Diphenylcarbazide Research Articles

Reactive Condensation of Cr Vapor on Aluminosilicates Containing Alkaline Oxides

This study is part of a series with the objective of improving fundamental understanding of reactive condensation of Chromium (Cr) vapors, which are generated from Cr containing alloys used in many high-temperature (>500 °C) process environments and can form potentially problematic condensed hexavalent (Cr(VI)) species downstream. This study specifically focuses on the effects of alkaline oxide additives in aluminosilicate fibers on Cr condensation and speciation. Cr vapors were generated by flowing high-temperature (800 °C) air containing 3% water vapor over chromia (Cr2O3) powder, with aluminosilicate fiber samples positioned downstream where the temperature decreases (<500 °C). Total condensed Cr and ratios of oxidation states were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES) and diphenyl carbazide (DPC) colorimetric/direct UV–vis spectrophotometric analyses. Results indicate presence of hexavalent Cr (Cr(VI)) species condensed on all samples investigated. The ratio of Cr(VI) to total Cr detected was consistently higher on aluminosilicate fiber samples containing alkaline oxide (CaO and MgO) additions. Computational thermodynamic equilibrium modelling corroborated experimental results showing stabilities of Ca and Mg chromate (Cr(VI)) compounds. Comparative results and analyses are presented and discussed to help inform mechanistic understanding and future related research and engineering efforts.

(Digital Presentation) Reactive Evaporation of Cr Vapors from Chromia-Alkaline Oxide Mixtures Generated in 800℃ Air and Subsequent Condensation Onto Aluminosilicate Fibers

This research aims to improve fundamental understanding of the reactive evaporation and condensation of Chromium (Cr) vapors, which are generated from Cr containing alloys used in many high-temperature (>500℃) process environments and can form potentially problematic condensed hexavalent (Cr(VI)) species downstream. This study focuses on the effects of alkaline oxides present in the Cr source on the resultant Cr evaporation and condensation. Vapor species were generated by flowing high-temperature (800℃) air containing 3% water vapor over chromia (Cr2O3) and mixtures of chromia with calcium oxide (CaO) or magnesium oxide (MgO) powders. Lab-grade quartz and alumina fiber samples were positioned downstream from the Cr-alkaline oxide source where the temperature decreases (<500℃) to collect condensed vapor species. Total condensed Cr and ratios of oxidation states were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES) and diphenyl carbazide (DPC) colorimetric/direct UV-VIS spectrophotometric analyses. Preliminary results indicate a decrease in partial pressures of generated Cr vapor species as well as a decrease in condensed Cr species on the aluminosilicate fibers when alkaline oxides are present in the Cr source compared to a pure Cr source. These results also indicate presence of hexavalent Cr (Cr(VI)) species condensed on all samples investigated. Computational thermodynamic equilibrium modelling corroborated the experimental results showing partial pressures of produced vapor species in the presence of alkaline oxides as well as stabilities of condensed Cr compounds on the fiber samples. Comparative results and analyses are presented and discussed to help inform mechanistic understanding and future related research and engineering efforts. Figure 1

Identification of Bacteria Capable of Chromium Bioremediation from the Environment

With the increased urbanization and industrial development, the environment is getting polluted severely day by day. In Bangladesh, the capital city Dhaka is surrounded by a circular river system, most of which are highly polluted due to discharge of municipal and industrial untreated waste water that has been overloaded with different types of toxic heavy metals. Cr (VI) being used in various activities of industries and its improper treatment lead to contamination of the environment. This study aimed to isolate bacteria with chromium bioremediation potential from the environment. A total of 71 bacteria were isolated, of which all grew in the presence of 100 ppm, 93% in 200 ppm, 46% in 400 ppm, 6% in 600 and 4% in 1000 ppm chromium. Fourteen bacteria selected for chromium reduction by Diphenyl Carbazide Assay showed 23-89% reduction. Of these 14 isolates, 5 were tested for biosorption of chromium. Variable sorption of upto 69% was observed. The 16s rDNA of 6 candidate bacteria were sequenced. These isolates were identified as Kurthia gibsonii, Acinetobacter schindleri, Pseudomonas aeruginosa, Exigubacterium sp., Rhodococcus sp., and Bacillus sp. The reduction potential was found to be highest for Bacillus species (78%) and lowest for Kurthia gibsonii (4.8%). This study has successfully identified six potential bacterial candidates for the bioremediation of chromium (VI). Further research into the mechanisms adopted by these bacteria and genetic manipulation will help to formulate a single or mixture of isolates that can efficiently remove hexavalent chromium from polluted water. Plant Tissue Cult. &amp; Biotech. 34(1): 71-81, 2024 (June)

