Adsorption of heavy metal ions to floc-type biosorbents

Adsorption of cadmium and lead ions to floc-type biosorbents was reported in this work. Two types of biosorbents containing a marine microalga, Heterosigma akashiwo (Hada) Hada, or a purple non-sulfur bacterium, Rhodobacter sphaeroides, were prepared. The micro-organisms inactivated by steam sterilization were immobilized in casein floc and cross-linked with glutaraldehyde. In the present immobilizing method, we obtained the biosorbents comprising as much as 67% of micro-organism on a dry-weight basis. Simple metal-binding models were applied to explain the adsorption mechanism of bivalent metal ions to the biosorbents. The results showed that casein acted as both the immobilizing material and the adsorbent material. The adsorption of bivalent metal ions to the biosorbents was due to bidentate binding to the acidic sites on casein and monodentate binding to the acidic sites on micro-organisms. The metal-binding constants and the binding capacities of micro-organisms were scarcely influenced by immobilization.     

Adsorption of heavy metal ions by immobilized phytic acid

Applied Biochemistry and Biotechnology - Phytic acid (myoinositol hexaphosphate) or its calcium salt, phytate, is an important plant constituent. It accounts for up to 85% of total phosphorus in...     

Adsorption of heavy metal ions on galvanic sludges and disposal of the sludges in soil

The sorption capacity of ferritized galvanic sludge toward nickel(II), zinc(II), and copper(II) ions was studied. Sorption isotherms were plotted, and quantitative characteristics of adsorption were determined. Ferritized sludges are stable in the natural environment and thus can be disposed of in soil in an environmentally friendly way.     

Adsorption of heavy metal ions onto dithizone-anchored poly (EGDMA-HEMA) microbeads

The dithizone-anchored poly (EGDMA-HEMA) microbeads were prepared for the removal of heavy metal ions (i.e. cadmium, mercury, chromium and lead) from aqueous media containing different amounts of these ions (25-500 ppm) and at different pH values (2.0-8.0). The maximum adsorptions of heavy metal ions onto the dithizone-anchored microbeads from their solutions was 18.3, Cd(II); 43.1, Hg(II); 62.2, Cr(III) and 155.2 mg g(-1) for Pb(II). Competition between heavy metal ions (in the case of adsorption from mixture) yielded adsorption capacities of 9.7, Cd(II); 28.7, Hg(II); 17.6, Cr(III) and 38.3 mg g(-1) for Pb(II). The same affinity order was observed under non-competitive and competitive adsorption, i.e. Cr(III)>Pb(II)>Hg(II)>Cd(II). The adsorption of heavy metal ions increased with increasing pH and reached a plateaue value at around pH 5.0. Heavy metal ion adsorption from artificial wastewater was also studied. The adsorption capacities are 4.3, Cd(II); 13.2, Hg(II); 7.2, Cr(III) and 16.4 mg g(-1) for Pb(II). Desorption of heavy metal ions was achieved using 0.1 M HNO(3). The dithizone-anchored microbeads are suitable for repeated use (for more than five cycles) without noticeable loss of capacity.     

Adsorption of heavy metal ions from aqueous solution by polyrhodanine-encapsulated magnetic nanoparticles

The influence of salt concentration on the terminal velocities of gravity-driven single bubbles sliding along an inclined glass wall has been investigated, in an effort to establish whether surface forces acting between the wall and the bubble influence the latter's mobility. A simple sliding bubble apparatus was employed to measure the terminal velocities of air bubbles with radii ranging from 0.3 to 1.5 mm sliding along the interior wall of an inclined Pyrex glass cylinder with inclination angles between 0.6 and 40.1°. Experiments were performed in pure water, 10 mM and 100 mM KCl solutions. We compared our experimental results with a theory by Hodges et al. which considers hydrodynamic forces only, and with a theory developed by two of us which considers surface forces to play a significant role. Our experimental results demonstrate that the terminal velocity of the bubble not only varies with the angle of inclination and the bubble size but also with the salt concentration, particularly at low inclination angles of ～1-5°, indicating that double-layer forces between the bubble and the wall influence the sliding behavior. This is the first demonstration that terminal velocities of sliding bubbles are affected by disjoining pressure.     

