هیوا دارایی

Humic acid (HA) is produced by the decomposition of plant and animal debris in surface water. The presence of HA in the water disinfection process is considered as the main precursor for disinfection by-products. The present study aim was to evaluate photo catalyst degradation of HA, using MnFeN-tridoped TiO2 nanoparticles. The study was conducted in a lab-scale batch photo-catalytic reactor using the interval experimental method. MnFeN-tridopedTiO2 nanoparticles were synthesized by sol-gel method and characterization of nanoparticles was determined by XRD, FTIR, SEM and EDX techniques. The effect of different parameters such as pH (3-11), catalyst dose (0.5-2.5gr coating on glass bed), initial HA (2-50mg/l) on the degradation efficiency of HA were investigated. Also photo catalyst degradation of HA by TiO2، N-dopedTiO2 و FeN-codopedTiO2 nanoparticles was studied in optimal conditions. The results showed that efficiency of photo catalytic degradation of HA in optimum conditions (pH=3, nanoparticle dose of 1.5 gr and the concentration of HA 10 mg) were 86.72%.and 63.05% under ultraviolet and visible light, respectively. The results showed that photo catalytic degradation of HA using MnFeN-tridopedTiO2, increased with increasing catalyst dose and decreased with increasing initial concentration of pollutant and pH. Also the results showed photo catalytic activity of doped TiO2 is higher compared to pure TiO2.

In this study, the effects of pulse elecrocoagulation (PEC) process on apple juice clarification was investigated. Influences of three variables of pulse time (1, 3 and 5 seconds), process time (5, 10, 30 and 45 minutes), and electrical current (0.03, 0.1 and 0.5 Ampere) on process efficiency were studied in three repeats. The results revealed that the minimal turbidity 5 NTU was achieved at 0.03 ampere of electrical current, 5 minutes of pulse time, process time 30 minutes, and natural juice pH (pH=3.5). In order to attaint apple juice turbidity standard level, the synergistic effect of low amounts of pectinase, amylase, and gelatine fining agents were used as co-coagulant. Using this method reached turbidity up to 3 NTU wich is very close to industrial standard turbidity (2 NTU) and this level is generaly required to produce stable clarified juice. This study showed that PEC can successfully be used as an alternative or an auxiliary method for juice clarification because of high turbididy removal potential in noticeable lower process time and lower amounts clarifying agents.

Background and Diazinon is an organophosphorus insecticide, which is classified as a relatively dangerous product by the World Health Organization. Entrance of this pollutant into water resources can have detrimental effects on human health and environment. The aim of the present study was to evaluate the performance of pulsed alternative current and the electrocoagulation-flotation (ECF) processes in removal of diazinon from aqueous solutions.
An applied laboratory-scale experiment was designed. Diazinon removal was performed using ECF and pulsed alternative current in a 750 ml borosilicate glass intermittent flow reactor, equipped with a magnetic stirrer, an electrical source, a pulsar, and four aluminum electrodes. The optimized operating conditions were also assessed using 10-500 mg/L of diazinon.
According to the results, the removal efficiency of diazinon was found to range between 5% to 85%. Investigation of ­the operational parameters demonstrated significance of the initial concentration of diazinon, current density, the number of pulses, and electrical conductivity in efficiency of ECF process. The maximum removal efficiency of diazinon was found to be 85% (213 mg of diazinon), which was achieved in an operating condition with pH=7, current density of 46.7 A/m2, electrical conductivity of 600 μS/cm, and process time of 45 min.
According to this study, ECF method could be used along with pulsed alternative current for removal of high concentrations of diazinon from wastewater.Additional processes are needed to meet the standards of drinking water.

Millions of liters colored effluent is daily discharged into the environment by textile industries. These effluents are usually non-biodegradable and pose a serious problem to human and aquatic life. The aim of this study was to evaluate the degradation of acid black 1 using ZnO nanoparticle doped with the CuO as a catalyst in presence of the sunlight.
This study was an applied research in which ZnO:CuO nanoparticle was synthesized and its chemical properties was evaluated by X-ray diffraction (XRD). To evaluate the photocatalytic efficiency of synthesized nanoparticles, acid black 1 was prepared and the effects of parameters such as initial dye concentrations, photocatalyst dose, and pH on the photocatalytic process were studied. The results were analyzed using kenetic equations.
The results showed that the synthesized particles are heterogeneous and have nanoscale size with no agglomeration. Dye degradation decreased with increasing the dye concentration and nanoparticle dose. It is observed that photocatalysis degradation rate of dye to increase with decreasing solution pH, because hydroxyl radicals are the dominant reactive oxidant under acidic pH. It was also found that the photocatalysis degradation to follow the Langmuir-Hinshelwood kinetic equation.
It is concluded that the synthesized nanoparticles have a high potential for dye degradation comparing to pure ZnO and can be used as an effective photocatalyst for degradation of dyes form colored effluents.

