In this study, the polyoxometalate-titanium dioxide nanocomposite (SiW11-TiO2) was synthesized using the hydrothermal method and characterized by FT-IR, XRD, FE-SEM/EDS, BET, and TEM techniques. The performance of this nanocomposite as a nanophotocatalyst was then investigated for the degradation of the dyes DR 23 and DB 166 under various conditions, including irradiation time, photocatalyst dosage, dye solution concentration, and pH, under visible light from a sodium lamp and sunlight. The results demonstrated that this photocatalyst, using only 10 mg at acidic pH and within 30 minutes, could significantly degrade these dyes, with a marked increase in degradation efficiency under sunlight. The kinetic study of the degradation reaction indicated that the process follows pseudo-first-order kinetics. Additionally, experimental results revealed that the SiW11-TiO2 nanocomposite exhibited superior photocatalytic activity compared to SiW11 alone. This nanocomposite not only has the capability to completely degrade azo dyes but also demonstrated stability and reusability up to 12 cycles and effective performance in real sample applications.
Sulfur in fuel is one of the main sources of pollutants that cause environmental problems. In addition, the presence of sulfur impurities leads to corrosion problems in refinery units and deactivation of the catalyst used in refineries; therefore, desulfurization of fuel is very necessary. The use of green technologies to solve this problem is of interest to many researchers. Deep eutectic solvents (DES) are considered as solvents similar to ionic liquids and have attracted increasing attention in separation and extraction processes due to their features such as environmental compatibility and very low price. In this study, a deep eutectic solvent (DES) was prepared by mixing triethanolamine (TEOA) as the hydrogen bond donor (HBD) and choline chloride (ChCl) as the hydrogen bond acceptor (HBA). This DES was then used in extractive desulfurization to remove thiophene (Th). The results were compared with those obtained when TEOA acted as the HBA in the DES and the efficiency of TEOA in both HBD and HBA roles in desulfurization was evaluated. Response surface methodology (RSM) was used to model and optimize the extraction process. Three operating parameters affecting desulfurization, the DES component ratio (HBA: HBD), the initial sulfur content, and the mass ratio of DES to model fuel (DES:MF), were selected. Under optimal operating conditions for both DES, the maximum extraction efficiency in one stage was 70.3 and 71.8%, respectively.
.Nano photocatalyst based on SrFe2O4-CuO composite was synthesized by easy chemical method. The scanning electron microscope image shows the bonding of SrFe2O4 and CuO. Ultraviolet-visible spectroscopy has calculated the energy gap of SrFe2O4-CuO nanocomposite and it is lower than CuO. EDS spectroscopy was performed to confirm the presence of strontium, iron, copper and oxygen elements. The crystal size of CuO nanoparticles and SrFe2O4-CuO nanocomposite is 29.12 and 39.81 nm, respectively. The surface area for samples of CuO nanoparticles and SrFe2O4-CuO nanocomposite is equal to 15.12 mg2/g and 45.23 mg2/g. After the successful synthesis of SrFe2O4-CuO nanocomposite, it was used in the photocatalytic removal of Eriochrome Black T pollutant under ultraviolet light irradiation. The removal ability of SrFe2O4-CuO was higher than CuO nanoparticles. SrFe2O4-CuO nanocomposite showed excellent stability and reusability. The identified nanoparticles are very active under UV light irradiation, and hydroxyl radicals and super dioxide showed a major contribution to dye removal.
