فهرست مطالب حدیثه معصومی

In this study, the solubility results and tie-lines in ternary systems (water + butyric acid + organic solvent) were obtained at 298.2 K and 101.3 kPa. Methyl ethyl ketone and diethyl ether were selected as organic solvents. The binodal curves were determined experimentally using the cloud point method. The tie-line results were obtained using acid-base titration, Karl-Fisher method, and refractive index measurement. Both ternary systems show type one of liquid-liquid equilibrium. For investigation of the quality of both ternary systems, Othmer-Tobias and Hand equations were correlated with the empirical results. The distribution coefficients and selectivity factors were calculated in both ternary systems to evaluate the solvent's ability in extracting butyric acid from an aqueous solution. The average separation factor was calculated at 41.12 for methyl ethyl ketone and 296.71 for diethyl ether, respectively. Finally, for each system, the experimental tie-lines were correlated by a thermodynamic model including NRTL and UNIQUAC; also, the binary interaction parameters were estimated.

In this research, the adsorption of nickel ions in the batch system by orange peel carbon has been investigated and the effect of factors such as pH, contact time, initial concentration of nickel in solution, adsorbent amount, and the temperature has been considered. The surface details and functional groups were investigated by SEM and FTIR analyzes, respectively. In the study of the effect of pH, the highest percentage of nickel uptake for orange peel carbon occurred at pH = 6, which is equivalent to 58 mg/g. With increasing the contact time between the adsorbent and the solution and after 210 minutes, the adsorption percentage increased to 98.57%. In the study of the effect of the initial concentration of nickel in the range of 20 to  150 mg/L, the results showed that with increasing concentration, the percentage of adsorption decreased from 98% to 96%, and with increasing the amount of adsorbent from 0.01 to 0.1 g per 25 ml. Nickel solution, the adsorption percentage increased from 90% to 98%. The effect of temperature showed that with increasing the temperature from 25 to 45°C, the percentage of adsorption decreased from 99% to 97.8%. Thermodynamic properties were studied at three temperatures of 25, 35, and 45°C. The negative free energy value of the standard Gibbs (∆ Go) which is equivalent to -121.3 kJ / mol, indicates that the adsorption process is spontaneous and physical. In the kinetic study of the contact time effect, it was observed that the results fit well with the second-order kinetic model with a correlation coefficient of 99%. In investigating the effect of the initial concentration of nickel in solution and fitting experimental data with Langmuir, Freundlich, Temkin, Dubin Radushkovich isotherms, and according to the values ​​obtained at R2, Freundlich's isotherm had the highest compatibility with 100% correlation coefficient.

In this research, adsorption of Zinc ion was investigated at batch system using spirulina microalgae and Magnetic microalgae. The effect of important parameters such as pH of the solution, absorbent contact time, the initial concentration of Zn(II) ion, adsorbent dosage and temperature were investigated on The removal efficiency and  adsorption capacity. Also adsorbent features were studied by using SEM photographs and FT-IR spectroscopy. The maximum Zinc ion adsorption occurred in pH=6. The optimum adsorbent dosages were determined 0.03 g for spirulina microalgae and Magnetic microalgae. So at optimum pH and adsorbents dosage for 150 mg/l initial zinc ion concentration 84.43% and 96.56% of removal efficiency was obtained for spirulina microalgae and Magnetic microalgae, respectively. Removal efficiency increased by increasing contact time between adsorbent and solution and after passing 10 min for spirulina microalgae and Magnetic microalgae reached to equilibrium. Examining kinetic models showed that pseudo-second order kinetic model had best fit for adsorbents. In investigating Zinc ion initial concentration in range of 50-300 mg/l, results showed by increasing initial concentration, efficiency decreased. Also experimental data of spirulina microalgae and Magnetic microalgae solutions had best fit by sips and Langmuir, respectively. Investigating temperature effect showed, by increasing temperature, removal efficiency decreased for spirulina microalgae and Magnetic microalgae. The thermodynamic parameter was studied in 298, 303, 313 and 323 Kelvin.

