Study on desorption of Mn, Fe, and Mg from TMP and evaluation of the complexing strength of different chelating agents using side reaction coefficients 10th EWLP, Stockholm, Sweden, August 25–28, 2008

Abstract Chelation of thermomechanical pulp (TMP) was studied in this work. The desorption of Mn, Fe, and Mg due to their impact on peroxide bleaching was investigated. The desorption experiments were performed with EDTA, citric acid, oxalic acid, and formic acid as chelating agents at different pH. Chelation experiments with EDTA were carried out at pH 3–11. Sodium dithionite was used as the reducing agent in studying chelation with EDTA in a reducing environment. Mn was very effectively desorbed with EDTA from TMP at pH <10 and the reducing environment further improved the removal of all the studied metal ions from TMP with EDTA. Citric acid also removed Mn effectively from TMP at pH 5. The thermodynamic stability constants of different metal chelates do not present the correct picture of how strongly the metal ions are bound by the chelating agents in different conditions. But by means of the side reaction coefficients (α M(L)-coefficients) it is also theoretically possible to evaluate and compare the real binding strengths between the metal ions and different chelating agents at varying pH values and other solution conditions. In this study, a theory is given for the calculation of side reaction coefficients. Values of the α M(L)-coefficients, for the pH range 0–14, are presented for EDTA, DTPA, and also for some other new potential environmentally friendly chelating agents.

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The Malachite Green Biodegradation in Bioreactors on Various pH Domains

Revista de Chimie ◽

10.37358/rc.19.8.7472 ◽

2019 ◽

Vol 70 (8) ◽

pp. 2996-2999

Author(s):

Viorel Gheorghe ◽

Catalina Gabriela Gheorghe ◽

Andreea Bondarev ◽

Vasile Matei ◽

Mihaela Bombos

Keyword(s):

Malachite Green ◽

Contact Time ◽

Dominant Species ◽

Wastewater Treatment Plants ◽

Organic Substances ◽

Biological Degradation ◽

Growth Promoters ◽

Ph Values ◽

Biological Sludge ◽

Ph Range

In the experimental study was studied the malachite green colorant biodegradation in biological sludge with biological activity. The biodegradability tests were carried out in laboratory bioreactors, on aqueous solutions of green malachite contacted with microorganisms in which the dominant species is Paramecium caudatum, in a pH range between 8 and 12, temperatures in the ranges 25-350C, using pH neutralizing substances and biomass growth promoters. The colorant initial concentrations and those obtained after biological degradation depending on the contact time, at certain pH values, were established through UV-Vis spectrometry. The studies have shown the measure of possible biological degradation of some organic substances with extended uses, with largely aromatic structure, resistance to biodegradation of microorganisms, commonly used in wastewater treatment plants.

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Efficient Preconcentration of Cu2+, Zn2+ and Fe3+ with an Agarose-Schiff Base Sorbent

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20070908 ◽

2007 ◽

Vol 72 (7) ◽

pp. 908-916 ◽

Cited By ~ 3

Author(s):

Payman Hashemi ◽

Hatam Hassanvand ◽

Hossain Naeimi

Keyword(s):

Schiff Base ◽

Metal Ions ◽

Metal Ion ◽

Good Accuracy ◽

Kinetic Studies ◽

Sample Volume ◽

Effects Of Ph ◽

Glass Column ◽

High Concentrations ◽

Ph Range

Sorption and preconcentration of Cu2+, Zn2+ and Fe3+ on a salen-type Schiff base, 2,2'- [ethane-1,2-diylbis(nitrilomethylidyne)]bis(2-methylphenol), chemically immobilized on a highly crosslinked agarose support, were studied. Kinetic studies showed higher sorption rates of Cu2+ and Fe3+ in comparison with Zn2+. Half-times (t1/2) of 31, 106 and 58 s were obtained for sorption of Cu2+, Zn2+ and Fe3+ by the sorbent, respectively. Effects of pH, eluent concentration and volume, ionic strength, buffer concentration, sample volume and interferences on the recovery of the metal ions were investigated. A 5-ml portion of 0.4 M HCl solution was sufficient for quantitative elution of the metal ions from 0.5 ml of the sorbent packed in a 6.5 mm i.d. glass column. Quantitative recoveries were obtained in a pH range 5.5-6.5 for all the analytes. The volumes to be concentrated exceeding 500 ml, ionic strengths as high as 0.5 mol l-1, and acetate buffer concentrations up to 0.3 mol l-1 for Zn2+ and 0.4 mol l-1 for Cu2+ and Fe3+ did not have any significant effect on the recoveries. The system tolerated relatively high concentrations of diverse ions. Preconcentration factors up to 100 and detection limits of 0.31, 0.16 and 1.73 μg l-1 were obtained for Cu2+, Zn2+ and Fe3+, respectively, for their determination by a flame AAS instrument. The method was successfully applied to the metal ion determinations in several river water samples with good accuracy.

