Solar photodegradation of methyl orange in the presence of cations (Pb 2+ and Fe 2+ ) and anions (Cl -and SO4 2-)

  • John Akatch Vaal University of Technology
  • A Davhana Vaal University of Technology
  • M Masilela Vaal University of Technology


The discharge of dyes from textile industries into water bodies is  harmful to aquatic life due to the dye color which prevents light from penetrating the water. As a result, it is necessary to decolorize textile water before it is discharged into receiving water bodies. Current decolorization methods such a membrane processes and adsorption are costly due the need to replace the treatment media. Recently, solar photocatalysis has been developed as an alternative and low cost method of treating dyes. Photocatalysis has been observed to be very robust for the degradation of  organic chemicals; however, photocatalysis reaction could be inhibited by inorganic chemicals. This is important since textile wastewater usually has dissolved ions. In this work, the effect of cations (Pb2+and Fe2+) and anions (Cl-and SO42-) on the photocatalysis of methyl orange (MO) was investigated. Nano TiO2  catalysts were employed for MO photocatalysis in glass fluidized bed reactors under solar illumination. The effect of catalyst loading and concentration of Pb2+, Fe2+, Cl-and SO4 2-ions between  0.03 and 0.09 mM were investigated. It was found that the optimum catalyst loading was 200 mg/L. The presence of Pb2+ ions below a concentration 0.03 mM resulted in a reduction in the removal of MO. However, an increase in MO removal was observed in the presence of Fe2+, Cl-and SO42- ions at all concentrations as well as in the presence of Pb2+ions above 0.03 mM. This work showed that the enhancement or inhibition of the photocatalysis reaction depends on the type and concentration of the ion present in solution. As a result, ions which enhance photocatalysis should not be eliminated before photocatalysis while inhibiting ions should be removed from the wastewater before photocatalysis treatment.
Keywords—  ions, methyl orange, solar photocatalysis,  textile wastewater
Sep 25, 2017
How to Cite
AKATCH, John; DAVHANA, A; MASILELA, M. Solar photodegradation of methyl orange in the presence of cations (Pb 2+ and Fe 2+ ) and anions (Cl -and SO4 2-). Proceedings of Sustainable Research and Innovation Conference, [S.l.], p. 63-66, sep. 2017. ISSN 2079-6226. Available at: <>. Date accessed: 24 feb. 2018.