Given the common challenge of low solubility of many drugs in water, it is vital to implement novel methods to improve it. One method that is widely used across various applications is the use of co-solvents. In particular, Deep Eutectic Solvents have been recognized for their potential in the pharmaceutical industries. This potential is due to their environmental compatibility, cost-effectiveness, and desirable properties. Due to the large number and variety of deep eutectic solvents, it is not possible to perform experimental studies to determine the effect of Deep Eutectic Solvents on the solubility of drugs in water. Thus, it is vital to have thermodynamic models, to help researchers to estimate how the co-solvents enhance the solubility of drugs. This research investigates the performance of five relevant thermodynamic models. The investigated models are all empirical and require regression on the experimental data of each system to be used, which makes them non-predictive. Therefore, to overcome this issue, for the first time, the Khayam-Rajabi-Haghbakhsh model (KRH) has been developed as the first comprehensive and accurate predictive model for estimating the solubility of various drugs in water considering Deep Eutectic Solvents as co-solvents. For the development of this model, a comprehensive data bank including 1489 experimental data points for 13 different drugs and 17 Deep Eutectic Solvents has been used. The AARD% of this model has been calculated to be 13.00, indicating a high level of accuracy. Statistical analysis demonstrates acceptable and unbiased performance across all Deep Eutectic Solvents and drugs investigated. This model is widely utilized for various drug systems, water, and Deep Eutectic Solvents as co-solvents due to its comprehensiveness, accuracy, and capability to estimate drug solubility without needing experimental data.
With the increase of crude oil consumption and the decrease in extractable resources, the development of new methods to enhanced oil recovery has become of particular concern. One advanced and exploited method in recent years is employing external fields, especially electric fields, to reduce the attraction forces between crude oil and water, which improves the production of oil trapped in reservoirs. In this study, the effects of different electric fields with voltage range of (3-9) V and frequency within (100-900) Hz on the interfacial tension of the crude oil–water system were investigated. The results showed that this property has a significant dependency on the electric field parameters, and that the highest voltage and the frequency adjusted at the optimum value, decreased it from the initial value of 32.0 to 8.8 mN/m, equivalent to a 72.5% reduction and also enhanced oil recovery. This phenomenon is mainly due to the increased adsorption of natural crude oil surfactants at the interface and the creation of electrohydrodynamic flows. In addition, investigations on the performance of electric fields demonstrated that electric field with optimum frequency exhibits higher efficiency attributed to the continuous displacement of the poles.
In this study, the performance of the Box–Behnken, central composite and D-optimal designs (BBD, CCD or DOD, respectively) were compared for the use in modeling and optimizing the new study of the removal of phthalocyanine dye using magnetic nanoparticles iron oxide modified by ployaspartic acid (Fe3O4-PAs). As a case study, removal percent (%R) of phthalocyanine dye has been evaluated with all these experimental design approaches. The advantages and limitations of these different response surface techniques have been experimentally considered. All three designs were efficient in the statistical modeling and optimization of the influential process factors such as initial concentration of phthalocyanine dye (C), and adsorbent dosage (m), pH but the central composite design was the most consistent design due to the prediction closer to the experimental data. Based on the results of CCD, the optimized conditions for C, m, and pH variables are 40 mg/L, 9 mg, and 3.3 respectively that lead to %R = 99. In addition to these studies, the investigations of the dye desorption and the adsorbent reusability are complementary divisions of this research.
In this study, a highly sensitive and accurate aptasensor for carbamazepine detection is proposed based on the combination of hollow gold nanospheres with aptamers. Hollow gold nanospheres with unique advantages are immobilized on the surface of a glassy carbon electrode, and then the aptamer sequence is attached with high density on the surface of the hollow gold nanospheres. By adding carbamazepine to the embedded sensing surface and forming a carbamazepine/aptamer complex, the steric hindrance of the surface is increased and the electron transfer of the electrochemical probe (ferro/ferricyanid) on the surface is limited. Thus, carbamazepine is measured in the range of 1 femtomolar to 900 nanomolar with a detection limit of 3.3333 attomolar. The lack of response in the presence of other species with similar structures or properties, as well as the results of the satisfactory analysis of human biological fluid samples, indicates the very high selectivity of the aptasensor. The proposed strategy for the non-invasive measurement of carbamazepine was found to be in accordance with the principles of green chemistry in terms of two international indicators.
