利用DMO-M离子交换树脂除去稀溶液中的汞

A mercaptan-containing resin, DMO-M, with high redox capacity- 6.00 mequiv/g, prepared by reacting mercaptoacetyl chloride with the aminophenol resin Duolite A-7 in free-base form has been used to remove mercury in dilute aqueous solution. The resin has high mercury removal capacity; 1200mg/g. Sodium chloride affects the equilibrium sorption of mercury on the resin. At lower pH values, below 1.76, mercury sorption of the resin was greatly reduced. The sorbed mercury is partially removed by 2 mol/L HCl solution containing 5% thiourea.     

Electroless recovery of gold chloride using inherently conducting polymers

Conducting polymers deposited onto reticulated vitreous carbon (RVC) were shown to remove gold from aqueous solutions in a facile and highly efficient fashion. For acidic solutions with initial [AuCl₄]^? concentrations between 0.1 and 1000 ppm, gold recoveries >90% were obtained. Experiments, conducted using solutions containing 0.1 ppm [AuCl₄]^?, also demonstrated that the composite materials were significantly more effective at recovering gold than activated carbon. Gold removal from solutions containing [AuCl₄]^? and much higher concentrations of iron was highly selective. Copyright © 2004 Society of Chemical Industry     

Removal of Cd(II) and Cu(II) from aqueous solutions using mesoporous silicate containing zirconium and iron

The present work elucidates an environmental friend by process for heavy metals removal from aqueous solutions using mesoporous silicate, containing zirconium and iron. The process comprises the three following steps: (1) synthesis and characterization of mesoporous silicate bed (the prepared adsorbent materials were characterized by powder X-ray diffraction, nitrogen isotherms, FTIR, TGA, and SEM). (2) Evaluation of the efficiency of this new adsorption bed for Cu and Cd removal from aqueous solutions. (3) Study of metal concentration (50-1000 ppm), stirring time (0.5-5 h) and pH (1.5-12) effects on the adsorption power using batch techniques. Results obtained indicate that under optimum conditions, pH in the vicinity of 5-6, Zr-M has the maximum adsorption capacity for both cations Cu and Cd. On the other hand, ZrFe-M1 containing a higher molar ratio of iron showed lower adsorption capacity for the cations Cu and Cd.     

Preparation of Sulfonamide Containing Cellulose Based Sorbent for Removal of Mercury Ions

A new sulfonamide containing cellulose based sorbent was prepared in three steps; poly (acrylonitrile) (PAN) grafting onto cellulose by redox polymerization method, amination of PAN grafted cellulose with ethylenediamine, and sulfamidation with benzene sulfonyl chloride. The resulting polymeric sorbent, which had a sulfonamide content of 3.4 mmol/g, was effective for the removal of mercury ions from aqueous solutions. The mercury sorption capacity of the sorbent is around 1.95 mmol/g under non-buffered conditions. The experiments performed under identical conditions with some metal ions reveal that Cd(II), Mg (II), Zn(II), and Fe(III) ions are also extractable in low quantity (0.02–0.46 mmol/g). The sorbed mercury can be eluted by repeated treatment with hot acetic acid.     

Solvent extraction of metals from chloride solutions

A review is presented of a series of investigations into the extraction of copper, iron, zinc and cadmium into kerosene solutions of Lix or Kelex reagents from aqueous solutions containing chloride ions. The effects of chloride ions on the extraction of copper and iron were smaller than might have been expected to result from the formation of inextractable metal chlorocomplexes, and the extractants retained their selective properties. Extraction with Kelex 100 from chloride solution increased the separation between zinc and cadmium, in comparison with sulphate solutions.     

Performance and cycling of the iron-ion/hydrogen redox flow cell with various catholyte salts

A redox flow cell utilizing the Fe²⁺/Fe³⁺ and H₂/H⁺ couples is investigated as an energy storage device. A conventional polymer electrolyte fuel cell anode and membrane design is employed, with a cathode chamber containing a carbon felt flooded with aqueous acidic solution of iron salt. The maximum power densities achieved for iron sulfate, iron chloride, and iron nitrate are 148, 207, and 234 mW cm^?2, respectively. It is found that the capacity of the iron nitrate solution decreases rapidly during cycling. Stable cycling is observed for more than 100 h with iron chloride and iron sulfate solutions. Both iron sulfate and iron chloride solutions display moderate discharge polarization and poor charge polarization; therefore, voltage efficiency decreases dramatically with increasing current density. A small self-discharge current occurs when catholyte is circulating through the cathode chamber. As a result, a current density above 100 mA cm^?2 is required to achieve high Coulombic efficiency (>0.9).     