In this research, the adsorption of phosphoric acid from an aqueous solution was investigated at different temperatures (298, 308, and 318 K) by using different adsorbents such as wheat bran and banana peels, in a batch system. FTIR and SEM analysis were used, in order to determine the functional groups in the structure of adsorbents and the surface characteristics of adsorbents, respectively. In the adsorption experiments, the effect of important parameters such as the effect of contact time, the amount of adsorbent temperature, and initial acid concentration was investigated. Equilibrium time was determined 40 and 50 minutes for wheat barn and banana peels. The highest percentage of adsorption for banana peel and wheat peel was measured at 71% and 59.8% for 1 g /L phosphoric acid, respectively. The optimum amount of adsorbent was determined 3g. Investigation of the temperature demonstrated that the percentage of removing phosphoric acid decreased by increasing the temperature. Different models of adsorption isotherms such as Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models were applied to analyze the equilibrium data at different temperatures and Langmuir and Temkin isotherm have the most agreement with experimental data for absorbents. Different kinetic models such as pseudo-first order, pseudo-second order, Elovich, and intra-particle diffusion model were chosen to describe the kinetic of adsorption, and the pseudo-second-order model for wheat barn and Elovich for banana peels have the best agreement with experimental data for each adsorbent. Thermodynamic parameters like standard Gibbs free energy changes of adsorption (ΔG oads), standard enthalpy changes of adsorption (ΔH oads), and standard entropy changes of adsorption (ΔS oads) were calculated by using equilibrium constant values at different temperatures. The negative value of (ΔG oads) demonstrated that adsorption of phosphoric acid by adsorbents is a spontaneity process and negative values of (ΔH oads) showed that adsorption of phosphoric acid on adsorbents is exothermic. The absorption capacity of banana peel and wheat bran was achieved20 and 11 mg/g, respectively. As a result, banana peel was the appropriate absorbent in this work.

In this research, the adsorption of Mg (II) was studied in a batch system by using zeolite, and the influence of effective parameters on the adsorption, such as initial pH, adsorbent dosage, contact time, initial Mg (II) concentration and temperature were investigated. Also, the surface characteristics and structure of the adsorbents were respectively obtained by SEM and FT-IR. The pH experimental results showed that the maximum adsorption efficiency of Mg (II) ion occurs at pH=7. By increasing the contact time between the adsorbent and solution, adsorption efficiency was raised, and after 60 minutes, equilibrium is reached. Results showed the adsorption efficiency decreased by increasing the initial concentrations of Mg (II) in the range of 50-250 ppm in solution, and the effect of adsorbent dosage showed that adsorption efficiency increased by increasing the adsorbent dosage from 0.5g to 2.5g. In addition, the higher adsorption of Mg (II) was observed at higher temperatures, which proves the endothermic behavior of the adsorption process. Thermodynamic parameters were investigated in three temperatures 25, 35, and, 45°Ϲ. The negative value of the Gibbs free energy (ΔG˚) showed that the adsorption process was spontaneous. Positive value enthalpy (ΔH˚) indicated that the adsorption process was endothermic, and positive value entropy (ΔS˚) can be attributed to the increased randomness at the interface of the adsorbent and the solution. The experimental results for the effect of exposure time were examined for the kinetic study with three different models: Pseudo-First order, Pseudo-Second order, and Intra-Particle diffusion. Among these models, the best fit was observed for pseudo-second-order. The study for initial concentration of Mg (II) in the solution was studied by Langmuir, Freundlich, Temkin, and Dubnin-Radushkevich isotherms, and the best fit for the adsorbent was observed by Langmuir isotherm and the Langmuir maximum sorption capacity was found to be 4.77 mg/g at 45°C.

