Faculty Publications
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Item Exploring the synergistic interactions of TiO2, rGO, and g-C3N4 catalyst admixtures in a polystyrene nanocomposite photocatalytic film for wastewater treatment: Unary, binary and ternary systems(Elsevier Ltd, 2019) Das, S.; Mahalingam, H.Reduced graphene oxide (rGO) as well as graphitic carbon nitride (g-C3N4) were synthesised and blended along with TiO2 at specific ratios in polystyrene photocatalytic films to find out the optimum efficiency. The prepared photocatalysts were characterised by scanning electron microscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR) and contact angle analyser. The SEM, XRD, and FTIR analysis indicated that the nanoparticles were evenly distributed on the surface of the polystyrene film. The stability of the polymer film with respect to possible leaching of the embedded catalyst particles was evaluated by ICP-OES analysis. The photocatalytic activity of the admixture was evaluated using remazol turquoise blue dye as a model organic pollutant, and it was found that the photocatalytic ternary admixtures displayed much higher photocatalytic activity (99%) than the unary (89%) or binary (94%) mixtures indicating the synergistic effect of these catalysts. The effect of catalyst ratio, immobilisation, pH, initial dye concentration, irradiated light source, the presence of H2O2 and reusability of the film were also evaluated. The degradation of the dye is confirmed by TOC analysis (40% reduction), and HPLC/MS was used to identify the final degraded compounds. © 2019 Elsevier Ltd.Item Dye degradation studies using immobilized pristine and waste polystyrene-TiO2/rGO/g-C3N4 nanocomposite photocatalytic film in a novel airlift reactor under solar light(Elsevier Ltd, 2019) Das, S.; Mahalingam, H.Complex dyes are not completely removed in most wastewater treatment plants and thus released into nearby waterbodies posing problems to aquatic life and humans. In this study, a chemically synthesized nanocomposite photocatalyst containing TiO2, rGO and g-C3N4 immobilized in a polystyrene film is evaluated for the degradation of the Cu-phthalocyanine complex dye (Remazol Turquoise Blue, RTB) in a multiphase airlift reactor under sunlight. Both pristine and waste polystyrene were used in the synthesis of the film. The characterisation of the powder photocatalyst composite as well as the immobilized photocatalyst film is performed using particle size analyzer, SEM-EDX, BET, XRD, XPS, FTIR, and ICP-OES. The optimization of various parameters affecting the photocatalytic decolourization such as the g-C3N4 quantity in the composite catalyst, catalyst loading, the initial concentration of dye, use of waste polystyrene and catalyst reuse has been studied thoroughly. The photocatalytic treatment of RTB dye under optimum conditions for 90min shows that the decolourization (60%) and degradation (51.43%) as measured by TOC analysis are quite similar. The possible breakdown compounds from the parent molecule after the photocatalytic operation are identified by HPLC-MS. In conclusion, the immobilized nano-composite photocatalyst incorporated into a multiphase airlift reactor, is a very promising system to improve the water quality by TOC reduction, before discharge to nearby natural water sources. © 2019 Elsevier Ltd.Item Novel immobilized ternary photocatalytic polymer film based airlift reactor for efficient degradation of complex phthalocyanine dye wastewater(Elsevier B.V., 2020) Das, S.; Mahalingam, H.Reduced graphene oxide (rGO) as well as graphitic carbon nitride (g-C3N4) catalysts were synthesized and a physical admixture of rGO and g-C3N4 along with TiO2 in the ratio of 1:1:1 by weight was immobilized in a polystyrene film using the facile solvent casting method. An internal loop airlift reactor with a working volume of 1.2 litres incorporating the prepared polymer-based photocatalytic film was designed and tested for the photocatalytic degradation of remazol turquoise blue dye synthetic wastewater. The reactor parameters affecting the photocatalytic activity such as airflow rate and Di/Do (ratio of draft tube diameter to outer tube diameter) were evaluated. The successful operation of the reactor obtained using the ternary immobilized catalyst mixture film gave 92.25% total organic carbon reduction and 94% decolourization within 140 min, compared to 91% decolourization by the slurry form within 40 min. Complete and quicker decolourization of the dye was also demonstrated under the influence of O3 or H2O2. The immobilized catalyst was successfully reused four times. The ternary catalyst admixture employed in this work and the unique design of the photocatalytic reactor helps to increase the degradation rate of toxic textile effluents thus making it suitable for larger scales of treatment. © 2019 Elsevier B.V.