The recovery and recycling of mercury from fluorescent lamps using photocatalytic techniques

BACKGROUND: Release of mercury from fluorescent lamps must be minimized to avoid its hazardous effects on human beings and other living organisms. Because of this, increasing attention is given to the improvement of existing techniques for its recovery as well as the development of new ones. This paper describes the application of heterogeneous photocatalysis for the selective reduction of mercury from fluorescent lamps. The whole process involves mercury chemical extraction using aqueous solutions of sodium hypochlorite. After pH adjustment of the resulting aqueous solution, the photocatalytic reduction of mercury is performed in the presence of titanium dioxide and citric acid as an auxiliary organic agent. RESULTS: Mercury removal from the aqueous solution is higher than 99% and the final residual concentration is 4 ppb. A mixture of different mercury compounds is obtained in solid form deposited on the titanium oxide photocatalyst which can easily be redissolved into a small volume of sodium hypochlorite. Metallic mercury could be obtained from the residual Hg(II) solution by conventional cementation techniques with iron as reducing agent. CONCLUSION: Results show high efficiencies of the photocatalytic technique for recovery and recycling of mercury from fluorescent lamps. Copyright © 2009 Society of Chemical Industry     

Mercury(II) removal from aqueous solutions by adsorption on multi-walled carbon nanotubes

Our aim was to test how MWCNTs can be used as a new adsorbent for mercury(II). Multi-walled carbon nanotubes (MWCNTs) have been used for removal of mercury from aqueous solutions. Mercury removal from aqueous solutions by batch adsorption was investigated. Equilibrium isotherms, such as Freundlich, Langmuir, Temkin, Harkins-Jura, were tested. Kinetic studies based on Lagergren first-order, pseudo-second-order and Elovich rate expressions were done. The batch experiments were conducted at three different temperatures (17, 27 and 37 °C) and different pHs of the initial solution. Error function analysis shows that mercury(II) removal obeys pseudo-second order kinetics and Freundlich isotherm equation. Finally, the effects of solution pH and temperature on the adsorption were studied.     

双硫腙接枝聚氨酯泡塑吸附材料的制备及其除汞性能的研究

研究了双硫腙(H2D2)接枝聚氨酯泡塑(PU Foam)吸附材料的制备,考察了螯合泡塑的合成及从含汞废水中除汞的最佳条件。结果表明,该吸附材料对Hg2+具有良好的螯合吸附作用,且除汞效果明显,对8 mg/L含Hg2+废水,在pH为6,固液比为1∶100,温度15℃条件下螯合反应4 h,汞去除率可高达99.99%以上,一次处理后溶液中Hg2+含量低于0.000 8 mg/L,达到了国家饮水标准。且由吸附等温线可知,该过程属于Langmuir单分子层吸附过程,饱和吸附量为2.17 mg/g,可对水中痕量Hg2+进行深度吸附处理。由此,获得了一种新型的、合成工艺简单、成本低廉的含汞废水处理材料。     

Preparation of the Sulfonamide Containing Block Copolymer as Polymeric Sorbent for Removal of Mercury from Aqueous Solutions

A new sulfonamide containing polymeric sorbent for the removal of mercury ions from waste waters was prepared starting from poly(glycidyl methacrylate)-b-poly(ethylene glycol)-b-poly(glycidyl methacrylate) (PGMA- b -PEG- b -PGMA) triblock copolymer prepared by using the ATRP method. Epoxy groups on the block copolymer were functionalized with amino groups. Ammonia-functionalized PGMA- b -PEG- b -PGMA was treated with excess of benzenesulfonyl chloride to obtain a sulfonamide-based polymeric sorbent. The sulfonamide containing the polymeric sorbent with a 3.5 mmol · g^?1 total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 3.12 mmol g^?1 under non-buffered conditions. Experiments performed in identical conditions with several metal ions revealed that Cd(II), Pb(II), Zn(II), Fe(III), and Fe(II) also were extractable in quantities (0–0.45 mmol/g). The sorbed mercury can be eluted by repeated treatment with 4 M HNO₃ without hydrolysis of the sulfonamide groups.     

Fluoride Ions Behavior in the Presence of Corrosion Products of Iron: Effects of Other Anions

The behavior of fluoride ions in the presence of corrosion products of iron in drinking and water solutions was analyzed and the adsorption capacities of the iron oxides (corrosion products of iron) for fluoride ions were determined. Drinking water containing naturally 2.45 mg of fluoride ions per liter was characterized and the concentrations of other anions were determined. The effect of contact time, the initial concentration of fluoride ions, and the effect of other anions naturally present in the drinking water were considered. The kinetic results could be adjusted to the pseudo-second order model, which indicated that the sorption mechanism was chemisorption and the equilibrium was reached in 24 hours. The presence of bicarbonate and chloride ions diminishes the removal efficiency of the fluoride ions, whereas other anions (sulfate, phosphate, and nitrate) did not show any significant effect. The results reflect that the iron oxides products from the corrosion of a hydraulic infrastructure allow the removal of fluoride ions from water.     