The aim of this study was to investigate the distribution of lactic acid in polymer-salt aqueous two phase systems. Accordingly, four temperatures of 25, 30, 35 and 40°C were considered and at each temperature, three different salts including sodium sulfite, disodium tartrate dihydrate and sodium dihydrogen phosphate and two different molecular masses of polyethylene glycol 30% by weight (4000 and 8000 g/mol) was tested in aqueous two-phase system. Also, the percentage of acid extraction at pH 5 to 9 and the effect of polymer concentration were investigated. The effect of polymer molecular mass, polymer concentration, salt type, salt concentration and temperature change on the extraction percentage was evaluated. It was observed that in all three systems, with increasing the molecular weight of the polymer, temperature, salt concentration, polymer concentration and pH, the extraction efficiency decreases. The optimum values of polymer molecular weight, temperature, salt concentration and pH were determined as 4000 g/mol, 25 °C, 25% by weight of sodium sulfite, disodium tartrate dihydrate and sodium dihydrogen phosphate and 5.5 to 6.5, respectively. In addition, the optimal polymer concentration was determined to be 30% by weight. Finally, the extraction values for sodium sulfite, disodium tartrate dihydrate and sodium dihydrogen phosphate were calculated to be 53.205, 50.149 and 19.549%, respectively.

In this research, the efficiency of the photocatalytic process of zinc oxide nanoparticles in removing Basic Red 46 azo dye from the aqueous solution has been investigated in a batch system, exposed to UV light with a power of 15 W. Also, the number of samples and data analysis were predicted using design expert software. According to the results, with increasing the initial concentration of the dye solution, the percentage of photocatalytic degradation decreases, and with enhancing the catalyst concentration to an optimal value equal to 1 g/L, the removal efficiency of the dye increases. In addition, the percentage of dye removal is directly related to the duration of radiation. According to the analysis of the results in the design expert software, the maximum removal of the Basic Red 46 azo dye was obtained at pH =11 and the contaminant concentration was 45 mg/L with an amount of 0.61 g/L of zinc oxide as catalyst in 86 minutes.

Novel separation methods that are necessary for the purification of biomolecules and carboxylic acids at industries, are expanding. Therefore, these methods should be fast, selective, and easy to scale up. The aqueous two-phase system is an effective separation procedure for the purification of materials. The purification of biomolecules and carboxylic acids is extremely selective by this method and also, the separation process is conducted in one step. This research aimed to investigate the effects of molecular weight of polyethylene glycol, pH, salt concentration, and salt type in polymer/salt aqueous two-phase systems. In this research, purification of malic acid in aqueous two-phase systems containing polyethylene glycol 4000 and 8000 g/mol, different concentration sodium di hydrogen phosphate, diammonium hydrogen phosphate, and di potassium hydrogen phosphate were studied. After investigating the effective factors, the best operation conditions for malic acid extraction was obtained in a system composed of  PEG4000, 0.25 (w/w) sodium di hydrogen phosphate at pH=5. The purification parameters such as partition coefficient of malic acid and yield were achieved 0.85 and 80%, respectively.

Aqueous two-phase systems provide a suitable environment for the separation of biomolecules, because in such systems there is sufficient water at all stages of the process, and on the other hand, the purpose is to isolate biomolecules and maintain their activity. The purpose of this study was to investigate the effective parameters on the extraction of Ascorbic acid with Sulfate salts and Polyethylene glycol polymer in aqueous two-phase systems. The effect of molecular weight of polyethylene glycol (4000 and 8000 g / mol), salts (MnSO4, Na2SO4, MgSO4), salt concentration, and pH effect on the formation of the two-phase system at temperatures of 32, 37, and 42 °C as investigated. The results showed that by increasing the molecular weight of the polymer, the coefficient of isolation and ascorbic acid extraction percentage decreased. Also, increasing the concentration of salt and temperature, the coefficient of isolation, and the percentage of extraction of Ascorbic acid increases. The separation of Ascorbic acid largely depends on the type of salt. MnSO4 salt showed a higher extraction percent (37.4%) than two other salts. The distribution coefficient of Ascorbic acid was found to be higher at (pH = 5), and the maximum Ascorbic acid distribution coefficient for the best salt (MnSO4) was obtained at 0/423.

