Browsing by Author "Jang, Larry K."

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Addition of copper-sequestering agents to alginate gel to enhance copper recovery from aqueous media
(1995-11) Jang, Larry K.; Nguyen, Duy V.; Kolostyak, K.; Geesey, Gill G.
A mixture of sodium alginate and sodium polystyrenesulfonate (NaPSS) was used as the absorbent for copper in this work. A viscous solution of the mixture was dispensed into a copper-containing solution circulating in a loop fluidized bed reactor to form alginate gel in situ. Batch absorption data was treated by Langmuir model to yield copper binding capacity and binding stability constant. Results were compared with those of our previous work in which no NaPSS was added to Na-alginate. Based on the Langmuir parameters, the critical copper concentration above which the addition of NaPSS can enhance the copper loading of the alginate gel was calculated. The ratio of copper loading of the alginate gel with the addition of NaPSS to that without the addition of NaPSS at any copper concentration was predicted as well. Similar calculations were made for the case of using the mixture of Na-alginate and Microcystis as the copper absorbent.
Binding of Metal Ions by Extracellular Polymers of Biofilm Bacteria
(1988-11) Geesey, Gill G.; Jang, Larry K.; Jolley, John G.; Hankins, Michael R.; Iwaoka, Teika; Griffiths, Peter R.
Exopolymers which anchor sessile bacteria to metallic surfaces exhibit the capacity to bind copper ions with high affinity. Ionized carboxyl groups on the polymers appear to participate in cupric ion binding. Formation of complexes between the polymers and cupric ions results in the release of protons from the polymer molecule. Attenuated total reflectance Fourier transform infrared spectroscopy showed that polymers composed of acidic polysaccharides promote ionization and deterioration of metallic copper surfaces. X-ray photoelectron spectroscopy studies revealed that the ionic state of the surface-derived copper varied depending on the type of acidic polysaccharide that was in contact with the surface. The results suggest that exopolymers elaborated by adherent bacteria can enhance corrosion of the surfaces with which they are associated.
Effect of pH on the absorption of cu(ii) by alginate gel
(1995-01) Jang, Larry K.; Nguyen, Duy V.; Geesey, Gill G.
The absorption of copper from synthetic solutions of cupric sulfate (initial Cu concentration: 200 ppm, initial pH: 2.4 or 3.4) in a batch loop fluidized bed reactor by alginate gels was investigated. Compared to the results obtained without addition of sulfuric acid [Jang L. K., Geesey G. G., Lopez S. L., Eastman S. L. and Wichlacz P. L., Wat. Res. 24, 889–897 (1990)], the copper-binding efficiency of the alginate gels at pH 3.4 was affected mildly by the acidity of the solution; at pH 2.4, the percent copper recovered was reduced by roughly one-half. In this work, an extended Langmuir model that took into account the competition between monovalent hydrogen ions and divalent cupric ions for the carboxyl groups on the alginate molecules was derived. This model yielded the binding group density of the alginate gel and binding stability constants for cupric alginate and alginic acid simultaneously. The new model was shown to be superior to the simple Langmuir model that expressed the results as conditional copper binding stability constant and capacity at a given pH. Application of the extended Langmuir model to the prediction of copper binding at pH 2 is also illustrated.
Environmental Progress
(1990-11) Jang, Larry K.; Brand, W.; Resong, M.
Alginate (a biopolymer from kelp and some bacterial strains) is known to absorb copper favorably in the presence of other cations. In this work, the feasibility of using a 2-liter batch three-phase (air/liquid/alginate gel) loop fluidized bed reactor to polish water containing 10–150 ppm dissolved copper was investigated. Three methods were tested: (1) Calcium alginate spheres, prepared by dispensing sodium alginate (3.2 wt. % in water) into a 0.05 M calcium nitrate solution, were used as the absorbent, (2) the alginate spheres were formed in situ by dispensing the sodium alginate solution directly into the reactor fluid, and (3) same as (2) except that a trace amount of EDTA was added to the alginate solution. Batch absorption data showed that Method 3 yielded the best result; the concentration of dissolved copper was successfully reduced from 140 ppm to 10 ppm with 3.2 g sodium alginate and 0.2 g EDTA used. However, when the initial concentration was below 40 ppm, both Method 2 and Method 3 are not recommended because the concentration of dissolved copper was too low to allow in situ formation of alginate spheres. Method 1 was found to be useful for treating water containing 10 ppm dissolved copper. But the competition from calcium seriously affected the effective capacity of the alginate for copper. The application of the classical shell progressive model to describe the absorption kinetics was discussed.
