Removal of sarafloxacin from aqueous solution through Ni/Al-layered double hydroxide@ZIF-8.

In recent years, excessive amounts of drugs such as antibiotics have been used to combat COVID-19 and newly discovered viruses. This has led to the production and release of significant amounts of drugs and their metabolites as toxic pollutants in aquatic systems. Therefore, pharmaceutical wastes must be removed efficiently before entering the environment and entering water sources. In this research, Ni/Al-LDH@ZIF-8 nanocomposite was synthesized from layered double hydroxides and metal-organic frameworks and used to remove the antibiotic sarafloxacin (SRF) in the aqueous medium. The work aimed to develop the performance and combine the features of the adsorbent compounds such as high surface area, adjustable porosity, and low-density structure. Different methods implemented to analyze the nanocomposite, such as Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. The experiment utilized the central composite design to evaluate statistics and the response level method to optimize the factors affecting the absorption process. The initial concentration of SRF, adsorbent dose, pH, and contact time were considered in this experiment. The results showed an increase in the removal efficiency of SRF to 97%. Statistical studies showed that the optimal adsorption conditions are as follows: initial concentration of SRF 40 mg·L-1, pH 6.3, adsorbent dose of Ni/Al-LDH@ZIF-8 49 mg, and contact time of 44 min. According to the model of isotherms parameters, the adsorption process is more consistence with the Freundlich model with the absorption capacity of 79.7 mg·g-1. The pseudo-second-order model described the adsorption kinetics data.

Simple and green approach for photoluminescent carbon dots prepared from faba bean seeds as a luminescent probe for determination of Hg+ ions and cell imaging.

In this research, for the first time, a dedicated sensor was designed to detect Hg+ ions using photoluminescent carbon dots (CDs). Due to the preferred green synthesis of CDs from bio-resources, carbohydrate-rich faba bean seeds as a potential carbon precursor were applied to the synthesis of CDs. The CDs were prepared from the faba bean seeds using the hydrothermal method in an aqueous solution in the absence of substances such as an acid or base and any other additives. The synthesized CDs exhibited maximum emission intensity at 387 nm when excited at 310 nm and their luminescence quantum yield was calculated to be ~5.94%. Then, the fluorescence emission of CDs was examined in the presence of different metal ions. Results revealed that the CDs had good selectivity towards the Hg+ ions, so the fluorescence emission was significantly changed in the presence of these ions with a limit of detection (LOD) as low as 0.35 µM. Furthermore, because of their very low cytotoxicity, these CDs can be applied for cell imaging.

Fe3 O4 and bimetal-organic framework Zn/Mg composite peroxide-like catalyze luminol chemiluminescence for specific measurement of atropine in Datura plant.

Atropine (AT) is an anticholinergic drug. AT is abundantly in Datura plant seeds. Fe3 O4 @Zn/Mg MOF (Fe3 O4 @MOF) composite was synthesized. The compound had a high peroxidase-like activity in a chemiluminescence (CL) reaction. Addition of AT quenched CL. The linear range and limit of detection were 5-600 µg L-1 and 2 × 10-2 µg L-1 . This method is fast, reversible, and selective, without biodegradability effects, high accuracy, and precision for measuring AT in the Datura plant.

New Fluorescent Nanosensor for Determination of Diazepam Using Molecularly Imprinted Mn-doped ZnS Quantum Dots.

In this study, molecularly imprinted Mn-doped ZnS quantum dots were used as nanosensors to determine diazepam and its metabolites. Mn-doped ZnS quantum dots (QDs) capped with L-cysteine were prepared using a sodium thiosulfate precursor and characterized by various methods. Methacrylic acid was used as a precursor for the synthesis of MIP Mn-doped ZnS QDs and then used to measure diazepam in various samples. The linear dynamic range, coefficient of determination, and detection limit were found to be 0.3 - 250 µmol/L, 0.989 and 8.78 × 10-2 µmol/L, respectively. The interference studies showed that the prepared nanosensor was selective for diazepam and its metabolites.

Synthesis, optical properties and tuning size of CdSe quantum dots by variation capping agent.

