Coexistent Ions Research Articles

Phosphate adsorption by a Cu(II)-loaded polyethersulfone-type metal affinity membrane with the presence of coexistent ions

A polyethersulfone (PES)-type metal affinity membrane loading Cu(II) was employed to remove phosphate from the solution. Techniques of scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and solid-state nuclear magnetic resonance spectroscopy (NMR) were used to characterize the membrane. Effects of pH, initial phosphate concentration, temperature, contact time, as well as the coexistent Cl−, SO42−, Mg(II), and Ca(II) on the phosphate adsorption by this membrane were evaluated. The adsorption kinetics and the adsorption isotherms of the membrane toward phosphate were investigated. In addition, the breakthrough curves of the membrane were measured. The coexistent Cl−, SO42−, Mg(II), and Ca(II) ions decreases the phosphate uptake of the membrane. Their negative effects on the uptake of phosphate follow the order: SO42−>Mg(II)>Cl−>Ca(II), considering the existent concentrations of them in seawater. Adsorption isotherms and adsorption kinetics of this metal affinity membrane toward phosphate are fitted to the Langmuir and the Lagergren second-order models. The phosphate uptake of the membrane is a spontaneous and endothermic process. In spite of the presence of these four ions, the PES-type metal affinity membrane shows an excellent uptake of phosphate. Therefore, the PES-type metal affinity membrane loading Cu(II) will be valuable for removing phosphate from seawater.

Effects of anions on bio-chemical degradation of nitrate in groundwater

Combining denitrifying bacteria with sodium oleate-nanoscale zero-valent iron (SONZVI) has been proven to be effective for aqueous phase nitrate remediation. However, the effects of coexistent ions on nitrate reduction in a groundwater environment, which is at low temperature and under anoxic, light-excluded conditions, remain elusive. In this study, nitrate reduction by microbial-NZVI was evaluated via batch tests in the presence of common anions (SO4 2−, PO4 3− and Cl−) in two different environments: groundwater environment and room environment. The results showed that nitrate was largely reduced within 10 days in an SONZVI + cell reactor in the groundwater environment, while only 79 % of the nitrate was reduced over 10 days in the room environment. In the groundwater environment, the removal efficiency could be accelerated by chloride or phosphate, but inhibited by sulfate. There were mainly two reaction stages, which were chemical reduction degradation and denitrifying degradation. Pseudo-first-order kinetics was used to describe the two reaction stages. In the first stage, the existence of the anions inhibited nitrate degradation. The synergistic effects of these anions on nitrate removal followed the order of Cl−, SO4 2−, and PO4 3−. The results implied that using microbial-NZVI is a potential approach for in situ remediation of groundwater with nitrate contamination.

A two fluorophore embedded probe for collective and ratiometric detection of Hg2+ and F− ions

A novel fluorescein-rhodamine dyad probe has been synthesized and its chemosensory applications are explored. Anion and cation specific responses of the probe permit ratiometric detection of Hg2+ and fluoride ions, individually and collectively, with different fluorescence outputs. The presence of other commonly coexistent ions does not affect the Hg2+ and fluoride ion detection ability of the probe. The probe is highly sensitive to Hg2+ and fluoride ions and it can detect Hg2+ and fluoride ions even at ppb level concentrations. The probe is non-toxic under the experimental conditions, cell permeable and useful for the imaging of intracellular Hg2+ and fluoride ions.

Thiol-functionalized polysilsesquioxane as efficient adsorbent for adsorption of Hg(II) and Mn(II) from aqueous solution

Thiol-functionalized polysilsesquioxane was synthesized and used for the adsorption of Hg(II) and Mn(II) from aqueous solution. Results showed that the optimal pH was about 6 and 5 for Hg(II) and Mn(II), respectively. Adsorption kinetics showed that the adsorption equilibriums were established within 100min and followed pseudo-second-order model. Adsorption isotherms revealed that the adsorption capacities increased with the increasing of temperature. The adsorption was found to be well described by the monolayer Langmuir isotherm model and took place by chemical ion-exchange mechanism. The thermodynamic properties indicated the adsorption processes were spontaneous and endothermic nature. Selectively adsorption showed that PMPSQ can selectively adsorb Hg(II) from binary ion systems in the presence of the coexistent ions Mn(II), Cu(II), Pb(II), Co(II), and Ni(II). Based on the results, it is concluded that PMPSQ had comparable high adsorption efficiency and could be potentially used for the removal of Hg(II) and Mn(II) from aqueous solution.

