Biochar Chemistry in a Weathered Tropical Soil: Kinetics of Phosphorus Sorption

The phosphorus (P) chemistry of biochar (BC)-amended soils is poorly understood. This statement is based on the lack of published research attempting a comprehensive characterization of biochar’s influence on P sorption. Therefore, this study addressed the kinetic limitations of these processes. This was accomplished using a fast pyrolysis biochar made from a mix of waste materials applied to a highly weathered Latossolo Vermelho distrofico (Oxisol) from São Paulo, Brazil. Standard method (batch method) was used. The sorption kinetic studies indicated that P sorption in both cases, soil (S) and soil-biochar (SBC), had a relatively fast initial reaction between 0 to 5 min. This may have happened because adding biochar to the soil decreased P sorption capacity compared to the mineral soil alone. Presumably, this is a result of: (i) Inorganic phosphorus desorbed from biochar was resorbed onto the mineral soil; (ii) charcoal particles physically covered P sorption locations on soil; or (iii) the pH increased when BC was added SBC and the soil surface became more negatively charged, thus increasing anion repulsion and decreasing P sorption.

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Influence of soil pH on inorganic phosphorus sorption and desorption in a humid brazilian Ultisol

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832005000500004 ◽

2005 ◽

Vol 29 (5) ◽

pp. 685-694 ◽

Cited By ~ 38

Author(s):

Shinjiro Sato ◽

Nicholas Brian Comerford

Keyword(s):

Soil Ph ◽

Ph Value ◽

Tropical Soils ◽

Inorganic Phosphorus ◽

Phosphorus Sorption ◽

Tropical Regions ◽

P Sorption ◽

Phosphorus Desorption ◽

P Desorption ◽

P Bioavailability

Liming is a common practice to raise soil pH and increase phosphorus (P) bioavailability in tropical regions. However, reports on the effect of liming on P sorption and bioavailability are controversial. The process of phosphorus desorption is more important than P sorption for defining P bioavailability. However few studies on the relationship between soil pH and P desorption are available, and even fewer in the tropical soils. The effects of soil pH on P sorption and desorption in an Ultisol from Bahia, Brazil, were investigated in this study. Phosphorus sorption decreased by up to 21 and 34 % with pH increases from 4.7 to 5.9 and 7.0, respectively. Decreasing Langmuir K parameter and decreasing partition coefficients (Kd) with increasing pH supported this trend. Phosphorus desorption was positively affected by increased soil pH by both the total amount of P desorbed and the ratio of desorbed P to initially sorbed P. A decreased K parameter and increased Kd value, particularly at the highest pH value and highest P-addition level, endorsed this phenomenon. Liming the soil had the double effect of reducing P sorption (up to 4.5 kg ha-1 of remaining P in solution) and enhancing P desorption (up to 2.7 kg ha-1 of additionally released P into solution).

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KINETIC STUDIES ON THE HYDROLYSIS OF BENZOYLCHOLINE BY HUMAN SERUM CHOLINESTERASE

Canadian Journal of Biochemistry and Physiology ◽

10.1139/y56-068 ◽

1956 ◽

Vol 34 (1) ◽

pp. 637-653 ◽

Cited By ~ 6

Author(s):

W. Kalow ◽

K. Genest ◽

N. Staron

Keyword(s):

Kinetic Studies ◽

Reaction Rates ◽

Serum Cholinesterase ◽

Initial Reaction ◽

Ultraviolet Spectrophotometry ◽

First Order ◽

Low Concentrations ◽

Kinetics Of ◽

Hydrolysis Of ◽

Substrate Concentrations

Benzoylcholine stands out from other known substrates of serum cholinesterase because of its high apparent affinity for this enzyme combined with a rapid rate of destruction. The reaction kinetics of the hydrolysis of benzoylcholine can be studied by ultraviolet spectrophotometry, since the absorbance decreases in proportion to the concentration of substrate. Kinetic data obtained by measuring initial reaction rates, and by analyzing continuous hydrolysis curves, are the same within the range of experimental error. The enzymatic data are compatible with the assumption that in the presence of high substrate concentrations a complex consisting of esterase and two substrate molecules is formed. This complex is hydrolyzed more slowly than the complex containing one molecule of substrate which is formed at low concentrations of benzoylcholine. Alkaline hydrolysis of benzoylcholine follows the kinetics of a first order reaction.