Uncovering an effecient binary system as a chemosensor for visual and fluorescence detection of chromium (VI) in water samples

There is an urgent requirement for the development of sensitive and quick sensors to monitor chromium (VI) due to its substantial carcinogenic and mutagenic properties. A coexisting system of coumarin 334 and diphenylcarbazide (C334/DPC) was used in this study as a fluorescent chemosensor to detect Cr(VI) ions. Upon the addition of Cr(VI), a purple chelate complex (Cr(III)-diphenylcarbazone) was produced, which resulted from the quantitative reaction between Cr(VI) ions and diphenylcarbazide (DPC), whereas no interaction between Cr(VI) and coumarin 334 took place. More interestingly, the absorption spectra of purple (Cr(III)-diphenylcarbazone) complex (λmax = 540 nm) were overlapped with emission and excitation spectra of coumarin 334 (λex/em = 453/492), resulting in the efficient quenching of coumarin 334 (C334) via the inner filter effect. Furthermore, the semi-quantitative estimation of Cr(VI) ion concentration may be achieved by visually watching the progressive color transformation of the probe from yellow to red after the addition different concentration of Cr(VI). The calibration plot for determination of Cr(VI) by this method is ranging from 0.048 to 268 μM. DFT calculations were conducted to enrich our understanding about the mechanism of action. This approach demonstrates an excellent selectivity and sensitivity for Cr(VI) including a detection limit of 48 nM. The new sensor was successfully applied to water samples (tap, mineral, and waste waters). The accuracy was confirmed by the atomic absorption spectroscopy.

Leachability of hexavalent chromium from fly ash-marl mixtures in Sarigiol basin, Western Macedonia, Greece: environmental hazard and potential human health risk

Hexavalent chromium (Cr (VI)) is an environmental contaminant brining high concerns due to its higher toxicity and mobility in comparison with trivalent chromium Cr(III). Cr (VI) has been linked with several adverse health effects, including respiratory diseases, lung cancer, and skin irritation. The primary sources of it in the environment are industrial activities.Most of the time, fly ash made of lignite can release Cr(VI) when it comes into contact with water in an aquatic environment. The objective of this study is the investigation of Cr (VI) concentration in leachates of fly ash and marl mixtures and the determination of its solubility under different pH conditions. Samples of fly ash were collected from the Power Plant of Agios Dimitrios. Additionally, samples of marl were collected from the mine of South Field, and both samples were mixed and prepared in in different proportions (% w.t.). The leaching experiments were carried out according to the EN-12457/1-4 (2003) standard under different pH conditions and chemical analysis of the leachates were performed by spectrophotometry with diphenylcarbazide (DPC). The environmental footprint of Cr (VI) in the study area was significant, especially in mixtures containing higher concentrations of fly ash. A critical pH range between 6 to 12 is observed. At acidic pH values, a high release of Cr (VI) was observed, while at the mentioned critical values (pH 10–12), a gradual decrease in its leachability was noticed. The high concentrations of Cr (VI) in the industrial area studied require immediate actions in terms of managing and limiting the potential hazardous impacts on the environment and by extension on the public health by developing appropriate prevention strategies.Graphical abstract

Treatment of acidic electroplating effluent from small scale industries using batch and continuous flow adsorption reactor

If electroplating effluent discharges aren’t properly treated, they have a detrimental effect on the aquatic ecology. The effluent characteristics comprise heavy metals that were toxic and causes carcinogenic effects. Among the conventional methods, adsorption being the most economically viable and technically straightforward. This study focuses on the removal of hexavalent chromium ion from the electroplating effluent using commercial activated carbon in both batch and continuous flow experiments. In column studies, various grades of commercial activated carbon were tested, with 80 × 200 mesh size yields complete Cr6+ removal. The batch study revealed that 83% removal was achieved at 5g of 80 × 200 mesh size activated carbon. The isotherm studies indicated a better fit with the Langmuir model and kinetics studies indicated pseudo-second order kinetics. Continuous flow experiments with an 80 × 200 mesh size activated carbon bed showed an upward trend in pH. However, Cr6+ removal efficiency decreased over time. UV–vis spectroscopy using the Diphenyl carbazide method confirmed Cr6+ concentrations. Morphological and elemental analyses were conducted using SEM and Edax, revealing significant changes before and after treatment. These findings underscore the effectiveness of activated carbon in mitigating the environmental impact of electroplating effluents, particularly in Cr6+ removal.