Adsorption behaviour of metal ions on hydroximate resins

Some new chelating ion-exchange resins containing a hydroxamic acid moiety attached to a divinylbenzene styrene (DVBS) copolymer, i.e. glycine hydroximate in DVBS (GH-DVBS). anthranilic acid hydroximate in DVBS (AAHDVBS), malonic acid dihydroximate in DVBS (MAH-DVBS) and iminodiacetic acid dihydroximate in DVBS (IDAAH-DVBS). have been synthesized and their various physicochemical characteristics studied. The degree of retention of metal ions by the resins at equilibrium has been determined in terms of the molar distribution coefficient (k(d)). In general, the resins having a dihydroximate moiety are found to be more efficient compared to monohydroximate resins. However, it is of interest to note that the monohydroximate derivative of amino acid (GH-DVBS) showed better metal retention capability than the dihydroximate of carboxylic acid (MAH-DVBS). The selectivity of the resins for transition and highly charged metal ions is quite high compared to that for alkaline earth metals. All the synthesized resins can be utilized for the separation of a mixture of metal ions because the differences in the distribution coefficient values are large enough to permit good separations on columns. However, the GH-DVBS resin was tried for the separation of copper cobalt and copper nickel mixtures at pH 5.5 using the column mode of operation.     

Adsorption of some bivalent heavy metal ions from aqueous solutions by manganese nodule leached residues

The leached residue, generated after selective extraction of Cu, Ni, and Co in sulfur dioxide-ammonia leaching of manganese nodules, was characterized and batch isothermal adsorption experiments were conducted at ambient temperature to evaluate the effectiveness of the water-washed leached residue for removal of different bivalent metal ions from aqueous synthetic solutions. The effects of pH, initial metal ion concentrations, amount of adsorbent, interfering ions, and heat treatment were also investigated. The uptake of metal ions increased with increasing pH. Under identical conditions the adsorption capacity increased in the order Cd(2+)相似文献   

ESCA-studies on activated silicagel surfaces preconcentrating heavy metal ions

Summary The theoretical ion-exchange capacity of an aminosilylated silicagel surface loaded with dithiocarbamate (DTC) groups was calculated by correlation of the results of a BET measurement, a quantitative determination of the concentration of reactive single hydroxyl groups on the surface, and ESCA intensities. ESCA spectra suggest many functional groups to be thiuram disulfide ones and not DTC ones as believed before. Quantitative ESCA measurements show that aminosilylated silicagel surfaces are only partially transformed to the DTC form. In spite of their chemical instability, the concentration of heavy metal ions (Pb²⁺) in aqueous solution and their ESCA intensities after immobilization on the activated silicagel surface are linearily correlated with each other in the ppm region.Professor Dr. Carl Mahr zum 80. Geburtstag in Dankbarkeit gewidmet.     

Preconcentration of heavy metal ions on reversibly precipitated polymeric systems

A procedure is proposed for the preconcentration of heavy metal ions in the analysis of aqueous media. It consists in the addition of components of reversibly precipitated polymeric systems to the solution, and precipitation of the polymer-metal complex, followed by its dissolution upon changing of the medium’s acidity. The procedure is tested on model solutions of copper, zinc, and lead ions and their mixture (0.001–0.01 mg/L). It is found that the interpolymer complex of poly-N-vinylimidazole with polymethacrylic acid ensures the complete extraction of metal ions and their preconcentration of more than 30-fold.     

Interaction of heavy metal ions with ammonium humates

Sorption properties of ammonium humates with respect to Fe(III), Cu(II), Al(III), Ni(II), Pb(II), and Zn(II) are studied. The effect of the metal ion concentration on the ammonium humate consumption is examined and the corresponding dependences are analyzed using regression equations. The IR spectra of brown coal humic acids, ammonium humates, as well as Fe, Cu, Ni, Zn, Pb, and Al humates are presented.     

Optical sensors for determination of heavy metal ions

A review is given on optical means for single shot testing (probing) as well as continuous monitoring (sensing) of heavy metal ions (HMs). Following an introduction into indicator based approaches, we discuss the types of indicator dyes and polymeric supports used, as well as existing sensing schemes for HMs. The wealth of information is compiled in the form of tables and critically reviewed. Notwithstanding the tremendous work performed so far, it is obvious that still severe limitations do exist in terms of selectivity, limits of detection, dynamic ranges, applicability to specific problems, and reversibility. On the other hand, such sensors have found — and will find — their application whenever rapid and cost-effective testing is required, where personnel is scarce or unskilled, and in field tests. Despite their limitations, the number of such sensors (and of irreversible probes) for HMs is likely to increase in future.     