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Kinetic studies on the reaction between cytochrome c oxidase and ferrocytochrome c

Biochemical Journal ◽

10.1042/bj1470145 ◽

1975 ◽

Vol 147 (1) ◽

pp. 145-153 ◽

Cited By ~ 75

Author(s):

M T Wilson ◽

C Greenwood ◽

M Brunori ◽

E Antonini

Keyword(s):

Cytochrome C ◽

Cytochrome C Oxidase ◽

Time Course ◽

Kinetic Studies ◽

Initial Reaction ◽

Fast Phase ◽

Ferrocytochrome C ◽

Cytochrome C2 ◽

Kinetics Of ◽

Flow Experiments

In stopped-flow experiments in which oxidized cytochrome c oxidase was mixed with ferrocytochrome c in the presence of a range of oxygen concentrations and in the absence and presence of cyanide, a fast phase, reflecting a rapid approach to an equilibrium, was observed. Within this phase, one or two molecules of ferrocytochrome were oxidized per haem group of cytochrome a, depending on the concentration of ferrocytochrome c used. The reasons for this are discussed in terms of a mechanism in which all electrons enter through cytochrome a, which, in turn, is in rapid equilibrium with a second site, identified with ‘visible’ copper (830 nm-absorbing) Cud (Beinert et al., 1971). The value of the bimolecular rate constant for the reaction between cytochromes c2+ and a3+ was between 10(6) and 10(7) M(-1)-S(-1); some variability from preparation to preparation was observed. At high ferrocytochrome c concentrations, the initial reaction of cytochrome c2+ with cytochrome a3+ could be isolated from the reaction involving the ‘visible’ copper and the stoicheiometry was found to approach one molecule of cytochrome c2+ oxidized for each molecule of cytochrome a3+ reduced. At low ferrocytochrome c concentrations, however, both sites (i.e. cytochrome a and Cud) were reduced simultaneously and the stoicheiometry of the initial reaction was closer to two molecules of cytochrome c2+ oxidized per molecule of cytochrome a reduced. The bleaching of the 830 nm band lagged behind or was simultaneous with the formation of the 605 nm band and does not depend on the cytochrome c concentration, whereas the extinction at the steady-state does. The time-course of the return of the 830 nm-absorbing species is much faster than the bleaching of the 605 nm-absorbing component, and parallels that of the turnover phase of cytochrome c2+ oxidation. Additions of cyanide to the oxidase preparations had no effect on the observed stoicheiometry or kinetics of the reduction of cytochrome a and ‘visible’ copper, but inhibited electron transfer to the other two sites, cytochrome a3 and the undetectable copper, Cuu.

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Partial Purification and Characterization of Catalase from Banana Peels

Baghdad Science Journal ◽

10.21123/bsj.13.2.392-398 ◽

2016 ◽

Vol 13 (2) ◽

pp. 392-398

Author(s):

Baghdad Science Journal

Keyword(s):

Gel Filtration ◽

Maximum Velocity ◽

Kinetic Studies ◽

Maximal Activity ◽

Partial Purification ◽

Purification And Characterization ◽

Km Value ◽

Almost All ◽

Kinetics Of

Catalase (EC 1.11.1.6) is a well known enzyme which exists in almost all living creatures exposing to oxygen (such as plants, bacteria, and animals). It is a very necessary enzyme to protect the cell from oxidative detriment by reactive oxygen species (ROS). The aim of this study is the partial purification and characterization of Catalase enzyme from Banana peels. In this study, fresh banana peels are treated with 70 % ethanol ,further separated with chloroform ,water and ethyl acetate respectively .The supernatant of the enzymatic sample which is treated with chloroform is loaded into gel filtration column with Sephadex G-100 (1.0 x 90 cm) equilibrated with pH7 buffer media (phosphate buffer 0.1 M). Kinetic studies of the purified enzyme activity are measured and characterized .The maximal activity (26.04 units/mg) of catalase is observed with chloroform buffer extraction. The kinetics of catalase; Michalis constant Km and maximum velocity Vmax is determined using Linweaver- Burk plot, The Km value for catalase (434.7mM), Vmax (100 m mole min -1). Characterization results demonstrate that the optimal pH for activity is (7.6). And the optimal temperature for activity is 30?C .The present study indicates that Banana peels is a good source of catalase enzyme.

