Photocatalytic Removal of Toluene Vapour Pollutant from the Air Using Titanium Dioxide Nanoparticles Supported on the Natural Zeolite.

Background: The emission of volatile organic compounds (VOCs) in industrial and urban areas has adverse effects on the environment and human health. Toluene, the main pollutant among the VOCs, has wide applications in different industries such as plastics, adhesives, silicone sealant, paint, etc. This study aimed to remove of toluene from the air by using TiO2 nanoparticles supported on the natural zeolite using the photo-catalytic process. Methods: This is an experimental study that was conducted in 2017 in the Chemical Agents Laboratory of the Occupational Health Engineering Department at Jundishapur University in Ahvaz. Toluene vapour decomposition was carried out using UV/ZE, UV/TiO2, and UV/TiO2-ZE under continuous flows conditions. The effects of toluene initial concentration, retention time, and nanocomposite surface weight on toluene vapour decomposition were also investigated. Results: When UV/TiO2 and UV/TiO2-ZE systems are performed, increasing the initial toluene concentration reduces the efficiency of photocatalytic decomposition. The SEM images of TiO2-ZE catalyst show that zeolite pores were occupied by titanium dioxide nanoparticles. Moreover, the combination of titanium dioxide nanoparticles and zeolite has an incremental effect on toluene decomposition. Increasing retention time raises toluene decomposition, and the increased nanocomposite surface weight raises decomposition to the maximum level (70%) at 33.68 mg/cm2 weight and then decreases. Conclusion: The increasing toluene decomposition rate by using the TiO2-ZE nanocomposite can be due to the incremental effect of absorption and photocatalytic decomposition.

A nano curcumin-multi-walled carbon nanotube composite as a fluorescence chemosensor for trace determination of celecoxib in serum samples.

A novel method is presented here for trace determination of celecoxib by fluorescence detection using curcumin nanoparticles (CurNPs) loaded on multi-walled carbon nanotubes with carboxyl functional groups (CurNPs-MWCNT-COOH). For the synthesis of CurNPs-MWCNT-COOH, CurNPs were retained on carbon nanotubes with the aid of ultrasound waves. The sensing method is based on monitoring the quenching of synthesized CurNPs-MWCNT-COOH fluorescence by celecoxib. The morphology of CurNPs-MWCNT-COOH was studied by transmission electron microscopy (TEM) of the composite alone and in the presence of celecoxib. The effects of several parameters on the production of CurNPs-MWCNT-COOH and determination of celecoxib such as the Triton X-100 concentration, the amount of MWCNT-COOH and the pH were evaluated and optimum conditions were established. The calibration graph was found to be linear in the range of 20-220 ng mL-1 for celecoxib in the initial solution. The detection limit based on three times the standard deviation of the blank was 5.8 ng mL-1 for celecoxib and relative standard deviations (RSD) of 3.6% and 1.8% were obtained for eight replicate determinations of 60 ng mL-1 and 180 ng mL-1 of celecoxib, respectively. The method was applied to the determination of celecoxib in serum samples.

Experimental and modeling analyses of COD removal from industrial wastewater using the TiO2-chitosan nanocomposites.

In the present study, titanium oxide (TiO2) nanoparticles, chitosan, and several nanocomposites containing different mass dosages of TiO2 and chitosan have been applied as the adsorbent for COD removal from the industrial wastewater (Bouali Sina Petrochemical Company, Iran). The FESEM, XRD, and FTIR tests have been employed to characterize TiO2 nanoparticles, chitosan, and fabricated nanocomposites. Then, the effect of adsorption parameters, including TiO2-chitosan mass ratio (1:1, 1:2, and 2:1), adsorbent content (0.25-2.5 g), temperature (20-50 °C), pH (3-11), solution volume (100-500 mL), and contact time (30-180 min) on the COD reduction has also been monitored both experimentally and numerically. The Box-Behnken design of the experiment approves that TiO2-chitosan (1:1), adsorbent content of 2.5 g, temperature = 20 °C, pH 7.4, solution volume of 100 mL, and contact time = 180 min are the condition that maximizes the COD removal (i.e., 94.5%). Moreover, the Redlich-Peterson and Pseudo-second order models are the best isotherm and kinetic scenarios to describe COD removal's transient and equilibrium behaviors. The maximum monolayer COD adsorption capacity of the TiO2-chitosan nanocomposite is 89.5 mg g-1. The results revealed that the industrial wastewater COD is better to remove using the TiO2-chitosan (1:1) at temperature = 20 °C.

