ظرفیت جذب

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, the synthesis of L/Fe3O4-methionine and graphene oxide and graphene aerogel nanocomposites (Fe3O4/L-Met/GO, Fe3O4/L-Met, Fe3O4/L-Met/GA) was carried out. Then the structure of the synthesized nanocomposites was confirmed by FT-IR, FE-SEM and BET analyses. Then, the effect of different experimental parameters such as initial pH and contact time on the process of cadmium surface adsorption were investigated. The results showed that the highest percentage of cadmium absorption (90%) occurred at Ph=6 by Fe3O4/L-Met/GA nano adsorbent. Therefore, the cadmium (Cd2+) absorption capacity by Fe3O4/L-Met/GA nanocomposite (212.31 mg/g) is higher than the cadmium (Cd2+) absorption capacity by Fe3O4/L-Met nanocomposites (201.23 mg/g). ) Obtained. Adsorption kinetics data showed excellent fit with pseudo-second-order models (R2>0.99) and Freundlich isotherm models.showed high adsorption capacity towards Cd2+ (212.31 mg/g), which was significantly higher than Fe3O4/L-Met (201.23 mg/g). Finally, adsorption kinetics, isotherm studies were investigated. Absorption data showed excellent fit with quasi-second order models (R2> 0.99) and Freundlich isotherm models.

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.

Effective removal of pollutants from industrial effluents in order to restore these waters to the cycle, and also from the environmental point of view is very important. BTEX is an indicator of Volatile Organic Compounds (VOCs). In this study, the BTEX adsorption method was applied to the MOF-199 nano-absorbent. the MOF-199 was initially synthesized by hydrothermal method and characterized by XRD, FE-SEM, and BET analyses. Adsorption test was performed under NPT conditions and HPLC technique was used for analysis, which confirmed the experimental results of absorption. The equilibrium adsorption isotherms were plotted at 298 ° K. According to the results, the BTEX adsorption isotherm with MOF-199 can be detected with Langmuir isotherm as well as Freundlich isotherm. by comparing the values of the maximum adsorption capacity (qmax) of compounds, the amount of MOF-199 adsorption capacity for benzene and xylene was 108.695 (mg/g), and for ethylbenzene and toluene, 107.526 and 83.333 (mg/g) was obtained, respectively.

Graphene aerogels are ultralight 3D graphene structures with a density of about 10 mg/cm3, unique electrical properties, and high compression capability. In order to produce them, first graphene hydrogel is produced, then the liquid in the graphene hydrogel is replaced by air so that the volume and structure of the gel do not change. For graphene hydrogel drying, special drying methods such as freeze drying or super-critical drying, or the newest drying method, which is ambient pressure drying using ice templating are needed. In this study, graphene aerogels were produced by ambient pressure drying without the need for special apparatus or specific pressure and temperature with a density of 10.6 g/cm3 and the preparation parameters were optimized. It was found that for the preparation of graphene aerogels with higher porosity and lower density, it is appropriate to select the initial concentration of graphene oxide 4 mg/ ml, the gelation time of 7 h, and the ice templating time of 48 h. It was also found that the lower-density aerogels were more compressive. As the stresses on the specimens increased, their electrical conductivity increased and their electrical resistance decreased. Their thermal conductivity was also measured as 0.029 W/m.K, which is in the range of good thermal insulation. The adsorption capacity of diesel oil, petroleum, edible oil, and ethanol by graphene aerogels was measured 88.5, 59.6, 42.6, and 55.2 g/g, respectively. Regarding the methylene blue adsorption, it was observed that the highest adsorption occurs in the first 15 minutes, so the graphene aerogels can be used as adsorbent of methylene blue and other dyes with similar structures from water and industrial effluents.

Today, continuous researches and extensive researches are being done in the world for the synthesis of new types of adsorbents, in order to remove toxic metals with high ionic absorption capacity along with non-toxic nature and biodegradable properties. Until now, various ionic impurities have been removed in different ways. High absorption capacity and performance, hydrophilic properties, regeneration ability and non-toxicity have made hydrogels a good competitor for removing various aquatic pollutants including heavy metal ions. Hydrogels have porous, three-dimensional structures and chemically sensitive functional groups that enable them to easily capture metal ions and dyes from wastewater and release these toxic pollutants by changing the conditions of the aqueous solution. The hydrophilic nature of hydrogel adsorbents causes a flexible network of polymer chains to form, which allows polluting molecules to quickly penetrate the network with water and stable complexes with functional groups. to form They are three-dimensional hydrophilic polymers that absorb large amounts of water and swell to form a solid gel while maintaining their physical structure without dissolving. Due to their high potential for effective removal of heavy metals and dyes, they are very suitable for water and wastewater treatment. This article discusses recent advances in water and wastewater treatment by hydrogels and the selectivity, efficiency and reusability of hydrogels in this field.