Utilizing Radioisotopes for Trace Metal Speciation Measurements in Seawater

Croot, Peter; Heller, Maija; Schlösser, Christian; Wuttig, Kathrin

doi:10.5772/23182

Cited by 5 publications

(8 citation statements)

References 160 publications

(158 reference statements)

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“…However, after the rayon fibers hydrolysis and the removal of the flame-retardant pigment, the recovered solubilized glucose was ultrafiltrated to remove all the impurities that can be released from a textile material such as the oils used in the spinning process and all elements that could interfere with the subsequent fermentation step such as Zn- and Na-sulfate solutions. In fact, the contribution of zinc ions to the antimicrobial activity and the reduction of microorganism viability is well-known; , therefore, as already previously reported for ocean seawater, the use of ultrafiltration membranes can be applied to reduce the trace metals in the final permeate volume. , …”

Section: Resultsmentioning

confidence: 99%

Enzymatic Recycling of High-Value Phosphor Flame-Retardant Pigment and Glucose from Rayon Fibers

Vecchiato

Skopek

Jankova³

et al. 2017

ACS Sustainable Chem. Eng.

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Viscose (also known as Rayon) filaments are obtained from regenerated cellulose and are used in many different sectors mainly as reinforcement material in tires and other cord applications and in the clothing industry. The incorporation of a phosphor-containing pigment imparts flame-retardancy properties to these fibers, which then can be used as part of personal protection textiles delivering wear comfort. There are no recycling strategies for these materials being brought to landfills or chemically degraded since incineration is difficult because of their flame retardancy. In this study, an enzyme-based strategy for the recovery of glucose and of the phosphor pigment without altering their chemical structures was developed as a circular economy solution. Rayon fibers were completely hydrolyzed by a cellulase preparation while 98% of the glucose (reducing sugar assay and HPLC analysis) and more than 99% of the flame-retardant pigment present in the fibers was recovered. The recovered pigment was analyzed via 1H, 13C, and 31P NMR, and the purity >95% was comparable to that of the commercially available pigment. The recovered glucose was successfully used as carbon source for ethanol production by Saccharomyces cerevisiae while the recycled phosphor pigment was reused in viscose filament production leading to similar mechanical properties like those measured for virgin fibers. This work presents an environmentally friendly recycling strategy of functional rayon fibers for the recovery of the two major components, namely, glucose and the pigment.

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Section: Resultsmentioning

confidence: 99%

Enzymatic Recycling of High-Value Phosphor Flame-Retardant Pigment and Glucose from Rayon Fibers

Vecchiato

Skopek

Jankova³

et al. 2017

ACS Sustainable Chem. Eng.

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“…This approach has recently been described (Croot et al, 2011 ) however a brief account is given here. Starting from the mass balance for soluble iron in seawater:…”

Section: Methodsmentioning

confidence: 99%

The Importance of Kinetics and Redox in the Biogeochemical Cycling of Iron in the Surface Ocean

Croot¹,

Heller²

2012

Front. Microbio.

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It is now well established that Iron (Fe) is a limiting element in many regions of the open ocean. Our current understanding of the key processes which control iron distribution in the open ocean have been largely based on thermodynamic measurements performed under the assumption of equilibrium conditions. Using this equilibrium approach, researchers have been able to detect and quantify organic complexing ligands in seawater and examine their role in increasing the overall solubility of iron. Our current knowledge about iron bioavailability to phytoplankton and bacteria is also based heavily on carefully controlled laboratory studies where it is assumed the chemical species are in equilibrium in line with the free ion association model and/or its successor the biotic ligand model. Similarly most field work on iron biogeochemistry generally consists of a single profile which is in essence a “snap-shot” in time of the system under investigation. However it is well known that the surface ocean is an extremely dynamic environment and it is unlikely if thermodynamic equilibrium between all the iron species present is ever truly achieved. In sunlit waters this is mostly due to the daily passage of the sun across the sky leading to photoredox processes which alter Fe speciation by cycling between redox states and between inorganic and organic species. Episodic deposition events, dry and wet, are also important perturbations to iron cycling as they bring in new iron to the system and alter the equilibrium between iron species and phases. Here we utilize new field data collected in the open ocean on the complexation kinetics of iron in the surface ocean to identify the important role of weak iron binding ligands (i.e., those that cannot maintain iron in solution indefinitely at seawater pH: αFeL < αFe′) in allowing transient increases in iron solubility in response to iron deposition events. Experiments with the thermal O2- source SOTS-1 also indicate the short term impact of this species on iron solubility also with relevance to the euphotic zone. This data highlights the roles of kinetics, redox, and weaker iron binding ligands in the biogeochemical cycling of iron in the ocean.

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“…Measurements of the dissociation rate of organic ligand complexes can therefore provide estimates of K cond Fe’L , a key parameter for incorporating Fe into ocean biogeochemical models. Previous studies have used electrochemical methods − or radioisotope exchange , to measure kinetic constants of Fe binding by marine organic ligands, but these approaches obtain average values that represent a complex ligand mixture.…”

Section: Introductionmentioning

confidence: 99%

Slow Kinetics of Iron Binding to Marine Ligands in Seawater Measured by Isotope Exchange Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

Boiteau

Repeta

2022

Environ. Sci. Technol.

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Current understanding of dissolved iron (Fe) speciation in the ocean is based on two fundamentally different approaches: electrochemical methods that measure bulk properties of a heterogeneous ligand pool and liquid chromatography mass spectrometry methods that characterize ligands at a molecular level. Here, we describe a method for simultaneously determining Fe−ligand dissociation rate constants (k d ) of suites of naturally occurring ligands in seawater by monitoring the exchange of ligandbound 56 Fe with 57 Fe using liquid chromatography−inductively coupled mass spectrometry. Values of k d were determined for solutions of ferrichrome and ferrioxamine E. In seawater, the dissociation rate constant of ferrichrome (k d = 10 × 10 −8 s −1 ) was greater than that of ferrioxamine E (k d = 3.6 × 10 −8 s −1 ). The rates for both compounds were over twice as fast in seawater compared with pure water, suggesting that seawater salts accelerate dissociation. Isotope exchange experiments on organic extracts of natural seawater indicated that ligand-binding sites associated with chromatographically unresolved dissolved organic matter exchanged Fe more quickly (k d = 1.8 × 10 −5 s −1 ) than amphibactin siderophores (k d = 2.15 × 10 −6 s −1 ) and an unidentified siderophore with m/z 709 (k d = 9.6 × 10 −6 s −1 ). These findings demonstrate that our approach can bridge molecular-level ligand identification with kinetic and thermodynamic metal-binding properties.

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Utilizing Radioisotopes for Trace Metal Speciation Measurements in Seawater

Cited by 5 publications

References 160 publications

Enzymatic Recycling of High-Value Phosphor Flame-Retardant Pigment and Glucose from Rayon Fibers

Enzymatic Recycling of High-Value Phosphor Flame-Retardant Pigment and Glucose from Rayon Fibers

The Importance of Kinetics and Redox in the Biogeochemical Cycling of Iron in the Surface Ocean

Slow Kinetics of Iron Binding to Marine Ligands in Seawater Measured by Isotope Exchange Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

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