An equilibrium model for absorption of multiple divalent metals by alginate gel under acidic conditions
(1999-08) Jang, Larry K.; Nguyen, Duy V.; Geesey, Gill G.
An extended Langmuir model was proposed in this work to describe the simultaneous absorption of multiple divalent metal ions and hydrogen ions from acidic metal-containing aqueous media by an absorbent having one kind of active functional group. A viscous Na–alginate solution was directly dispensed dropwise into the acidic aqueous media containing dissolved copper and zinc to form spherical Cu–Zn–H–alginate gels which subsequently absorb these ions until final equilibrium was reached in batch experiments. Initial pH of the aqueous media was in the range of 2.6–5.4. Binding group density and binding stability constants of alginic acid, cupric alginate and zinc alginate were obtained simultaneously by fitting data to the proposed model developed in this work. Application of the constants obtained to the prediction of the extent of absorption of copper and zinc from an aqueous medium having an initial pH in the range of 2.6–5.4 is illustrated and compared with experimental results.
Extracellular polymers for metal binding
(1990) Geesey, Gill G.; Jang, Larry K.
Interactions between metal ions and capsular polymers
(1989) Geesey, Gill G.; Jang, Larry K.
An iterative procedure based on donnan equilibrium for calculating the polymer-subphase volume of alginic acid
(1989-05) Jang, Larry K.; Harpt, Nathan; Uyen, Ty; Grasmick, Daniel; Geesey, Gill G.
A numerical iterative procedure is presented to predict the polymer-subphase volume that is formed when anionic polysaccharides such as alginic acid (polyuronic acid from kelp) are suspended in an aqueous solution. (The aqueous region surrounding the polymer chain where a strong electrostatic attractive force for counterions exists is defined as the separate polymer subphase within the colloidal phase enclosed by the polymer coil.) Based on the phase-partition model of Marinsky et al.5 and Donnan equilibrium theory, this iterative procedure utilizes the base titration data of the acidic polysaccharide at different ionic strengths as well as the osmotic properties of the sodium form of the polysaccharide. No detailed structural information of alginic acid is required. The resulting calculations show that the polymer subphase, which accounts for a small fraction of the total solution volume, should be regarded as the reaction zone for acid dissociation and metal binding reactions. The volume of polymer subphase thus calculated may also serve as an excellent index for the morphology of the polymer molecule at different ionic strengths, degrees of ionization, polymer concentrations, and extent of polymer-metal binding.
The osmotic coefficients of the sodium form of some polymers of biological origin
(1989-08) Jang, Larry K.; Quintero, Ernesto J.; Gordon, Grisel; Röhricht, Markus; Geesey, Gill G.
The osmotic coefficients ϕp,Na of dilute solutions of the sodium form of some weakly acidic polymers are theoretically predicted in this work. Based on the measured value 0.73 of γNa, the activity coefficient of free Na+, of the completely ionized humic acid (sodium salt) in a salt-free solution, the effective interligand distance b is calculated to be 11.34 Å by using Manning's counterion condensation theory [Manning, G. S. (1969) J. Chem. Phys.51(3), 924]. The corresponding values of γNa (measured experimentally) and b for the completely ionized exopolymer of Pseudomonas atlantica are 0.624 and 7.57 Å when cultivated at a dilution rate D = 0.015 h−1, 0.647 and 8.19 Å at D = 0.025 h−1, and 0.613 and 7.29 Åat D = 0.06 h−1. For alginic acid (in the completely ionized sodium form), γNa = 0.40 and b = 4.71 Å. The osmotic coefficients ϕp,Nafor the partially and the completely ionized polymers are then predicted with Manning's theory as well.
Selectivity of alginate gel for cu vs co
(1995-01) Jang, Larry K.; Nguyen, Duy V.; Geesey, Gill G.
The selectivity of the kelp alginate gel for copper compared to cobalt was investigated. When copper and cobalt existed at relatively high concentrations (100 ppm each), Na-alginate solution was directly dispensed into the mixed solution circulating in a loop fluidized bed reactor to produce CuCo-alginate gels in situ. Two extended Langmuir models were derived and tested against experimental data in this work: Model 1 was a general Langmuir model for two absorbates competing for the same type of binding site. Model 2 was based on the “egg-box” model for gelation of sodium alginate in the presence of divalent metal ions with the assumption that each metal ion would bind two carboxyl groups on neighboring uronate residues that formed the “site”. It was found that Model 1 data better and parameters obtained from Model 1 were used to predict the amount of Na-alginate needed to “polish” a cobalt solution containing a trace amount of copper.
Sorption equilibrium of copper by partially-coagulated calcium alginate gel
(1990-06) Jang, Larry K.; Geesey, Gill G.
