Removal of Cr(VI) from Aqueous Solutions Using Thermal Power Plant Gas Purification Waste (Reduction and Adsorption of Hexavalent Chromium), Interpretation of Mechanism: Disposal of Waste and Residues

Flue Gas Desulfurization System (FGD) is a treatment system that has been made mandatory in thermal power plants for sulfur retention in recent years. FGD systems have been made mandatory in coal-based energy generating systems, especially in order to reduce the increasing greenhouse gas effect and to prevent the release of coal-derived sulfur oxides into nature. The hot waste steam from the boiler is sent to the FGD columns and milk of lime is fed to absorb the sulfur oxides. After treatment, thermal power plant gas treatment waste (PW) with a high content of gypsum is produced. In this study, the removal of chromium from aqueous solutions by PW was investigated. Cr(VI) adsorption studies were optimized using Taguchi analysis. In this context, L25 Taguchi orthogonal array was applied using 5 factors and 5 levels to optimize experimental parameters such as pH, dosage, contact time, concentration, temperature which affect adsorption. Elemental analysis, BET, TGA, XRD, XRD, FT-IR analyses were applied to determine the physicochemical properties of the waste. Adsorption isotherms and kinetics were also studied to investigate the Cr(VI) removal and mechanism of the material. The optimum experimental conditions were determined as initial pH 2.13, concentration 20 mg/L, dosage 22.5 g/L, time 12 h and temperature 32.5 degrees C by Taguchi method. Under these conditions, 100% Cr(VI) removal was successfully achieved. The results obtained show that PW is successful in Cr(VI) removal. The utilization of FGD waste is very important in terms of sustainability and environment. An alternative method has been presented as a solution to the increasing depletion of global water resources and the increasing need for land for PW storage.