Reaction Stability Test of Hexavalent Chromium Complex with 1,5-Diphenylcarbazide in Analysis using UV Visible Spectrophotometer

A reaction stability test of hexavalent chromium complex with 1,5-diphenyl carbazide in analysis using a UV Visible Spectrophotometer has been done in this study. This study aims to find out the colored complex stability for the reaction of chromium hexavalent and diphenyl carbazide in the analysis of hexavalent chromium using a UV Vis spectrophotometer in terms of time. The sample was measured in 540 nm of wavelength with 10, 30, 60, 90, 120, and 180-minute time intervals. Each interval was carried out with two times replications. There were no significant differences in the colored complex until the 180-minute time interval, and the measurement of Cr(VI) concentration showed similar results. This analysis exhibits a level of precision and accuracy, evident from the RPD values below 10 % and the recovery values falling within the range of 90 – 110 %. It means that the reaction of hexavalent chromium complex with 1,5-diphenyl carbazide in analysis using a UV Visible Spectrophotometer is stable.

Influence of Water Concentration on High-Temperature Reactive Condensation of Chromium Vapors Generated in 800 °C Air

Reactive evaporation of chromium (Cr) from stainless steels used in solid oxide electrochemical systems, such as solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) systems, is well-documented. However, the condensation and interactions of volatilized Cr species onto and with surrounding interfaces during complex and dynamic system exposures is less understood. Understanding these interactions during operation is critical for improving system performance and safeguarding environmental, health and safety, as some condensed species contain toxic hexavalent Cr (Cr(VI)). The objective of this study is to investigate the condensation pathways of Cr vapors within representative high-temperature system environments. To accomplish this objective, Cr vapors, produced by high-temperature (800 °C) air exposures of trivalent chromium (Cr(III)) oxide (Cr2O3) powder with variable moisture content, were condensed onto various ceramic materials at lower temperatures (<400 °C). The total amount of Cr and ratios of oxidation states were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES) and diphenyl carbazide (DPC) colorimetric/direct UV–vis spectrophotometer analyses. Increased Cr condensation was observed with increased water content, with similar Cr(VI) to total Cr ratios. Results and interpretations are discussed in context of improving understanding of Cr reactive condensation in SOFC/SOEC and related high-temperature materials and systems.

Adsorption of Chromium (VI) from Aqueous Solution Using Nano TiO2 Doped Strong Base Anion Exchange Resin

Background: The evolution of environmentally-safe methods for treating hazardous chemicals in wastewater, particularly urban and industrial wastewater, has increased interest over recent years. The chromium-containing wastewater is produced by industries from steel, metallurgical, electroplating, chemical, refractory, leather tanning, dye manufacturing, mining, cementing, textiles, etc. Consequently, advanced techniques are essential for treating chromium-polluted water. Objective: The prime objective of this effort was to assess the adsorption performance of nanoTiO2 (nanoparticles of average crystallite size 19.15 nm) doped strong base anion exchange resin (TDTulsion) for Cr(VI)to that of the host Tulsion A-62 (MP). Methods: The tests were carried out in batches in the temperature-controlled water bath shaking unit, with 30 ml of the aqueous solution containing Cr(VI) and a certain amount of resin being stirred for 6 hours at 303 K. Using a standard diphenylcarbazide (DPC) procedure at 540 nm, the solution was spectrophotometrically analyzed for Cr(VI). Results: The majority of the Cr(VI) ions are adsorbed by the anion exchange resins Tulsion A- 62(MP), and TD-Tulsion is in the pH range of 4.0 to 5.0. The maximal sorption capacity of Cr (VI) was established to be 181.5 and 204.8 mg/g for Tulsion A-62(MP) and TD-Tulsion, respectively. Conclusion: The TD-Tulsion has a substantially better adsorption capacity than Tulsion A-62(MP) under similar conditions. The outcomes show that modifying anion-exchange resin with nano titanium dioxide improves adsorption performance in Cr(VI) removal from drinking water and contaminated water.