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Ideal pH for the adsorption of metal ions Cr6+, Ni2+, Pb2+ in aqueous solution with different adsorbent materials

Open Agriculture ◽

10.1515/opag-2021-0225 ◽

2021 ◽

Vol 6 (1) ◽

pp. 115-123

Author(s):

Luísa P. Cruz-Lopes ◽

Morgana Macena ◽

Bruno Esteves ◽

Raquel P. F. Guiné

Keyword(s):

Heavy Metals ◽

Metal Ions ◽

Walnut Shell ◽

Lead Adsorption ◽

Viable Solution ◽

Chestnut Shell ◽

Adsorption Processes ◽

Irreversible Effects ◽

Optimal Values ◽

Ph Range

Abstract Industrialization increases the number of heavy metals released into the environment. Lead (Pb2+), nickel (Ni2+) and chromium (Cr6+) are among these toxic metals and cause irreversible effects on ecosystems and human health due to their bio-accumulative potential. The decontamination through adsorption processes using lignocellulosic wastes from agricultural and/or forestry processes is a viable solution. Hence, this work aimed at studying the effect of pH on the biosorption of the metal ions using four different by-product materials: walnut shell, chestnut shell, pinewood and burnt pinewood. These experiments were conducted with solutions of the three heavy metals in which the adsorbents were immersed to measure the rate of adsorption. A range of pH values from 3.0 to 7.5 was used in the experiments, and the concentrations were determined by atomic absorption. The results showed different behaviour of the biosorbent materials when applied to the different metals. The lead adsorption had an ideal pH in the range of 5.5–7.5 when the walnut shell was used as an adsorbent, corresponding to values of adsorption greater than 90%, but for the other materials, maximum adsorption occurred for a pH of 7.5. For the adsorption of chromium, the pH was very heterogeneous with all adsorbents, with optimal values of pH varying from 3.0 (for chestnut shell) to 6.5 (for walnut shell and wood). For nickel, the best pH range was around pH 5, with different values according to the lignocellulosic material used. These results indicate that the tested biosorbents have the potential to decontaminate wastewater in variable extensions and that by controlling the pH of the solution; a more efficient removal of the heavy metals can be achieved.

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The Role of the Disulfide Bridge in the Copper (II) Binding by the Cyclic His4-Peptide

International Journal of Molecular Sciences ◽

10.3390/ijms22126458 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6458

Author(s):

Aleksandra Pieniężna ◽

Weronika Witak ◽

Aneta Szymańska ◽

Justyna Brasuń

Keyword(s):

Metal Ions ◽

Coordination Mode ◽

Transition Metal Ions ◽

Disulfide Bridge ◽

Chain Flexibility ◽

Vis Spectroscopy ◽

Ph Range ◽

Cd Studies ◽

Metal Ratios

In this paper, we present studies on the influence of the disulfide bridge on the copper (II) ions’ binding abilities by the cyclic His4-peptide. The studied ligand HKHPHRHC-S-S-C consists of nine amino acids. The cyclic structure was obtained through a disulfide bridge between two cysteinyl groups. Moreover, this peptide is characterized by the presence of four His residues in the sequence, which makes it an interesting ligand for transition metal ions. The potentiometric and spectroscopic (UV-Vis spectroscopy and circular dichroism spectroscopy (CD)) studies were carried out in various molar ligand to metal ratios: 2:1, 1:1, and 1:2, in the pH range of 2.5–11 at 25 °C. The results showed that the cyclic His4-peptide promotes dinuclear complexes in each of these systems and forms the final dinuclear species with the {NIm, 3N-amide}{NIm, 3N-amide} coordination mode. The obtained data shows that cyclization by the formation of the disulfide bond has an impact on the peptide chain flexibility and appearance of additional potential donors for metal ions and influences the copper (II) ions’ coordination.

