نشریه کاربرد شیمی در محیط زیست
پیاپی 29 (زمستان 1395)

In this work we have developed a new method for determination of diazepam based on fluorescence quenching of quantum dots of cadmium sulfide. The quantum dots of CdS which have a good solubility and were stable in water, were exhibited a good fluorescence. Diazepam is one of the long acting benzodiazepines and has several p bonds in its chemical structure. Here, the effects of important parameters on the determination of diazepam were studied and optimized. Phosphate was identified as the most adequate buffer, and pH=7 as the optimum pH value and the addition of 50 μL of cadmium sulfide quantum dot solution was known as optimum condition. Calibration curve with a linear correlation coefficient of 0.9964 in the concentration range of 0.1-1.2 μg/L were obtained. Relative standard deviation for two different concentrations of diazepam were 1.17 (200 μg/L), and 1.64 (500 μg/L). Limit of detection were obtained to be 75 μg/L. This method presented as a simple, economic, sensitive, and relatively free from significant interferences from other species existing in the medium.

For the production of polystyrene expansion of benzoyl peroxide initiator is used as a powder. If the starter is prepared as a suspension in production of the polymer will have a large effect. This primer is normally deposited in water and is not suspended. In this project using suspending agents with different amounts of effort to be prepared suspensions of the initiator. Benzoyl oxide suspension is filled with different materials such as HEC, PVP in 40% of our preparation in suspension of BPO dissolved in dichloromethane is used. After completion of the above tests have concluded that the BPO agent dissolved in dichloromethane at HEC 40% best answer to the production of polystyrene expansion has given us.

The Mentha pulegium essential oil nanodispersions were prepared using combined spontaneous emulsification and solvent displacement techniques. The effects of hydrophobic and hydrophilic emulsifiers, namely, Tween 20 and Span 20, were studied on average particle size, particle size distribution, zeta potential, conductivity and turbidity of prepared nanodispersions. The results showed that the concentrations of emulsifiers had significant effects on all studied characteristics.  Except for particle size in which the smallest nanoparticles was obtained at the highest concentration of Tween 20, the average concentrations emulsifiers led to the production of the most desirable nanodispersions (smaller particle size, size distribution, turbidity and higher net zeta potential and conductivity). Therefore, proper choice of formulation variables can give the most desirable nanodispersions with pharmaceutical and food formulations uses.

Heparin is widely used as an anticoagulant in a variety of surgical procedures, such as kidney dialysis and open heart surgery, to accelerate the inactivation of clotting factor used. In this work, a simple and sensitive method for measuring fluorescence heparin has been reported. The proposed method is based on fluorescence silencing effect of heparin is graphene quantum dots. Graphene quantum dots produced graphene by thermal pyrolysis method is simple and has been identified by TEM. RSD to five Measurement 0.5 mg heparin  40% is equal to.

Desulfurization of fossil fuels such as gasoil  is one of the important factors in pollution control of the environment because of sulfur dioxide emission due to combustion into the atmosphere. Conventional methods for desulfurization of gasoil for its aromatic contents have been considered. To this approach,biodesulfurization methods have been examined  for desulfurization of sulfur containing  aromatic compounds. Pseudomonas aeruginosa supported on poly vinyl alcohol has been used for biodesulfurization of dibenzothiophene as gasoil model compound in n-hexane as  the solvent . The obtaining results according to UV-Spectrophotometer analysis at 325 nm showed that 93.8 % of DBT at the optimum condition of primary concentration about 20 ppm , pH= 7 ,adsorbent dose of 0.5 g, in 35°C and after 7 hrs of contact time has been removed. Equilibrium data and adsorption kinetics have been observed to obey the Freundlich isotherm and pseudo first-order kinetic models, respectively. Also the recovery of suppored biomass has been investigated.The alteration in surface morphology of biosorbent after supporting on polymer was investigated by FT-IR  spectroscopy and SEM images.

The risk analysis process in industry is one of the most important process. Organizations are trying to identify the risks of different processes and classify and rank them and identify the most important risks. The refinery is one of the most important sectors of the industry, which needs a lot of this classification. Therefore, in this research, the risk assessment in Abadan combined cycle power plant has been investigated. The aim of this study is among the applied research and the practical procedures to be placed in the category of descriptive survey. At first, risk clusters were determined that identified the risk in the 143 safety cluster. By doing this research can be recognized approaches to risk in proportion to important risks should be taken.

In this research bis(2-hydroxy-3nitrophenyl)methane were synthesized from condensation of 2-nitrophenol and formaldehyde in present of sulfuric acid as catalyst. The novel complexes were prepared by the reaction of ligand and Co(II) in 1:1 and 2:1 molar ratio. The complexes were characterized by FT-IR, UV-Vis, mass spectroscopy and molar conductance. Spectral data confirmed that Coordination number around each atom is four with square planner geometry. The synthesized compounds were screened for their in vitro antibacterial activity against Gram-negative and Gram-positive bacterial strains. The results of these studies showed that the metal complexes have more antibacterial activity against species as compared with the non-complexed ligand. Among the tested compounds the most effective antibacterial agent was CoL2 with inhabitation zone of 20, 18, 12 and 20 for E.Coli, S.aureus, B.sabtilis and S.marcescens respectively.

In this study, the first nano photocatalyst  titanium dioxide / iron were synthesized by sol-gel method. The average size of about 28-47 nm is synthesized nano-photocatalysts.The purpose of using UV irradiation and nano photocatalyst /UV nitrate removal from wastewater. Nitrate concentrations in this study were evaluated 50 concentrations to 130 mg per liter. In order to determine the optimum concentration of nitrate concentrations in the revival of photocatalyst nano 0.1-0.6 mg/Lit was used. To determine the optimum pH from pH, 2 to 9 were used. Exposure time and temperature, respectively  and 30-180 min and 20-40 ° C  was used. Photocatalytic nitrate removal efficiency increased with increasing duration but by increasing the concentration has been declining. The most efficient mode of eliminate the initial concentration of 50 ppm and 120 minutes of time is the amount equal to 87.7 percent is removed.pH optimum efficiency for nitrate removal by nano photocatalyst, which is equal to 2 percent is 89  that shows the best removal occurred in acidic conditions. The highest value in concentration of 0.5 mg photocatalytic nano is equivalent to 89.1 percent.Increasing the temperature from 20 to 40 ° C nitrate removal efficiency of 54 to 91 percent increase. Among the steps taken, the use of UV light to remove nitrate does not work alone, but it seems that the process of photocatalyst nano / UV nitrate removal efficiency is good.