جستجوی مقالات مرتبط با کلیدواژه "جذب سطحی" در نشریات گروه "علوم پایه"

One way to compensate for water shortages, especially in the agricultural sector, is to use recyclable water, including agricultural water, domestic and industrial wastewater. On the other hand, removing pollutants in these waters is particularly important. Due to the high cost and low efficiency of other pollutant removal methods, biological adsorption methods with low cost have good efficiency for removing pollutants, including cadmium. In this study, cadmium absorption in aqueous solutions was studied using Champia Kotschyana Harvey. Effect of effective variables such as concentration of cadmium ions (0.5-5 mg/L), absorbent value (7-1 gr/L), solution pH (3-8) and contact time (90-90 min) with model response level method became. The design of the Box- Behken was used for experimental data and the best level of independent variables, namely the initial concentration of cadmium ion, pH, contact time and adsorbent value, were selected. Under suitable conditions (pH=4, adsorbent value = 1.5 g/L, contact time = 36.53 min, cadmium initial concentration = 3.3 mg/L) adsorption capacity and cadmium removal percentage, respectively 3/1 mg/ g and 80/14 obtained. Kinetic and isotherm studies showed that the second-order Kinetic model and the isotherm Langmuir well corresponded to cadmium absorption data. According to the results, the Champia K. Harvey alga biomass can be used to adsorb cadmium from aqueous solutions.

Red mud, as the Bayer process (aluminum production from bauxite) tailing with high pH (10-13) and solubility for heavy metals, has many destructive environmental effects. Red mud using in various industries with the aim of reducing its environmental effects has not been achieved due to the high cost of transportation, but its special physic-chemical properties, including the presence of various metal oxides in its composition, high specific area and the presence of surface-active sites, it was used for many applications, including environmental pollutants adsorption. Factors such as the storage time and kind of production process are effective on the constituent compounds and ion exchange capability of red mud. As the time storage increases, the number and activity of ion exchange phases and adsorption properties of red mud decrease. Compared to natural absorbents such as coconut shell, volcanic ash, and animal skin waste; red mud has a higher adsorption capacity, and compared to synthetic adsorbents, it has less costs to use. Although the specific area of red mud (22-35 m2/g) is lower compared to expensive adsorbents such as activated carbon (1000-1100 m2/g), it has a specific area compared to natural and cheap adsorbents (1-10 m2/g). Among anionic and metal contaminants, red mud has been more successful than other pollutants and adsorption capacity for phosphate and cadmium were 192 and 50 mg/g, respectively. Among affective factors on adsorption, temperature, time, and pH are the most important factors for various contaminants by red mud. A variety of thermal methods, acid washing, washing with sea water and the use of additives have been used to improve the adsorption properties, modify the surface, and reduce the pH of red mud. Among these methods, combination of acid washing-thermal methods, acid washing-precipitation with ammonia and cationic acid washing-surfacing methods are more effective.

The use of natural adsorbents in wastewater treatment is one of the efficient methods that, due to the availability of raw materials, the cost of the process is significantly reduced. Various natural organic and inorganic compounds can be used as adsorbents in this field. Contamination of water resources with aromatic compounds is one of the environmental problems that has attracted the attention of researchers. In general, phenolic compounds and their derivatives have harmful effects on living organisms even in low concentrations because the nitro aromatic componds have toxicity and mutagenic nature. According to the studies conducted in this field, the adsorption method using biochar can be a suitable method for removing aromatic compounds from the aqueous media.

In this study, due to the production of a large amount of biomass in Iran, the use of these compounds in the preparation of biochar as an adsorbent and its application to remove nitro phenol from water have been investigated. For this purpose, straw and stubble of pirozi garden of Tehran has been used as biomass. A laboratory system that is designed and constructed for this purpose, was used to prepare biochar. Biochar was prepared at a temperature of 350 °C and was used as an adsorbent after washing and drying. In order to assesse the general characteristics of the prepared biochar, surface morphology was performed by SEM analysis, surface chemical characteristics was assessed by FTIR analysis, heavy metal content was investigated by MOOPAM method using atomic absorption spectroscopy, and specific surface area of the produced biochar was checked by BET analysis. Also, the process has been modeled and optimized statistically using the CCD method.