金属离子在多孔硅表面和吸附与电镀过程中金属在多孔硅表面的淀积

刚制备的多孔硅与金属盐溶液接触会产生金属离子在多孔硅表面和吸附现象。实验显示这一现象只发生在新鲜的多孔硅表面, 而存放一月以后的样品不具备此性质。文中把这一现象归因于新鲜的多孔硅表面电子的富集, 溶液中金属离子从多孔硅表面获得电子而附着。多孔硅表面电镀金属过程中, 一定电压下电镀电流密度在起始阶段逐渐下降, 可以用一个指数关系式较好地描述, 在本文中有一个唯象模型予以解释。     

金属离子在多孔硅表面和吸附与电镀过程中金属在多孔硅表面的淀积

刚制备的多孔硅与金属盐溶液接触会产生金属离子在多孔硅表面和吸附现象。实验显示这一现象只发生在新鲜的多孔硅表面, 而存放一月以后的样品不具备此性质。文中把这一现象归因于新鲜的多孔硅表面电子的富集, 溶液中金属离子从多孔硅表面获得电子而附着。多孔硅表面电镀金属过程中, 一定电压下电镀电流密度在起始阶段逐渐下降, 可以用一个指数关系式较好地描述, 在本文中有一个唯象模型予以解释。     

Adsorption behaviour of some metal ions and their oxinates on Zeokarb-226

Summary To develop a preconcentration technique for trace elements in aqueous solution, the adsorption behaviour of some metal ions and their oxinates on a weak carboxylic acid resin (Zeokarb-226) in the H⁺ form was investigated. Results indicate that under the conditions of the experiment, the resin behaves like a chelating ion-exchanger and that by selecting appropriate conditions, a group of ions such as U(VI), Th(IV), Pb(II), Hg(II), Fe(III) may be separated from many other ions.

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Adsorptionsverhalten einiger Metallionen und ihrer Oxinate an Zeokarb-226

Zusammenfassung Das Adsorptionsverhalten einiger Metallionen und ihrer Oxinate an dem schwachen Carbonsäureharz Zeokarb-226 (H⁺-Form) wurde untersucht, um ein Anreicherungsverfahren für Spurenelemente in wäßriger Lösung zu entwickeln. Die Ergebnisse zeigen, daß sich das Harz unter den gegebenen Bedingungen als Chelataustauscher verhält und geeignet ist für die selektive Anreicherung von z.B. U(VI), Th(IV), Pb(II), Hg(II) und Fe(III).

     

Adsorption and redox reactions of heavy metals on Fe-Mn nodules from Chinese soils

Adsorption of heavy metals and redox reactions of Cr(W) ions on Fe-Mn nodules from five soils of China were investigated by chemical analysis, equilibrium adsorption/redox, and X-ray photoelectron spectroscopy (XPS). Results show that Mn is mainly present as Mn(3+) and Mn(4+) forms in Fe-Mn nodules. The maximum adsorption amounts for different heavy metal ions follow the order Pb(2+) approximately Cu(2+)>Zn(2+)>Co(2+)>Ni(2+)>Cd(2+). The adsorption capacity for heavy metals by Fe-Mn nodules from calciaquert in Shandong province (N5-1) is the highest, while that from hapludalf in Shandong province (N6-1) is the lowest. About 44-100% of the heavy metals adsorbed on Fe-Mn nodules were dissolved in 0.1 mol/L hydroxylamine hydrochloride (HAHC). The maximum amounts of Cr(VI) production by Fe-Mn nodules follow the order of N1-1 (69 mmol/kg)>N4-1 (57 mmol/kg)>N2-1 (52 mmol/kg)>N5-1 (44 mmol/kg). Based on the content of MnO(2) in Fe-Mn nodules dissolved in HAHC, the amount of Cr(VI) production by Mn oxides in N1-1, N2-1, N4-1, and N5-1 is 326, 624, 726, and 482 mmol/kg (MnO(2)), respectively. We propose that the amounts of Cr(VI) production through oxidation Cr(III) by Mn oxides are related to the types of Mn oxides in Fe-Mn nodules.     

Binding heavy metal ions with polymerized onion skin

Red onion skin is highly effective for binding heavy metal ions from aqueous solutions. Color leaching can be prevented and the physical characteristics of the substrate can be improved by treatment with formaldehyde in an acidic medium. Batch and column experiments have been conducted with Cu²⁺, Cd²⁺, Zn²⁺, Ni²⁺, Hg²⁺, and Pb²⁺. Almost quantitative removal of the metal ions from solution can be achieved by using columns of the treated onion skin. Competition of the various metal ions for the substrate has been investigated. The capacity of the substrate in the majority of the metal ions studied is well above 1 meq/g. The use of polymerized onion skin to remove heavy metal ions from domestic and industrial wastewater to safe levels has been recommended as a cheap and effective alternative for commercial ion-exchange resins.     

