Decoloring Methyl Orange under Sunlight by a Photocatalytic Membrane Reactor Based on ZnO Nanoparticles and Polypropylene Macroporous Membrane

Abstract

Decoloring methyl orange (MeOr) under sunlight was conducted in a photocatalytic membrane reactor (PMR). Zinc oxide nanoparticles (ZnO NPs) were suspended in the solution or immobilized on the membrane. The membrane was modified by grafting 2-hydroxyethyl methacrylate (HEMA) to enhance the adsorption of ZnO NPs on the hydrophobic membrane surface and improve the membrane permeability. The results show that the water fluxes through the modified membranes are higher than that through the unmodified membrane. After introducing ZnO NPs to the membrane, the water fluxes still rise with the immobilization degree of ZnO NPs. For the PMR with ZnO NPs in suspension, the photocatalytic decoloration percent (PDP) was over 98.2% after 40 min under sunlight. For the PMR with ZnO NPs immobilized on the membrane, the max of PDP was 74.3% after 6 h under sunlight, and maintained at 72% after repeated uses for five times. These results demonstrate that photocatalytic membrane reactor (PMR) based on ZnO NPs and polypropylene macroporous membrane(PPMM) could be applied in decoloring dyes.

Improving natural sunlight photocatalytic efficiency of ZnO nanowires decorated by iron oxide cocatalyst via a simple drop method

“…Results presented correspond to suspended catalyst, justifying the better degradation efficiency than for the fixed catalyst. Indeed, 200 mL of MO at 10 ppm treated by 0.05 g of ZnO nanoparticles in suspension under natural sunlight (Wuhu, Anhui province, China, July 2010) were totally degraded after 40 min, whereas only 74% of degradation was reached after 6h with ZnO nanoparticles immobilized on a polymeric membrane [38] . Moreover, the weak weight of fixed photocatalyst introduced, less than 1 mg, could also justify the difference between the results issue from different experimental conditions.…”

Sonochemical degradation of azithromycin in aqueous solution

“…By optimizing the effective parameters of degradation efficiency, the azithromycin concentration that had the highest degradation efficiency in optimal conditions, was selected. For this purpose, different concentrations (10,20,40,70, and 100 mg/L) of azithromycin solution were prepared under optimal conditions (pH = 3, temperature = 40°C, catalyst concentration = 1 g/L and H 2 O 2 concentration = 50 mg/L) was sonolyzed for 15 minutes. Figure 8 shows the azithromycin degradation percentage at 5 different concentrations.…”

“…Using this combined method in the presence of titanium dioxide (TiO 2 ), 84% of diclofenac was removed from water in 30 minutes (19). Zinc oxide nanoparticles are cheap and its catalytic properties will be appeared if the input energy be more than the energy required for its stimulation (20). Accordingly, the ultrasonic process with ZnO as a catalyst, can be used in the process of sonocatalysis (ultrasonically assisted catalysis) to purify water resources.…”

“…The concentrations of azithromycin solution were determined by dissolving different amounts of azithromycin powder in 100 mL of methanol (20,40,70, and 100 mg/L). The solution was adjusted at various pHs ( (15,20,40,50,75, and 100 mg/L) were tested using an ultrasonic device at a frequency of 35 kHz. Samples were taken at selected times, filtered through Whatman no.…”