Novel separation procedures that are essential for the purification of biomolecules in biotechnology industries, are developing. Hence, these methods should be rapid, selective, and easy to scale up. The aqueous two-phase system is an efficient method for the purification of materials. The purpose of the present work was to investigate the various parameters such as temperature, pH, salt concentration, and salt type in the polymer/salt system. In this research, purification of malic acid in the aqueous two-phase system which is containing polyethylene glycol 4000 g/mol and three variant salt (dipotassium hydrogen phosphate, diammonium hydrogen phosphate, and disodium hydrogen phosphate) were studied. According to the results, the optimum D and Y%  for extraction of malic acid was identified 0.85 and 80%, under these conditions, including 25% (w/w) disodium hydrogen phosphate at T=25°C and pH=5, respectively.

In this study, the single-leaf of parsley and also bulk of particles at temperatures of 46, 58, and 68°C and the thickness of 0.13 to 0.17 mm and the period from 0 to 140 minutes in a laboratory fixed bed dryer dried. Also, the single leaf of parsley and the mass dried in the sun. To dry the parsley in the dryer, five samples were considered for each temperature and the weight of samples during the drying process is continuously recorded until changes in the volume of samples to zero. Then the influence of parameters such as the temperature of the drying rate is examined. Equilibrium time and humidity were observed to be 140 minutes and 0.0003, respectively. Also, the process kinetics curve shows that more drying occurs in the descending phase due to the low external resistance to mass and heat transfer. In studying the effect of temperature, it was observed that with increasing temperature from 46 to 68℃, parsley reaches equilibrium humidity with a greater slope. Then drying process of a single leaf, and parsley mass, using feed-forward neural networks and leading, was modeled and the results of the neural network with the results obtained from experimental data were compared. The best result by a feed-forward neural network for single-leaf parsley with Levenberg - Marquardt algorithm, and 13 neurons and the coefficient of determination 0.9987 and parsley mass with nine neurons optimized and coefficient 0.9993obtainedwhich demonstrates the high accuracy of the artificial neural network.

In this research, adsorption of valeric acid from aqueous solution was investigated at different temperatures (25, 35 and 45°C) by using activated carbon in a batch system. In order to determine the functional groups in structure of adsorbent and surface characteristics of adsorbent, FTIR and SEM analysis were used, respectively. In the adsorption experiments, the effect of important parameters such as effect of contact time, the amount of adsorbent, temperature and initial acid concentration were investigated. Equilibrium time was determined 120 min. The optimum amount of adsorbent was determined 1.0g (for 40ml of solution). Investigation of the temperature effect demonstrated that the percentage of removed valeric acid increased by increasing the temperature. Different types of adsorption isotherms models such as Langmuir, Freundlich, and Temkin models were applied to analyze the equilibrium data at different temperatures and Langmuir isotherm had the most agreement with experimental data at different temperatures (with maximum R2 values). The maximum adsorption capacity by using Langmuir isotherm model was determined 196.078 mg/g. Different kinetic models such as pseudo- first order, pseudo-second order, Elovich and intraparticle diffusion model were chosen to describe the kinetic of adsorption, and pseudo-second order model had the best agreement with experimental data for each adsorbents. Thermodynamic parameters like standard Gibbs free energy changes of adsorption ( Gads  ) , standard enthalpy changes of adsorption ( Gads  ) and standard entropy changes of adsorption ( Gads  ) were calculated by using equilibrium constant values at different temperatures. Negative value of (Gads) demonstrated that adsorption of valeric acid was spontaneity and positive values of ( Gads  ) showed that adsorption of valeric acid on adsorbent was endothermic.