Influence of anions on Reactive Red 43 removal in electrochemical coagulation process

The electrochemical coagulation technique (EC) and potentiodynamic polarization tests were used to evaluate the influence of some anions as chloride, sulfate and nitrate on the removal of Reactive Red 43 (RR43) as a model pollutant using aluminum and iron anodes. Higher removal efficiency was obtained using aluminum anodes in the presence of chloride ions. Potentiodynamic polarization tests and determination of total Al³⁺ concentration showed that sulfate ions inhibit the release of Al³⁺ from the anode while in the existences of chloride and nitrate current efficiency was higher than 100%. Dye removal efficiency was considerably decreased by increasing the anion concentration and adding sulfate and nitrate to the solution containing chloride. In EC using iron anodes, the higher removal efficiency was achieved in the presence of chloride and sulfate ions. Potentiodynamic polarization tests revealed that the passive layer formation on the iron surface in the solution containing nitrate caused a considerable decrease in the current and removal efficiency. This passive layer was destroyed by adding chloride ions and in this condition, the removal efficiency and quantity of Fe²⁺ ions increased remarkably. According to the results, iron anode was more efficient than aluminum in the removal of RR43.     

Kinetics of oxidation of cuprous chloride by oxygen in aqueous hydrochloric acid solutions

The rates of absorption of oxygen into aqueous cuprous chloride solutions containing hydrochloric acid were measured at 15, 25 and 35°C using a baffled agitated vessel operated batchwise and the experimental results were analyzed with the chemical absorption theory. The reaction between oxygen and cuprous chloride was found to be second order, i.e. first order with respect to oxygen and CuCl₂^? ion which is the actual reactive species in aqueous cuprous chloride solutions containing hydrochloric acid. The reaction rate constants were calculated and correlated as a function of temperature.     

Metal sorption properties of sulfur-chlorinated jojoba wax bound to polystyrene beads

A new solid extractant (designated PS-DETA-JS) in which sulfur-chlorinated jojoba wax is bound via an amine spacer group to polystyrene beads was synthesized. The absorption of mercury cations from acidic solutions and of chromate anions from saline solutions onto PS-DETA-JS was investigated. The sorption of mercury ions by the solid extractant was compared with that by liquid-sulfurized jojoba wax impregnated inside macroporous resins. The static and dynamic properties of dichromate sorption from 2–20 g/L NaCl solutions at pH 4.1 were studied. Selective sorption of Cr(VI) was obtained at low chromate concentrations (∼ 6 ppm) in saline aqueous solutions. Complete regeneration of the PS-DETA-JS resin was achieved after the reduction of Cr(VI) to Cr(III) and the elution of the Cr(III) with 1N HCl. © 1997 John Wiley & Sons, Inc.     

Removal of Fe(III) ion from aqueous solution by adsorption on raw and treated clinoptilolite samples

Iron (III) adsorption from aqueous solutions onto raw and pretreated clinoptilolite was investigated here. Various parameters for iron removal; initial solution pH, contact time and metal ion concentration were optimized. The equilibrium data were modeled by both the Langmuir and Freundlich adsorption isotherms at optimal conditions. Adsorption capacities of raw samples and those pretreated with Na₂S₂O₈ at 20 °C , 70 °C and with HNO₃ at 20 °C were all similar but samples pretreated with HNO₃ at 70 °C were significantly different; iron (III) removal from samples pretreated with HNO₃ decreased with increasing pretreatment temperature. Tests with Fe⁺³ solutions containing phenol, CsCl or KCl, indicated the continued presence of these ions in zeolite which either promoted or retarded the adsorption of iron. The Fe⁺³ adsorption capacity of clinoptilolite pretreated with HNO₃ at 70 °C was about two times greater with, than without, CsCl and KCl. The kinetics of iron adsorption from aqueous solution were also investigated using the first-order Lagergren equation and a pseudo-second-order model.     

N235-环烷酸萃取分离稀土中的铁

为制备高纯稀土,降低非稀土杂质铁含量,对添加环烷酸的Ｎ２３５萃取分离铁进行了实验研究．Ｆｅ（ＩＩ）的萃取率随有机相Ｎ２３５浓度增加、环烷酸添加量减少及水相酸度增加而增加．添加少量环烷酸的Ｎ２３５萃取剂基本不萃取料液中的稀土,但料液中稀土的存在有助于铁萃取．经过７级逆流萃取实验,ＲＥＯ中的Ｆｅ２Ｏ３由０．５８％降到１０－６．     

Characteristics of the removal of mercury vapor in coal derived fuel gas over iron oxide sorbents