Arsenic Adsorption by Activated Carbon with Different Amounts of Basic Sites under Different Solution pH and Coexistent Ions

The bamboo-based and bead-shaped activated carbon (BAC) were used to examine the effects of textural properties and surface chemistry, respectively, on As(V) adsorption. The relationships between solution pH, coexistent ions and/or arsenic species and As(V) adsorption by BAC were also investigated. The Langmuir and pseudo-second order kinetics models were employed to evaluate the prepared activated carbon for As(V) adsorption. The results showed that As(V) adsorption was strongly attributed to surface properties, that is, basic sites rather than textural properties. The fittings of adsorption data to the kinetics models revealed that As(V) adsorption would be governed by diffusion process rather than collision process. Among various acidity regulators (HCl, HNO3, and H2SO4), the pH adjustment by HCl induced the highest adsorption amount at pH 5.5, indicating that the inhibition effect of Cl− ion for As(V) adsorption was much less than and ions. The effective arsenic species for As(V) adsorption was , and the decrease in the adsorption amount in acidic condition would be due to the inhibition by excess of Cl− ion, while the decrease in the adsorption at pH more than 5.5 would be attributed to the increase in OH− ion or to the influence of increased hydrogen arsenate species ().

Probing the turbulent ambipolar diffusion scale in molecular clouds with spectroscopy

We estimate the turbulent ambipolar diffusion length-scale and magnetic field strength in the massive dense cores CygX-N03 and CygX-N53, located in the Cygnus-X star-forming region. The method we use requires comparing the velocity dispersions in the spectral line profiles of the coexistent ion and neutral pair H13CN and H13CO+ (J = 1 → 0) at different length-scales. We fit Kolmogorov-type power laws to the lower envelopes of the velocity dispersion spectra of the two species. This allows us to calculate the turbulent ambipolar diffusion scale, which in turn determines the plane-of-the-sky magnetic field strength. We find turbulent ambipolar diffusion length-scales of 3.8 ± 0.1 and 21.2 ± 0.4 mpc, and magnetic field strengths of 0.33 and 0.76 mG for CygX-N03 and CygX-N53, respectively. These magnetic field values have uncertainties of a factor of a few. Despite a lower signal-to-noise ratio of the data in CygX-N53 than in CygX-N03, and the caveat that its stronger field might stem in part from projection effects, the difference in field strengths suggests different fragmentation efficiencies of the two cores. Even though the quality of our data, obtained with the Institut de Radio Astronomie Millimetrique (IRAM) Plateau de Bure Interferometer, is somewhat inferior to previous single-dish data, we demonstrate that this method is suited also for observations at high spatial resolution.

Magnetic Flocculation Technology for Copper and Zinc Ions Removal from the Tin Smelting Wastewater

Magnetic flocculation technology was investigated for the removal of copper and zinc ions from simulated tin smelting wastewater, and the effects of magnetic powder dosage, flocculant dosage, and pH on the removal of copper and zinc ions were estimated. The results show that the effluent quality is poor with magnetic powder, PAC and PAM separately dosed, but when magnetic powder is combined with PAC or PAM, the excellent effluent quality is obtained with the removal rate of the copper and zinc ions of more than 90% and 70% respectively. In addition, under the condition of magnetic powder dosage of 30g/L and PAC dosage of 60mg/L, pH show more significant effect on zinc ions than copper ions with pH increased from 5 to 10, and the removal rate of zinc ions increase by about 24%, while the removal rate of copper ions only increase by about 2.5%. Compared with the system with single metal ion, the coexistent ion system has excellent heavy metal removal efficiency, namely the copper ions removal rate increase by 3.42%, and the zinc ions removal rate increase by 0.46%. Moreover, magnetic flocculation technology presents the characteristics of shorter time of flocculation and sedimentation, smaller volume of the flocs and faster separation velocity.

Adsorptive removal of sulfonamide antibiotics in livestock urine using the high-silica zeolite HSZ-385

The adsorptive removal of seven sulfonamide antibiotics using the high-silica zeolite HSZ-385 from distilled water, synthetic urine and real porcine urine was investigated. The pH greatly affected the adsorption efficiency, and the amounts of all sulfonamide antibiotics adsorbed on HSZ-385 decreased at alkaline conditions compared with that at neutral conditions. During storage, the pH and ammonium-ion concentration increased with urea hydrolysis for porcine urine. We clarified that the adsorption efficiency of sulfonamides in synthetic urine was equivalent to that in distilled water, suggesting that adsorption behavior was not affected by coexistent ions. HSZ-385 could adsorb sulfonamide antibiotics in real porcine urine even though the non-purgeable organic carbon concentration of porcine urine was 4-7 g/L and was two orders of magnitude higher than those of sulfonamides (10 mg/L each). Moreover, the adsorption of sulfonamides reached equilibrium within 15 min, suggesting that HSZ-385 is a promising adsorbent for removing sulfonamides from porcine urine.