Estimation of Toxic Hexavalent Chromium (Cr6+) in Metal Components Present in Electronic and Electrical Materials with or without using Coordinating Ligands

The aqueous solutions of toxic hexavalent chromium have been analyzed using diphenyl carbazide (DPC) dissolved in organic solvents as a coordinating ligand since early nineteen hundreds. The chemistry is not clear due to the formation of an unstable, suggested organometallic complex, which is only An intermediary. The structure of the same could not be determined or is hypothetical even today with a further suggested, molecular structure in which instead of pi bonded delocalization of benzene rings expected to be as in sandwich compounds, electron empty d-orbital of hexavalent chromium facilitating the electron transfer and giving the observed color of the obtained complex as in inner field coordinating complexes. The electrical and electronic equipment requires the estimation of hexavalent chromium up to ~0.2 % (~2000 ppm) present in high chromium containing solid matrix, with DPC using standard International Electro-technical Commission (IEC) method.&#x0D; However, the visible yellow color can be directly measured on UV-Vis spectrophotometer with the hexavalent chromium stripped or leached out into acidic aqueous solutions from these materials using the known IEC method for leaching. The presence of interfering ions is ruled out with the leaching procedure given in it. Therefore, the stability of these aqueous acidic solutions containing hexavalent chromium was checked for 16 days. So that direct measurement can be done without DPC.&#x0D; Screws, Fork Pivot Bore and Rat Trap Box containing hexavalent chromium were analyzed and compared with and without DPC. It is noted that the analysis of these materials can satisfactorily be achieved easily or simply without adding DPC on UV-Vis spectrophotometer or any other organic ligands or using high-end equipment such as Ion Chromatography (IC).

Isolation and Molecular Characterization of Chromium Reducing Haloalkaliphilic Bacteria from Alkaline Lonar Lake

Heavy metals generated mainly through many anthropogenic processes, and some natural processes have been a great environmental challenge and continued to be the concern of many researchers and environmental scientists. This is mainly due to their highest toxicity even at a minimum concentration as they are nonbiodegradable and can persist in the aquatic and terrestrial environments for long periods. Chromium ions, especially hexavalent ions (Cr(VI)) generated through the different industrial process such as tanneries, metallurgical, petroleum, refractory, oil well drilling, electroplating, mining, textile, pulp and paper industries, are among toxic heavy metal ions, which pose toxic effects to human, plants, microorganisms, and aquatic lives.The present study deals with isolation and molecular characterization of bacteria from alkaline lonar crater, having ability to survive and remediate the chromium. In the present study, 26 bacterial isolates were obtained from twelve samples of water, matt and sediment collected from Lonar Lake. Among these isolates, a well characterized isolate ASJ 21 was subjected for molecular characterization on the basis of 16S rRNA gene sequencing. On the basis of 16S rRNA gene sequencing, isolate ASJ 21 was identified as Lysinibacillus mangiferihumi. The chromium remediation ability of Lysinibacillus mangiferihumi was studied spectrophotometrically by using Di-phenyl carbazide assay and the study revealed that the isolate Lysinibacillus mangiferihumi reduced 88% of chromium and rate reduction of chromium was found to be 0.916 µg/mL after 96h of incubation period, showing the ability of microorganisms to tolerate the chromium concentration at alkaline pH and potential to remediate and detoxify hexavalent Chromium (VI) to trivalent Chromium (III) as well.

Terra Rossa Soil as an Adsorbent to Remove Hexavalent Chromium in Aqueous Solutions