Modulation of the toxic effects of zinc oxide nanoparticles by exogenous salicylic acid pretreatment in Chenopodium murale L.

Due to many uses of zinc oxide nanoparticles (ZnO NPs) in various industries, the release of these particles in the environment and their effects on living organisms is inevitable. In this study, the role of salicylic acid (SA) pretreatments in modulating the toxicity of ZnO NPs was investigated using a hydroponic system. After pretreatment with different concentrations of SA (0, 25, 75, and 150 µM), Chenopodium murale plants were exposed to ZnO NPs (50 mg L-1). The results showed that exogenous SA increased the length, weight, chlorophyll, proline, starch, and soluble sugars in the plants. Besides, SA pretreatments improved water status in the plants treated with ZnO NPs. In SA-pretreated plants, increased activity of catalase (CAT), guaiacol peroxidase (GPX), and superoxide dismutase (SOD) was associated with a decline in electrolyte leakage (EL %) and membrane peroxidation. Under NPs stress, SA pretreatments increased the content of phenolic compounds by increasing the activity of phenylalanine ammonia-lyase (PAL). Exogenous SA reduced the translocation of larger amounts of Zn to the shoots, with more accumulation in the roots. This result can be used to produce healthy food from plants grown in environments contaminated with nanoparticles. It seems that all concentrations of SA reduced the symptoms of ZnO NPs toxicity in the plant by strengthening the function of the antioxidant system and increasing the content of some metabolites. Findings also suggest that SA pretreatment can compensate for the growth reduction caused by ZnO NPs.

Determination of Tetracycline Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplet Followed by HPLC-UV System.

BACKGROUND: Tetracyclines (TCs) are a group of broad-spectrum antibiotics that may be used to control bacterial diseases in humans or are applied as feed additives to enhance growth in farm animals. TCs are released into the aquatic environment via different pathways. Many analytical methods combined with a preconcentration step have been introduced for the determination of TC in various environmental samples. OBJECTIVE: The objective this paper is developing reliable analytical methods for determination of TC trace in various environmental samples. METHOD: In the present work, combined ultrasound-assisted and dispersive liquid-liquid microextraction according to the solidification of floating organic drop as a sample preconcentration procedure for determining TC hydrochloride HPLC in water and serum samples was used. RESULTS: A series of parameters, including the type and volume of disperser and extraction solvents, salt effect, extraction time, and pH of solution influencing the extraction efficiency of UA-DLLME-SFO was examined. Enrichment factors were in the range of 125-137 for TC hydrochloride under optimum conditions. The linear range was calculated from 0.005 to 3 mg/L and LOD at 0.002 mg/L. RSDs were in the range of 2.7 to 3.2 (n = 5). The UA-DLLME-SFO method used in water and serum samples revealed good extraction recoveries with RSD of 2.7-4.3%. CONCLUSIONS: This method significantly decreased the organic solvent volume from 3 mL to 90 µL, also LOD and linear ranges were lower than or almost close to levels obtained in other research studies. In this procedure, an ultrasound bath enhanced the mixing and contact between the sample solution and the extraction solvent.

Dendrimer-modified magnetic nanoparticles as a sorbent in dispersive micro-solid phase extraction for preconcentration of metribuzin in a water sample.

