The single salt approximation for the major components of seawater: association and acid–base properties

In this note we propose the use of the single salt approximation for the composition of seawater. This approximation has been applied to a synthetic seawater. Association and acid-base properties h..

Sequestration of Alkyltin(IV) Compounds in Aqueous Solution: Formation, Stability, and Empirical Relationships for the Binding of Dimethyltin(IV) Cation by N- and O-Donor Ligands

The sequestering ability of polyamines and aminoacids of biological and environmental relevance (namely, ethylenediamine, putrescine, spermine, a polyallylamine, a branched polyethyleneimine, aspartate, glycinate, lysinate) toward dimethyltin(IV) cation was evaluated. The stability of various dimethyltin(IV) / ligand species was determined in NaClaq at t = 25°C and at different ionic strengths (0.1 ≤ I/mol L−1 ≤ 1.0), and the dependence of stability constants on this parameter was modeled by an Extended Debye-Hückel equation and by Specific ion Interaction Theory (SIT) approach. At I = 0.1 mol L−1, for the ML species we have log K = 10.8, 14.2, 12.0, 14.7, 11.9, 7.7, 13.7, and 8.0 for ethylenediamine, putrescine, polyallylamine, spermine, polyethyleneimine, glycinate, lysinate, and aspartate, respectively. The sequestering ability toward dimethyltin(IV) cation was defined by calculating the parameter pL50 (the total ligand concentration, as −log CL, able to bind 50% of metal cation), able to give an objective representation of this ability. Equations were formulated to model the dependence of pL50 on different variables, such as ionic strength and pH, and other empirical predictive relationships were also found

sequestration of organometallic compounds by synthetic and naturally occurring polycarboxylate ligands binding of monomethylmercury ii by polyacrylic and alginic acids

AbstractThe sequestering capacity of synthetic and naturally occurring polycarboxylate ligands towards mono-methylmercury(II) was evaluated by stability quantitative data on the interaction of CH3Hg+ with different molecular weight synthetic polyacrylates (2 and 20kDa average M.wt) and alginate (70–100 kDa) extracted from brown algae Macrocystis pyrifera. The influence of ionic medium was evaluated by measurements on the CH3Hg+-polyacrylate systems in NaNO3 medium at different ionic strengths (0.10, 0.25, 0.50 and 0.75 mol L−1), and a Debye-HiJckel type equation was used for the dependence of complex formation constants on ionic strength. Measurements on the CH3Hg+ - alginate system were carried out at l = 0.10 mol L−1 in NaNO3 medium. By using the stability data, the sequestering capacity of both ligands towards monomethylmercury(II) was determined at different pH values. Results obtained show that the binding ability of polyacrylic ligands (PAA) is stronger than the alginate (AA), following the trend PA..

speciation of poly amino carboxylic compounds in seawater

AbstractIn this work quantitative data on the interaction of EDTA and EGTA with the major inorganic components of seawater are reported. Protonation constants and alkali and alkaline earth metal complex formation constants are reported at different ionic strengths (0< l/mol L−1≤1). These formation data were obtained from potentiometric measurements in several single and mixed electrolyte media (such as artificial seawater). Potentiometric measurements in artificial seawater (containing Na+, K+, Mg2+, Ca2+, Cl−and SO42−) were analysed by using the single salt approximation (the artificial seawater being considered as a single salt BA whose ions have fractional charge -zanion = zcation = 1.117). Several species BpHrL (L = EDTA or EGTA) are formed and their formation constants are reported at different salinities. Present results, together with similar data on the complexing capability of NTA, DTPA and TTHA towards inorganic components of natural fluids, allowed to find general conclusions on the important c..

Chemical speciation of nucleotide 5′-monophosphates in the presence of biogenic amines

The interaction of adenosine-, uridine-, inosine- and guanosine-5'-monophosphates with protonated ethylenediamine, putrescine, cadaverine, spermidine and spermine, was studied potentiometrically, a..

speciation of chitosan with low and high molecular weight carboxylates in aqueous solution

Quantitative data on the speciation of chitosan (310kDa) with low and high molecular weight carboxylates in aqueous solution are reported. The following carboxylic ligands were considered: monocarboxylate (butyrate); dicarboxylates (malonate, succinate, azelate); tricarboxylate (1,2,3-propanetricarboxylate); tetracarboxylate (1,2,3,4-butanetetracarboxylate); polyacrylates (2.0 and 20kDa); polymethacrylate (5.4kDa). The investigation was performed by potentiometry at t ¼ 25 � C, at low ionic strength (without addition of supporting electrolyte) and at I ¼ 0:15mol L � 1 (NaCl). For all the systems the formation of (chitosan)LHi species was found (L ¼carboxylic ligand; i ¼1 to 4 depending on the carboxylic ligand considered). The stability of proton–chitosan–carboxylate species depends on the number of carboxylic groups involved in the complexation, and it was possible to calculate a rough free energy value per bond DGn ¼� 15 � 2kJ mol � 1 . By using the stability data, the quantitative sequestering capacity of chitosan towards the carboxylates here considered [expressed as the–log(total chitosan concentration) necessary to bind 50% of carboxylate, i.e., pL50] was calculated for different pH values, at low ionic strength and at I ¼ 0:15mol L � 1 . The pL50 values, ranging from 3 to 7, show that chitosan is quite a strong sequestering agent towards carboxylates. Evidences were also obtained for the different behaviour between low and high molecular weight carboxylates

Thermodynamic Behavior of Polyalcohols and Speciation Studies in the Presence of Divalent Metal Cations

The acid–base properties and complexing ability of some biologically relevant polyalcohols (erythritol, sorbitol, maltol, and ethylmaltol) toward bivalent metal cations have been determined by pote..

