PERFORMANCE OF MODIFIED HETEROGENEOUS NOVEL PAN CATALYST FOR THE REMEDIATION OF REACTIVE ORANGE 16 (RO16)

This study evaluated the performance of a heterogeneous Fenton system in the form of a novel modified PAN Catalyst for the remediation of the azo dye Reactive Orange 16 (RO16). The modified PAN crosslinked catalyst comprises amidoxime, amidrazone groups chelated to iron 3+. The surface of these catalyst fibres also comprises particulates of iron oxide sulphate species. The effects of H2O2, catalyst loading, pH, temperature, shock load, and turbidity have been studied in both batch and continuous flow both with and without UVc assistance. The effectiveness in the removal of the azo dye in terms of decolouration, loss of aromaticity and consumption of H2O2, COD, and TOC were compared and evaluated. The result shows that the H2O2/Fe and UVc/H2O2/Fe systems are both suitable treatment technologies in the treatment of dye (RO16) and that unlike other conventional methods there is no production of sludge. The experiment was carried out by optimising the following parameters (e.g., RO16, PAN catalyst, H2O2, pH and temperature). The volume was fixed and not changed. In the batch mode, variable conditions were optimised (e.g., 50ppm RO16, volume 100mL, 6 g PAN catalyst, pH 3, 125 mg/L H2O2, and 300C), the extent of decolorization and loss of aromaticity with assisted UV at 100 mins was found to be 99.99 % and 81% respectively. For the UV-unassisted batch mode catalytic oxidation at 100 minutes (at similar conditions), the results showed a decolourisation of 95% at 494nm and a loss of aromaticity of 60% at 254nm. The consumption of H2O2 concentration was determined as 27.79% for unassisted UV and 78.86% for assisted UV at 100 minutes of catalytic oxidation. The UV assisted reaction in the degradation of RO16 achieved about 99% removal of colour at 494nm in 60 mins which was much quicker than the 100 minutes needed without UV assistance. At 60 mins the UV-assisted reaction consumed 43 (mg/L) H2O2. The continuous flow treatment with the H2O2/Fe system (where there was no UV assistance) was applied at these optimum conditions with a retention time of 2 hours 55 minutes in the treatment of Reactive Orange 16 (RO16) to give ~57% and ~ 87% of loss of aromaticity and discolourisation, respectively. The deactivated PAN catalyst was successfully regenerated in- situ after the 1st and 2nd cycles resulting in a lifetime of 57 days of catalytic activity for fresh PAN catalyst, 28 days for 2nd cycle regenerated PAN catalyst and 7 days for 3rd cycle regenerated PAN catalyst. The deactivation of the PAN catalyst occurred due to the loss of iron and some loss of functional groups. The UV-assisted continuous flow (with a retention time of 3 hours 32 minutes) decolorisation and loss of aromaticity of RO16 for UVc/H2O2/Fe system were 98.5% and 91%, respectively. The 1st cycle PAN catalyst deactivated at 54 days of catalysis. The regenerated catalyst lasted about 72 days for 2nd cycle of catalysis and after a further regeneration lasted for 65 days for the 3rd cycle of catalysis. The regeneration techniques were initially 2 hours (impregnation) but were then changed to 24 hours impregnation with the latter resulting in the longer lifetime of the catalyst. This study has revealed that the regeneration system increased the lifetime of the PAN catalyst significantly increasing its cost-effectiveness and the extent of RO16 degradation with UVc/H2O2/Fe catalysis was significantly better than H2O2/Fe.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

De Montfort University

Year dc:date.issued

2024

Author dc:creator

• Ali, Mohammad Ahmad

Licence

• https://dora.dmu.ac.uk/bitstreams/059254d1-f9e9-43e4-8a8b-613794370f8b/download