using CuSnO2TiO2 nanocomposites: Adsorption data interpretation by statistical modeling

The study explores CuSnO2TiO2 nanocomposite's efficacy as a CR dye adsorbent in wastewater treatment. Surface morphology evaluation utilized transmission electron microscopy (TEM), selected area electron diffraction (SAED), and elemental analysis techniques (EDS). Experiments were conducted to ascertain the wavelength at which the highest absorbance occurs and to evaluate the stability of CR solutions over time, depending on their concentration and/or pH. These parameters were shown to be very relevant. Batch mode experiments assessed various factors influencing adsorption: contact duration (120 minutes), pH levels (3 to 10), adsorbent dose (50 to 200 mg/L), and temperatures (298 to 318 K). At equilibrium, CuSnO2TiO2 nanocomposite exhibited an adsorption capacity of 277 mg/g, dependent on adsorbent dosage, temperature, pH (pH=7), and initial CR dye concentration (50 mg/L). Pseudo-second-order kinetics best fitted the removal data, while equilibrium data aligned well with the Freundlich model. Thermodynamic analysis indicated an exothermic and spontaneous adsorption process.