Ferric ion-triggered surface oxidation of galena for efficient chalcopyrite-galena separation

The efficient separation of chalcopyrite(CuFeS2)and galena(PbS)is essential for optimal resource utilization.However,find-ing a selective depressant that is environmentally friendly and cost effective remains a challenge.Through various techniques,such as mi-croflotation tests,Fourier transform infrared spectroscopy,scanning electron microscopy(SEM)observation,X-ray photoelectron spec-troscopy(XPS),and Raman spectroscopy measurements,this study explored the use of ferric ions(Fe^(3+))as a selective depressant for ga-lena.The results of flotation tests revealed the impressive selective inhibition capabilities of Fe^(3+)when used alone.Surface analysis showed that Fe^(3+)significantly reduced the adsorption of isopropyl ethyl thionocarbamate(IPETC)on the galena surface while having a minimal impact on chalcopyrite.Further analysis using SEM,XPS,and Raman spectra revealed that Fe^(3+)can oxidize lead sulfide to form compact lead sulfate nanoparticles on the galena surface,effectively depressing IPETC adsorption and increasing surface hydrophilicity.These findings provide a promising solution for the efficient and environmentally responsible separation of chalcopyrite and galena.

Facile and large-scale synthesis of green-emitting carbon nanodots from aspartame and the applications for ferric ions sensing and cell imaging

A facile, economical and green strategy to prepare green-fluorescent nitrogen-doped carbon nanodots （N- CDs） with a quantum yield （QY） of approximately 31.91% has been built up, while aspartame was employed as the carbon-nitrogen source for the first time. The prepared N-CDs exhibited ultrahigh brightness, favorable strong photostability and negligible cytotoxicity. The outstanding optical properties are mainly derived from the their robost composition and steric distribution of the doped nitrogen atoms, which have been characterized detailedly. The obtained N-CDs showed highly selective and sensitive response toward ferric ions （Fe3＋） through a fluorescence static quenching process in a wide linear range of 0.005-60 μmol/L. The detection limit was as low as 1.43 nmol/L, allowing the analysis of Fe3＋ in a very simple method. The excitation-dependent luminescent behavior of the obtained N-CDs guaranteed the multicolor emissive property when they were used in cell imaging. And the application for intracellular Fe3＋ sensing further verified this novel N-CDs may open more opportunities in biosensor, bioimaging and biological assay.

Photochemical decomposition of 1H,1H,2H,2H-perfluorooctane sulfonate(6:2FTS)induced by ferric ions

Perfluorooctane sulfonate（PFOS） had wide applications,such as in the electroplating industry,but its use was restricted in 2009 by the Stockholm Convention,due to its environmental persistence and potential hazards.As the most common PFOS alternative,lH,lH,2H,2H-perfluorooctane sulfonic acid（6：2FTS） and its salts have been increasingly used.However,little is known about its photochemical decomposition.This paper reports the ferric ion-induced efficient decomposition and defluorination of 6：2FTS under 254 nm ultraviolet（UV） irradiation;the underlying mechanisms were also investigated.In the presence of 100 ｜imol/L ferric ion and at pH 3.0,the first-order decomposition rate constant of 6：2FTS（10 mg/L） was 1.59/hr,which was 6 times higher than for direct UV photolysis.The effects of the ferric ion concentration and the solution pH on the 6：2FTS photodecomposition were investigated and the optimal reaction conditions were determined.In addition to fluoride and sulfate ions,shorter-chain PFCAs（C2-C7） were detected as major intermediates.The addition of hydrogen peroxide or oxalic acid accelerated the decomposition of 6：2FTS under UV irradiation,but not its defluorination,indicating that hydroxyl radicals can directly react with 6：2FTS but not with the shorter-chain PFCAs.Accordingly,a mechanism for 6：2FTS photochemical decomposition in the presence of ferric ion was proposed,which comprises two reaction pathways.First,hydroxyl radicals can directly attack 6：2FTS,leading to C- C bond cleavage.Alternatively,6：2FTS coordinates with ferric ion to form Fe（III）-6：2FTS complexes,which can undergo ligand-to-metal charge transfer under UV irradiation,causing C-S bond cleavage.

