Photoremoval of Ibuprophenin and Oxytetracycline and some microorganisms from a pharmaceutical wastewater via Ag-Fe3O4 nanocomposites

Abstract

ABSTRACT

In  İzmir Turkey, a pharmaceutical industry wastewater produces drugs and antibiotics. The removals of these parameters were not sufficient with the conventional activated sludge process. In order to remove these organics some photocatalysts like Fe₃O₄   and FeO were solely used with enhanced magnetic properties. However low photodegradation yields (75-77%) were detected for the Ibuprophenin drug and Oxytetracycline antibiotic. Although Ag effectively destroys the pharmaceutical chemicals and the pathogenic microorganisms the low photogenerated carrier-separation efficiency limits its application in water treatment. Therefore, it is practically significant to develop a magnetic material to a couple of  Ag with Fe3O4  through heterojunctions to separate the nanocomposite magnetically from wastewaters.  In order to improve the photocatalytic degradation of Fe₃O_4, Ag was loaded onto a magnetic nanoparticle to develop Ag-Fe₃O₄ nanocomposite under laboratory conditions.   On the other hand, the toilet wastewater was mixed with the process wastewater due to the dilution purpose of pollutants in the pharmaceutical wastewater. Due to the high working personnel capacity of the industry  (10,000 people)  the concentrations of Salmonella, Pseudomonas, yeast, fungi, total coliforms, fecal coliforms, and heterotrophic bacteria were found to be high in the raw pharmaceutical industry wastewaters. Therefore, in this study to maximize the removal yields of these pollutants and organisms with Ag-Fe₃O₄ photodegradation the operational conditions were optimized.  The effect of increasing Ag-Fe₃O₄ nanocomposite concentrations (0.05- 6.0 mg/l), pollutant concentrations (10- 500 mg/l), contacting times (5-90 mins), pH levels (4.00-10.00), power (10- 100 W/m²), on the photodegradation yields of organisms (Salmonella, Pseudomonas, yeast, fungi, total coliforms, fecal coliforms, heterotrophic bacteria) and ibuprophene, oxytetracycline removal yields were studied.  The particle shapes and properties were investigated with field emission scanning electron microscope (FESEM) and fourier transform infrared spectrophotometer (FTIR), X-ray diffraction (XRD). The XRD pattern of Ag-Fe₃O₄ nanocomposites showed the same diffraction peaks at 26.9°, 33.0°, 38.3°, 55.1°, 65.7°, and 68.7° for Ag and at 28.26°, 34.53°, 44.01°, and 61.88° for Fe₃O₄, indicating a good coupling of Ag and Fe₃O₄ with no change in their crystal structure. The maximum organism and pollutant yields were detected at 1 mg/l Ag-Fe₃O₄ nanocomposite concentration, after 45 mins at a pH 7.00 and 5.00 for Ibuprophenin drug and Oxytetracycline antibiotic, respectively.  99% treatment yields were recorded for ibuprophene, oxytetracycline, and organisms during photocatalysis. The recovery studies with Ag-Fe₃O₄ NPs showed that all organisms and both pollutants can be used 120 times with the same yields. The photodegradation kinetics was found to be pseudo-first-order and the rate constants  (k) for oxytetracycline and ibuprophene were calculated as  5 × 10⁻² min⁻¹, and 5.02 × 10⁻² min⁻¹, respectively.  From 1.5 mg/l  Ag- Fe3O4 nanocomposite  0,95  mg/l Fe3+  and   0,39 mg/l Ag +1 was leached during ibuprophene photodegradation. For oxytetracycline from 1.5 mg/l  Ag- Fe3O4 nanocomposite  0,89  mg/l Fe3+  and   0,34 mg/l Ag +1 was leached.