The characteristics of a novel method for Hg removal using H₂S and sorbents containing iron oxide were studied. Previously, we have suggested that this method is based on the reaction of Hg and H₂S over the sorbents to form HgS. However, the reaction mechanism is not well understood. In this work, the characteristics of the Hg removal were studied to clarify the reaction mechanism. In laboratory made sorbents containing iron oxide were used as the sorbent to remove mercury vapor from simulated coal derived fuel gases having a composition of Hg (4.8 ppb), H₂S (400 ppm), CO (30%), H₂ (20%), H₂O (8%), and N₂ (balance gas). The following results were obtained: (1) The presence of H₂S was indispensable for the removal of Hg from coal derived fuel gas; (2) Hg was removed effectively by the sorbents containing iron oxide in the temperature range of 60-100 °C; (3) The presence of H₂O suppressed the Hg removal activity; (4) The presence of oxygen may play very important role in the Hg removal and; (5) Formation of elemental sulfur was observed upon heating of the used sample.     

Graphite felt as an efficient porous electrode for impurity removal and recovery of metals

The properties of graphite felt as an efficient flow-through or flow-by electrode are demonstrated by the removal of traces of mercuric ions from aqueous electrolyte solutions. A simple and direct method is suggested for the determination of the concentration-distribution profile of the electro-deposit on the electrode. The data are compared to those obtained for electrodes used by other authors. It is concluded that mass transport and other properties are much better for the graphite felt than for the other electrodes, thus making it attractive for the use in electrochemical reactors.     

Electrochemical mineralization of sodium dodecylbenzenesulfonate at boron doped diamond anodes

Results are reported of the electrochemical oxidation of sodium dodecylbenzenesulfonate (SDBS), a common surfactant, at boron-doped diamond anodes. The measured critical micelle concentration (CMC) for SDBS in water at 24 °C was almost 150 mg dm⁻³, but this decreased to almost 30 mg dm⁻³ in 0.1 M sodium sulfate. Cyclic voltammetry of a boron doped diamond (BDD) electrode in aqueous SDBS solutions exhibited oxidation current densities at very positive potentials; however, solutions of monomers at concentrations <CMC gave rise to higher current densities than in higher concentration solutions that formed micelles. Galvanostatic electrolyses, with samples analyzed for Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD), were performed in an electrolytic flow cell without separator, operating in batch recycle mode, using solutions containing SDBS at initial concentrations of 25 and 250 ppm. SDBS in basic media (pH = 12) exhibited lower TOC removal rates than in acidic or neutral solutions, due to concurrent oxidation of dissolved carbonates at potentials less positive than required for water oxidation, as evident in cyclic voltammograms. Decreasing the [electrolyte]/[surfactant] ratio from 200 to 10 increased TOC removal rates. For solutions containing monomers, TOC removal rates also increased with flow rate in the second part of the electrolysis, corresponding to reaction of smaller, fragmented organic compounds. When COD removal from a solution containing SDBS micelles was mass transport controlled, current efficiencies were constant at ca. 50%, due to dimerisation of hydroxyl radical to H₂O₂ and its oxidation to dioxygen.     

Performance of hollow fiber supported liquid membrane on the extraction of mercury(II) ions

The extraction and recovery or stripping of mercury ions from chloride media using microporous hydrophobic hollow fiber supported liquid membranes (HFSLM) has been studied. Tri-n-octylamine (TOA) dissolved in kerosene was used as an extractant. Sodium hydroxide was used as a stripping solution. The transport system was studied as a function of several variables: the concentration of hydrochloric acid in the feed solution, the concentration of TOA in the liquid membrane, the concentration of sodium hydroxide in the stripping solution, the concentration of mercury ions in the feed solution and the flow rates of both feed and stripping solutions. The results indicated that the maximum percentages of the extraction and recovery of mercury ions of 100% and 97% were achieved at the concentration of hydrochloric acid in the feed solution of 0.1 mol/l, the concentration of TOA at 3% v/v, the concentration of sodium hydroxide at 0.5 mol/l and the flow rates of the feed and stripping solutions of 100 ml/min. However, the concentration of mercury ions from 1–100 ppm in the feed solution had no effect on the percentages of extraction and recovery of mercury ions. Thus, these results have identified that the hollow fiber supported liquid membrane process has high efficiency on both the extraction and recovery of mercury (II) ions. Moreover, the mass transfer coefficients of the aqueous phase (k _i ) and membrane or organic phase (k _m ) were calculated. The mass transfer coefficients of the aqueous phase and organic phase are 0.42 and 1.67 cm/s, respectively. The mass transfer coefficient of the organic phase is higher than that of the aqueous phase. Therefore, the mass transfer controlling step is the diffusion of the mercury ions through the film layer between the feed solution and the liquid membrane.