scholarly journals Abiotic Transient Nitrite Occurrences from Nitrate Reduction through Goethite-Mediated Fe(III)/Fe(II) Cycle with Labile Organic Materials and Ammonia

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1202
Author(s):  
Hyeoksun Choi ◽  
Sanghwa Oh
Keyword(s):  
Citric Acid ◽  
Natural Organic Matter ◽  
Reaction Rate ◽  
Organic Materials ◽  
Syringic Acid ◽  
Point Of Zero Charge ◽  
Adsorptive Removal ◽  
Ph Values ◽  
Long Time ◽  
Abiotic Reduction

The abiotic reduction of NO3− to NO2−—coupled with the oxidation of labile organic materials such as citric acid, syringic acid and natural organic matter (NOM) and NH4+ through the goethite-mediated Fe(III)/Fe(II) cycle under anaerobic condition—was investigated at pH values of 4 and 7. The concentrations of the produced Fe2+ and NO2− were monitored. At a pH of 4, concentrations of Fe2+ increased, except for citric acid; no NO2− was detected. The reason why it was not detected is unclear. A possible reaction was the adsorption of NO2− onto goethite at pH < point of zero charge (pzc) of goethite (6.42) due to electrical attractive force. The maximum production of NO2− at a pH of 7 was in the order of citric acid >> syringic acid > NOM. However, Fe2+ was not detected at this pH even though Fe2+ should be required for NO2− production. To better understand of these phenomena, the adsorptive removal of Fe2+ and NO2− onto goethite was experimentally investigated. More than 90% of the produced Fe2+ and NO2− could be removed rapidly by adsorption onto the surface of goethite at pH 7 and 4, respectively. In addition, the reaction of Fe2+ with NO3− appeared to determine the overall reaction rate of the Fe(III)/Fe(II) cycle because of its relatively slow reaction rate. Using these results, we conclude that NO2− can be produced from NO3− reduction through Fe(III)/Fe(II) cycle with labile organic materials and ammonium at a pH of 7; especially, Fe(III)/Fe(II) cycle with citric acid results the maximum NO2− production higher than 600 μM for a long time (over 200 h) and then disappeared. But, the reasons for its disappearance were not addressed in this study.

200kv superconducting cryo electron microscope

1987 ◽  
Vol 45 ◽  
pp. 642-643
Author(s):  
M. Iwatsuki ◽  
Y. Kokubo ◽  
Y. Harada ◽  
J. Lehman
Keyword(s):  
Electron Microscope ◽  
Structure Analysis ◽  
Organic Materials ◽  
Strong Interactions ◽  
Specimen Preparation ◽  
Great Effort ◽  
Electron Microscopic ◽  
Crystal Fields ◽  
Special Skill ◽  
Long Time

In recent years, the electron microscope has been significantly improved in resolution and we can obtain routinely atomic-level high resolution images without any special skill. With this improvement, the structure analysis of organic materials has become one of the interesting targets in the biological and polymer crystal fields.Up to now, X-ray structure analysis has been mainly used for such materials. With this method, however, great effort and a long time are required for specimen preparation because of the need for larger crystals. This method can analyze average crystal structure but is insufficient for interpreting it on the atomic or molecular level. The electron microscopic method for organic materials has not only the advantage of specimen preparation but also the capability of providing various information from extremely small specimen regions, using strong interactions between electrons and the substance. On the other hand, however, this strong interaction has a big disadvantage in high radiation damage.

Citric acid modified waste cigarette filters for adsorptive removal of methylene blue dye from aqueous solution

2021 ◽  
pp. 50655
Author(s):  
Aafia Tehrim ◽  
Min Dai ◽  
Xiange Wu ◽  
Malik Muhammad Umair ◽  
Imran Ali ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Citric Acid ◽  
Blue Dye ◽  
Methylene Blue Dye ◽  
Adsorptive Removal

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

Holzforschung ◽  
2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Kim Granholm ◽  
Pingping Su ◽  
Leo Harju ◽  
Ari Ivaska
Keyword(s):  
Citric Acid ◽  
Metal Ions ◽  
Chelating Agents ◽  
Side Reaction ◽  
Sodium Dithionite ◽  
Thermomechanical Pulp ◽  
Peroxide Bleaching ◽  
Ph Values ◽  
Reducing Environment ◽  
Ph Range

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.

