Novel synthesis, characterization, and application of calcium ferrate (VI) in water treatment

Abstract

Abstract Poor raw water quality has led science and technology research to explore more environmentally friendly water treatment methods, such as advanced oxidation processes. Ferrate (VI) salts have been regarded as a new green oxidant, cost-effective, and coagulant/flocculent in a single mixing and dosing unit in wastewater treatment. This research aimed to synthesize calcium ferrate (CaFeO4), a benign green chemical that can be utilized to treat water and wastewater through a facile wet oxidation process, with minimal increase in electrical conductivity. This study used the wet oxidation approach to synthesize stable aqueous calcium ferrate in an alkaline media using distilled water. During process optimization, CaFeO4 was synthesized and named 60-CaFeO4, 70-CaFeO4, 80-CaFeO4, and 90-CaFeO4, where the numbers represent the synthesis temperature. The prepared CaFeO4 was characterized using XRD, FT-IR, UV–Vis, TEM, SEM, Raman, and redox titration. FT-IR analysis confirmed the presence of the Fe–O stretching vibrations in all the freeze-dried CaFeO4 powders, signifying the successful preparation of the materials. The physicochemical characteristics of raw water, such as turbidity, color, COD, pH, EC, and TDS, were analyzed before and after treatment with CaFeO4. A jar test was performed to evaluate the reactivity and efficiency of the CaFeO4 toward wastewater treatment through coagulation/flocculation processes. After coagulation using CaFeO4, the pollutants levels were reduced COD (43.56–71.56%) and turbidity (97–99%), signifying the effectiveness of the as-prepared materials. CaFeO4 was successfully produced at various temperatures and was stable enough to be stored at room temperature for over six months without significantly decomposing. Graphical abstract

Keywords

• Calcium ferrate (VI)
• Green coagulant chemical
• Wastewater treatment
• Wet oxidation method
• Jar test
• Water treatment