1Centre for Renewable Energy and Water, Vaal University of Technology, Private Bag X021, Vanderbijlpark, 1900, SOUTH AFRICA
2Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria, Private Bag X680 Pretoria, 0001, SOUTH AFRICA
Wastewater from molasses processing contains a large amount of coloured substances that give a recalcitrant dark brown colour and high organic load to the effluent. Photocatalytic decolourization of molasses wastewater was performed using titanium dioxide catalyst coated on the surface of South African natural zeolite using the solid-solid dispersion method. Addition of hydrogen peroxide as an oxidant was investigated and 30W UV-Clamp was used as source of irradiation. The Chemical Oxygen Demand (COD) of the wastewater treated was varied from 20 g/L to 1 g/L. Batch experiments were conducted in a thermostatic shaker fitted with the UV lamp. The effects of pH, catalyst loading, oxidant dosage and irradiation time on the COD reduction and decolourization of the Molasses Waste Water (MWW) were investigated in this study. The highest colour removal of more than 90% was achieved at pH = 4 and oxidant dosage of 1.47 mM, while low COD removal (< 20%) was observed during photodegradation. A H2O2/UV/TiO2 system achieved higher colour removal of 97% compared to a UV/TiO2 system which achieved 44% while H2O2/UV system achieved 34% colour removal. The rate of decolourization was found to fitpseudo - first order reaction kinetics with the highest rate constant value of 1.36 x 10-2 min-1.
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