In the present study, Ni-W-P nanocomposite coatings were prepared by electroless method. The surface morphology and composition of the coatings were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) while the crystal structure of the coatings was analyzed by X-ray diffraction (XRD). The corrosion of these coatings in 3.5% sodium chloride solution was investigated by Tafel polarization and electrochemical impedance spectroscopy methods, and the corrosion parameters including corrosion potential, corrosion current density, and corrosion resistance were obtained. Also, the parameters affecting the properties of these coatings such as pH, temperature, and the amount of sodium tungstate in the electroless bath were investigated. Accordingly, the optimal value of the parameters was determined as pH=8, temperature 95 oC, and sodium tungstate content of 16 g/l. Corrosion analyses showed that the presence of tungsten in the Ni-P composite coating greatly improves the corrosion properties and increases corrosion resistance. The highest inhibition efficiency for Ni-P and Ni-W-P coatings using the Tafel polarization method was obtained 37.4% and 80.6%, respectively.
Cycloaliphatic epoxy resins, due to the presence of saturated six-carbon rings with a flexible space shape in the main structure, have the ability to be used in the manufacture of high-performance composite parts and have received the attention of composite industries. Researchers have succeeded in synthesizing this resin in various ways and have achieved acceptable chemical, physical, mechanical, thermal and electrical properties, but they have always faced problems in the synthesis method, production process and raw materials, and this limits the use of the above resins. With the aim of improving the synthesis methods and using commercial monomers, this research tries to take a step towards the application of cycloaliphatic epoxy resins. For this purpose, the synthesis and characterize tri-functional cycloaliphatic epoxy resin of diglycidyl-4,5-epoxy-cyclohexane-1,2-dicarboxylate (ECDAD) using raw material of tetrahydrophthalic anhydride was performed by four different methods and the optimal route was presented. For the synthesis of cycloaliphatic epoxy resin, the processes of epoxidation of carboxylic acid with epichlorohydrin, allylation of carboxylic acid with allyl bromide, direct epoxidation of double bond of branches and double bond of cycloalkene with compounds of 3-chloroperoxybenzoic acid (m-CPBA) and trichloroisocyanuric acid (TCCA) were used and different methods were compared. Generally, the epoxidation of alkenes has challenges such as low purity, long reaction time, high cost, and difficult separation, therefore, in this article, a suitable and practical method for the epoxidation of alkenes using TCCA was presented. In this research, two epoxy resins (bi-functional and tri-functional) were synthesized and their synthesis steps were investigated and confirmed by FT-IR, 1H-NMR, 13C-NMR analysis and the measurement of the epoxy equivalent weight (EEW). The EEW of the synthesized resins of bi- and tri-functional was 152 and 108 (g/eq), respectively, and their curing process was evaluated and confirmed using DSC analysis.
Hydrogen sulfide (H2S), a major issue in the sour oil and gas industries, is a highly corrosive and toxic gas produced on a large scale in these industries. Photocatalytic degradation of H2S with the aim of producing fuel is a novel and sustainable approach to solving the problem, supplying clean hydrogen fuel and eliminating this dangerous environmental pollutant. In this photon-based green strategy, the targeted design and easy synthesis of semiconducting energy materials are crucial from an applied standpoint. In this research, without consuming an external reducing agent, the adsorbing rGO/CoMn₂O₄ nanocomposite was synthesized through a one-pot hydrothermal route and employed to effectively produce hydrogen gas via photocatalytic splitting of an alkaline H₂S solution. XRD, FTIR, and Raman analyses showed that graphene oxide (GO) is reduced during the hydrothermal process without the need for a reducing additive. High-resolution transmission electron microscopy (HRTEM) investigations confirmed the attachment of the constituent particles of the composite. Bisulfide sorption studies revealed that the nanocomposite photocatalyst has a high capacity for adsorbing the reactant species (13.97 wt.%). BET, UV-Vis, and PL spectroscopic analyses showed that the presence of rGO in the nanocomposite increases the surface area of the photocatalyst, and by enhancing photon absorption and reducing electron-hole recombination, more hydrogen is generated. The rate of hydrogen release was 5217 (μmol H_2)/(g_cat.h), indicating the good performance of the synthesized nanocomposite photocatalyst for pollutant removal and conversion into clean fuel.