The sorption equilibrium of dissolved copper by spherical partially-coagulated gels of calcium alginate was investigated in this work. The gels were formed by dispensing a viscous algin (food grade sodium alginate from kelp) solution with a multi-tip dispenser into 0.05 M CaCl2 solution in a loop fluidized bed reactor. The resultant semi-rigid spherical gels were then transferred to another reactor operated batch wise to absorb dissolved copper at low concentrations (10-40 ppm). When the concentration of the inert neutral salt NaNO3, added to the reactor fluid was 0.01 M, the amount of copper absorbed was found to be substantially higher than that at 0.1 MNaN03. The conventional Langmuir's model based on the concentration of copper in solution yielded different values of conditional stability constant at different ionic strengths in the reactor fluid. However, by defining the copper-binding stability constant on the basis of copper activity in the gel phase with the competition from calcium for metal binding sites taken into account, a unique copper-binding stability constant and a unique calcium-binding stability constant were obtained. The numerical procedure for estimating the activity of copper in the gel fluid was modified from Jang et al. Water Research, 1990)
Two-phase model for describing the interactions between copper ions and exopolymers from alteromonas atlantica
(1992-08) Geesey, Gill G.; Bremer, Philip J.; Smith, James J.; Muegge, M.; Jang, Larry K.
Interactions between copper ions and exopolymer from the marine film-forming bacterium Alteromonas atlantica were evaluated by a two-phase model that treats the polymer as if it exists in a phase separate from the bulk solution. The model takes into account electrostatic interactions and molecular volume changes within the polymer phase to determine the copper activity in the domain where copper interacts with the ligands on the polymer molecule(s). The volume of the polymer phase varied with pH, ionic strength, and copper ion concentration. Exopolymer recovered from chemostat cultures grown at different dilution rates exhibited unique interligand distances, number of ionizable ligands, and molecular volumes. The variations in physical properties, in part, reflected differences in polymer chemistry. The exopolymer contained a lower density of ionizable groups and a smaller molecular volume per number of ionizable groups than alginic acid. The numerical procedure yielded a stability constant of 1 × 105 L/mol for a type I complex between copper ion and exopolymer produced at a dilution rate of 0.02 h−1 that was valid over a range of hydrogen ion concentrations and ionic strengths. The approach provided useful insight on how environmental variables affect the physicochemical properties of microbial exopolymers. Key words: exopolysaccharide, metal ions, chemostat culture.
A two-phase model for determining the stability constants for interactions between copper and alginic acid
(1990-01) Jang, Larry K.; Harpt, Nathan; Grasmick, Daniel; Vuong, L. N.; Geesey, Gill G.
The two-phase model used previously to calculate the polymer-subphase volume of alginic acid was applied to interpret the dependence of apparent metal binding equilibrium on environmental conditions. In this model, the polymer subphase, a small aqueous region surrounding the polymer chain, was considered as a separate phase in the aqueous solution and as a protonation-deprotonation and metal binding reaction zone. Three factors were taken into account when treating experimental data: (1) the electric field due to the charged ligands on the polymer molecule, (2) the effective concentration of ligands based on polymer-subphase volume, and (3) the competition from hydrogen ions for the metal binding sites. The data of base titration of alginic acid in the presence of trace amounts of copper at different alginic acid concentrations and ionic strengths yielded unique intrinsic stability constants for complexes formed between a cupric ion and one or two binding ligands.
Use of a gel-forming biopolymer directly dispensed into a loop fluidized bed reactor to recover dissolved copper
(1990-07) Jang, Larry K.; Geesey, Gill G.; Lopez, S. L.; Eastman, S. L.; Wichlacz, Paul L.
A novel technique for the recovery of copper from synthetic aqueous solutions containing 60–200 ppm dissolved copper was developed in this work. A viscous solution of sodium alginate (a kelp-derived biopolymer known to bind copper) was dispensed dropwise by using a multi-tip dispenser into the synthetic solution circulating in an air-lift glass loop fluidized bed reactor. Upon contact with the copper-containing solution, the alginate gelled into stable spheres which continued to circulate in the reactor to absorb copper. The percent of copper recovered at the lower ionic strength (0.01 M NaNO3) was found to be greater than that at the higher ionic strength (0.1 M NaNO3) of the solution. (Consequently, the conditional copper-binding stability constant for the former case was greater.) An intrinsic copper-binding stability constant, independent of the ionic strength of the solution, was obtained by using a two-phase model modified from our recent work (Jang et al., J. Polymer Sci., Part B27, 1301–1315, 1989; J. phys. Chem.94, 482–488, 1990c).