In this study cadmium selenium quantum dots (CdSe QDs) were synthesized with different capping agents namely, l-cysteine, mercaptosuccinic acid and thioglycolic in aqueous solution. The effect of capping agent on the nucleation and particle growth process was investigated. Electronic absorption and emission fluorescence spectroscopy techniques were applied to map out the size evolution of the QDs. The methods of SEM, EDX, XRD and FTIR were also used for characterization of the prepared samples. The average diameters of the synthesized quantum dots were estimated using different methods. Results revealed that the order of particles size was obtained as follow: CdSe-MSA > CdSe-LCY > CdSe-TGA. Results also showed that the TGA has the strongest binding ability with the QDs surface; in contrast MSA has the weakest binding ability. Results indicated that there is a mutual relationship between changing the bandwidth and the rate of growing particle size of the quantum dot, so that the particles with slow growing rate (CdSe-TGA, 12 h) its bandwidth varies smoothly. Also the magnitude of bandwidth of the spectrum is fairly dependent to the size of the CdSe QDs during the growth process. The quantum dots with larger size (CdSe-MSA) have the fluorescence spectra with broader bandwidth. The trend of the particles growth was discussed in details. Results revealed that the kind of capping agents are considerably influence on the nucleation as well as particle growth processes.

Comprehensive spectroscopy studies of photoelimination process of toxic metals ions from aqueous solution by using CdS and CdS@magnetized powder activated carbon assisted magnetic stir bar.

In this study, a simple and novel photocatalytic tool was proposed and developed for photoelimination of toxic metal ions in aqueous solution. CdS quantum dots capped with thioglycolic acid and CdS @ magnetized powder activated carbon (CdS@MPAC) fixed on magnetic stir bar was constructed and applied for photoelimination of toxic metal ions in aqueous solutions. The production and contribution of hydroxyl (OH) and superoxide (O2-) species generated during photoelimination process were investigated. The photoelimination of Cd(II), Co(II), Cu(II), Mn(II), Ni(II) and Pb(II) metal ions was performed at neutral pH (7.0 ±â€¯0.1) with the same experimental circumstances. Maximum removal efficiency was achieved with 0.360 M of CdS@MPAC under 3.0 h daylight irradiation. Photoelimination mechanisms of Cu2+ with CdS QDs were also investigated. Finally, this method was successfully applied for elimination of toxic metal ions from real sample.

Exploration of charge carrier delocalization in the iron oxide/CdS type-II heterojunction band alignment for enhanced solar-driven photocatalytic and antibacterial applications.

Recyclable magnetic photocatalysts of iron oxide (IO)/CdS core/shell nanocrystals (CSNCs) were prepared by a facile sequential one-pot method using 3, 3'-thiobispropanoic acid (TDP) as a bridge. The CSNCs showed redshift in absorption edge, decrease in the optical band gap, reduced exciton decay rates and increment in particle size. Quenching studies have been employed to understand the position of the electron/hole wave-functions at the IO/CdS interface. Antimicrobial tests have also been performed using broth tube dilution and disc diffusion methods against S. aureus. Additionally, photocatalytic properties of IO/CdS CSNCs have been evaluated for the decomposition of xylenol blue. In comparison with CdS quantum dots (QDs) and iron oxide nanoparticles (IONPs), the IO/CdS CSNCs showed improved photocatalytic and bactericidal activities. Finally, levels of oxidative damage to proteins and lipids were evaluated.

Magnetically Separable Fe3 O4 @CdS Type-II Nanohybrids with Excellent Photocatalytic Activity and Antibacterial Properties.

A magnetically separable Fe3 O4 @CdS type-II core-shell nanohybrid (NH) photocatalyst, with excellent antibacterial properties and photocatalytic activity, was synthesized and characterized by means of structural, elemental, and morphological analyses. Steady-state and time-resolved emission and absorption spectroscopy were also exploited to realize the location of charge-carrier wave functions in the NHs. The antibacterial activity of NHs was then evaluated against Escherichia coli (1.4×108  CFU mL-1 ; CFU=colony forming units) and Staphylococcus saprophyticus (1.2×108  CFU mL-1 ) as model strains of Gram-negative and -positive microbes. Compared with CdS and Fe3 O4 , the as-synthesized Fe3 O4 @CdS composite exhibited highly improved bactericidal activity and recyclability. Concentration values of 5.0 and 4.0 mg mL-1 were required for Fe3 O4 @CdS NHs to inhibit the growth of E. coli and S. saprophyticus, respectively. The contribution of OH. radicals to photocatalysis at the Fe3 O4 @CdS surface was also considered. Moreover, thiobarbituric acid reactive substances and protein carbonyl assay protocols have been exploited to monitor levels of oxidative damage to lipids and proteins in cells. Additionally, the photocatalytic activity of Fe3 O4 @CdS NHs was monitored for the degradation of xylenol orange dye. Compared with CdS and Fe3 O4 , as-synthesized Fe3 O4 @CdS displayed superior performances in the photodegradation of xylenol orange. Possible mechanisms involved in the degradation of xylenol orange are also discussed.

Determination of Diclofenac and N-Acetylcysteine by an Optimized Luminescence Method Using CdS Quantum Dots as Sensitizers.