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

1989 ◽  
Vol 52 (8) ◽  
pp. 571-573 ◽  
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 &gt; LA &gt; CA ≥ MA &gt; HCl at all incubation times and temperatures. When based on equal molar concentration, the activity appeared to be CA ≥ MA &gt; LA ≥ AA &gt; HCl at 35 and 25°C, and MA &gt; CA &gt; AA ≥ LA &gt; 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).

scholarly journals Aeration / Stripping of n-Butyl Mercaptan in aqueous environment

2013 ◽  
Vol 8 (2) ◽  
pp. 103-112
Keyword(s):  
Experimental Data ◽  
Water Quality ◽  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Chemical Equilibrium ◽  
Reaction Rate ◽  
Reaction Parameter ◽  
Ph Values ◽  
Neutral Compound

Μany applications in water quality management have a common key water quality parameter, dissolved oxygen, resulting to the critical role of aeration. On the other hand, in municipal and industrial wastewater, especially where aeration is applied, the presence of volatile organic compounds (VOCs) causes several concerns including a direct threat to humans, partly due to their emission from treatment tanks. pH, temperature and Henry’s Law govern VOCs’ speciation and consequently their emission characteristics. Limited data and simplifications of available mass-transfer models pose obstacles to a realistic approach, especially in the presence of a chemical equilibrium, for example in the case of mercaptans. In the present study the importance of oxygen transfer and stripping of a VOC (n-butyl mercaptan) on aeration’s overall effectiveness are examined separately. Clean water oxygenation and stripping of mercaptan to an inert gas (nitrogen) were studied aiming to consider mass transfer aspects and to investigate the influence of chemical equilibrium between ionic and neutral form of the target compound in neutral and alkaline solutions. Using appropriate mass transfer relationships (dynamic method), experimental data were analyzed for the determination of overall mass transfer coefficient ( kOL,O2α ) of oxygen. Correlating kOL,O2 α with the corresponding mass transfer coefficient of n-butyl mercaptan in neutral solutions (calculated according the model proposed by Matter-Muller et al. [1]), a value of ratio βy of 0.566 is found, close to the reported values of other VOCs with similar values of Henry’s constant. At alkaline pH however the conventional simplified model fails to predict realistic values of mass-transfer coefficients. A coupled differential algebraic equation system, based on mass balances, taking into account dissociation of the compound to be stripped and assuming chemical non-equilibrium conditions during stripping, was developed. Reaction parameter k2 was calculated with non-linear least-squares analysis. The model predicts satisfactorily the experimental data and it provides a useful tool for the semibatch stripper design in situations where a reversible reaction is involved. At pH values below 8.5 mercaptan concentration falls exponentially whereas above 10.5 it tends to linearity. The bubble equilibrates and mercaptan transferred depends upon solubility and not diffusivity. Especially after depletion of initial neutral compound, transport depends upon neutral/ionic form speciation. The effectiveness of stripping n-butyl mercaptan, at a given pH, is mainly determined by a proportionality constant considered as “fugacity capacity” (removal effect on the process) and by a reversible reaction rate constant k2 (kinetic effect on the process). The ‘’fugacity capacity” is determined by hydrophobicity (i.e. low solubility and high limiting activity coefficient) rather than pure-component volatility (i.e. vapor pressure or boiling point). High limiting activity coefficient promotes mercaptan emission due to established vapor-liquid equilibrium, while the low reaction parameter k2, controls neutral compound quantity. At high pH, where ionic form predominates, experimental data showed that stripping was almost independent of the gas flow rate applied. A strong sensitivity of the model to uncertainty of γ∞ was found: γ∞ controls emission rate and through this the dynamic variations of neutral/ionic concentration profiles whereas reaction rate law parameter k2 controls the neutral/ionic transformation and it is the crucial quantity which governs the process at high pH values.