This study was conducted to synthesize magnetic nanoparticles (MNPs) modified with generation 5 (G5) polyamidoamine (PAMAM) dendrimer and apply them as a sorbent in the dispersive-micro-solid phase extraction (D-µ-SPE) method for preconcentration of metribuzin in water samples. The characterization of synthesized nanoparticles was performed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), and vibrating sample magnetometry (VSM). The effects of sample solution pH, the terminal group type, dendrimer generation, ionic strength, sorbent dosage, and desorption conditions on the removal efficiency were investigated. The linear range was calculated from 25-1000 µg L-1 and the LOD was 10 µg L-1. The recovery percentages for the spiked real samples ranged from 95.3% to 103.5% and relative standard deviations (RSD%) were in the range of 87.2-92.1 and 4.2 to 6.3 (n = 5) respectively. Applying the method developed in this work in water samples revealed good extraction recoveries with a RSD of 5.6-7.3%.

ZnO nanoparticles-induced oxidative stress in Chenopodium murale L, Zn uptake, and accumulation under hydroponic culture.

To understand toxic effect of Zn oxide nanoparticles (ZnO NPs) on Chenopodium murale, 40-day-old plants were exposed to 10, 50, and 250 mg L-1 of NPs using hydroponic system under controlled light and temperature conditions. Aboveground parts and roots were harvested 3 and 6 days after treatments and evaluated for some growth and biochemical indices. By increasing the concentration of ZnO NPs, the content of Zn increased in the roots more than the shoots. Our findings showed that all ZnO NPs treatments resulted in a decrease in growth, total chlorophyll content and soluble proteins, while the content of carotenoids, lipid peroxidation, leaf hydrogen peroxide (H2O2), and leaf electrolyte leakage increased significantly compared with the control. These changes, along with increased proline content and catalase (CAT), guaiacol peroxidase (GPX), and superoxide dismutase (SOD) activities in the treated plants, suggest that all concentrations of ZnO NPs used in this study strongly induced oxidative stress. A decline in growth-related indicators can be considered as an indicator of ZnO NPs phytoxicity in C. murale. Based on the concentration of Zn dissolved in the solution, the effects of Zn released into the nutrient solution may be greatly involved in induction of toxicity and retardation of growth at least under our experimental conditions. The results of this study suggest that an important mechanism of ZnO NPs phytotoxicity may be the exacerbation of oxidative stress and damage to biomembranes.

Separation and pre-concentration of Sunset Yellow in beverages and effervescent vitamin C tablets by a new flotation technique prior to spectrophotometric determination.

A new, simple, low cost, high efficiency, and rapid floating technique was developed for the determination of Sunset Yellow in beverage and effervescent vitamin C. The method is based on two main steps: 1)- formation of dye-surfactant complex by the addition of a cationic surfactant, cetyltrimethylammonium bromide, to the solution containing an anionic dye (Sunset Yellow) and 2)- flocculation of the dye-surfactant complex with the participation of sodium perchlorate as a coagulant followed by aggregation and enlargement of the flocs while floating at the top of the solution. After the extraction, separated and preconcentrated Sunset Yellow was investigated by spectrophotometric determination. IR spectrum, scanning electron microscopy (SEM), and light microscopy were used to characterise the flocs. The effects of different parameters such as pH, concentration of surfactant, concentration of sodium perchlorate, and temperature on the extraction of dye were investigated and optimized. Under optimum conditions, a linear calibration curve was obtained in the range of 0.05-5 mg L-1. The detection limit (3Sb/m) was 0.02 mg L-1 with a preconcentration factor of 25. The relative standard deviation (RSD) for 0.1 mg L-1 of Sunset Yellow was 2.6% (n = 10). The applicability of the method was evaluated by measuring the amount of dye in beverage and effervescent vitamin C. Interferences of typical cations and anions which may participate in the matrices were also checked. The amount of Sunset Yellow found in real samples was 1.32-3.89 mgL-1.

Novel magnetic hollow zein nanoparticles for preconcentration of chlorpyrifos from water and soil samples prior to analysis via high-performance liquid chromatography (HPLC).