Preconcentration of lead from aqueous solution with activated carbon cloth prior to analysis by flame atomic absorption spectrometry: a multivariate study

In this work, the preconcentration of lead (Pb) was carried out by complexation with 2-(5-bromo-2-pyridilazo)-5-(diethylamino)phenol (5-Br-PADAP) and adsorption on an activated carbon cloth (ACC) prior to analysis by flame atomic absorption spectrometry (FAAS). The surface morphology of the ACC was studied by scanning electron microscopy and the adsorption capacity was determined by batch adsorption experiments. To evaluate the effects of several variables at once, the Plackett–Burman experimental design was used as a multivariate strategy. Important variables affecting the adsorption and preconcentration such as pH, ligand concentration, flow rate, eluent concentration and volume were investigated. No obvious negative effect of coexistent ions was observed. Validation was carried out by analyzing certified reference materials; sewage sludge (BCR 144R), human urine and whole blood. The proposed method was applied in the determination of Pb in tap water, urine and blood samples.

A functional graphene oxide-ionic liquid composites–gold nanoparticle sensing platform for ultrasensitive electrochemical detection of Hg2+

A simple and sensitive electrochemical assay strategy of stripping voltammetry for mercury ions (Hg(2+)) detection is described based on the synergistic effect between ionic liquid functionalized graphene oxide (GO-IL) and gold nanoparticles (AuNPs). The AuNPs-GO-IL modified onto glassy carbon electrode (GCE) resulted in highly enhanced electron conductive nanostructured membrane and large electroactive surface area, which was excellently examined by scanning electron microscopy and cyclic voltammetry. After accumulating Hg(2+), anodic stripping voltammetry (ASV) was performed, and differential pulse voltammetry (DPV) was employed for signal recording of Hg(2+). Several main experimental parameters were optimized, i.e., deposition potential and time of AuNPs were -0.2 V and 180 s, respectively, and accumulation potential and time of Hg(2+) were -0.3 V and 660 s, respectively. Under the optimal conditions, this AuNPs-GO-IL-GCE sensor attained a good linearity in a wide range of 0.1-100 nM (R = 0.9808) between the concentration of the Hg(2+) standard and peak current. The limit of detection was estimated to be 0.03 nM at a signal-to-noise ratio of 3σ. A variety of common coexistent ions in water samples were investigated, showing no obvious interferences on the Hg(2+) detection. The practical application of the proposed sensor has been carried out and demonstrated as feasible for determination of trace levels of Hg(2+) in drinking and environmental water samples.

Spectrofluorimetric determination of trace nitrite with o-phenylenediamine enhanced by hydroxypropyl-β-cyclodextrin

A simple and sensitive spectrofluorimetric method was developed for the determination of nitrite in environmental and food samples. The method was based on the selective reaction of o-phenylenediamine with nitrite in acidic medium to form benzotriazole, which exhibited strong fluorescence at 568nm with excitation at 420nm in alkaline medium. The detection limit and sensitivity of the proposed method were improved by hydroxypropyl-β-cyclodextrin through complexation. The linear calibration range for nitrite was 0.04–0.8μgmL−1 with a detection limit of 13.6ngmL−1 (S/N=3.29). The relative standard deviation for ten determinations of 0.1 and 0.4μgmL−1 nitrite were 1.38% and 2.01%, respectively. Twenty-eight coexistent ions were examined, and no serious interference for most of ions was observed. The proposed method was successfully applied for the determination of nitrite in the water, sausage and soil samples with recoveries of 95.5–108.5%. The results were in good agreement with the recommended AOAC method.

Adsorption of arsenate on Cu/Mg/Fe/La layered double hydroxide from aqueous solutions

A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized and used for the removal of arsenate from aqueous solutions. The purpose of incorporation of La3+ into LDHs was tried to enhance the uptake efficiency of arsenate and broaden the application field of LDHs functional materials. Effects of various physico-chemical factors such as solution pH, adsorbent dosage, contact time and initial arsenate concentrations on the adsorption of arsenate onto Cu/Mg/Fe/La-LDH were investigated. Results showed that the removal efficiency of arsenate increased with the increment of the lanthanum content in Cu/Mg/Fe/La-LDH adsorbents, and the optimized lanthanum content was 20% of the total trivalent metals composition (Fe3+ and La3+). The adsorption isotherms can be well described by Langmuir equation, and the adsorption kinetics of arsenate followed the pseudo-second-order kinetic model. Coexistent ions such as HPO42−, CO32−, SO42−, Cl− and NO3− exhibited obvious competition with arsenate for the adsorption on Cu/Mg/Fe/La-LDH. The solution pH significantly affected the removal efficiency, which was closely related to the change of arsenate species distribution under different pH conditions. The predominant adsorption mechanism can be mainly attributed to the processes including ion exchange and layer ligand exchange.

