جستجوی مقالات مرتبط با کلیدواژه « Response surface » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

Hypothesis: Medicinal compounds, pharmaceutical substances and their metabolites enter the environment through hospital, domestic and pharmaceutical industries. Conventional technologies are not able to treat such wastewaters fully and therefore they are abundantly found in water. So far, various chemical, physical and biological methods have been used to remove medicinal compounds from aqueous solutions. In this research, PVDF/g-C3N4/Chitosan as a new and powerful membrane was prepared and removal of cefixime from aqueous solutions was investigated using response surface methodology (RSM).

PVDF/g-C3N4/Chitosan membrane was prepared by immersing the PVDF/g-C3N4 membrane in a solution containing different percentages of chitosan. To evaluate the efficiency of the PVDF/g-C3N4/chitosan membrane in removing cefixime, the response surface methodology was used based on the central composition design and four parameters, i.e., chitosan percentage, g-C3N4 value, pH of solution and cefixime concentration were selected as dependent variables. The quadratic model was used to calculate the four dependent variables.

The results showed that among the studied parameters, chitosan had a major effect on the structural properties of the PVDF/g-C3N4/chitosan membrane due to the conversion of polyvinylidene fluoride membrane to hydrophilic ones. According to the results, the maximum cefixime removal by the PVDF/g-C3N4/chitosan membrane was about 81.34% at a solution pH of 4.42, 3.19% chitosan, 0.11 g g-C3N4 and cefixime concentration of 42.51 mg/L. The numerical optimization results showed a slight difference between the predicted number (81.34%) and the experimentally obtained number (78.21%). Also, the high correlation coefficient (99.41%) showed that the response surface methodology has a high potential for predicting and optimizing the cefixime removal process by PVDF/g-C3N4/chitosan membrane with a small number of experiments.

Today, due to the use of eggs as a complete food package, directly and indirectly, it is important to maintain quality. In this study, fresh eggs purchased and after placing the samples under UV rays with different levels of parameters, they were divided into two groups of impregnated and not impregnated sunflower oil. The samples were then stored for two days and then, the biochemical properties were determined for them including the percentage of fat and crude protein, pH and total ash. In the statistical analysis, the results for pure fat were the highest and the lowest was 48.3333 (20 lamps- 3 hours irradiation time) and 33.3333 (60 lamps- 1 hour irradiation time). In the study of the effects of the number of lamps and UV irradiation time on total ash, no significant changes were made at different levels of the parameters. There were also significant changes in the number of LED lamps and irradiation times in the raw protein review so that the highest level of protein in the parameters studied in this section was 40 lamps and 1 hour of irradiation and the lowest level The protein was about 20 lamps and 2 hours of ultraviolet radiation. In the pH check, the increase in the number of ultraviolet lamps and irradiation time reduced the amount of pH; As a result of the inverse relationship between the increase in the number of LED lamps and the irradiation time with the pH value. Also performing impregnated eggshell sunflower oil was a decrease in pH value.

The lack of uniform distribution of temperature in the product is one of the main problems of thermal processes. The modeling of microwave pistachio (Ahmadaghaee cv.) thermal process was studied using response surface method (RSM). The optimum conditions were determined in order to achieve the highest uniformity of temperature distribution in the product. Independent quantitative variables included the heating time (20-50 s) and the microwave power (630-900 w). In addition, an Independent qualitative variable included the position of the thermometer in six positions in the container. The dependent variable (response) is the temperature of the product under microwave heating. These experiments were performed separately for two cubic and cylindrical containers. The results of analysis of variance showed that all the main effects and the interaction are significant (P< 0.01). According to the results, the uniformity of temperature distribution in the product was more cubic than the cylindrical container. The uniformity of temperature distribution in the minimum power (630 w) was greater than the maximum power (900 w). The optimum conditions were determined in order to maximize the uniformity of temperature distribution for cylindrical containers with a heating time of 44 to 45 seconds and power of 720 to 750 watts. These conditions for the cube containers were obtained with a heating time of 44 to 47 seconds and power of 630 to 670 watts. The accuracy of the model was evaluated by calculating the root mean square error (RMSE). The low value of RMES in all six positions of the product indicates the proximity of the experimental and predicted values and confirms the model's accuracy.