Removal of Chlorine Ions from Desulfurization Wastewater by Modified Fly Ash Hydrotalcite

The effective removal of chlorine ion from the desulfurization slurry is of great significance to the stable operation of the desulfurization system. Modified fly ash hydrotalcites were prepared by alkali/acid-combined roasting and microwaving and used as an adsorbent for chlorine ion in desulfurized wastewater. The specific surface area and porosity of different adsorbents were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The impacts of pH, temperature, adsorbent dosage, and adsorption shaking time on adsorption performance were investigated. Results showed the alkali-combined roasting-modified fly ash hydrotalcite has the optimum removal effect on Cl^-. The optimal adsorption performance was achieved when the pH was 8, the adsorption temperature was 60 °C, the mass concentration of adsorbent was 10 g/L, the adsorption shaking time was 180 min, and the removal percentage of Cl^- was 68.1%. The adsorption isotherm was consistent with the Langmuir isotherm model, and the adsorption saturation was 694.4 mg/g, which belonged to monolayer adsorption.