Examining the characteristics of the prepared biochar showed that the prepared biochar has nano structure, which will lead to an increase in the surface area. Based on the results, specific surface area was 0.42 m2/g, the porosity volume was 0.04 cm3/g, and the average diameter of the holes was 361.76 nm. Also, the analysis of heavy metals in the produced biochar showed that the measured metal values are less than the allowable range of presence of heavy metals in biochar based on the IBI standard. After designing the experiment and performing the relevant experiments, statistical analysis was performed on the results. The results of statistical analysis showed that the process is well fitted with a quadratic model and has good accuracy. According to the prediction of the model, after 60 minutes of the process, this adsorbent can remove about 84.8% of nitrophenol with an initial concentration of 16.2 ppm, at pH = 4.2, using 47.12 mg of adsorbent per 100 ml of solution. In order to confirm the correct performance of the model, the process was experimentally checked under optimal conditions, and the average removal efficiency was 82.7%.

According to the obtained results, biochar as a natural material can be used as an adsorbent to remove nitroaromatic compounds. Also, the use of biochar, in addition to wastewater treatment, it leads to biomass waste management.

The Earth's surface is covered by 75% water. However, only 3% of this water is freshwater, and just 1% of that freshwater is accessible for human consumption. In most instances, humans are responsible for introducing pollutants into water. Dyes are among the most significant pollutants found in textile wastewater. As a result of its economic feasibility and high selectivity, adsorption has gained widespread popularity as a technique for treating organic dyes. In this research, a novel magnetic adsorbent was developed and utilized to remove certain toxic dyes.

In this research, Gum Arabic has been utilized as a natural and biodegradable polymer for the preparation of an effective adsorbent. To enhance the surface area, efficiency and stability of this natural polymeric adsorbent, citric acid has been employed as a green crosslinker. According to our findings, ,Gum Arabic has been polymerized for the first time with citric acid as a crosslinker and utilized for the removal of cationic dyes. Additionally, a crosslinked Gum Arabic polymer synthesized using citric acid has been incorporated with magnetite nanoparticles, ensuring its facile recovery from the medium upon application of a magnetic field. Furthermore, the prepared magnetic Gum Arabic was employed for the removal of Crystal Violet (CV), Malachite Green (MG), and Methylene Blue (MB) dyes from aqueous samples.

In this study, the impact of various parameters, including initial dye solution concentration, solution pH, contact time between the adsorbent and the dye solution, adsorbent dosage, and dye solution temperature, on the removal efficiency of   cationic dyes from aqueous samples was investigated. According to the results, the adsorption capacity of the adsorbent (CL-GA/Fe3O4) increased with increasing dye solution concentration, reaching maximum levels of 209.80, 205.12, and 177.12 mg/g for MB, CV, and MG, respectively. Additionally, the removal efficiency for these dyes increased with increasing solution pH, reaching 99.43% (MB), 97.13% (MG), and 96.62% (CV) at a pH of 6. Furthermore, the removal efficiency of dyes increased with increasing adsorption temperature, indicating an endothermic process. It is noteworthy that in this study, both MB and MG dyes reached their maximum removal efficiency after 20 min. In contrast, CV reached its maximum removal efficiency within a 15-min time frame. In this investigation, the Langmuir model showed a significantly better fit to the adsorption data compared to the Freundlich model, indicating its accuracy in describing monolayer adsorption. Additionally, this study revealed that the obtained adsorption kinetic data fit well with the pseudo-second-order model. This suggests that chemisorption likely plays a significant role in the rate-limiting step of the adsorption process.

In this research, a novel nano adsorbent (CL-GA/Fe3O4) based on crosslinked Gum Arabic with citric acid and magnetized with Fe3O4 nanoparticles was employed for the removal of cationic dyes. To validate the effectiveness of the (CL-GA/Fe3O4) adsorbent, various characterization techniques, including FT-IR, FESEM, EDX, Zeta potential, and VSM, were employed. The findings of this study demonstrate the development of an innovative and efficient adsorbent for dye removal, which holds significant importance in addressing environmental challenges.

In this research, the performance of aluminum phosphide (Al12P12) nanocage as adsorbent and sensor for removal and detection of primidone was evaluated using density functional theory. Negative adsorption energy values showed that the interaction between drug and nanoabsorbent is empirically possible. The negative values of enthalpy changes and Gibbs free energy changes showed that the process of adsorption is exothermic and spontaneous. Partial values of thermodynamic equilibrium constant showed that drug-adsorbent interaction is reversible and has a balanced state. The effect of solvent and temperature on the interactions was also evaluated and the results showed that the presence of water as solvent has no significant effect on interactions and on the other hand, the adsorption process is more effective at lower temperatures. On the other hand, the drastic changes in nanostructure band gap from 3.378 eV to 9.955 eV showed that the electrical conductivity during the adsorption process has been reduced and this nanocage can be used as a sensitive electrochemical sensor to detect primidone.