Dendrimers have antibacterial properties and can be used against microbial infections as alternative antibacterial agents with minimal side effects. In this study we evaluated and compared nanostructure macromolecules called Poly (amidoamine) dendrimer generation 4 (PAMAM-G4) with conventional antibiotics in relation to resistance of isolated bacteria from water resources.
523 samples were collected from 108 water resources and membrane filter method was used for bacterial species isolation. Resistance of isolated species to amoxicillin, erythromycin, tetracycline and ciprofloxacin antibiotics was determined by measuring zones of inhibition and then compared to the resistance of these species to PAMAM-G4 dendrimer as an antibacterial agent. Also we measured maximum inhibitory concentration (MIC) of dendrimer against isolated bacteria.
7.4% of samples showed bacterial contamination. Frequency rates of isolated microbial species were as follows: Escherichia coli (28.2%), Proteus (12.8%), Klebsiella (17.9%), Enterobacter (15.3%), Pseudomonas (17.9%), Bacillus subtilis (5.1%) and Staphylococcus aureus (2.56%). Gram-negative species revealed high resistance to PAMAM-G4 dendrimer based on the measurement of zones of inhibition. PAMAM-G4 dendrimer didnt have any effect on inhibition of the growth of Enterobacter and Pseudomonas. MIC's against Escherichia coli, Klebsiella and Proteus were 1250, 500 and 1250 µg/ml respectively. Gram-positive species showed a good response to PAMAM-G4 dendrimer, so that the MIC's for Staphylococcus aureus and Bacillus subtilis were 1 and 2.5 µg/ml, respectively.
Because of increased number of resistant species to conventional antibiotics, PAMAM-G4 can be considered as a potent antibacterial agent against gram-positive bacteria.

Dyes beside having negative effects on environmental aesthetic sight have serious negative biological and chemical effects on environment. The propose of this study is to remove photocatalistics of acid red 18 using ZnO nanoparticle synthesized with hydrothermal method discontinuous system. In this experimental study first the source reactor and radiation were designed and constructed. Experiments were performed under stable conditions in pH (4, 7, and 10) with a contact time (10, 20, 30, 45 and 60) to determine the optimum pH. Then pH was fixed and effect of the initial concentration of nanoparticles (0.25, 0.5, 1, 2 and 3) grams per liter and various concentrations of Acid Red 18 (10, 25, 50, 100 and 200) milligrams per liter were studied. The results showed that the red dye removal efficiency of the process under study has directly increased with degree of acidity, so in acidic and alkaline efficiency was 83% and 1/59. It was also found that by lowering the initial dye concentration andincreaseing the contact time and concentration of nanoparticles, the removal efficiency was increased. Photocatalytic process coupled with ZnO nanoparticles synthesized by hydrothermal method in removal of Acid Red 18 has done best and the efficiency is seemed to be considerable. we� suggest that the efficiency of the removal of dyes and other pollutants needs to be further investigated.