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KINETIC STUDIES ON THE HYDROLYSIS OF BENZOYLCHOLINE BY HUMAN SERUM CHOLINESTERASE

Canadian Journal of Biochemistry and Physiology ◽

10.1139/o56-068 ◽

1956 ◽

Vol 34 (3) ◽

pp. 637-653 ◽

Cited By ~ 37

Author(s):

W. Kalow ◽

K. Genest ◽

N. Staron

Keyword(s):

Kinetic Studies ◽

Reaction Rates ◽

Serum Cholinesterase ◽

Initial Reaction ◽

Ultraviolet Spectrophotometry ◽

First Order ◽

Low Concentrations ◽

Kinetics Of ◽

Hydrolysis Of ◽

Substrate Concentrations

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Kinetics of phosphorus sorption in soils in the state of Paraíba¹

Revista Brasileira de Ciência do Solo ◽

10.1590/s0100-06832011000400024 ◽

2011 ◽

Vol 35 (4) ◽

pp. 1301-1310 ◽

Cited By ~ 6

Author(s):

Hemmannuella Costa Santos ◽

Fábio Henrique Tavares de Oliveira ◽

Ignácio Hernan Salcedo ◽

Adailson Pereira de Souza ◽

Valério Damásio da Mota Silva

Keyword(s):

Soil Properties ◽

Clay Content ◽

The State ◽

Phosphorus Sorption ◽

P Adsorption ◽

Soil P ◽

P Sorption ◽

P Concentration ◽

Elovich Equation ◽

Kinetics Of

The soil P sorption capacity has been studied for many years, but little attention has been paid to the rate of this process, which is relevant in the planning of phosphate fertilization. The purpose of this experiment was to assess kinetics of P sorption in 12 representative soil profiles of the State of Paraíba (Brazil), select the best data fitting among four equations and relate these coefficients to the soil properties. Samples of 12 soils with wide diversity of physical, chemical and mineralogical properties were agitated in a horizontal shaker, with 10 mmo L-1 CaCl2 solution containing 6 and 60 mg L-1 P, for periods of 5, 15, 30, 45, 60, 90, 120, 420, 720, 1,020, and 1,440 min. After each shaking period, the P concentration in the equilibrium solution was measured and three equations were fitted based on the Freundlich equation and one based on the Elovich equation, to determine which soil had the highest sorption rate (kinetics) and which soil properties correlated to this rate. The kinetics of P sorption in soils with high maximum P adsorption capacity (MPAC) was fast for 30 min at the lower initial P concentration (6 mg L-1). No difference was observed between soils at the higher initial P concentration (60 mg L-1). The P adsorption kinetics were positively correlated with clay content, MPAC and the amount of Al extracted with dithionite-citrate-bicarbonate. The data fitted well to Freundlich-based equations equation, whose coefficients can be used to predict P adsorption rates in soils.

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Characterization of the Periodate Oxidation of Glycerol and Related Compounds, and Application toward Determination of Serum Triglyceride Concentrations

Clinical Chemistry ◽

10.1093/clinchem/20.6.645 ◽

1974 ◽

Vol 20 (6) ◽

pp. 645-648 ◽

Cited By ~ 5

Author(s):

D A White ◽

D S Miyada,1 ◽

R M Nakamura

Keyword(s):

Periodate Oxidation ◽

Serum Triglyceride ◽

Kinetic Studies ◽

Initial Reaction ◽

Automated Method ◽

First Order Kinetics ◽

Excess Substrate ◽

Related Compounds

Abstract The periodate oxidation of glycerol was examined to see if it could be quantitated from its yield of an equimolar amount of formaldehyde. End-product studies, carried out with glycerol and related compounds by an automated method, indicated that oxidation was almost completed within the time span of the analysis. Kinetic studies at pH 4.0 with excess substrate indicated pseudo-first-order kinetics with respect to periodate consumption. The rate constant for glycerol is 57 x 10-2 min-1; the reaction with glycolaldehyde was too rapid to measure. These results indicate that it is the initial reaction of periodate with glycerol that is rate-limiting instead of the secondary reaction with glycolaldehyde, and that these reactions occur concomitantly. We conclude that it is extremely unlikely that any practicable glycerol analysis can be based on the equimolar formation of formaldehyde.

