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Background: Nowadays, international concern about the impact of antibiotic residues on the environment increased and their removal has received a lot of consideration. The aim of this study was to investigate the efficiency of Fenton’s advanced oxidation process (H2O2/Fe+2) in sulfadiazine antibiotic removal from aqueous solutions. Materials and Methods: An experimental-laboratory scale study was done on a synthetic wastewater containing sulfadiazine antibiotic with 0.079, 0.19, and 0.47 mM concentrations under Fenton’s process. Then optimal values of affecting parameters, such as initial antibiotic concentration, molar ratio of reagents, [Fe+2] and [H2O2] concentration, detention time, and pH, were determined. The discharged effluent analyzed by HPLC-UV to identify the antibiotic residues. Results: The results showed that the optimal parameters in the Fenton’s oxidation process to remove the sulfadiazine included antibiotics at pH 3.5, molar ratio of [H2O2] / [Fe +2] equal to 1.5, and contact time of 15 minutes, respectively. In these optimal conditions, the efficiency of removal of antibiotic in concentrations of 0.079, 0.19, and 0.47 mM were 99.82%, 97.97% and 78.23% and the wastewater COD removal degrees were 83.33%, 78.57%, and 78.57%, respectively. Conclusion: The experiments showed the efficient removal of sulfadiazine antibiotic in wastewater by Fenton’s oxidation process. The efficiency of this method can also be considered in eliminating other antibiotics resistant to biological treatment

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Background: Naphthalene is a polyaromatic hydrocarbon (PAH_s) present in many water sediments. This study evaluated the performance of UV/H₂O₂ reaction to decompose naphthalene in the aqueous solution.

Materials and Methods: It was an experimental-laboratory study. A one liter cylindrical glass reactor was used for performing all degradation experiments. The radiation source was a low pressure mercury UV lamp emitting at 254 nm (30 W, UV-C) which was placed above a batch photoreactor for UV/H₂O₂ experiments and different concentrations of H₂O₂ (5, 10, 15, 20, 25 and 30 mg/L) were tested.

Results: In 15 mg/L naphthalene in UV/H₂O₂ system and reaction times 5, 10, 20, 30, 40, 50, 60, 100 and 120 minutes, 15, 28, 31 , 36, 42, 52, 56, 73 and 59.5% naphthalene removal efficiencies were observed and COD removal efficiencies in reaction times 5, 10, 20, 30, 40, 50, 60, 100 and 120 minutes, 22, 38, 45, 61.5, 67.5, 70, 80, 88.5 and 76 % were observed. When the initial pH values were 3, 4, 5, 6, 7,9, 10 and 12 the naphthalene removal efficiency was approximately 75.8, 63.4, 62, 58.5, 44.8, 35.8 and 30%, respectively, with UV/H₂O₂ system.

Conclusion: The experimental results of this study suggested that the dosages with 20 mg/L H₂O₂ at pH= 3 with 2.8 W/cm² UV intensity (254 nm) provided the optimal operation conditions for the mineralization of naphthalene yielding a 73% mineralization efficiency after 100 minutes of reaction time.

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        Background: Dendrimers are a subset of branched structures that have certain structural order. The aim of this study was to investigate the performance of Polypropylenimine-G2 (PPI-G2) dendrimers in removal of Escherichia coli, Proteus mirabilis, Bacillus subtilis and Staphylococcus aureus from aqueous solution .

        Materials and Methods: In this experimental study , initially dilution of 10³ CFU/ml was prepared from each strain of bacteria . Then , different concentrations of dendrimers (0.5, 5, 50 and 500 µg/ml) was added to water . In order to determine the efficiency of dendrimers in removal of bacteria, samples were taken at different times (0, 10, 20, 30, 40, 50 and 60 min) and were cultured on nutrient agar medium . Samples were incubated for 24 hours at 37 ° C and then the number of colonies was counted .

       Results: By the increasment of dendrimer concentration and contact time , the number of bacteria in aqueous solution decreased. In times of 40 , 50 and 60 minutes, and the concentrations of 50 and 500 µg/ml, all kinds of bacteria in aqueous solution were removed . 0.5 µg/ml of dendrimer concentration had not effect in reducing the number of Escherichia coli and Proteus mirabilis . The effect of dendrimer on gram-negative bacteria was weaker than gram-positive bacteria.

       Conclusion: Results of this study indicated that PP I -G2 dendrimer is able to remove Escherichia coli , Proteus mirabilis , Staphylococcus aureus and Bacillus subtilis in aqueous solution. However, using dendrimers can be considered as a new approach for drinking water disinfection but it requires further wide range studies.

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Background: Dendrimers are macromolecules with regular three-dimensional structure that have many branches. The aim of this study was to investigate the fficiency of Nano Polyamidoamine–G5 (NPAMAM-G5) dendrimers in removal of Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa, Proteus mirabilis and Staphylococcus aureus from aqueous solution.

Materials and Methods: In this experimental study, initially, dilution of 10³ CFU/ml was prepared from each strain of bacteria. Then, different concentrations of dendrimers (0.025, 0.25, 2.5 and 25 µg/ml) in the ambient temperature (23-25°C) was added to water. In order to determine the efficiency of dendrimers in removal of bacteria, samples were taken at different times (0, 10, 20, 30, 50 and 60 min) and were cultured on nutrient agar medium. Samples were incubated for 24 hours at 37 ° C and then the number of colonies was counted.

Results: There is a direct relation between antibacterial properties of dendrimers in aqueous solution and increasing the dendrimer concentration and contact time. At a concentration of 25 μg/ml and 60 minutes, all kinds of bacteria except Staphylococcus aureus, and at 30 minutes, E. coli and Klebsiella bacteria, were removed by 100% The concentration of 2.5 μg/ml at 60 minutes of  bacteria, Escherichia coli, Klebsiella and Proteus mirabilis, 100% Were removed. All concentrations of dendrimer at different times were reduced bacteria.

Conclusion: Results of this study indicated that NPAMAM–G5 dendrimer is able to remove Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa, Proteus mirabilis and Staphylococcus aureus from aqueous solution.