A simple, sensitive and selective chemiluminescence method is proposed for the determination of Acetylcysteine and Diclofenac in pharmaceutical samples. The method is based on the measuring light intensity of NaHCO3-H2O2 @ CdS chemiluminescence system in the absence and presence of Acetylcysteine and Diclofenac. It was found that the intensity of chemiluminescence is increased by addition of acetylcysteine while the light intensity is decreased with increasing diclofenac concentration. The CdS quantum dots nanoparticles were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometry and Fluorescence spectroscopy. The optimum conditions for maximizing the CL emission intensity were studied by means of a Box-Behnken experimental design combined with response surface modeling (RSM) and quadratic programming. Under the optimal conditions, results for measurement of diclofenac was found as follows: linear range 1 × 10-5 - 1 × 10-9 Molar with R2 = 0.98, limit of detection 5 × 10-10 Molar and relative standard deviation of 2.4% for diclofenac; and for N-acetylcysteine was : linear range 1 × 10-6 - 1 × 10-9 Molar, the limit of detection 5 × 10-10 Molar, and the relative standard deviation of 3.4%.

UV-Vis Spectrophotometry and Multivariate Calibration Method for Simultaneous Determination of Theophylline, Montelukast and Loratadine in Tablet Preparations and Spiked Human Plasma.

Resolution of binary mixtures of theophylline (THEO), montelukast (MKST) and loratadine (LORA) with minimum sample pre-treatment and without analyte separation has been successfully achieved by multivariate spectrophotometric calibration, together with partial least-squares (PLS-1), principal component regression (PCR) and hybrid linear analysis (HLA). Data of analysis were obtained from UV-Vis spectra of three compounds. The method of central composite design was used in the ranges of 2-14 and 3-11 mg L-1 for calibration and validation sets, respectively. The models refinement procedure and their validation were performed by cross-validation. The minimum root mean square error of prediction (RMSEP) was 0.173 mg L-1 for THEO with PCR, 0.187 mg L-1 for MKST with PLS1 and 0.251 mg L-1 for LORA with HLA techniques. The limit of detection was obtained 0.03, 0.05 and 0.05 mg L-1 by PCR model for THEO, MKST and LORA, respectively. The procedure was successfully applied for simultaneous determination of the above compounds in pharmaceutical tablets and human plasma. Notwithstanding the spectral overlapping among three drugs, as well as the intrinsic variability of the latter in unknown samples, the recoveries are excellent.

Selective Determination of Atropine Using poly Dopamine-Coated Molecularly Imprinted Mn-Doped ZnS Quantum Dots.

In this study, a selective method for the determination of atropine in pharmaceutical formulations was proposed. L-cysteine capped Mn-doped ZnS quantum dots (QDs) were prepared in an in-situ method using sodium thiosulfate precursor and characterized by spectrofluorometer, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM) and X-ray diffractometer (XRD). Dopamine hydrochloride was used as a precursor for preparation of poly dopamine-coated molecularly imprinted Mn-doped ZnS quantum dots. Finally, these prepared molecularly imprinted Mn-doped ZnS quantum dots were used for determination of atropine in pharmaceutical formulations. The obtained linear range for determination of atropine was in the range of 2 × 10(-8) - 7 × 10(-6) M, with a correlation coefficient (R(2)) of 0.9889; and the detection limit (S/N = 3) was 3.2 nM.

Determination of Montelukast in Plasma Using ß - Cyclodextrins Coated on CoFe2O4 Magnetic Nanoparticles in Luminol-H2O2 Chemiluminescence System Optimized by Doehlert Design.

A novel chemiluminescence method using ß - cyclodextrins coated on CoFe2O4 magnetic nanoparticles is proposed for the chemiluminometric determination of montelukast in plasma. The effect of coated ß - cyclodexterinon CoFe2O4 magnetic nanoparticles in the chemiluminescence of luminol-H2O2 system was investigated. It was found that ß - cyclodexterin coated on CoFe2O4 magnetic nanoparticles could greatly enhance the chemiluminescence of the luminol-H2O2 system. Doehlert design was applied in order to optimize the number of experiments to be carried out to ascertain the possible interactions between the parameters and their effects on the chemiluminescence emission intensity. This design was selected because the levels of each variable may vary in a very efficient way with few experiments. Doehlert design and response surface methodology have been employed for optimization pH and concentrations of the components. Results showed under the optimized experimental conditions, the relative CL intensity (ΔI) is increased linearly in the concentration range of 0.003-0.586 µgml(-1) of montelukast with limit of detection (LOD) 1.09 × 10(-4) µgml(-1) at S/N ratio of 3, limit of quantitative (LOQ) 3.59 × 10(-4) µgml(-1) and the relative standard deviation 2.63 %. The method has been successfully applied to the determination of montelukast in plasma of human body. Results specified that relative chemiluminescence intensity (ΔI) has good proportional with the montelukast concentration with R(2) = 0.99979. The test of the recovery efficiency for known amounts of montelukast was also performed, the recoveries range obtained from 98.2 to 103.3 %, with RSDs of <4 % indicated that the proposed method was reliable.