Herein, magnetically hollow zein nanoparticles were synthesized and used as a magnetic sorbent for the preconcentration of chlorpyrifos and its analysis by high-performance liquid chromatography (HPLC). Morphology of the sorbent was characterized by transmission electron microscopy (TEM). In this study, the effects of important parameters such as pH of the solution, adsorption and desorption time, type and volume of desorption solvent, and salt addition were investigated. Under optimized experimental conditions, the linear range was from 50 to 2000 µg mL-1, and an LOD of 25 µg L-1 was calculated. The relative standard deviations (RSD) varied from 3.8 to 5.1% (n = 5). The enrichment factors for 50 and 100 µg L-1 samples were calculated as 187 and 210, respectively. The developed method was successfully applied in soil and water samples and showed good extraction recoveries.

Hollow Fiber Liquid Based Microextraction of Nalidixic Acid in Urine Samples Using Aliquat 336 as a Carrier Combined with High-Performance Liquid Chromatography.

A new and simple hollow fiber liquid-phase microextraction was used in conjunction with HPLC for the extraction and quantitative determination of nalidixic acid (NA) in human urine samples. This study considers this technique an alternative to common methods of hollow fiber microextraction based on pH gradient and electromembrane extraction of NA in human urine samples. In this research, the drug was extracted from the source phase (donor phase) into a modified organic phase with Aliquat 336 (hydrophobic ion-pair reagent) as a carrier able to impregnate pores of the hollow fiber. In this study, the effects of several factors were tested on the extraction efficiency of the drug. Under optimum conditions, the linearity of the method was observed over the range 0.05-2.0 µg mL(-1) with a correlation coefficient of r = 0.9983. The results of tests on the method determined a good sensitivity with a limit of detection of 0.008 µg mL(-1). The intra-day relative standard deviation (n = 9) for 0.8 µg mL(-1) was 6.2%, and the inter-day relative standard deviation (n = 5) for 0.8 µg mL(-1) was 5.6%. This new strategy was successfully applied to analyze a real urine sample with satisfactory results.

Zinc oxide nanostructure-modified textile and its application to biosensing, photocatalysis, and as antibacterial material.

Recently, one-dimensional nanostructures with different morphologies (such as nanowires, nanorods (NRs), and nanotubes) have become the focus of intensive research, because of their unique properties with potential applications. Among them, zinc oxide (ZnO) nanomaterials has been found to be highly attractive, because of the remarkable potential for applications in many different areas such as solar cells, sensors, piezoelectric devices, photodiode devices, sun screens, antireflection coatings, and photocatalysis. Here, we present an innovative approach to create a new modified textile by direct in situ growth of vertically aligned one-dimensional (1D) ZnO NRs onto textile surfaces, which can serve with potential for biosensing, photocatalysis, and antibacterial applications. ZnO NRs were grown by using a simple aqueous chemical growth method. Results from analyses such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that the ZnO NRs were dispersed over the entire surface of the textile. We have demonstrated the following applications of these multifunctional textiles: (1) as a flexible working electrode for the detection of aldicarb (ALD) pesticide, (2) as a photocatalyst for the degradation of organic molecules (i.e., Methylene Blue and Congo Red), and (3) as antibacterial agents against Escherichia coli. The ZnO-based textile exhibited excellent photocatalytic and antibacterial activities, and it showed a promising sensing response. The combination of sensing, photocatalysis, and antibacterial properties provided by the ZnO NRs brings us closer to the concept of smart textiles for wearable sensing without a deodorant and antibacterial control. Perhaps the best known of the products that is available in markets for such purposes are textiles with silver nanoparticles. Our modified textile is thus providing acceptable antibacterial properties, compared to available commercial modified textiles.

Colorimetric disposable paper coated with ZnO@ZnS core-shell nanoparticles for detection of copper ions in aqueous solutions.

In this study, we have proposed a new nanoparticle-containing test paper sensor that could be used as an inexpensive, easy-to-use, portable, and highly selective sensor to detect Cu(2+) ions in aqueous solutions. This disposable paper sensor is based on ZnO@ZnS core-shell nanoparticles. The core-shell nanoparticles were synthesized using a chemical method and then they were used for coating the paper. The synthesis of the ZnO@ZnS core-shell nanoparticles was performed at a temperature as low as 60 °C, and so far this is the lowest temperature for the synthesis of such core-shell nanoparticles. The sensitivity of the paper sensor was investigated for different Cu(2+) ion concentrations in aqueous solutions and the results show a direct linear relation between the Cu(2+) ions concentration and the color intensity of the paper sensor with a visual detection limit as low as 15 µM (∼0.96 ppm). Testing the present paper sensor on real river turbulent water shows a maximum 5% relative error for determining the Cu(2+) ions concentration, which confirms that the presented paper sensor can successfully be used efficiently for detection in complex solutions with high selectivity. Photographs of the paper sensor taken using a regular digital camera were transferred to a computer and analyzed by ImageJ Photoshop software. This finding demonstrates the potential of the present disposable paper sensor for the development of a portable, accurate, and selective heavy metal detection technology.