Scythian Leather Quiver from Bulgakovo

2020 ◽  
Vol 26 (1) ◽  
pp. 146-171
Author(s):  
Marina N. Daragan
Keyword(s):  
Organic Materials ◽  
The North ◽  
Long Time ◽  
Unknown Objects

Abstract What were items of Scythian archer’s equipment? What materials were used, and how were they produced? These issues remain currently practically unknown. Objects made from organic materials (wood, leather, and textile) in Scythian burials are lost or provide little information. For this reason almost nothing about Scythian archery equipment (bow and quiver) has been known for a long time. This article describes and analyzes the only well preserved quiver found in the Scythian burial of the 4th century BC in the North Pontic Region. The details of a leather quiver bag, a wooden stiffening plate, wooden painted arrows with bronze arrowheads have survived.

Coagulation-Direct Filtration of Soft, Low Alkalinity Humic Waters

1999 ◽  
Vol 40 (9) ◽  
pp. 55-62 ◽  
Author(s):  
Bjørnar Eikebrokk
Keyword(s):  
Natural Organic Matter ◽  
Pilot Scale ◽  
Quality Parameters ◽  
Efficient Removal ◽  
Direct Filtration ◽  
Ph Values ◽  
Optimum Ph ◽  
Calcium Sources ◽  
Ph Conditions ◽  
Removal Efficiencies

Optimisation of coagulation-direct filtration processes with respect to efficient removal of humic substances, i.e. natural organic matter (NOM) has gained a lot of focus in many countries over the last years. This paper presents experimental results from pilot scale research studies aimed at optimising the coagulation-direct filtration process applied to soft and humic raw waters with low turbidity and alkalinity levels. Comprehensive tests of 3 types of raw waters with different NOM content, 5 types of coagulants, and 3 calcium sources for the purpose of corrosion control have been conducted. Removal efficiencies with respect to relevant water quality parameters are presented, with typical relationships between raw water NOM content, coagulant dose requirements and pH. Generally, when applying metal-based coagulants, residual metal concentration was the critical parameter regarding minimum coagulant dose requirements. Typical NOM removal efficiencies were in the range of 75-90% and 40-70% with respect to colour and organic carbon, respectively. Optimum pH conditions for the removal of NOM and/or residual metals do not always coincide with that of turbidity. The experiments also showed that poly-aluminium and ferric chlorides might have some benefits over alum in terms of dose requirements and range of optimum pH values, and that chitosan may be used for colour removal with good results.

Adsorptive Removal of Natural Organic Matter during Drinking Water Treatment

1999 ◽  
Vol 40 (9) ◽  
pp. 183-190 ◽  
Author(s):  
S. G. J. Heijman ◽  
A. M. van Paassen ◽  
W. G. J. van der Meer ◽  
R. Hopman
Keyword(s):  
Organic Matter ◽  
Ion Exchange ◽  
Natural Organic Matter ◽  
Exchange Resin ◽  
Drinking Water Treatment ◽  
Ion Exchange Resin ◽  
Batch Experiments ◽  
Colour Removal ◽  
Adsorptive Removal ◽  
First Choice

For the removal of DOC (and colour) several treatment steps are suggested. If it is also necessary to remove hardness nanofiltration is probably the first choice. For colour removal without softening a number of adsorbents are suggested in the literature. In order to estimate the costs of these treatment steps a dynamic column model based on batch experiments was used to predict the service time of the columns filled with different adsorbents. Also the (on site) regeneration of the different adsorbents was investigated in batch experiments. Especially the ion exchange resin was very promising. The costs of the treatment of one m3 water with a column filled with an ion exchange resin was estimated for the investigated case at 0.05 Euro.

