Manganese Based Oxidative Technologies For Water/Wastewater Treatment
Manganese is a commonly occurring mineral found in soil and sediments that takes part in chemical reactions in groundwater and soil systems. It plays a significant role in controlling the environmental fate and transport of organic and inorganics by facilitating redox reactions. The reactivity of manganese oxides with some emerging contaminants like 4-tert octylphenol (OP) in aqueous systems is yet to be explored. Additionally, manganese's use within treatment systems designed to remove trace organics is yet to be fully developed.
This research work explores the reactivity of manganese oxide to degrade OP in aqueous systems. The rate equation has been determined by conducting experiments at various conditions of oxide and organic loading as well as different pH's. The reaction order was found to be ? 1.1 for both oxide as well as the organic. The reactivity was much higher under acidic conditions. The presence of metals and humic acids greatly reduced the reactivity. The primary reaction by-product observed in the system was 4-(2,4,4-trimethylpentan-2yl)benzene-1,2-diol. Magnetic manganese ferrites were further created in the laboratory using a novel combustion method in order to blend the catalytic properties of manganese with the magnetic and structural properties of ferrites. These laboratory prepared catalysts were thoroughly characterized using XRD, SEM, TEM, HR-TEM, and BET. Their magnetic properties have also been studied. These manganese ferrites offer the potential to enhance hydroxyl radical production within catalytic ozonation systems. Thus their catalyst effectiveness was determined by measuring R_(ct), ozone exposure, hydroxyl radical production, and ozone decomposition. The effect of catalyst type, catalyst dosage, pre-ozonation, pH, and presence of dissolved organic matter (DOM) on the hydroxyl radical production during catalytic ozonation was also explored. An increase in ozone dosage, catalyst dosage, and PVA content enhanced organic removal in the system. Organic removal was lower at a decreased system pH, in the presence of DOM, and with increasing levels of Mn incorporated into the catalyst. Pre-ozonation of the catalyst at lower dosages did not have an effect on the system, though extensive pre-ozonation greatly reduced catalyst activity. Overall, R_(ct) and organic removal were not correlated.