Degradation Of Fulvic Acid By Advanced Oxidation Technologies Based On The Application Of Peroxide

Fulvic Acid (FA) means the water soluble substance of Humic Acid (HA), which widely exists in natural water. A large amount of FA in water can also influence the human health and cause the pollution of environment. For instance, FA can react with chlorine, forming the chloride which is one of the environmental hazards. Recently, there are three traditional ways used to deal with the humic acid, including biochemical method, physical and chemical method, and advanced oxidation processes. Eelectro-Fenton oxidation, anodic oxidation and activated persulfate oxidation chemistry all have advantages of low investment, low cost, fast reaction speed and wide applicability, which have shown a wide prospect of application.This article mainly studies the influence of some factors of Fenton oxidation process such as H2O2 dosage, the molar ratio of H2O2/Fe+, and coagulation processes on the TOC removal, and the degradation of fulvic acid using UV-visible spectroscopy and so on. In addition, we also studies the influence of some factors of electro-Fenton oxidation process such as different cathodes, pH, voltage, Fe2+ dosage on the TOC removal and the degradation of fulvic acid. Moreover, the influence of some factors of activated persulfate oxidation chemistry such as sodium persulfate, Fe2+ dosage, and temperature on TOC removal.For degradation of 100 mg/L fulvic acid using Fenton oxidation process, under the pH=3.0, H2O2 concentration of 400 mg/L,10:1 molar ratio of H2O2/Fe2+ and reaction time of 240 min,88.3% of TOC removal and almost complete color removal were achieved. For degradation of 100 mg/L fulvic acid using electro-Fenton oxidation process using a hydroxyl-functionalized multi-walled carbon nanotubes modified porous carbon cathode as the cathode and Ti/SnO2-Sb2O5-IrO2 as the anode, under pH=3.0, voltage of 3.0 V, Fe2+ concentration of 0.8 mmol/L, and reaction time of 240 min,74.5% of TOC removal was obtained. For degradation of 100 mg/L fulvic acid using activated persulfate oxidation chemistry, under T=50℃, pH=3.0,Na2S2O8 concentration of 2000 mg/L, and reaction time of 240 min,55.9% of TOC removal and almost complete color removal were achieved.The results showed that Fenton oxidation process was the most efficient way to deal with humic acid, whereas it needed the acidic environment and produced much sludge. Eelectro-Fenton oxidation process took the second place when dealing with humic acid, and it does not need the addition of the H2O2 and produce less sludge than Fenton oxidation process. Activated persulfate oxidation chemistry has the lowest efficiency when dealing with humic acid, and it needed the largest amounts of oxidant. Compared with these three advanced oxidation processes, Fenton oxidation process and electro-Fenton oxidation process can be considered as the alternative methods for the removal of humic acid.