In this paper, a sensitive fluorescence sensor based on nitrogen and sulfur-doped graphene quantum dots (S, N-GQDs) for the formaldehyde detection in detergent samples was reported. The synthesized S, N-GQDs was carefully characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy techniques in details. Under the optimized conditions, a linear range of 0.5-1200 μg mL-1 and a detection limit of 0.3 μg mL-1 were achieved for the formaldehyde detection using the developed fluorimetry method (excitation and emission wavelength were 360 and 440 nm respectively). Important parameters which could be affect the fluorescence quenching such as interaction time between the S, N-GQDs and formaldehyde as well as pH were optimized. According to experimental studies, the decrease of absorption in the presence of formaldehyde is the main reason for the fluorescence quenching of S, N-GQDs. According to experimental results, the developed method represented suitable accuracy and precision for the formaldehyde measurement. This method was successfully applied for the measurement of formaldehyde in detergent samples with acceptable selectivity and sensitivity.
This research employed a method using high-performance liquid chromatography with a visible-ultraviolet detector (HPLC-UV-Vis) to measure Benidipine Hydrochloride in pharmaceutical, human urine, and serum samples. The proposed method was validated based on the guidelines of the International Conference on Harmonisation (ICH) after optimizing various chromatography conditions and other experimental parameters.Optimal results were obtained using an ACE 5µm C18 column (150 mm × 6.4 mm; 0.5µm) at 45 °C. The mobile phase consisted of acetonitrile: buffer (40 mM ammonium acetate) in a ratio of 75:25 v/v% adjusted to a pH of 6.75 at a flow rate of 0.1 mL/min. A wavelength of 238 nm was selected. The method was fully validated, and the validation parameters included a linear range of 0.15-25.00 mg/L and a correlation coefficient of 0.999 for all samples. The detection limits of Benidipine Hydrochloride were found to be 0.46, 1.20, and 8.30 µg/L in acetonitrile, serum, and human urine, respectively. The quantification limits in acetonitrile, serum, and human urine were 1.50, 3.80, and 27.00 µg/L, respectively. The precision, between-day and within-day, represented by the relative standard deviation (%RSD), was found to be 0.13% and 0.27% respectively in the buffer/acetonitrile solution. The average relative recovery values ranged between 97.00% and 105.00%. Thus, the proposed method is rapid and precise, and it can be successfully employed in pharmacokinetic studies and routine clinical performance.
In this study, the selective oxidation of aromatic amines using hydrogen peroxide as an green oxidant and a polyoxometalate catalyst modified with first-row transition metals in a silica matrix was performed. Initially Mono substituted Keggin type Polyoxometalates with first row transition metals (TBA)X[PW11MO39].nH2O (M= Cr, Mn, Fe, Co, Ni, Cu, Zn) were synthesised and then incorporated into a silica matrix by using sol-gel method. The synthesized compounds were characterized using techniques such as EDAX, CHNS, XRD, SEM, and TG-DTG. For selecting the best catalyst, oxidation of aniline was performed with all catalysts and polyoxometalate substituted with Fe showed best catalytic activity. After optimization reaction conditions, oxidation of different aromatic amine was performed and Fe substituted polyoxometalates showed excellent catalytic activity for selective oxidation of different amines to corresponded nitro in heterogeneous system. The studies indicated that the catalysts have good recovery capabilities and can be reused multiple times without significant loss in activity.