In this research, graphene oxide-silver (GO-Ag) nanocomposites (NCs) was prepared using tamarindus indica extract (green reducer). These NCs was characterized by conventional methods such as Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction Pattern (XRD), Scanning Electron Microscopy (FE-SEM), X-ray Energy Diffraction Spectroscopy (EDS), Raman spectroscopy and TGA thermal analysis. The as-prepared NCs was used as an absorbent in the process of removing lead ions from aqueous solution. The surface absorption process of lead ions by GO-Ag NCs and the factors affecting this absorption process: such as the concentration and pH of the lead solution, the amount of adsorbent (GO-Ag) used, the contact time of the adsorbent with the solution and the temperature of the absorption process were investigated. The removal percentage of lead ions and adsorption capacity were 97.70 % and 152.60 mg/g for 50.0 mL of lead(II) solution 125.0 ppm and pH = 5.0 in the presence of 0.040 g of GO-Ag (2:1) with a contact time of 7 minutes, respectively. On the other hand, experimental evidence showed that the surface adsorption process of lead(II) ion on GO-Ag substrate follows pseudo-second order kinetics and the Langmuir adsorption isotherm model can be considered for it.

Nowadays, supramolecular hydrogels as a new type of three-dimensional compounds based on non-covalent interactions have attracted the attention of many scientists of different sciences due to their diverse and easy preparation methods and unique characteristics compared to their covalent counterparts. Therefore, in the present research, green cellulose nanoparticles was prepared from cotton by acid hydrolysis process and then separately functionalized with citric acid and pyridine pendant groups in order to create anionic and cationic components. Next, supramolecular hydrogels were prepared through electrostatic interactions between the mentioned components. The successful preparation of hydrogel was investigated using Fourier transform infrared spectroscopy, SEM and X-ray diffraction. Study of the morphology of the hydrogel showed a porous structure containing holes of different sizes. Also, the investigation of the crystal structure of the hydrogel showed its high crystallinity. Finally, the removal of methylene blue cationic dye from industrial wastewater was investigated through the absorption process and using the prepared hydrogel as an adsorbent. Also, the effect of methylene blue initial concentration and contact time at room temperature on the absorption process was investigated. The study of absorption kinetics showed that the absorption process follows the second-order absorption kinetics. The maximum absorption capacity obtained for this adsorbent was 97 mg/g. The present study showed that the prepared supramolecular hydrogel, in addition to features such as biocompatibility, avalability, and simple and fast preparation, has a good potential for methylene blue absorption.

In this study, processed chicory leaf powder was used as a natural adsorbent to remove cobalt ions from aqueous media. Natural adsorbents were characterization by several methods include X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform spectroscopy (FTIR), Brunauer-Emmet-Teller (BET) and Particle size analyzer (PSA). A set of experiments was performed to detect the optimal conditions and to investigate the effects of various parameters such as initial concentration, contact time, adsorbent dose, solution pH and temperature on the percentage of removal. The optimal conditions for cobalt removal were: pH = 6-8, contact time 20 min, adsorbent dose 20 mg and initial concentration 15 (mg L-1). Adsorption data showed that the adsorption process is more compatible with Langmuir's isotherm. The kinetic data were consistent with the quasi-second-order model with a valid correlation coefficient. Calculation of thermodynamic values ​​showed that the adsorption process is spontaneous, with decreasing entropy and exothermic. Finally, the introduced sorbent was compared with a strong adsorbent such as carbon nanotubes doped with silver nanoparticles (Ag2O-MWCNT). The optimal conditions for the removal of cobalt ions by the processed synthetic adsorbent were: initial concentration of 10 mg L-1, contact time of 40 min, amount of adsorbent 30 mg and pH = 7. Adsorption data showed that the adsorption process for cobalt ions is compatible with Freundlich's isotherm. The kinetic data were consistent with the quasi-second-order model with a valid correlation coefficient. Calculation of thermodynamic values ​​showed that the adsorption process was spontaneous and exothermic. The results of this comparison show that the introduced natural adsorbent performs even better than the synthetic and expensive adsorbent and provides a promising outlook if further processing and modifications are performed on this adsorbent.

