Indium porphyrin - colloidal activated carbon composites for photocatalytic activity against an organic pollutant and bacteria

Three indium porphyrins with different substituents were adsorbed onto colloidal activated carbon (CAC) and employed for the photodegradation of methylene blue (MB) and antibacterial activity against E. coli. The porphyrins are: the symmetrical 5,10,15,20-tetrakis(4-acetamidophenyl) (3) and 5,10,15,20-tetrakis[4-(prop-2-yn1yloxy) phenyl] (4) and the asymmetrical 5,10,15-tri-4-acetamidophenyl-20-(pyren-1-yl) (2) chloroindium (III) porphyrins. 3/CAC and 4/CAC removed methylene blue better than 2/CAC in water, both in the presence and absence of H2O2. The low activity of the asymmetric 2/CAC was due to aggregation. The inhibitory zone approach was employed to study the antibacterial properties (against Escherichia coli) using CAC and porphyrinloaded CAC composites. Peroxide-free trials showed no inhibitory zones. For inactivation (in the dark and light), the wells with 0.5 % H2O2 demonstrated antibacterial action. CAC and porphyrin/CAC composite wells had similar inhibitory diameters in the presence of H2O2. The improved dye removal effectiveness and high antibacterial activity of porphyrin/CAC composites in the presence of H2O2 suggest their applicability in treating industrial effluents containing dyes and high quantities of microbial contaminants, such as hospital effluents.