Background and There is growing application of dendrimers in the world, therefore, this study was conducted to evaluate the effect of antibacterial properties of generation-2 and 4 poly (amidoamine) dendrimer (PAMAM) on some bacteria isolated from water resources. Water samples were collected from drinking water resources. Bacteria were isolated and identified using differential biochemical tests. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against gram-positive and gram-negative bacteria were calculated. Standard discs were prepared by different concentrations of dendrimer (0.5, 5, 50 and 500 μg/ml) and evaluated through disc agar diffusion method on Muller-Hinton agar plates. Finally, the inhibition zone diameter was measured and the effect of temperature and pH was investigated on antimicrobial activity of dendrimers. The main isolated bacteria from water resource were Escherichia coli, Pseudomonas aeruginosa, klebsiella oxytoca, Bacillus subtilis, and staphylococcus aureus. The results showed completely similar MIC and MBC for each isolated bacteria in both generations which were as follows: Escherichia coli 1250 and 2500 μg/ml, klebsiella oxytoca 500 and 1250 μg/ml, staphylococcus aureus 1 and 5 μg/ml, and Bacillus subtilis 2.5 and 5 μg/ml, respectively. No MIC and MBC were observed on Pseudomonas aeruginosa. Also, it was found that PAMAM dendrimer was more potent towards the gram positive bacteria than the gram negative bacteria. Although amino terminated G4 PAMAM dendrimer has more functional groups, but no significant difference was observed in its antimicrobial activity compared to that of the G2 PAMAM dendrimer. Amino-terminated generation 2 poly(amidoamine) dendrimer exhibited a positive impact on the removal of main isolated strains. Therefore, it might be used as a safe and effective material for water disinfection in future.

In this study، graphene oxide was used as a nanostructured adsorbent with properties supposedly better than other common adsorbents to remove 4-chlorophenol from aqueous solutions. For this purpose، graphene oxide was initially synthesized using the Hummer''s method and x-ray diffraction and scanning electron microscopy were employed to identify its morphology and structure. The variables involved in the absorption process (including 4-chlorophenol initial concentration، adsorbent dosage، and pH) were investigated based on the one-factor-at-a-time method. Eventually، the data were confirmed against the Langmuir and Freundlich isotherms. It was found that the adsorption process reached equilibrium in 20 minutes. A dosage of 0. 4 g/L graphene oxide at pH=8 brought about 90% removal of 10 mg/L 4-chlorophenol within 5 minutes. The adsorption isotherm was described well by the Langmuir isotherm model and the values for R2 and RL were recorded as 0. 99 for and 0. 34، respectively. Being a low cost and highly efficient process، the adsorption process using graphene oxide adsorbent may be recommended for the reduction and elimination of pollutants in the environment، especially those in aqueous solutions.

Organic dyes are the major pollutants produced in many industries and have different adverse effects on water resources. The aim of this study was to synthesize a novel adsorbent with high adsorption capacity and evaluate its efficiency in removing organic dyes from aqueous solutions in a batch system. This study was an applied research in which carbon nanotube composite-dendrimer was synthesized and its chemical properties was evaluated by fourier transform infrared spectroscopy. Acid blue 1 dye was selected as a model to evaluate the decolorization capacity of the adsorbent. The effects of the parameters influencing the adsorption process such as initial dye concentration, adsorbent dose, pH and the effect of inorganic salts were also studied. Longmuir and Freundlich isotherm models and pseudo first order and pseudo-second-order kinetic models were used for data evaluation. In this study removal of acid black 1 dye by carbon nanotube-dendrimer composite followed the Longmuir and Freundlich isotherm and pseudo-second-order kinetic models. We also found that the synthesized adsorbent had a maximum adsorbent capacity equal to 690 mg/g, when the concentration of dye was 100 mg/l. We concluded that carbon nanotube composites – dendrimer can be used as an effective adsorbent for removal of dyes form colored effluents.

Nowadays, the increasing concentration of pollutants in water resources, especially ground water, has been a matter of concern. Nitrate has been considered as a chemical indicator of water pollution for a long time. The aim of this study was to determine the chemical characteristics of drinking water and changes of nitrate in drinking water in Diwandareh villages. This was a cross-sectional study to determine the quality of drinking water of 30 villages in Divandareh. A total of 60 samples were obtained in two phases from water supplies and were analyzed according to the standard methods. Descriptive statistics, Piper, Schuler and Wilcox diagrams were used to interpret the results. The results showed that apart from nitrate, the concentrations of the other chemical quality parameters were below the standard limits. The mean and standard deviation of nitrate during the first and second stages of sampling in water sources were 26.13 ± 25.61 mg L-1 and 28.47 ± 29.80 mg L-1, respectively. According to Schuler diagram, the drinking water quality was moderate to good. Although the mean nitrate concentration in 80% of samples was lower than the latest national standard for nitrate, continuation of the current trend, particularly in the agricultural activities and uncontrolled use of groundwater resources in agriculture will change and lower the quality of water. Therefore, monitoring of agricultural practices and fertilizer use are necessary.