Kaolinite is a phyllosilicate clay of type 1:1 which is usually associated with iron oxides in nature. The clay is abundant in Terra Rossa soils which is located in the Gunungkidul, karst area. Based on the structure and nature of it’s the charge, it has the potential to adsorb anionic heavy metals, especially hexavalent chromium. Heavy metal chromium in the form of hexavalent is very dangerous for human health and the metal is mostly produced from the waste of leather tanning factories that are widely available in Yogyakarta. The purpose of this study was to investigate the possibility of using Terra Rossa soil as an adsorbent to remove heavy metal Cr (VI) from aqueous solution. The experiment was carried out by mixing the adsorbent with a dose of: 1 – 4.5 grams of fine soil, Φ 0.5 mm into a 50 ml solution containing 10 ppm chromium with pH 5 and 3. Stirred at 200 rpm for 2 hours, then centrifuged 3500 rpm for 20 minutes. The filtrate was given phosphoric acid and diphenyl carbazide and then measured using a spectrophotometer with a wavelength of 540 nm. The results showed that the average percentage of chromium removal at pH 5 = 30%, while pH 3 = 49%. The adsorbent absorption (mg/g) decreased in line with increasing adsorbent dose. Absorption graphs of Freundlich and Langmuir models in pH3 solution show R2=0.9264 and 0.9361 respectively, while in pH5 solution the R2 values are 0.3752 and 0.3461, respectively. Adsorption capacity according to Freundlich = 1.7331 mg/g, while according to Langmuir = 5.28 mg/g with adsorption site affinity 0.1894 L/mol.

Micellization of a cationic and an anionic surfactant in the presence of diphenylcarbazide in aqueous media and the effect of micelle surface charge on the complexation of the solubilised ligand with metal ions

ABSTRACT In the present study, we carried out conductometric and surface tension analyses to report the critical micelle concentration (CMC) of tetradecyltrimethyl ammonium bromide (TTAB) and sodium dodecyl sulphate (SDS) as a function of the concentration of a diphenylcarbazide (DPC). It is found that the micellization of TTAB becomes unfavourable while that of SDS becomes favourable in the presence of DPC. This indicates a substantial difference in the mutual interaction of the sparingly soluble ligand with the cationic and the anionic surfactants. The complexation ability of the solubilised DPC with hydrated Zn(II) and Cd(II) ions at varying concentrations of the cationic and anionic surfactants was studied by UV–Vis spectral analyses. With increasing the concentration of both surfactants up to their respective CMC values, the absorbance of the metal–DPC complex increases. However, the absorbance of the complex in TTAB micelles sharply decreases, showing almost zero values beyond the CMC, but that in SDS remains almost steady with increasing the concentration of the surfactant, as evidenced from the visible spectra.

The Influence of Water Concentration on High-Temperature Reactive Evaporation and Condensation of Cr in 800°C Air

Deleterious reactive evaporation of chromium from stainless steels commonly used in solid oxide electrochemical systems is well-documented; however, interactions between Cr vapor species and surrounding interfaces during complex and dynamic system exposures is poorly understood. Understanding the interactions between Cr vapor species and downstream components during operation is critical for improving system performance and safeguarding environmental, health and safety, as many condensed Cr compounds contain toxic and carcinogenic hexavalent chromium Cr(VI). Furthermore, the interactions between volatilized Cr species and surrounding interfaces are dependent upon dynamic chemical environments. The objective of this study is to systematically investigate and report on condensation pathways of Cr vapors within representative system environments with variable water concentrations. To accomplish this objective, an experimental platform was designed to generate Cr vapor species from the reactive evaporation of chromia (Cr2O3) powder with high-temperature (>1100 K) air/H2O mixtures, and expose downstream ceramic insulation materials (e.g., aluminosilicate fibers) at reduced temperatures (<600 K). Insulation material chemical compositions investigated include pure silica (SiO2) and alumina (Al2O3) to combinations thereof with and without inclusions of alkaline earth metals (e.g., Ca, Mg, Sr). Materials are studied as a function of exposure conditions using complementary materials characterization tools such as SEM-EDX, XPS, and diphenyl carbazide reactions to assess Cr(VI) concentrations. Reactive evaporation of Cr from chromia occurs in the presence of oxygen and/or water vapor to form various Cr-containing vapor species. Thermodynamic data reveals an equilibrium partial pressure increase of several orders of magnitude at elevated (>500 K) temperatures for all Cr vapor species. In the presence of water vapor, the partial pressure of Cr oxyhydroxide (CrO2(OH)2(g)) is greater by many several orders of magnitude and becomes the dominant species up to ~1500 K. The research objective is to explore effects of water vapor in air on Cr condensation and speciation on different ceramic insulation materials. The experimental setup thus far has exposed aluminosilicate fibers to volatilized Cr species from Cr oxide powder at 1100 K for 150 hours under varying water vapor conditions: 0 vol%(dry), 3 vol%, and 10 vol% H2O. Preliminary results show an increase in Cr(VI) formation on fibers exposed to volatile Cr species as water vapor content increases. See Figure 1 for an overview of the experimental concept, Cr(VI) test kit, and preliminary results for dependency on water vapor. Analyses of these results will be presented and discussed in context of potential implications for SOFC/SOEC systems. Figure 1