Membrane-based processes have attracted significant attention as economical methods for separation. In this study, mixed matrix membranes were fabricated by incorporating UiO-66-(COOH)2 into a poly(ether-block-amide) matrix at various loading percentages using the solution casting and solvent evaporation method. FT-IR, XRD, TGA, DSC, and FESEM analyses were employed to evaluate the properties of the mixed matrix membrane. Pure CO2 and N2 gas permeability through the membranes was measured at 25°C and 2 bar. Results showed that incorporating 15 wt% of UiO-66-(COOH)2 into the poly(ether-block-amide) matrix led to a 135% and 127% increase in CO2 permeability and CO2/N2 selectivity, respectively, compared to the pure membrane. The effect of increasing temperature and pressure on the gas transport behaviour of this membrane was also investigated. Increasing temperature resulted in an increase in CO2 permeability and a decrease in CO2/N2 selectivity, while increasing pressure led to an increase in both. At 6 bar and 25°C, a 174% and 145% increase in CO2 permeability and CO2/N2 selectivity, respectively, was registered compared to the pure membrane.
In the present study, copper oxide (CuO) nanosheets were synthesized by a bottom-up (hydrothermal) method. The structural properties, morphology and particle size of the synthesized nanosheets were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) analyses. In addition, the photocatalytic properties of the hydrothermally synthesized nanosheets in the removal of the organic dye reactive black 5 were studied and on the other hand, the photocatalytic activity of these nanosheets was compared with spherical copper oxide nanoparticles. The charge transfer during the photocatalytic process and electrochemical properties of the nanosheets and the nanoparticles were investigated by photocurrent, photoluminescence and impedance analyses, respectively. The results showed that copper oxide nanosheets had a higher removal rate (79.42) than copper oxide nanoparticle (32.23). On the other hand, increasing the photocurrent density and decreasing the electrochemical impedance value support the reduction of the recombination rate of the electron-hole pair generated by the light in the nanosheets compared to the copper oxide nanoparticles. Also, the increase in the surface area of the nanosheets compared to the copper oxide nanoparticles led to the creation of active sites for the generation of hydroxyl radicals by the holes created in the valence band to increase the photocatalytic efficiency. Finally, the copper oxide nanosheets can be introduced as highly active photocatalysts for the removal of dye and pharmaceutical pollutants.
The construction and investigation of the properties of the molecular imprinting polymer (MIP) adsorbent to remove the copper ion pollutant from the aqueous environment was carried out in this research. In the first stage, iron/silica core-shell nanoparticles were made by co-precipitation method, and then functionalization and in-situ polymerization were done with monomer and target ion (copper), and finally, by washing the copper ion, the molecular imprinting polymer adsorbent was obtained. FTIR, XRD, TEM, FESEM, EDX, BET and VSM tests were performed to determine the absorbent properties. The results showed that the formation of the core-shell structure for iron/silica nanoparticles was successfully established and then the spherical structure of the polymer absorbent with an average particle size of about 30-40 nm was well formed. The results of the absorption tests for copper ion showed that the optimum amount of adsorbent dose is about 18 mg and the best amount of absorption occurs at a pH of about 7. High adsorption capacity, good selectivity and reusability for molecular role polymer adsorbent were observed in adsorption tests. The results of the adsorption-desorption tests showed that after 6 reuses of the adsorbent, a slight decrease (about 8%) in the adsorption removal occurred. To verify the adsorption performance, the synthesized adsorbent was placed in contact with a power plant water sample and showed an adsorption rate of 88% for copper ions.
This study investigates the effect of temperature and consequently the thermodynamic study of the adsorption process of Direct Red 16 dye as a target pollutant in an aqueous environment using fixed LECA/Zirconia adsorbent substrates. For this purpose, a mineral compound called LECA (as a stable substrate) and zirconia nanoparticles (as adsorbent) were prepared separately in the laboratory. Zirconia nanoparticles were coated onto LECA substrate surfaces to form fixed LECA/Zirconia adsorbent substrates. The successful fabrication of the substrates was confirmed by examining transmission and scanning electron microscopy images. To perform the adsorption process, the substrates were fixed on the inner walls of a double-walled hexagonal container. The effect of ambient temperature on the adsorption process was investigated by conducting several experiments at pH 2.7 in the temperature range of 5°C–40°C on solutions with an initial concentration of 30 mg/L of the target pollutant. The results show that temperature has a dual effect on pollutant removal efficiency in the initial and final stages of the adsorption process. In the second minute, increasing the temperature from 5°C to 40°C increased the removal efficiency from 44.1% to 55.7%. In the 30th minute, increasing the temperature from 5°C to 40°C decreased the removal efficiency from 93.2% to 89.3%. Thermodynamic studies showed that the negative values obtained for enthalpy (ΔH° = -18.51 (kJ/mol)), entropy (ΔS° = -0.049 (kJ/mol.K)), and Gibbs free energy (ΔG° < 0 (kJ/mol)) changes indicate exothermic physical adsorption, disorder reduction, and spontaneity of the adsorption process, respectively. The activation energy of the process was obtained by examining the effect of temperature on the second-order rate constants of the process based on the Arrhenius linear relationship, which is equal to 16.09 (kJ/mol).