scholarly journals Upaya Pengolahan Limbah Kotoran Babi Menggunakan Komposter Rumah Tangga

2018 ◽  
Vol 12 (2) ◽  
pp. 104
Author(s):  
Widya Sari ◽  
I Wayan Budiarsa Suyasa ◽  
I.G.B Sila Dharma
Keyword(s):  
Organic Materials ◽  
Raw Materials ◽  
Raw Material ◽  
Pig Manure ◽  
Vegetable Waste ◽  
Composting Process ◽  
Experiment Method ◽  
Long Time ◽  
Speed Up ◽  
Macro Nutrients

ABSTRACT        The production of pig manure waste potentially pollutes the soil, water and air. One of the most effective processing a waste treatments is through composting. The composting process takes a long time if not assisted by the activator as decomposers of organic materials in order to accelerate the composting process. Activators such as local microorganism (MOL) contain macro nutrients, micro and active microorganism that potentially decomposed organic materials, growth stimulants and pest/disease control agents such as to help speed up the composting process. This study aims to determine the C/N ratio of optimal raw materials for composting of pig manure and vegetable waste, determining the effect of adding local microorganism (MOL) to the length of time of composting and determining the effectiveness of business from composting of pig manure and vegetable waste based on the calculation of B/C ratio.        This research uses quantitative approach with experiment method. The first stage is the preparation of the raw material which is divided into three groups : composition 1 with 75% (pig manure) and 25% (vegetable waste), composition 2 with 50% (pig manure) and 50% (vegetable waste) and then composition 3 with 25% (pig manure) and 75% (vegetable waste). Furthermore, the best raw material composition was treated with variations of MOL addition of A (100 ml), B (300 ml), C (500 ml) and D (without MOL).        The results showed that the composition of the best raw material mixture was a mixture composition of 25% (pig manure) and 75% (vegetable waste) with a C/N ratio of 38.95. The effect of MOL addition indicates that the greater MOL volume the faster to composting process. The quality compost with addition of MOL has C/N ratio levels is (16,30), N-total (1,65%), P tersedia (8043,02 ppm), K tersedia (8857,40 ppm), Fe (1,87%), Mn (0,09%) Zn (480 ppm) in which that value meets the SNI 19-7030-2004. Based on analysis of B/C ratio obtained result of 1.04 where the value is approaching criteria B/C ratio more than 1.00 which means compost business feasible to be developed.   Keywords : Pig manure, MOL, time of composting, composter, B/C ratio

scholarly journals Adsorption studies of Mo and Vonto ferrihydrite

2008 ◽  
Vol 72 (1) ◽  
pp. 385-388 ◽  
Author(s):  
L. Brinza ◽  
L. G. Benning ◽  
P. J. Statham
Keyword(s):  
Binary System ◽  
Binding Sites ◽  
Point Of Zero Charge ◽  
High Uptake ◽  
Adsorption Efficiency ◽  
Adsorption Studies ◽  
Ph Values ◽  
Zero Charge ◽  
Kinetics Of

AbstractIn this paper, the kinetics of Mo and V (100 μM) uptake on ferrihydrite (FHY) were evaluated in batch, mono-sorbate systems at pH between 4 and 9, and in bi-sorbate systems in the presence of P (100 μM) at pH 7. In the Mo and V single-sorbate experiments, 100% adsorption was observed at pH values below 6 and 8, respectively. Above the point of zero charge (PZC = 7.97) of FHY, the adsorption efficiency for Mo dropped dramatically (20% at pH 8) while V showed high uptake efficiencies even at pH 9 (60% efficiency). The results from the bi-sorbate experiments (Mo-P and V-P) showed that at pH 7, P out-competed (97%) Mo for binding sites on FHY, while in the V-P binary system only ∼44% of the binding sites are occupied by P with the remaining sites being occupied by V.

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