Nitrogen containing reductants for the corrosion control of alloys relevant to nuclear reactors

A comparative study on the nitrogen containing reductants viz., 8-hydroxyquinoline (8-HQ) and Diphenyl carbazide (DPC) was carried out to evaluate them for corrosion control in systems of water cooled nuclear reactors especially under shut-down or cold conditions. Corrosion rates were measured both by weight loss and electrochemical techniques. Studies revealed complementary nature of the reductants. 8-HQ showed better dissolved oxygen scavenging capability, thermal and radiation stability while DPC was well retained in the liquid phase besides showed favourable red-ox potential and minimum pickup on ion exchange resins. The corrosion control efficiency of 8-HQ for carbon steel surface was 48% in comparison to open-air condition containing 8 mg/l of dissolved oxygen while it was 66% in the case of DPC. Both the reductants are equally good candidates for corrosion control with complementary properties and the choice will depend on the requirement of the plant at the time of actual field application.

Analysis of Hexavalent Chromium in Cement Samples From Countries Within and Outside the EU: A Study From the International Contact Dermatitis Research Group.

Background: Allergic contact dermatitis (ACD) caused by hexavalent chromium (Cr(VI)) is often severe and difficult to treat. The content of Cr(VI) in cement can be reduced by, for example, addition of iron(II) sulfate. Since 2005 the content of Cr(VI) in cement is regulated in the EU Directive 2003/53/EC and must not exceed 2 ppm. Since this regulation came into force, ACD caused by cement has markedly been reduced. Objective: To investigate Cr(VI) and total chromium content in samples of cement from countries within and outside the EU. Methods: The members of the International Contact Dermatitis Research Group (ICDRG) were invited to participate in the study with the aim to collect cement samples from geographically different areas. The content of Cr(VI) in the samples was estimated by the diphenyl carbazide spot test, atomic absorption spectroscopy was used to assess the total chromium content. Results: Forty-five cement samples were analyzed, containing amounts of Cr(VI) from <0.1 to >70 ppm. Twenty-one samples contained >2 ppm Cr(VI), 24 contained less. Four of 17 samples from within the EU contained >2 ppm Cr(VI), that is, higher amounts than stipulated in the EU directive, as compared with 17 samples from countries outside the EU. Conclusion: In countries outside the EU, significantly more cement samples contained >2 ppm Cr(VI).

Using QuEChERS sample preparation technique followed by ICP-Ms method to determination Cr(III) and Cr(VI) in seawater

Currently, Cr(III) and Cr(VI) are analyzed directly in trace level using anion-exchange liquid chromatography inductively coupled plasma mass spectrometry (LC – ICP – MS), which is well-known as an expensive and complicated method. Therefore, determination of Cr(VI) and Cr(III) by spectrometer or combine with ICP (or AAS) is seemly prefer to choose in almost laboratories although this method presents a higher limit of detection (LOD) and is influenced by salt ions in seawater. In this study, after forming reddish-violet complex by adding diphenylcarbazide (DPC) to seawater samples, a QuEChERS extraction technique was applied to separate Cr from high salt level matrix and transfer the Cr(VI)-DPC structure to the acetonitrile phase. In case of determination of total Cr, the Cr(III) in samples had to convert to Cr(VI) by oxidate with KMnO4 before adding DPC. Then, a digestion process with HNO3 – H2O2 mixture was implemented before analyzing Cr(VI) by ICP-MS. The Cr(III) is calculated indirectly based on total Cr and Cr(VI) results. This method had a linear concentration range of Cr(VI) from 0.02 to 50 µg/L with a detection limit of 0.015µg/L, the relative standard deviations under 3,03%, and the recovery was 92-108 % for seawater. According to the outcome of parallel experiment with common method, which used spectrometer and did not apply QuEChERS extraction step, the ICP-MS method presented a better result with smaller LOD, RSD, and recovery range.

Construction of Effective Nanosensor by Combining Semiconducting Polymer Dots with Diphenylcarbazide for Specific Recognition of Trace Cr (VI) Ion in Water and Vitro.