In this study, 3-Picrylamino-1,2,4-triazole interaction with carbon nanocone dots was evaluated by infrared (IR), natural bond orbital (NBO) and frontier molecular orbital (FMO) computations. The negative values of adsorption energy, enthalpy changes, Gibbs free energy variations showed 3-Picrylamino-1,2,4-triazole adsorption on the surface of carbon nanocone is exothermic, spontaneous and experimentally feasible. Structural parameters including the energy of HOMO and LUMO orbitals, bandgap, electrophilicity, chemical potential, chemical hardness, density and zero-point energy were also calculated and discussed. The remarkable decrease in bandgap after the 3-Picrylamino-1,2,4-triazole adsorption on the surface of carbon nanocone demonstrated that the electrochemical conductivity and electrocatalytic properties increased after adsorbate interaction with the adsorbent and carbon nanocone can be used for construction of new electrochemical sensor in order to 3-Picrylamino-1,2,4-triazole detection and quantitation. In addition, this phenomenon showed 3-Picrylamino-1,2,4-triazole complexes with carbon nanocone can be a more powerful energetic substance than the pure 3-Picrylamino-1,2,4-triazole molecule without the nanostructure.

This study includes the development of a new nanosorbent for the treatment of dye effluents. The designed and fabricated nanosorbent is comprised of a dendritic structure with symmetric primary amine active sites and a magnetic core. Employing various characterization techniques such as NMR, SEM, TEM, TGA, zeta potential, and CHN elemental analysis, the adsorption capacity of this material to remove methyl-orange dye has been investigated. The results reveal that the proposed nanosorbent offers an efficiency of approximately 68.9% with an adsorption rate of 166.2 g/min in the methyl-orange removal process. The rate constant obtained for methyl-orange adsorption on the nanodendrimer is higher than the previously reported ones, indicating a higher adsorption rate. The results of this new nanosorbent prove its high potential in adsorptive methyl-orange removal.

The aim of this study was to model the removal efficiency of cefixime by the Fenton method using a neural network. This model predicts experimental results well. In this model, the amount of hydrogen peroxide, iron catalyst, cefixime removal time, initial concentration of cefixime, and pH are the input parameters. The output variable is the removal percentage of cefixime. Total error squares (SSE), mean the square root of error (RMSE), adjusted coefficient of determination (), and coefficient of determination   in determining the number of optimal neurons in the middle of the performance index. According to the obtained results, the neural network model was able to predict the absorption efficiency with the sigmoid tangent transfer function in the hidden layer and the linear stimulus transfer function in the output layer. Also, the results of modeling the neural network with org-art showed that the grid with a 1-13-5 arrangement (5 neurons in the input layer, 13 neurons in the hidden layer, and 1 neuron in the output layer) had the best result in predicting the output. The correlation coefficients of all the levels of training, validation, and test 0.3 were 0.99436, 0.9993, and 0.96901, respectively. To predict the trend of changes, neural network tools have been used in MATLAB software.

The asphaltene present in crude oil creates various challenges for its production, processing, and transportation, with the most important ones being wellbore and pipeline fouling, deactivation, and poisoning of catalysts. In this study, the adsorption of asphaltene extracted from a crude oil sample on five iron oxide nanoparticles synthesized by the Pechini method, in the presence and absence of propylene oxide and polyethylene glycol as common agents used in the sol-gel method for gel formation, was investigated. Solutions with different percentages of asphaltene and toluene were prepared, and a specific amount of iron nanoparticles (4 g/l) was added to the solutions. The mixtures were shaken for 15 hours at 250 rpm. The unknown concentration of the samples was determined by UV-visible analysis. The results indicated that the iron oxide synthesized without propylene oxide and polyethylene glycol, with an adsorption capacity of 37.31%, exhibited the best performance in asphaltene adsorption and was economically more viable. The adsorption results were described using Langmuir and Freundlich isotherms, and the physical properties of the nanoparticles were determined by XRD and BET analyses.

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.