A Novel Enhancer for Fe^(2+)-Catalyzed Light Emission Reaction of Luminol and Dissolved Oxygen

EDTA was used as an enhancer for Fe 2+ catalyzed light emission from luminol oxidation by dissolved oxygen. As a result, the limit of detection for ferrous ion with flow injection analysis was improved by a factor of 160 by addition of EDTA to the luminol solution. Fe 2+ and Fe 3+ were determined simultaneously with a novel copper-coated zinc reductor minicolumn installed in one of the shunt after sample splitting in the manifold. The reductor minicolumn can be used for 3000 determinations at least. The dynamic range of determination was 1×10 -9 ～1×10 -5 mol·L -1 , with the limit of detection of 2.7×10 10 and 3.5×10 10 mol·L 1 ,for Fe 2+ and Fe 3+ , respectively. The preci sion for determination of 2×10 7 mol·L 1 of Fe 2+ and Fe 3+ was 2.3% and 4.0% (n=8), respectively, at a sampling rate of 60 h -1 . Cr 3+ and Co 2+ interfere. Fe 2+ and Fe 3+ in mixture were determined with satisfactory results. Samples of Fe 2+ and Fe 3+ were determined simultaneously and the results in good agreement with the standard spectrophotometric method. Indications were shown that EDTA functions as an enhancer, Fe 2+ as a catalyst, and oxygen is the oxidant of the chemiluminescent reaction, and the mechanism of the reaction was discussed.

Effect of ferric and bromide ions on the formation and speciation of disinfection byproducts during chlorination

The effects of ferric ion, pH, and bromide on the formation and distribution of disinfection byproducts （DBPs） during chlorination were studied. Two raw water samples from Huangpu River and Yangtze River, two typical drinking water sources of Shanghai, were used for the investigation. Compared with the samples from Huangpu River, the raw water samples from Yangtze River had lower content of total organic carbon （TOC） and ferric ions, but higher bromide concentrations. Under controlled chlorination conditions, four trihalomethanes （THMs）, nine haloacetic acids （HAAs）, total organic halogen （TOX） and its halogen species fractions, including total organic chlorine （TOC1） and total organic bromide （TOBr）, were determined. The results showed that co-existent ferric and bromide ions significantly promoted the formation of total THMs and HAAs for both raw water samples. Higher concentration of bromide ions significantly changed the speciation of the formed THMs and HAAs. There was an obvious shift to brominated species, which might result in a more adverse influence on the safety of drinking water. The results also indicated that high levels of bromide ions in raw water samples produced higher percentages of unknown TOBr.

Study on Catalytic Wet Oxidation of H_2S into Sulfur on Fe/Cu Catalyst

A wet catalytic oxidation at room temperature was investigated with solution containing ferric, ferrous and cupric ions for H2S removal. The experiments were carried out in a two step process, and the results obtained show that the removal efficiency of H2S can always reach 100% in a 300 mm scrubbing column with four sieve plates, and the regeneration of ferric ions in 200 mm bubble column can match the consumed ferric species in absorption. Removal of H2S, production of elemental sulfur and regeneration of ferric, cupric ions can all be accomplished at the same time. No raw material is consumed except O2 in flue gas or air, the process has no secondary pollution and no problem of catalyst degradation and congestion.

Carbenoxolone pretreatment and treatment of posttraumatic epilepsy

Gap junction blocking agents can inhibit spontaneous discharge frequency in cells. We established a rat model of posttraumatic epilepsy induced using ferric ions. Rats were intraperitoneally injected with carbenoxolone, 20 mg/kg, prior to and 30 minutes after model establishment, once a day for 14 consecutive days. Immunohistochemistry showed glial cell proliferation around a cortical focus and significantly increased connexin expression in posttraumatic epilepsy. However, carbenoxolone pretreatment or treatment significantly reduced connexin expression in the cortex, inhibited glial fibdllary acidic protein expression and ameliorated seizure degree in rats. These findings indicate that large amounts of glial cell proliferation and abnormal gap junction generation play a role in posttraumatic epilepsy, and that carbenoxolone may prevent and treat this disease.