Copper nanoparticles: a new colorimetric probe for quick, naked-eye detection of sulfide ions in water samples.

This study introduces a new method for the visual and spectrophotometric detection of chemical species using copper nanoparticles (Cu NPs). A simple method for the synthesis of Cu NPs for rapid colorimetric visual detection of sulfide ions (S(2-)) in water samples is described. The Cu NPs sensor detects sensitive and selective color change in the presence of micromolar levels of S(2-) that can be observed with the naked eye and monitored using a UV-vis spectrophotometer. The color change quantitatively correlates with the concentration of S(2-) from 12.5 × 10(-6)M to 50.0 × 10(-6)M. Samples of tap water and river water were spiked and analyzed using the proposed system. The results showed that the sensor exhibited excellent detection for S(2-) in the water samples. A main advantage of the new method is that it provides good selectivity for detecting S(2-) without the need for complex readout equipment. The proposed method has a high potential for rapid environmental monitoring of sulfide ions.

Localized surface plasmon resonance of gold nanoparticles as colorimetric probes for determination of Isoniazid in pharmacological formulation.

Isoniazid is an important antibiotic, which is widely used to treat tuberculosis. This study presents a colorimetric method for the determination of Isoniazid based on localized surface plasmon resonance (LSPR) property of gold nanoparticles. An LSPR band is produced by reducing gold ions in solution using Isoniazid as the reducing agent. Influences of the following relevant variables were examined and optimized in the experiment, formation time of gold nanoparticles, pH, buffer and stabilizer. These tests demonstrated that under optimum conditions the absorbance of Au nanoparticles at 530 nm related linearly to the concentration of Isoniazid in the range of 1.0-8.0 µg mL(-1) with a detection limit of 0.98 µg mL(-1). This colorimetric method has been successfully applied to the determine Isoniazid in tablets and spiked serum samples. The proposed colorimetric assay exhibits good reproducibility and accuracy, providing a simple and rapid method for analysis of Isoniazid.

Validity of bioconjugated silica nanoparticles in comparison with direct smear, culture, and polymerase chain reaction for detection of Mycobacterium tuberculosis in sputum specimens.

BACKGROUND: Tuberculosis is a public health problem worldwide, and new easy to perform diagnostic methods with high accuracy are necessary for optimal control of the disease. Recently, fluorescent silica nanoparticles (FSNP) has attracted immense interest for the detection of pathogenic microorganisms. The aim of this study was to detect Mycobacterium tuberculosis in clinical samples using bioconjugated FSNP compared with microscopic examination, polymerase chain reaction (PCR), nested PCR, and culture as the gold standard. METHODS: In total, 152 sputum specimens were obtained from patients who were suspected to have pulmonary tuberculosis. All samples were examined by the four techniques described. RESULTS: The assay showed 97.1% sensitivity (95% confidence interval [CI] 91-99.2) and 91.35% specificity (CI 78.3-97.1). Furthermore, assays using variable bacterial concentrations indicated that 100 colony forming units/mL of M. tuberculosis could be detected. There were no differences between the results obtained from two types of mouse monoclonal antibody against Hsp-65 and 16 KDa antigens. CONCLUSION: We performed this assay in a large number of clinical samples to confirm the diagnostic specificity and sensitivity of the test and can recommend its application for diagnosis of M. tuberculosis. We believe that this method is more convenient for routine diagnosis of M. tuberculosis in sputum and will be more easily applicable in the field, and with sufficient sensitivity.