Emerging pollutants from water are a significant concern in modern society, and surface adsorption has been identified as a promising method to eliminate them. Preparation of an effective adsorbent is crucial for the adsorption method. In this study, a new adsorbent of Metal organic frameworks, MIL-101(Cr)@ZnO, was synthesized by modifying MIL 101(Cr) with zinc oxide nanoparticles using the hydrothermal method. The adsorbent was characterized using XRD, FTIR, FESEM, EDX and BET analysis. The adsorbent's efficiency was evaluated by studies of adsorption equilibrium isotherms under optimal conditions pH = 9, amount of adsorbent 0.0035 g, volume 50 ml, time 60 minutes, at different temperatures (60, 40, 35 °C) and concentrations of methylene blue (6, 8, 9, 10, 11 mg/L). The equilibrium adsorption data were analyzed using Langmuir, Freundlich, Temkin, Alovich, and Dubinin-Radoshkevich(DR) two-parameter equilibrium isotherms models. The obtained results showed that the order of dye adsorption of the studied isotherms is as follows: Dubinin-Radoshkevich>Temkin>Freundlich>Alovich>Langmuir. Additionally, the order showed that the adsorption of methylene blue occurs in a multilayered form. The isotherm of Dubinin-Radoshkevich with the highest correlation coefficient (R2=0.9767) and low average free energy (E=0.975 J/mol) showed that physical adsorption is the dominant process of adsorption. The maximum adsorption capacity of Langmuir isotherm was determined at the temperature of 313 K with the value of qmax=258.7143 mg/g, the separation factor at the same temperature (RL=0.4364) indicating favorable adsorption. The Freundlich adsorption intensity and correlation coefficient values were n=1.3825 and R2=0.879, respectively. The heat of adsorption in the Temkin's model was calculated to be BT=57.192 J/mol, and the highest adsorption capacity was obtained from Elovich's isotherm qmax=333.3333 mg/g. Further, the amount of thermodynamic values showed that the adsorption process of the pollutant is a spontaneous and endothermic process. The present study's evidence indicates that the adsorption of methylene blue follows a physical process.

In recent years, research on the widespread use of biodegradable polymers, such as sodium alginate (SA), in removing pollutants from water sources has shown significant growth. The present study aims to evaluate the efficiency of SA hydrogels cross-linked with ferric chloride (for mechanical strength) in optimizing the removal of nickel (Ni) from aqueous solutions. Various factors, including Ni initial concentration, solution pH, amount of adsorbent, and contact time, were considered using response surface methodology (Box-Benken model). Based on the results of FTIR and SEM analyses, activated SA hydrogels were found to have hydroxyl and carboxyl functional groups, and their surface morphology was non-flat and prominent. The Ni removal values in the presence of SA hydrogels varied, with the minimum and maximum removal percentages being 53.39% and 85.43%, respectively. Increasing the initial Ni concentration resulted in a decreasing trend in Ni removal, while increasing contact time, solution pH, and amount of adsorbent led to an increasing trend in Ni removal. The evaluation of the data obtained from Ni removal using the Box-Benken model showed an accurate prediction (R2 higher than 0.98%) in optimizing Ni removal from aqueous solutions in the presence of SA. The possible mechanisms of Ni removal by SA hydrogel were identified as the formation of Van der waals bonds (physical adsorption), interaction with carboxylate anions, chelate formation between Ni ions and hydroxyl functional groups, and electrostatic interactions (due to the negative surface charge of SA). Overall, the results of this study demonstrate that SA has a suitable ability to remove Ni from aqueous solutions. However, future studies should investigate, compare, and integrate other activation methods, such as physical activation (combination with inorganic substances) and chemical activation (surface grafting) on the SA polymer, to improve the removal efficiency of heavy elements using this polymer.

In this study, montmorillonite modified by the hexadecyltrimethylammonium bromide (HDTMA-Br) was prepared by the reaction of the sodium montmorillonite with HDTMA-Br surfactant. The adsorbent structure was characterized using Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), power-spectral-density (PSD), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. Then, the efficiency of synthetized adsorbent was investigated for the removal of the chemical oxygen demand reduction (COD), biological oxygen demand (BOD), suspended solids (TSS), oil and grease and turbidity of the oilfield produced water. The exchange capasity was obtained 200 % for modified montmorillonite. The maximom of COD reduction was resulted 92.04 % at optimal conditions with the adsorbent dosage 0.3 g, pH = 7, and contact time 45 min. The advantages of this method are cheapness, safety, and reusability of the adsorbent, short time treatment, high adsorption capacity, easy separation of the adsorbent from the reaction medium.