In-situ synthesis of high stable CdS quantum dots and their application for photocatalytic degradation of dyes.

Photocatalysis based on semiconductor quantum dots, which utilize the solar energy can be used for elimination of pollutants from aqueous media and applied for water purification. In this paper, high stable CdS quantum dots (QDs) with good optical properties were successfully synthesized in a facile in-situ method, using Na2S2O3 as precursor and thioglycolic acid (TGA) as a catalyst, as well as capping agent in aqueous media. The synthesis process was optimized with a 2IV(7-3) fractional factorial design method. Then, we studied the degradation of some industrial dyes including: alizarin, acid violet, mordant red and thymol blue as a tool to check the photocatalytic activity of synthesized CdS QDs. Results specified that the synthesized CdS QDs are capable for degradation of organic dyes under visible light irradiation with good recycling stability during photocatalytic experiments. Structural and spectroscopic properties of the synthesized CdS QDs were studied by TEM, XRD and absorption and fluorescence spectroscopy techniques. The synthesized TGA-capped CdS QDs have sizes in the range of 2.65-2.93nm with cubic crystalline structures.

Sol-gel based optical sensor for determination of Fe (II): a novel probe for iron speciation.

A highly selective optical sensor for Fe (II) ions was developed based on entrapment of a sensitive reagent, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), in a silica sol-gel thin film coated on a glass substrate. The thin films fabricated based on tetraethoxysilane (TEOS) as precursor, sol-gel pH∼3, water:alkoxyde ratio of 4:1 and TPTZ concentration of 0.112 mol L(-1). The influence of sol-gel parameters on sensing behavior of the fabricated sensor was also investigated. The fabricated sensor can be used for determination of Fe (II) ion with an outstanding high selectivity over a dynamic range of 5-115 ng mL(-1) and a detection limit of 1.68 ng mL(-1). It also showed reproducible results with relative standard deviation of 3.5% and 1.27% for 10 and 90 ng mL(-1) of Fe (II), respectively, along with a fast response time of ∼120 s. Total iron also was determined after reduction of Fe (III) to Fe (II) using ascorbic acid as reducing agent. Then, the concentration of Fe (III) was calculated by subtracting the concentration of Fe (II) from the total iron concentration. Interference studies showed a good selectivity for Fe (II) with trapping TPTZ into sol-gel matrix and appropriately adjusting the structure of doped sol-gel. The sensor was compared with other sensors and was applied to determine iron in different water samples with good results.

Trace analysis of N-acetyl-L-cysteine using luminol-H2O2 chemiluminescence system catalyzed by silver nanoparticles.

N-Acetyl-L-cysteine (NAC) can inhibit the luminol-H2 O2 , reaction, which is catalyzed by silver nanoparticles. Based on this phenomenon a new method was developed for NAC determination. Under optimum conditions, a linear relationship between chemiluminescence intensity and NAC concentration was found in the range 0.034-0.98 µg/mL. The detection limit was 0.010 µg/mL (S/N =3), and the relative standard deviation (RSD) was <5% for 0.480 µg/mL NAC (n =5). This simple, sensitive and inexpensive method has been applied to measure the concentration of NAC in pharmaceutical tablets.

A highly efficient turn-on fluorescent sensor for determination of water in organic solvents.

2, 3 biphenyl quinoxaline 6-amine is a fluorescent compound in some organic solvents with an excitation wavelength at 435 nm and a fluorescence emission at 518 nm. The fluorescence intensity of 2, 3 biphenyl quinoxaline 6-amine is significantly reduced in the presence of bis-(2, 4, 6-trichlorophenyl) oxalate (TCPO) and Zn(2+) due to the nonfluorescent complex formation. The low stability of the complex in presence of trace amount of water results in decomposing complex, thereby recovering the photoluminescence of 2, 3 biphenyl quinoxaline 6-amine. Based on this fact, a turn-on fluorescence photoluminescence sensor for determination of water content in organic solvents was introduced for the first time.The fluorescence intensity of 2, 3 biphenyl quinoxaline 6-amine as a function of water concentration was used as a simple, sensitive and rapid method for determining trace amount of water in some organic solvents such as ethanol and methanol. The obtained results showed a good linear relationship between fluorescence intensity and the water content with a dynamic range of 0.0094 -1(v/v%), related coefficient of 0.9922 and limit of detection of 0.0026(v/v%). %).