Adsorption and desorption of uranium (VI) in aerated zone soil

In this paper, the adsorption and desorption behavior of uranium (VI) in aerated zone soil (from Southwest China) was systematically investigated using a static experimental method in order to provide useful information for safety assessment of the disposal of (ultra-)low uraniferous radioactive waste, as well as a potential remediation method for uranium-contaminated soils. The adsorption behavior of uranium (VI) was firstly studied by batch experiments as functions of contact time, pH, liquid/solid ratio, temperature, colloids, minerals and coexistent ions. The results indicated that the adsorption of uranium (VI) by natural soil was efficient at an initial concentration of 10 mg/L uranium (VI) nitrate solution with 100 mg natural soil at room temperature when pH is about 7.0. The adsorption was strongly influenced by the solution pH, contact time, initial concentration and colloids. The adsorption equilibrium for uranium (VI) in soil was obtained within 24 h and the process could be described by the Langmuir adsorption equation. For uranium (VI) desorption, EDTA, citric acid and HNO3 were evaluated under different conditions of temperature, concentration and proportion of liquid to solid. The adsorbed uranium (VI) on natural soil could be easily extracted by all these agents, especially by HNO3, implying that the uranium-contaminated soils can be remedied by these reagents.

Application of Using Sphingomonas-Paucimobilis of Sodium Alginate Fossilization Bacillus Subtilis Pellet to Heavy Metal of Mine Wastewater

This study use purely bacteria on suitable condition, eliminate other bacteria come in life-form bacteria. Through the orthogonal experiment obtains the optimum condition of sodium alginate fossilization bacillus subtilus pellet to chrome adsorption, and discusses the influence of single factor to the sodium alginate fossilization bacillus subtilus pellet to chrome adsorption, including the time, the temperature,pH, the initial adsorbent density, the speed of the shaker, the absorbent which the different periods of growth bacterium does, coexistent ion, desorption. From the research, we know the maximum adsorption rate to chrome is about 80%. Dynamics research indicated that in the several methods of the Sphingomonas-paucimobilis of chrome , the methods of embedded micro-organisms embodies much advantages ,as operating easily, effecting clearly, less pollution, costing low, etc.

Sphingomonas-Paucimobilis of Sodium Alginate Fossilization Bacillus Subtilis Pellet to Chrome of Mine Wastewater

This study use purely bacteria on suitable condition, eliminate other bacteria come in life-form bacteria. Through the orthogonal experiment obtains the optimum condition of sodium alginate fossilization bacillus subtilus pellet to chrome adsorption, and discusses the influence of single factor to the sodium alginate fossilization bacillus subtilus pellet to chrome adsorption, including the time, the temperature,pH, the initial adsorbent density, the speed of the shaker, the absorbent which the different periods of growth bacterium does, coexistent ion, desorption. From the research, we know the maximum adsorption rate to chrome is about 80%. Dynamics research indicated that in the several methods of the Sphingomonas-paucimobilis of chrome , the methods of embedded micro-organisms embodies much advantages ,as operating easily, effecting clearly, less pollution, costing low, etc.

Effect of common ions on nitrate removal by zero-valent iron from alkaline soil

Zero-valent iron (Fe0)-based permeable reactive barrier (PRB) technology has been proved to be effective for soil and groundwater nitrate remediation under acidic or near neutral conditions. But few studies have been reported about it and the effects of coexistent ions under alkaline conditions. In this study, nitrate reduction by Fe0 was evaluated via batch tests in the presence of alkaline soil and common cation (Fe2+, Fe3+ and Cu2+) and anion (citrate, oxalate, acetate, SO42−, PO43−, Cl− and HCO3−). The results showed that cation significantly enhanced nitrate reduction with an order of Fe3+>Fe2+>Cu2+ due to providing Fe2+ directly or indirectly. Most anions enhanced nitrate reduction, but PO43− behaved inhibition. The promotion decreased in the order of citrate>acetate>SO42−>Cl−≈HCO3−≈oxalate≫PO43−. Ammonium was the major final product from nitrate reduction by Fe0, while a little nitrite accumulated in the beginning of reaction. The nitrogen recovery in liquid and gas phase was only 56–78% after reaction due to ammonium adsorption onto soil. The solution pH and electric conductivity (EC) varied depending on the specific ion added. The results implied that PRB based Fe0 is a potential approach for in situ remediation of soil and groundwater nitrate contamination in the alkaline conditions.