Fluorescence Behavior and Emission Mechanisms of Poly(ethylene succinamide)and Its Applications in Fe^(3+)Detection and Data Encryption

Conventional fluorescent polymers are featured by large conjugation structures.In contrast,a new class of fluorescent polymers without any conjugations is gaining great interest in immerging applications.Polyamide is a typical member of the conjugation-free fluorescent polymers.However,studies on their electrophotonic property are hardly available,although widely used in many fields.Herein,poly(ethylene succinamide),PA24,is synthesized;its chemical structure confirmed through multiple techniques(NMR,FTIR,XRD,etc.).PA24 is highly emissive as solid and in its solution at room temperature,and the emission is excitation and concentration dependant,with an unusual blue shift under excitation from 270 nm to 320 nm,a hardly observed phenomenon for all fluorescent polymers.Quite similar emission behavior is also observed under cryogenic condition at 77 K.Its emission behavior is thoroughly studied;the ephemeral emission blue-shift is interpreted through Förster resonance energy transfer.Based on its structures,the emission mechanism is ascribed to cluster-triggered emission,elucidated from multianalyses(NMR,FTIR,UV absorbance and DLS).In presence of a dozen of competitive metal ions,PA24 emission at 450 nm is selectively quenched by Fe^(3+).PA24 is used as probe for Fe^(3+)and H_(2)O_(2) detections and in data encryption.Therefore,this work provides a novel face of polyamide with great potential applications as sensors in different fields.

Anomalous enhancement of fluorescence of carbon dots through lanthanum doping and potential application in intracellular imaging of ferric ion

An anomalous enhancement of fluorescence of carbon dots （CDs） was observed via lanthanum （La） doping. La-doped CDs （La-CDs） were prepared through microwave pyrolysis within 4 min. With La^3＋ doping, the emission band shifted from blue to green although LaB＋ is non-fluorescent. The quantum yield and fluorescence lifetime improved by about 20% and 35%, respectively. All experiment results indicate that La^3＋ doping is an effective way to tune fluorescence and improve the performance of CDs. Another unique attribute of La-CDs is high sensitivity to Fe^3＋. The La-CD-based fluorescence probe was established and used for sensitive and selective detection of Fe^3＋ with a limit of detection of 91 nmol/L. The proposed fluorescence probe also was successfully employed to visualize intracellular Fe^3＋ in live HeLa cells through cell imaging. It was also shown that yttrium exhibited the same fluorescence enhancement effect as La. The results may provide a new route for preparing CDs with special properties.

Ferric ion-ascorbic acid complex catalyzed calcium peroxide for organic wastewater treatment:Optimized by response surface method

Hydrogen peroxide(H_(2)O_(2))disproportionation,iron precipitation,and narrow pH range are the drawbacks of traditional Fenton process.To surmount these barriers,we proposed a ferric ion(Fe^(3+))-ascorbic acid(AA)complex catalyzed calcium peroxide(CaO_(2))Fenton-like system to remove organic dyes in water.This collaborative Fe^(3+)/AA/CaO_(2)system presented an obvious improvement in the methyl orange(MO)decolorization,and also effectively eliminated other dyes.Response surface method was employed to optimize the running parameters for this coupling process.Under the optimized arguments(2.76 mmol/L Fe^(3+),0.68 mmol/L AA,and 4 mmol/L CaO_(2)),the MO removal achieved 98.90%after 15 min at pH 6.50,which was close to the computed outcome of 99.30%.Furthermore,this Fenton-like system could perform well in a wide range of pH(3-11),and enhance the H_(2)O_(2)decomposition and Fe ions recycle.The scavenger experiment result indicated that hydroxyl radical,superoxide anion free radical,and singlet oxygen were acted on the dye elimination.Moreover,electron spin resonance analysis corroborated that the existences of these active species in the Fe^(3+)/AA/CaO_(2)system.This study could advance the development of Fenton-like technique in organic effluent disposal.

Biochemical Properties and Inhibition Kinetics of Phosphatase from Wheat Thylakoid Membranes

A phosphetase that hydrolyses phosphate monoesters has been Isolated from wheat thylakold membranes. Biochemical properties and inhibition kinetics of the phosphatase were Investigated using several Ions, organlc solvents, and Inhlbltors. Wheat （Trltlcum aestivum L. cv. PH82-2-2） thylakold membrane phosphatase activity was activated by Mg^2＋, Ca^2＋, and Fe^2＋ and was inhibited by Mn^2＋ and Cu^2＋. For example, enzyme activity was acUvated 34.81% by 2 mmol/l. Mg^2＋, but was Inhibited 22.3% and 8.5% by 2 and 1 mmol/L Cu^2＋, respectively. Methanol, ethanol and glycol were all able to activate enzyme activity. Enzyme activity was activated 58.5%, 48.2%, and 8.7% by 40% ethanol, methanol and glycol, respectively. From these results, It can be seen that the degree of actlvetlon of the phosphetase was greatest for ethanol and the type of acUvatlon was uncompetltlve. Moreover, the activity of the thylakold membrane phosphetase was Inhibited by molybdate, vanadete, phosphate, and fluoride and the type of Inhibition produced by these elements was uncompetltlve, non-competitive, competltlve and mixed, respectively.