Cyanide is one of the toxins and different ways to reduce it have been studied. These include ozone oxidation methods, ultraviolet radiation degradation, alkaline chlorination, and hydrogen peroxide degradation. Each of these methods has various disadvantages and advantages, but among them, surface adsorption is an effective and efficient method. On the other hand, zeolites, which are crystalline aluminosilicate and juicy alkali and alkaline earth metals, have the ability to absorb cations and anions. To prepare a cyanide solution, it was used sodium cyanide salt based on the standard method In this work, it has been studied the adsorption of cyanide ion from aqueous solutions using zeolite nanoparticles and the factors affecting on it. In this study, the factors of the effect of the initial pH of the solution, the effect of the initial concentration of the solution, the effect of the adsorbent amount, the effect of the contact time and the effect of temperature on the surface adsorption of cyanide ions with the nano-adsorbent zeolite clinoptilolite were investigated. And after the studies, the optimal and appropriate values for each of the effective parameters pH=6, contact time 40 min, adsorbent dosage 1g/l, temperature 22°C and initial concentration of 150 mg/l. Under these optimal conditions, the highest percentage of anion cyanide uptake was obtained on the nano-adsorbent of zeolite clinoptilolite 85%. The relationship between empirical data and the equation of Langmuir, Freundlich and Tamkin equations was also investigated. The R2 values for Langmuir, Frondelich, and Temkin's alliances were 0.8337, 0.9837, and 0.99, respectively, indicating that there was a greater match between the experimental data and the Temkin temperature than the other two.

In this paper, nanocrystals of zeolitic imidazolate frameworks (ZIF-8) were synthesized by solvothermal synthesis method, and their modification was conducted using molybdenum (Mo) promoter. The aforementioned modifications were carried out by two methods, including loading of Mo in ZIF-8 structure and also impregnation of ZIF-8 with Mo. Adsorption isotherms of CO2 and CH4 were determined according to the pressure decay method in the temperature and pressure ranges of 298-328 K and 1-4 bar, respectively. The obtained results indicate that presence of Mo promoter causes obvious changes in structural properties of the ZIF-8 nanocrystals, such as surface area, pores volumes, as well as, adsorption properties. Moreover, CO2 adsorption of the modified nanocrystals was obtained less than that of the parent ZIF-8. On the other hand, CO2/CH4 selectivity value of the modified ZIF-8 nanocrystals by impregnation has increased by 85% compared to non-modified ZIF-8.

In the presented method, modified magnetic nickel oxide was synthesized and identified for pre-concentration and determination of gemfibrozil in human serum samples, pharmaceutical wastewater and drug. Fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to identify magnetic nickel oxide nanoparticles. Some parameters affecting the extraction, including pH effect, amount and type of elution solvent, extraction time, etc., were optimized and investigated. The concentration factor was 120, the limit of detection (LOD) was 0.16 µg.L-1, and the linear range of the calibration curve was 0.05 to 10 µg.L-1. The adsorption capacity was 52.69 mg.g-1. This method was successfully used to determination of gemfibrozile in human serum samples, pharmaceutical wastewater and drug using UV-Vis spectrometer with recovery in the range of 0.98-0.104%. Then, the samples determined by the proposed method with the results of the standard high-performance liquid chromatography (HPLC) method were compared. The results were checked with T-test and showed that there is no significant difference between the two methods.

In this study, the performance of fullerene (C20) as an adsorbent and sensor for the removal and detection of cefalexin was scrutinized by density functional theory computations. The negative values of adsorption energies showed cefalexin interaction with the nanostructure is experimentally possible. The negative values of enthalpy changes and Gibbs free energy variations demonstrated cefalexin adsorption on the surfaces of the adsorbent is exothermic and spontaneous. The values of thermodynamic constants indicated cefalexin interaction with C20 is reversible, equilibrium and two-sided. The NBO results showed cefalexin adsorption on the pristine fullerene is a physisorption because of non-formation of chemical bonds. The influence of temperature on the adsorption process was inspected and the obtained results showed cefalexin interaction with the nanostructure is more favorable at lower temperatures. The computed DOS spectrums showed the bandgap of C20 experienced a +296.9% decline from 1.950 (eV) to 7.750 (eV). Hence, this nanostructure can be employed as a sensing material for the development of new electrochemical sensors for the detection of cefalexin.