In this study, the corrosion inhibition performance of five different surfactants, including three cationic surfactants: dodecyl trimethyl ammonium bromide (DOTAB), cetyl trimethyl ammonium bromide (CTAB), cetyl trimethyl ammonium chloride (CTAC) a nonionic surfactant: Triton X-100, and an anionic surfactants: sodium dodecyl sulfate (SDS), was investigated on A335 alloy steel in a 4M sodium hydroxide solution. To evaluate the corrosion behavior, electrochemical methods including Tafel polarization and electrochemical impedance spectroscopy were employed. The results showed that all surfactants reduced the corrosion rate of the steel sample, but the highest inhibition was related to DOTAB with an efficiency of 84.1% and SDS with an efficiency of 85.3%. FE-SEM images also confirmed the reduction of surface damage in the presence of these inhibitors. The results of this study indicate that the use of surfactants can be an effective and economical method to increase the corrosion resistance of A335 steel in alkaline environments.
In this research, nickel catalysts with cerium and rubidium promoters supported on activated carbon derived from almond shell pyrolysis were synthesized to produce hydrogen from vacuum distillation tower bottom residue of Tehran refinery. The catalysts were comprehensively characterized using multiple analytical techniques including ICP, BET, XRD, SEM, and EDX to determine their physical and chemical properties. These catalysts were subsequently tested in a pyrolysis reactor under variable temperature conditions in the presence of steam to optimize hydrogen production. The analysis revealed the formation of nickel nanoparticles with dimensions ranging from 40-60 nanometers distributed across the activated carbon support material. Experimental results demonstrated that maximum hydrogen production of 50.9% was achieved at an optimal temperature of 725°C. The implementation of nickel catalyst on activated carbon support significantly enhanced hydrogen yield to 54.5%. Furthermore, cerium oxide, through its distinctive oxidation-reduction cycle, actively participated in the activation of water molecules, resulting in an additional increase in hydrogen production to 57.3%. The catalytic pyrolysis of vacuum tower bottom residue using these enhanced nickel-based catalysts represents an effective and sustainable approach for hydrogen generation from heavy petroleum waste products, offering a valuable technological solution for converting refinery residues into clean energy resources.
The development of efficient photocatalysts for environmental remediation, particularly for the degradation of organic pollutants, has gained significant attention in recent years. This study focuses on the synthesis, characterization, and electrophoretic deposition (EPD) of Fe-doped TiO2 nanoparticles, as well as their application in the sonophotocatalytic degradation of methylene blue (MB), a common organic dye pollutant. The incorporation of iron (Fe) into the TiO2 lattice was aimed at enhancing its photocatalytic activity under visible light by reducing the bandgap and minimizing electron-hole recombination. The synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis. The electrophoretic deposition technique was employed to create thin films of Fe-doped TiO2 on conductive substrates for practical applications. The sonophotocatalytic performance of the Fe-doped TiO2 nanoparticles was evaluated by monitoring the degradation of MB under visible light irradiation. The results demonstrated that Fe-doped TiO2 exhibited superior efficiency (92% degradation in 30 minutes), highlighting its potential for wastewater treatment and environmental cleanup. To complete the research, the reusability of the catalyst was also investigated.