Two-dimensional nanomaterial based sensors for heavy metal ions

Two-dimensional (2D) nanomaterials are promising building blocks for sensors due to their unique physical, chemical, electronic, and optical properties. This review (with 253 references) first summarizes the historical developments of 2D nanomaterials and discusses the advantages of 2D nanomaterials when applied for constructing sensors. Next, their properties are discussed, with subsections on electronic, optical, mechanical and chemical properties. This is followed by an overview on methods for syntheses and the effects of positive and/or negative charges on the properties and in sensing applications. Then, recent advances in 2D nanomaterial-based electrochemical, fluorometric, colorimetric, electrochemiluminescent, photoelectrochemical, and field-effect transistor sensors are discussed. The discussion also includes the preparation of sensing elements, the roles of such nanomaterials, and assay strategies. Finally, on the basis of the current achievements in the field of 2D nanomaterials, the perspectives on the challenges and opportunities for the exploration of 2D nanomaterial-based sensors are put forward.

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Graphical Abstract ?

     

Biosorption of heavy metal ions by immobilized zoogloea and zooglan

ImmobilizedZoogloea and zooglan in calcium alginate-silica matrix was shown to have a high adsorption capacity for Cu and Cd ions. Our results showed that Cu-ion uptake in the presence of Ca and Mg ions can be enhanced using immobilizedZoogloea and zooglan. Heavy metal ion adsorption efficiency decreased in the following order: Cu > Cd > Zn > Cr. The adsorbed metal ions were desorbed completely using sulfuric acid. ImmobilizedZoogloea and zooglan which was repetitively regenerated adsorbed heavy metal ions without a loss of adsorption capacity.     

Pore-functionalized polymer membranes for preconcentration of heavy metal ions

Functionalized membranes containing carboxylate, phosphate and sulfonate groups were prepared by UV-initiator induced graft polymerization of the functional monomer (acrylic acid, ethylene glycol methacrylate phosphate (EGMP) and 2-acrylamido-2-methyl-1-propane sulfonic acid) with a crosslinker (methylenebisacrylamide) in the pores of poly(propylene) host membranes. The functionalized membranes thus obtained were characterized by gravimetry, FTIR spectroscopy, radiotracers and scanning electron microscopy for the degree of grafting and water uptake, presence of functional groups, ion-exchange capacity, and physical structure of the membranes, respectively. The uptakes of Cs⁺, Ag⁺, Sr²⁺, Cd²⁺, Hg²⁺, Zn²⁺, Eu³⁺, Am³⁺, Hf⁴⁺ and Pu⁴⁺ ions in the functionalized membranes were studied as a function of acidity of the equilibrating aqueous solution. Among the functionalized membranes prepared in the present work, the EGMP-grafted membrane (with phosphate groups) showed acid concentration dependent selectivity towards multivalent metal ions like Eu³⁺, Am³⁺, Hf⁴⁺ and Pu⁴⁺. The solvent extraction studies of EGMP monomer in methyl isobutyl ketone (MIBK) solvent indicated that divalent and trivalent metal ions form complexes with EGMP in 1:2 proportion, but the distribution coefficients of trivalent metal ions were significantly higher that for the divalent ions. The uptakes of Eu³⁺ ions in monomeric EGMP (dissolved in MIBK) and polymeric EGMP (in the forms of crosslinked gel and membrane) were studied as a function of concentration of H⁺ ions in the equilibrating solution. This study indicated that polymeric EGMP has better binding ability towards Eu³⁺ as compared to monomeric EGMP. The variation of distribution coefficients of Eu³⁺/Am³⁺ in gel and membrane as a function of H⁺ ion concentration in the equilibrating aqueous solution indicated that ionic species held in the membrane and gel were not same. These results indicated that proximity of functional groups (phosphate) plays an important role in metal ion binding with polymeric EGMP.     

Calorimetric investigations of urease inhibition by heavy metal ions

The subject of this publication is calorimetric investigations on the inhibitor effect of heavy metal ions on the enzyme urease. The obtained results allow quantification of the inhibitors (Cd²⁺-, As³⁺-, Zn²⁺-, Pb²⁺-ions) via the initial reaction rate of enzymatically catalysed urea hydrolysis. The interpretation potential of the calorimetric measurements is underlined by the determination of the inhibiting mechanisms for the example of Cd²⁺- and As³⁺-ions, the findings on the time regime of the inhibition process, and the detection of heavy metal ions in the ppm range. The use of several different buffer substance revealed the influence of the latter on the intensity of heavy metal inhibition. This opens the path to both the selective analysis of heavy metals via pattern recognition and to the improvement of detection sensitivity.