نشریه کاربرد شیمی در محیط زیست
پیاپی 38 (بهار 1398)

Hydrogels are three dimensional polymers that do not dissolve in water, but they swell. One of the most important physical properties of hydrogels is their swelling in water [1]. Polyvinylpyrrolidone is widely used for its biocompatibility behavier [2]. Methacrylic acid also has many uses due to its COOH group. In this project, co hydrogel (vinyl pyrrolidone-methacrylic acid) was prepared by using free radical polymerization at 65 ° C for 5 hours and45 minutes using AIBN as a initiator and methylene bis acrylamide as a crosslinking agent. Then, at different pH and different temperatures and intensity of different ions, the maximum swelling at pH = 12 and in the ratio 1: 1,8000%, and the minimum swelling at pH=12 in ratio 1:2 was obtained. To identify the structure we use FTIR and for thermal identification we use T.G.A. And the maximum degradation for these hydrogels was at 75 ° C due to the high swelling rate.

Malva sylvestris is one of the most important plants used in pharmaceutical and cosmetic industries is the health of most developed countries. The juice is a potent anti-oxidant strong disinfectant. The leaves and flowers of this plant have a great application in the provision of Medicine and treatment in traditional medicine. In this research, Malva sylvestris was collected from the Anzan Meshgin-Shahr area in the northwest of Iran. The essential oil was extracted by Clevenger's apparatus, GC and GC/MS devices were used for analysis of essential oil compounds and accurate measurements of the compounds. Then, the effect of the essential oil of the Malva sylvestris and control on the common bacteria of the oral infection evaluated in two ways: Disc deffusion And minimum inhibitory concentration (MIC). According to the results, the essential oil of the herb has a significant inhibitory effect on the types of gram negative and positive bacteria. Also, comparing the diameter of the non-growth of the plant with chlorhexin, it was found that the essence of the herb medicine showed relatively similar results to that of the chlorhexin. According to the findings, essential oil of the herb has a good anti-microbial effect against the common bacteria of oral infections. As a result, the essential oil of this plant with different concentrations, after completing studies, can be an appropriate alternative for chemical drugs and chemical mouthwashes in the treatment of oral bacterial infections.

In this study, the possibility of further reducing the amount of styrene monomers remaining in the product of ordinary and resistant polystyrene in the operating unit was investigated and the effect of vacuum pressure on evaporator tanks, and amount of water injected into the polymer content before entering the evaporator tanks, and polymer volume in Evaporative tanks and polymer temperature and the effect of operating parameters of polymerization and processing reactors on the amount of residual monomer have been studied and investigated. Also, the performance of the mechanism of evaporative tanks has been investigated and finally a conclusion has been made to optimize and reduce the styrene monomer. In the following, technical and practical suggestions for the necessary modifications based on the above are presented . In the following, technical and practical suggestions for the necessary modifications based on the above are presented . In the following, technical and practical suggestions for the necessary modifications based on the above are presented .

Due to the importance of water in life as well as environmental issues, its treatment is of particular importance. in general, in water and wastewater treatment, various methods are used, including sedimentation and filtration, and biological methods. one of the most important methods of water and wastewater treatment is coagulation of waste products in water by coagulants. In this method, sedimentation is done by a gravitational force. In the meantime, methods (addition of coagulants) can be used to increase the deposition rate. there are different types of coagulants, which are: inorganic (inorganic) coagulants, synthetic organic coagulants, natural coagulants. in this research, mineral coagulants of aluminum polychloride and polychloride aluminum sulfate and iron chloride and aluminum sulfate have been used. Aluminum polychloride sulfate in comparison with other inorganic purifiers has features such as lower consumption, less sludge production, fast settling. therefore, in this research, the method of making the mentioned material has been discussed and also the deposition rate of different coagulants has been studied. the results show that considering the constant settling time (90 minutes), the amount of sedimentation increases based on increasing the concentration of coagulants (up to a certain extent). also, in the constant concentration of coagulants, the amount of precipitation of aluminum polychloride sulfate is more than other cases

Thyme garden with the scientific name of thymus vulgaris from Lamiaceae genus has many medicinal values. Thymol is an active ingredient in the essential oil of this plant. Thymol is an important compound with many medicinal properties, one of the important properties of which is its antioxidant properties, which has led to the widespread use of this compound. In this work, using computational chemistry, which generally solves chemistry problems using mathematical and theoretical principles, the structure of thymol compound was optimized using Gaussian 09 software and using DFT functional including B3LYP with 6-31G* basis set and PCM and IEFPCM models for calculation of solvent energy. Then the half-wave potential was obtained using physical chemistry relationships, it converts to a half-wave potential. and the antioxidant properties of thymol in solvents(Ethanol, DMSO, Heptan) was investigated. The half-wave potential of thymol with PCM and IEFPCM methods, for ethanol solvent, the highest value was obtained. The more negative the half-wave potential, the more anti-oxidant property. The half-wave potential of thymol with PCM and IEFPCM methods, for ethanol solvent, the highest value was obtained. The more negative the half-wave potential, the more anti-oxidant property.

Environmental remediation deals with the removal of contaminants from environment for maintaining and restoring the quality of soil, water, and air and, more in general, for protecting human health. At present, a wide range of silica products is manufactured for applications in microelectronics, medicine, pharmacy and so on. A more ambitious use of nanosilicas is remediation of contaminated environments and, recently, their application in wastewater treatment has emerged as a fast-developing and attractive area of interest. Because of high surface area, silica nanoparticles show a very good adsorption capacity and a large specific reactivity. Recent studies have shown that hydrophilic and hydrophobic silica nanoparticles are very efficient in removing pollutants such as dyes, metallic species, and pesticides from water, and wastewaters. Another interesting benefit of silica nanoparticles as adsorbents is that they are considered non-toxic and not harmful to the environment. Moreover, nanosilica based technology shows an attractive cost-effectiveness ratio as it requires relatively cheap processing of raw materials. This paper has reviewed the recent progresses in remediation by silica nanoparticles and their synthesis methods.