Hexavalent chromium (Cr (VI)) ion, as highly toxic environmental pollution, severely endangers the ecological environment and public health. Herein, a fluorescent nanosensor (PFO-DPC) was constructed by combining semiconducting polymer dots with diphenylcarbazide (DPC) for sensing Cr (VI) ion in aqueous solution and living cells. DPC and poly (styrene-co-maleic anhydride) (PSMA) polymer mixed with polyfluorene (PFO) were utilized for selectively indicating Cr (VI) ion and improving the efficiency of detection, respectively. The presence of Cr (VI) ion effectively turned off the blue and green fluorescence of PFO-DPC in the aqueous environment, and the fluorescence quenching efficiency exhibited a good linear relationship between the range of 0.0 to 2.31 nM (R2 = 0.983) with a limit of detection (LOD) of 0.16 nM. The mechanism of fluorescence quenching could possibly be attributed to the internal filtration effect (IFE). Additionally, PFO-DPC showed a satisfactory performance in monitoring intracellular Cr (VI) ion. Our results indicate that the sensor is promising in various applications.

In-tube gel electro-membrane combined with microfluidic paper-based device: A green and miniaturized extraction mode for the chromium speciation

• In-tube gel electro-membrane was for the first time introduced as a scaled-down version of G-EME. • Extractions in transparent tube enable visual monitoring during the extraction processes. • With this new set-up, the DP/AP volume ratio can be easily increased to achieve a high enrichment factor. • Gel membrane and microfluidic paper-based analytical devices (µPADs) were a homemade fabrication. • The proposed workflow shows the ease of operation and is highly environmentally friendly. For the first time, in-tube gel electro-membrane microextraction (IT-G-EME) system followed by microfluidic paper-based analytical devices (µPADs) as a low-cost reading platform was fabricated for the speciation of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) as model cationic and anionic compounds. In this new miniaturized extraction mode, a transparent narrow-bore polymeric tube was used as housing of the aqueous acceptor phase (AP, 30 µL), while an agarose gel membrane was placed as a micro plug (2.5 mm) at the beginning of the tube. A circular shape vial (1.5 mL, pH 5.5) containing chromium species as donor phase (DP) was connected between two tubes which previously filled with gel membrane and aqueous AP. By applying electric potential, the positively charged Cr(III) and negatively charged Cr(VI) in the DP migrated selectively toward cathodic and anodic tubes, respectively. After extraction, each AP was analyzed by µPAD, which had already been modified with diphenylcarbazide (DPC). Under the optimized extraction conditions, a good limit of detection (LOD) equal to 7.0 µg L –1 was achieved for both analytes, while the extraction recoveries for Cr(VI) and Cr(III) were 72% and 84%. In addition, the developed approach was used for the quantification of chromium species in water samples.

Spectroscopic Properties and Micro-Structure for Promising Solar Cell Application of Ruthenium-Diphenyl Carbazide (RuDPC) Complex

The variation in the modes of a new ruthenium diphenyl carbazide complex (RuDPC) during changing of ruthenium (Ru) concentration within 0.01 ≤ X ≤ 0.09 in diphenyl carbazide (DPC) are investigated using IR analysis. Variation in some IR spectroscopic parameters during the increase of Ru content in pure DPC has been recorded. The variation in both the relaxation time and the rotational energy barrier for RuDPC samples at the mode 505 cm-1 supports a change that occurs at X ≈ 0.05. Micro-structure of RuDPC samples was studied by X-ray analysis and scanning electron microscopy. Moreover, SEM pictures and EDAX measurements were made revealing the strong Ru-signals indicating the presence of Ru and their distributions in the DPC matrix. Also results indicated that Ru inclusion in DPC matrix changes its morphology with a uniform distribution of Ru. Besides, X-ray diffraction patterns revealed RuDPC samples are represented by a mixture of amorphous and crystalline structure, wherever the phase-nature crystallization of RuDPC samples reinforced when the concentration of Ru is augmented. The crystal structure is changed to tetragonal structure after addition of ruthenium metal to pure orthorhombic DPC matrix. The spectroscopic properties of RuDPC complex is seemed to be dependent on its characteristics to the effect of radiation (FTIR), as a solar material in the application of this field; due to DPC is a photosensitive material, so that there are a number of optical applications which depend upon optically induced structure transition energy states for the complex.