Degradation Of Dye Waste Water By A Natural Ironsand Heterogeneous Fenton Reaction Under Solar Radiation

Synthetic dye wastewater due to its high content of organic matter, high toxicity, poorbiodegradability characteristics, has been of a problem of water pollution needed to besolved urgently. Heterogeneous Photo-Fenton System as a typical advanced oxidationprocess could overcome the main shortcoming of the classical homogeneous Fenton–likeprocess, such as the loss of catalyst, the formation of a large amount of iron-containingsludge during the reaction process, which made the system low cost and has a goodapplication prospect.A natural ironsand as highly efficient heterogeneous catalyst has been studied fordegradation and mineralization of organic pollutants in a Heterogeneous Photo-Fentonsystem under solar radiation in this paper. X-ray powder diffraction （XRD）, X-rayfluorescence spectroscopy （XRF） and Brunauer-Emmett-Teller （BET） were used in orderto determine the ironsand character. It was found that the natural ironsand exhibited highphotocatalytic activity for degradation and mineralization of the dye pollutants under thesunlight, the catalytic mechanism of which was high activation ability of H₂O₂to generatelots of OH through both homogeneous and heterogeneous Fenton’s reaction, and that aproper concentration of oxalic acid externally added to the Fenton-like system couldincrease the degradation rate of the dye pollutants observably, which is mainly due to theformation of photoactive iron oxide–oxalate species promoting regeneration of ferrous.Alizarin red S was chosen as model organic pollutant and factors affecting the dyedegradation were investigated. Alizarin red S degradation was excellent at pH3. When theironsand of6g/L and H₂O₂of300mg/L and oxalic acid of30mg/L were introduced tothe reaction solution, the degradation ratio of alizarin red S was over99%and theremoval ratio of total organic carbon （TOC） was more than94%in150min. Besides, thecatalytic activity of natural ironsand was evaluated. The results showed that the naturalironsand reused several times still had a higher catalytic activity and higher Service life.Simultaneously, natural ironsand as catalyst also has been studied for the degradation ofmethyl orange and Acid Fuchsin dye wastewater in Heterogeneous Photo-Fenton reactionsystem. Studies have shown that natural ironsand as catalyst in Heterogeneous Photo-Fenton reaction system demonstrates certain of universality for degradation of dyewastewater and achieves great degradation effect.Since this natural ironsand as heterogeneous catalyst shows many advantages such ashigh efficiency for the activation of H₂O₂, low cost, low consumption, easy withdrawaland so on, it is very promising for the development of advanced oxidation processes basedon a heterogeneous Fenton-like system with the aid of the natural ironsand.