The Effect of Divalent Metals on the Properties of Alginate Solutions. II. Comparison of Different Metal Ions.

Haug, Arne; Smidsrød, Olav; Larsen, Bjørn; Gronowitz, Salo; Hoffman, Ragnar A.; Westerdahl, Anders

doi:10.3891/acta.chem.scand.19-0341

Cited by 230 publications

(118 citation statements)

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“…This observation is in good agreement with the known higher affinity of Pb 2+ for the AA carboxyl groups and is consistent with the existing literature on alginatecontaining biomasses. 6,8,12,44 It is difficult to compare the above stability constants with literature results, given that the experiments were not performed using the same alginates, nor in the same intervals of pH, ionic strength, or metal-to-ligand ratios. In particular, the metal binding properties of the AA are very dependent on its guluronic acid content.…”

Section: Effects Of the Ionic Strengthmentioning

confidence: 99%

“…For example, guluronic-rich alginates are char-acterized by a higher affinity for divalent metals 12 because of a "zig-zag" structure that can easily accommodate divalent cations, i.e., the "egg-box model". [13][14][15] Biopolymer conformations are typically evaluated by measurements of their dimensions (gyration or hydrodynamic radii, persistence and contour lengths), as determined by intrinsic viscosity, nuclear magnetic resonance, or scattering techniques (e.g., X-ray, neutron, or light).…”

Section: Introductionmentioning

confidence: 99%

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Quantifying Pb and Cd Complexation by Alginates and the Role of Metal Binding on Macromolecular Aggregation

et al. 2005

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The Pb and Cd binding capacity of alginates were quantified by the determination of their complex stability constants and the concentration of complexing sites using H + , Pb 2+ , or Cd 2+ selective electrodes in both static and dynamic titrations. Centrifugation filter devices (30 kDa filter cutoff), followed by inductively coupled plasma mass spectrometry (ICP-MS) measurements of lead or cadmium in the filtrates, were used to validate the results. The influence of ionic strength, pH, and the metal-to-alginate ratio was determined for a wide range of metal concentrations. Because of their polyelectrolytic properties, alginates may adopt different conformations depending on the physicochemistry of the medium, including the presence of metals. Therefore, molecular diffusion coefficients of the alginate were determined by fluorescence correlation spectroscopy under the same conditions of pH, ionic strength, and metal-to-alginate ratios that were used for the metal binding studies. The complexation and conformational properties of the alginate were related within the framework of the nonideal competitive adsorption isotherm (NICA) combined with a Donnan approach to account for both intrinsic and electrostatic contributions.

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Section: Effects Of the Ionic Strengthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantifying Pb and Cd Complexation by Alginates and the Role of Metal Binding on Macromolecular Aggregation

et al. 2005

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“…As described in [33,34], the polyguluronates in alginic acid complex with calcium and other multivalent ions [35], which are present in most water sources, causing dissolved alginate that concentrates near the membrane to form a cross-linked gel. The sodium alginate used here (Sigma-Aldrich) has a molecular weight rating of 80,000-120,000 g/mol.…”

Section: Model Porous Foulantmentioning

confidence: 99%

Quantifying osmotic membrane fouling to enable comparisons across diverse processes

Tow

Lienhard

2016

Journal of Membrane Science

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In this study, a method of in situ membrane fouling quantification is developed that enables comparisons of foulant accumulation between desalination processes with different membranes, driving forces, and feed solutions. Unlike the conventional metric of flux decline, which measures the response of a process to fouling, the proposed method quantifies the foulant accumulation. Foulant accumulation is parameterized by two variables, cake structural parameter and hydraulic diameter, that are calculated from flux measurements using a model for salt and water transport through fouled reverse osmosis (RO) and forward osmosis (FO) membranes, including dispersive mass transfer in the FO membrane support layer. Model results show that pressure declines through the foulant layer and can, in FO, reach negative absolute values at the membrane. Experimental alginate gel fouling rates are measured within a range of feed ionic compositions where cake hydraulic resistance is negligible. Using both flux decline and cake structural parameter as metrics, the effect of feed salinity on RO fouling is tested and RO is compared to FO. When RO is fouled with alginate, feed salinity and membrane permeability affect flux decline but not foulant accumulation rate. Between FO and RO, the initial rates of foulant accumulation are similar; however, FO exhibits slower flux decline, which causes greater foulant accumulation over time. The new methodology enables meaningful quantification and comparison of fouling rates with the aim of improving fundamental understanding of fouling processes.

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“…In contrast, the fractional contents and sequence distributions of the M and G residues vary widely (54), and alginate structures are described as being composed of G blocks, M blocks, and MG blocks of various lengths. G blocks are of great biological and applied significance since they are a prerequisite for the formation of strong polymer gels in the presence of divalent cations like Ca 2ϩ (26).…”

mentioning

confidence: 99%

Identification and Characterization of anAzotobacter vinelandiiType I Secretion System Responsible for Export of the AlgE-Type Mannuronan C-5-Epimerases

et al. 2006

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Alginate is a linear copolymer of ␤-D-mannuronic acid and its C-5-epimer, ␣-L-guluronic acid. During biosynthesis, the polymer is first made as mannuronan, and various fractions of the monomers are then epimerized to guluronic acid by mannuronan C-5-epimerases. The Azotobacter vinelandii genome encodes a family of seven extracellular such epimerases (AlgE1 to AlgE7) which display motifs characteristic for proteins secreted via a type I pathway. Putative ATPase-binding cassette regions from the genome draft sequence of the A. vinelandii OP strain and experimentally verified type I transporters from other species were compared. This analysis led to the identification of one putative A. vinelandii type I system (eexDEF). The corresponding genes were individually disrupted in A. vinelandii strain E, and Western blot analysis using polyclonal antibodies against all AlgE epimerases showed that these proteins were present in wild-type culture supernatants but absent from the eex mutant supernatants. Consistent with this, the wild-type strain and the eex mutants produced alginate with about 20% guluronic acid and almost pure mannuronan (<2% guluronic acid), respectively. The A. vinelandii wild type is able to enter a particular desiccation-tolerant resting stage designated cyst. At this stage, the cells are surrounded by a rigid coat in which alginate is a major constituent. Such a coat was formed by wild-type cells in a particular growth medium but was missing in the eex mutants. These mutants were also found to be unable to survive desiccation. The reason for this is probably that continuous stretches of guluronic acid residues are needed for alginate gel formation to take place.

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The Effect of Divalent Metals on the Properties of Alginate Solutions. II. Comparison of Different Metal Ions.

Cited by 230 publications

References 0 publications

Quantifying Pb and Cd Complexation by Alginates and the Role of Metal Binding on Macromolecular Aggregation

Quantifying Pb and Cd Complexation by Alginates and the Role of Metal Binding on Macromolecular Aggregation

Quantifying osmotic membrane fouling to enable comparisons across diverse processes

Identification and Characterization of anAzotobacter vinelandiiType I Secretion System Responsible for Export of the AlgE-Type Mannuronan C-5-Epimerases

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