In situ incorporation of nickel nanoparticles into the mesopores of MCM-41 by manipulation of solvent-solute interaction and its activity toward adsorptive desulfurization of gas oil.

In this contribution, different amounts of nickel were incorporated into the mesopores of MCM-41 via an in situ approach. A hydrophobic nickel precursor was incorporated into the nanochannels of mesoporous silica by manipulation of solvent-solute interaction. The synthesized material was characterized using X-ray diffraction, nitrogen physisorption, temperature programmed reduction, and transmission electron microscopy. The results implicate the formation of MCM-41 with well-ordered hexagonal structure and establish also the presence of nickel nanoparticles inside the nanochannels of mesoporous silica. Adsorptive desulfurization of gas oil was conducted using the nickel-incorporated MCM-41 samples. The effects of nickel concentration, temperature of process and feed flow rate on the desulfurization process were examined. The MCM-41 containing 6 wt.% of nickel had both the highest breakthrough sulfur adsorption capacity and total sulfur adsorption capacity, which were 0.69 and 1.67 mg sulfur/g adsorbent, respectively. The breakthrough sulfur adsorption capacity was almost regained after reductive regeneration of spent adsorbent. The obtained results suggest that the method applied for the synthesis of Niy/MCM resulted in formation of well-dispersed, accessible and small nickel nanoparticles incorporated into the pores of MCM-41 which might be an advantage for adsorption of refractory sulfur compounds from low sulfur gas oil.

Studies of new peroxyoxalate-H2O2 chemiluminescence system using quinoxaline derivatives as green fluorophores.

Quinoxaline derivatives are a great interest as fluorescent emitters for peroxyoxalate chemiluminescence. Reaction of peroxyoxalates such as bis-(2,4,6-trichlorophenyl) oxalate with H(2)O(2) can transfer energy to fluorophore via formation of dioxetanedione intermediate. Two quinoxaline derivatives used as a fluorophore in this study which produce a green light in the chemiluminescence systems. The relationship between the chemiluminescence intensity and concentrations of fluorophore, peroxyoxalate, sodium salicylate and hydrogen peroxide was investigated. Kinetic parameters for the peroxyoxalate-chemiluminescence were also calculated from the computer fitting of the corresponding chemiluminescence intensity/time profiles. It was found that the biphenylquinoxaline can be used as an efficient green fluorescent emitter.

Simultaneous determination of paracetamol, phenylephrine hydrochloride and chlorpheniramine maleate in pharmaceutical preparations using multivariate calibration 1.

Resolution of binary mixtures of paracetamol, phenylephrine hydrochloride and chlorpheniramine maleate with minimum sample pre-treatment and without analyte separation has been successfully achieved by methods of partial least squares algorithm with one dependent variable, principal component regression and hybrid linear analysis. Data of analysis were obtained from UV-vis spectra of the above compounds. The method of central composite design was used in the ranges of 1-15 mg L(-1) for both calibration and validation sets. The models refinement procedure and their validation were performed by cross-validation. Figures of merit such as selectivity, sensitivity, analytical sensitivity and limit of detection were determined for all three compounds. The procedure was successfully applied to simultaneous determination of the above compounds in pharmaceutical tablets.

(31)P and (27)Al NMR studies of aqueous (2-hydroxyethyl) trimethylammonium solutions containing aluminum and phosphorus.

Phosphorus-31 and aluminum-27 nuclear magnetic resonance techniques have been used to characterize the distribution of soluble aluminophosphate species in aqueous solutions of (2-hydroxyethyl) trimethylammonium chloride (2-HETMACl), phosphoric acid, and aluminum sulfate. Soluble aluminophosphate cations obtain from reactions of hexaaqua aluminum cations [A1(H(2)O)(6)](3+), with phosphate ligands (i.e., H(3)PO(4), H(2)PO(4)(-), and acid dimers H(6)P(2)O(8) and H(5)P(2)O(7)(-)). (31)P NMR and (27)Al NMR spectroscopies are very powerful techniques for characterization of the species present in the solution. A number of solutions containing different mole ratio of Al/P were prepared. The assignment of the peaks to aluminate connectivities is attempted, clarifying earlier works and producing information on the equilibrium between various aluminum-containing species (different aluminophosphate complexes). At least seven separated resonances were observed by (31)P NMR spectroscopy indicating presence of different complexes in aluminum phosphate solutions.