Control of colloidal CaCO3 suspension by using biodegradable polymers during fabrication

Fabrication of homogenous CaCO3 particles is a significant step in assembling polyelectrolyte capsules. It is crucial to control the dimensions, the shape and the charge of the calcium carbonate particles in order to have homogenously separated and charged templates as final result. For this reason, previously. hey have been deeply investigated. Recently, crystallization of CaCO3 was done by adding poly (sodium 4-styrenesulfonate) (PSS) as negatively charged polymer and poly (allylamine hydrochloride) (PAH) as positively charged polymer and the results were surprising. The homogenous particles were separated and they carried the same charge of the used polymer. The aim of this work was to investigate the synthesis process of CaCO3 particles in different experimental conditions: calcium carbonate was produced in presence and in absence of water and with addition of appropriate polymers. In particular, chitosan (CHI) and poly acrylic acid (PAA) were chosen as biodegradable polymers whereas PSS and PAH were chosen as non-biodegradable polymers. Shape and diameter of particles were investigated by using transmission and scanning electron microscopy, elemental composition was inferred by energy dispersive X-ray analyses whereas their charges were explored by using zeta potential

Gigaspora margarita with and without its endobacterium shows adaptive responses to oxidative stress

Arbuscular mycorrhizal (AM) fungi experience oxidative stress during the plantâfungal interaction, due to endogenous reactive oxygen species (ROS) produced by fungal metabolism and exogenous ROS produced by plant cells. Here, we examine the responses to H2O2 in Gigaspora margarita, an AM fungus containing the endobacterial symbiont Candidatus Glomeribacter gigasporarum (CaGg). Previous studies revealed that G. margarita with its endobacterium produces more ATP and has higher respiratory activity than a cured line that lacks the endobacterium. This higher bioenergetic potential leads to higher production of ROS and to a higher ROS-detoxifying capacity, suggesting a direct or indirect role of the endobacterium in modulating fungal antioxidant responses. To test the hypothesis that the fungalâendobacterial symbiosis may enhance the fitness of the AM fungus in the presence of oxidative stress, we treated the fungus with a sublethal concentration of H2O2 and performed RNA-seq analysis. Our results demonstrate that (i) irrespective of the endobacterium presence, G. margarita faces oxidative stress by activating multiple metabolic processes (methionine oxidation, sulfur uptake, the pentose phosphate pathway, activation of ROS-scavenger genes); (ii) in the presence of its endobacterium, G. margarita upregulates some metabolic pathways, like chromatin status modifications and iron metabolism; and (iii) contrary to our hypothesis, the cured line responds to H2O2 by activating the transcription of specific ROS scavengers. We confirmed the RNA-seq findings by measuring the glutathione and ascorbate concentration, which was the same in both lines after H2O2 treatment. We conclude that both fungal lines may face oxidative stress, but they activate alternative strategies

Thermodynamic Solution Properties of a Biodegradable Chelant (L-glutamic-N,N-diacetic Acid, L-GLDA) and Its Sequestering Ability toward Cd2+

The thermodynamics of the interaction of L-glutamic-N,N-diacetic acid (GLDA) with protons was studied potentiometrically at different temperatures, ionic strengths and ionic media. Four protonation constants and corresponding enthalpy changes occurred at infinite dilution together with temperature and ionic strength coefficients. The medium effect was also interpreted in terms of the formation of weak complexes between the ligand and the cations of supporting electrolytes, resulting in a greater tendency of GLDA to chemically interact with Na+ rather than K+ and, in turn, (CH3)4N+. Formation constants of GLDA with Cd2+ were determined in NaCl(aq) at different ionic strength values. Five complex species were found, namely CdL2−, CdHL−, CdH2L0(aq), Cd2L0(aq), and Cd(OH)L3−, whose formation constant values at infinite dilution were log β = 12.68, 17.61, 20.76, 17.52, and 1.77, respectively. All the species results were relevant in the pH range of natural waters, although the Cd2L0(aq) was observed only for CCd ≥ CGLDA and concentrations of >0.1 mmol dm−3. The sequestering ability of GLDA toward Cd2+, evaluated by means of pL0.5, was maximum at pH~10, whereas the presence of a chloride containing a supporting electrolyte exerted a negative effect. Among new generation biodegradable ligands, GLDA was the most efficient in Cd2+ sequestration.The authors C.B., P.C., A.I., G.L. and C.D.S. thank the University of Messina for the Research and Mobility 2017 Project (cod. 009041). Authors thank COST action CA18202—Network for Equilibria and Chemical Thermodynamics Advanced Research for the support to this study. O.G.-L. is grateful to the project IT-742-13 for Consolidated Research Groups, funded by the Basque Country Government, for her post-doctoral contract