A simple,water-soluble,Fe^(3+)-selective fluorescent probe and its application in bioimaging

A simple, water-soluble, Fe3＋-selective fluorescent probe, derived from rhodamine B, was synthesized and characterized. The probe exhibits a fluorescence response toward Fe3＋ with acceptable sensitivity and selectivity and even facilitates visual or naked-eye detection of Fe3＋. The experiment results show that the response of the probe to Fe3＋ is pH-independent over a wide range of 4.0-10.0. In addition, fluorescence microscopic imaging experiments have proven that the probe is cell permeable and can be used for monitoring intracellular Fe3＋ in living cells.

Enhanced degradation of trichloroethene by calcium peroxide activated with Fe（III） in the presence of citric acid

Trichloroethene （TCE） degradation by Fe（III）- activated calcium peroxide （CP） in the presence of citric acid （CA） in aqueous solution was investigated. The results demonstrated that the presence of CA enhanced TCE degradation significantly by increasing the concen- tration of soluble Fe（III） and promoting H202 generation. The generation of HO· and O2^-· in both the CP/Fe（III） and CP/Fe（III）/CA systems was confirmed with chemical probes. The results of radical scavenging tests showed that TCE degradation was due predominantly to direct oxidation by HO·, while O2^-· strengthened the generation of HO· by promoting Fe（III） transformation in the CP/Fe （III）/CA system. Acidic pH conditions were favorable for TCE degradation, and the TCE degradation rate decreased with increasing pH. The presence of Cl·-, HCO3·-, and humic acid （HA） inhibited TCE degradation to different extents for the CP/Fe（III）/CA system. Analysis of Cl·- production suggested that TCE degradation in the CP/Fe （III）/CA system occurred through a dechlorination process. In summary, this study provided detailed information for the application of CA-enhanced Fe（III）-activated calcium peroxide for treating TCE contaminated groundwater.

Carbon Dots-Doped Electrospun Fibers for Simultaneous Metal Ion Detection and Adsorption of Dyes

The required treatment and monitoring of contaminants in wastewater reinforces the development of low-cost adsorbents/chemosensors,introducing advantages relative to the detection/removal of toxic metals and dyes.Herein,it is reported a two-step process of fabrication of fluorescent carbon dots via the hydrothermal treatment of amino acids for the following encapsulation in electrospun fibers.The prominent anionic behavior of electrospun fibers of Eudragit L100 was explored for adsorption of cationic dyes(methylene blue and crystal violet)-with the prevailing electrostatic interaction of parts being favored by the formation of monolayers on the surface of adsorbents.On the other hand,the controlled release of carbon dots(CDs)from fibers to the reactor can be explored for a second application:the nitrogen ligands from released glycine-based carbon dots can be explored to indicate the presence of metal ions in aqueous solution.Our experiment resulted in a quenching in the fluorescence of the CDs in order of 90%in the emission of particles in the response of the presence of Fe^(3+) ions,characterizing a promising perspective for this experimental system.

One-pot synthesis of nuclear targeting carbon dots with high photoluminescence

Carbon dots(CDs) are novel fluorescent nanomaterials with good water solubility, high resistance to photobleaching and low toxicity. While, there are few studies elaborate on the relationship among reaction conditions, properties and applications of CDs. In this study, a series of CDs are synthesized through a one-pot hydrothermal method, and different reaction conditions are carried out to study the influencing factors of CDs properties. As a result, with the increase of temperature and reaction time, the particle size and zeta potential of CDs increased, the maximum emission wavelength red-shifted and the fluorescence quantum yield(QY) improved. Among them, CD3006 has good water solubility and highest QY of 81.4%, which is beneficial for its applications in bioimaging and ion detection. CD3006 is almost nontoxic in cells at a concentration of 500 μg/m L. In addition, the positive charged CD3006 shows nuclear targeting potential because of its combination with DNA through electrostatic interaction in nucleus. The properties of CDs can be greatly enhanced by controlling reaction conditions, and it provides great application prospects.