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Irradiation behavior of pyrolytic silicon carbide

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074288 ◽

1983 ◽

Vol 41 ◽

pp. 72-73

Author(s):

R. J. Lauf

Keyword(s):

Silicon Carbide ◽

Fission Products ◽

Thermodynamics And Kinetics ◽

Neutron Fluences ◽

Fuel Particles ◽

Sic Coatings ◽

Irradiation Behavior ◽

Kinetics Of ◽

Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

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The Kinetics of Inhibition of the Action of Thrombin by the Fibrinopeptides Formed during the Clotting of Fibrinogen

Thrombosis and Haemostasis ◽

10.1055/s-0038-1655562 ◽

1966 ◽

Vol 16 (01/02) ◽

pp. 277-295 ◽

Cited By ~ 1

Author(s):

A Silver ◽

M Murray

Keyword(s):

Amino Acids ◽

Competitive Inhibition ◽

Amorphous Material ◽

Peptide Bond ◽

Initial Reaction ◽

Reaction Products ◽

Coagulation Mechanism ◽

Kinetics Of ◽

Kinetics Of Inhibition ◽

Burk Plot

SummaryVarious investigators have separated the coagulation products formed when fibrinogen is clotted with thrombin and identified fibrinopeptides A and B. Two other peaks are observed in the chromatogram of the products of coagulation, but these have mostly been dismissed by other workers. They have been identified by us as amino acids, smaller peptides and amorphous material (37). We have re-chromatographed these peaks and identified several amino acids. In a closed system of fibrinogen and thrombin, the only reaction products should be fibrin and peptide A and peptide B. This reasoning has come about because thrombin has been reported to be specific for the glycyl-arginyl peptide bond. It is suggested that thrombin also breaks other peptide linkages and the Peptide A and Peptide B are attacked by thrombin to yield proteolytic products. Thrombin is therefore probably not specific for the glycyl-arginyl bond but will react on other linkages as well.If the aforementioned is correct then the fibrinopeptides A and B would cause an inhibition with the coagulation mechanism itself. We have shown that an inhibition does occur. We suggest that there is an autoinhibition to the clotting mechanism that might be a control mechanism in the human body.The experiment was designed for coagulation to occur under controlled conditions of temperature and time. Purified reactants were used. We assembled an apparatus to record visually the speed of the initial reaction, the rate of the reaction, and the density of the final clot formed after a specific time.The figures we derived made available to us data whereby we could calculate and plot the information to show the mechanism and suggest that such an inhibition does exist and also further suggest that it might be competitive.In order to prove true competitive inhibition it is necessary to fulfill the criteria of the Lineweaver-Burk plot. This has been done. We have also satisfied other criteria of Dixon (29) and Bergman (31) that suggest true competitive inhibition.

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Elaboration and Characterization of the Properties of Refractory Cr Base Alloys

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.72.46 ◽

2010 ◽

Vol 72 ◽

pp. 46-52 ◽

Cited By ~ 1

Author(s):

Laurent Royer ◽

Stéphane Mathieu ◽

Christophe Liebaut ◽

Pierre Steinmetz

Keyword(s):

Mechanical Properties ◽

Melting Point ◽

Molten Glass ◽

Energy Production ◽

Creep Properties ◽

Refractory Alloys ◽

Industrial Use ◽

Kinetics Of ◽

Selection Of

For energy production and also for the glass industry, finding new refractory alloys which could permit to increase the process temperatures to 1200°C or more is a permanent challenge. Chromium base alloys can be good candidates, considering the melting point of Cr itself, and also its low corrosion rate in molten glass. Two families of alloys have been studied for this purpose, Cr-Mo-W and Cr-Ta-X alloys (X= Mo, Si..). A finer selection of compositions has been done, to optimize their chemical and mechanical properties. Kinetics of HT oxidation by air, of corrosion by molten glass and also creep properties of several alloys have been measured up to 1250°C. The results obtained with the best alloys (Cr-Ta base) give positive indications as regards the possibility of their industrial use.

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