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MCM-41 grafted with citric acid: The role of carboxylic groups in enhancing the synthesis of xanthenes and removal of heavy metal ions

Environmental Nanotechnology Monitoring & Management ◽

10.1016/j.enmm.2020.100410 ◽

2021 ◽

Vol 15 ◽

pp. 100410

Author(s):

Mohammed A. Mannaa ◽

Hatem M. Altass ◽

Reda S. Salama

Keyword(s):

Heavy Metal ◽

Citric Acid ◽

Metal Ions ◽

Heavy Metal Ions ◽

Carboxylic Groups ◽

Mcm 41

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The aquation of cis-Chlorodi(methyl sulphoxide)bisethylenediaminecobalt(III), cis-Chlorodimethylformamidebisethylenediaminecobalt(III), and cis-Chlorodimethylacetamidebisethylenediaminecobalt(III) ions

Australian Journal of Chemistry ◽

10.1071/ch9661821 ◽

1966 ◽

Vol 19 (10) ◽

pp. 1821 ◽

Cited By ~ 13

Author(s):

IR Lantzke ◽

DW Watts

Keyword(s):

Solvent Molecule ◽

Chloride Ion ◽

Side Reaction ◽

Base Hydrolysis ◽

Alkaline Solutions ◽

Replacement Reaction ◽

Ph Values ◽

Trigonal Bipyramidal ◽

Entropy Of Activation ◽

Solvent Replacement

The aquation of each of three octahedral chloro(solvent)bisethylene- diaminecobalt(III) ions, involving the solvent ligands dimethyl sulphoxide (DMSO), dimethylformamide (DMF), and dimethylacetamide (DMA), has been examined in solutions of different pH. In solutions of pH less than 6, the predominant reaction is replacement of the solvent molecule by water in an SN1 process, involving a trigonal bipyramidal transition state and resulting in a mixture of the trans- and cis- chloroaquo complexes. The slow loss of chloride ion is an accompanying side reaction. In solutions of pH greater than 6 base hydrolysis becomes important, and in alkaline solutions the rate of solvent loss is too fast to measure by conventional techniques. The rate of liberation of chloride ion is also greatly increased with increasing pH. Values of the activation energy, and entropy of activation, are reported for the solvent replacement reaction at a pH of 1.90.

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Effect of pH, Acidulant, Time, and Temperature on the Growth and Survival of Listeria monocytogenes

Journal of Food Protection ◽

10.4315/0362-028x-52.8.571 ◽

1989 ◽

Vol 52 (8) ◽

pp. 571-573 ◽

Cited By ~ 116

Author(s):

KENT M. SORRELLS ◽

DAVIN C. ENIGL ◽

JOHN R. HATFIELD

Keyword(s):

Antimicrobial Activity ◽

Acetic Acid ◽

Lactic Acid ◽

Listeria Monocytogenes ◽

Citric Acid ◽

Hydrochloric Acid ◽

Malic Acid ◽

Incubation Temperature ◽

Growth And Survival ◽

Ph Values

The effect of different acids, pH, incubation time, and incubation temperature on the growth and survival of four strains of Listeria monocytogenes in tryptic soy broth was compared. Hydrochloric acid (HCl), acetic acid (AA), lactic acid (LA), malic acid (MA), and citric acid (CA) were used to acidify tryptic soy broth to pH values 4.4, 4.6, 4.8, 5.0, and 5.2 pH. Incubation times were 1, 3, 7, 14, and 28 d at 10, 25, and 35°C. The inhibition of L. monocytogenes in the presence of high acidity appears to be a function of acid and incubation temperature. Based on equal pH values, the antimicrobial activity is AA > LA > CA ≥ MA > HCl at all incubation times and temperatures. When based on equal molar concentration, the activity appeared to be CA ≥ MA > LA ≥ AA > HCl at 35 and 25°C, and MA > CA > AA ≥ LA > HCl at 10°C. Greatest antimicrobial activity occurred at 35°C. Greatest survival occurred at 10°C and greatest growth occurred at 25°C. Final pH of the medium was as low as 3.8 in HCl at 28 d. All strains grew well at pH values lower than the minimum previously reported (5.5–5.6).

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