Effects of Halides on Reaction of Nucleosides with Ozone

GRAPHICAL ABSTRACT Ozone (O3), a major component of photochemical oxidants, is used recently as a deodorizer in living spaces. It has been reported that O3 can directly react with DNA, causing mutagenesis in human cells and carcinogenesis in mice. However, little is known about the effects of coexistent ions in the reaction of O3. In the present study, we analyzed the effects of halides on the reaction of O3 with nucleosides using reversed-phase high-performance liquid chromatography with ultraviolet detection. When aqueous O3 solution was added to a nucleoside mixture in potassium phosphate buffer (pH 7.3), the nucleosides were consumed with the following decreasing order of importance: dGuo > Thd > dCyd > dAdo. The effects of addition of fluoride and chloride in the system were slight. Bromide suppressed the reactions of dGuo, Thd, and dAdo but enhanced the reaction of dCyd. The major products were 5-hydroxy-2′-deoxycytidine, 5-bromo-2′-deoxycytidine, and 8-bromo-2′-deoxyguanosine. The time course and pH dependence of the product yield indicated formation of hypobromous acid as the reactive agent. Iodide suppressed all the reactions effectively. The results suggest that bromide may alter the mutation spectrum by O3 in humans.

Adsorption of Heavy Metal Ions with Magnetic Carbon-Coated Iron Nanoparitcles

Magnetic carbon-coated iron nanoparitcles were employed as adsorbent to study the adsorption characteristics of some metal ions, such as Cr, Ni, Cu, Pb, Zn. The effect of solution conditions such as pH, amounts of adsorbent, the co-existent ions was investigated. The results show that adsorption property of carbon-coated iron particles to heavy metal ions is improved at the condition of treated by H2O2, and at pH 8-9.5, Cr、Ni、Cu、Pb and Zn were retained on 30mg carbon-coated iron nanoparticles after shaking 3 min, and could be eluted by acid solutions(pH=1~2).

Removal of Nickle Ion from Mariculture Seawater with Marine Microorganism

This study use purely bacteria on suitable condition, eliminate other bacteria come in life-form bacteria. Through the orthogonal experiment obtains the optimum condition of sodium alginate fossilization Sphingomonas strain pellet to nickel bioremediation, and discusses the influence of single factor to the sodium alginate fossilization Sphingomonas strain pellet to nickel adsorption, including the time, the temperature, pH, the initial adsorbent density, the speed of the shaker, the absorbent which the different periods of growth bacterium does, coexistent ion, desorption. From the research, we know the maximum adsorption rate to nickel is about 85%. Dynamics research indicated that in the several methods of the sodium alginate of nickel, the methods of embedded micro-organisms embodies much advantages ,as operating easily, effecting clearly, less pollution, costing low, etc.

Temperature controlled ionic liquid-dispersive liquid phase microextraction for determination of trace lead level in blood samples prior to analysis by flame atomic absorption spectrometry with multivariate optimization

This paper described a new approach for the preconcentration of lead (Pb2+) by temperature controlled ionic liquid-dispersive liquid phase microextraction (TIL-DLME) prior to analyzing by flame atomic absorption spectrometry (FAAS). An ionic liquid (IL) 1-Butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] was used as an extractant solvent. The Pb2+ was complexed with ammonium pyrrolidinedithiocarbamate (APDC) and then entered into the infinite IL drops at high temperature (>70°C). Important variables affecting the microextraction efficiency such as pH, ligand concentration, amount of IL, temperature and incubation time were investigated. The results showed that the coexistent ions had no obvious negative effect on the determination of Pb2+. In the optimum experimental conditions, the limit of detection (LOD) and the enhancement factor (EF) were 0.13μgL−1 and 93, respectively. The relative standard deviation (RSD) of 10μgL−1 Pb2+ was 4.3%. The developed method was validated by determining Pb2+ in certified reference material (CRM) and the results showed that the determined values of Pb2+ were in good agreement with the certified value. The proposed method was applied satisfactorily for the preconcentration of Pb2+ in acid digested blood samples of children with different respiratory disorders.