Modeling time-dependent phosphate buffering capacity in different soils as affected by bicarbonate and silicate ions

Soil Research ◽  
2008 ◽  
Vol 46 (4) ◽  
pp. 315 ◽  
Author(s):  
Nirmal De ◽  
Samar Chandra Datta
Keyword(s):  
Control System ◽  
Sorption Isotherms ◽  
Buffering Capacity ◽  
Rate Of Change ◽  
Silicate System ◽  
Sorption Data ◽  
P Sorption ◽  
Freundlich Equation ◽  
Practical Implications ◽  
Different Soils

The aim of this paper was to establish a relationship between phosphate buffering capacity and time in the presence of specifically sorbed anions like bicarbonate and silicate. P sorption isotherms were obtained at different times of equilibration for 3 surface soil samples, namely, Typic Haplustept, Calcic Chromustert, and Ultic Paleustalf in 3 different systems namely, bicarbonate (0.001 m), silicate (0.001 m), and a control system without any bicarbonate or silicate and having a common concentration of 0.1 m NaCl. Phosphate sorption data at different times could be fitted very closely to a modified Freundlich equation of the form: X/m = KCntp, where X/m is the amount of phosphate sorbed at solution phosphate concentration C and time t in hours. The values of n and p were positive fractions (mostly) and found to vary with soils and ionic medium. The silicate system was more effective in decreasing P sorption. Phosphate buffering capacity, defined as the first-order partial derivative of X/m with respect to C, KntpCn–1, was calculated at a particular concentration of 0.3 mg/L (usual P concentration of soil solution) at different times from the optimised value of K, n, and p. Phosphate buffering capacity was maximum in the control system and found to increase with time. Bicarbonate and, particularly, silicate ion decreased buffering capacity drastically and also the rate of change of buffering capacity with time. The practical implications of this decrease in buffering capacity by bicarbonate and silicate ions is discussed.

Effects of decalcification on the phosphate sorption characteristics of eight calcareous soils

Soil Research ◽  
1990 ◽  
Vol 28 (6) ◽  
pp. 919 ◽  
Author(s):  
ICR Holford ◽  
M Chater ◽  
GEG Mattingly
Keyword(s):  
Calcareous Soils ◽  
Sorption Isotherms ◽  
Phosphate Sorption ◽  
Surface Equation ◽  
P Sorption ◽  
Surface Areas ◽  
Freundlich Equation ◽  
Sorption Parameters ◽  
Parameter Values ◽  
Sorption Characteristics

Phosphate sorption isotherms and parameter values were determined on eight calcareous soils which were carefully decalcified using a procedure which minimized changes in cation saturation. Calcite content of the original soils varied from 0.8 to 24 2% and calcite surface areas from 4 . 0 to 8.5 m2 g-1. Sorption parameters were derived from the Langmuir 'two-surface' equation. Decalcification increased phosphate sorption at low residual P concentrations (<0.8 mg L-1) but decreased it at higher concentrations. The higher P sorption was associated with an increase in affinity because the calculated sorption capacities of high-affinity surfaces were not increased. These sorption capacities were well correlated with iron oxide contents of the soils, so the increase in phosphate affinity of these surfaces was consistent with the decrease in pH (0.5 to 1.5 units) of the decalcified soils. The lower P sorption at higher concentrations was associated with a substantial decrease in sorption capacity of the postulated low-affinity surfaces. These latter decreases were quantitatively correlated with the calcite surface areas of the original soils. These and other changes in phosphate sorption characteristics support the utility of the Langmuir 'two-surface' equation in providing information, compatible with what would be expected from more complex mechanistic models, and which exceeds what one would expect from other simpler models such as the Freundlich equation. They also support an hypothesis that an important component of low-affinity surfaces of these calcareous soils is calcite on which organic anions are co-adsorbed.

Extractable iron and aluminium predict the P sorption capacity of Thai soils

Soil Research ◽  
2005 ◽  
Vol 43 (6) ◽  
pp. 757 ◽  
Author(s):  
W. Wiriyakitnateekul ◽  
A. Suddhiprakarn ◽  
I. Kheuruenromne ◽  
R. J. Gilkes
Keyword(s):  
Sorption Capacity ◽  
Stepwise Regression ◽  
Clay Content ◽  
Langmuir Equation ◽  
Soil Types ◽  
Sorption Data ◽  
P Sorption ◽  
P Sorption Capacity ◽  
Freundlich Equation ◽  
Extractable Iron

The objective of this study was to determine if dithionite- and oxalate-extractable Fe and Al can be used to predict the P sorption capacity of Thai soils. Forty-five samples from diverse soil types were taken from surface and subsurface horizons of soils on sandstone, shale/limestone, granite, and basalt. The samples were analysed for P sorption, dithionite- and oxalate-extractable Fe and Al (Fed, Feo, Ald, Alo), specific surface area (SSA), and other soil properties. Generally P sorption data for these soils were slightly better fitted by the Langmuir equation than the Freundlich equation. The Langmuir P sorption maximum ranged from 35 to 1111 μg/g with a median value of 370 μg/g soil. Soils developed on basalt had higher values of P sorption maximum (xm) (range 400–1111 μg/g, median 597 μg/g) than soils on other parent materials. Fed concentrations in soils (4–74 g/kg) were much higher than Feo concentrations (0.2–13.8 g/kg) with values of Feo/Fed ranging from 0.01 to 0.28 (median 0.09), indicating that most of the free iron oxides were crystalline. Amounts of Ald and Alo were about equal with median values of 1.6 and 1.0 g/kg, respectively. About 80% of the samples had SSA values <40 m2/g. Both the P sorption maximum and Freundlich k were linearly related to SSA (R2 = 0.77, 0.74), Ald (R2 = 0.78, 0.79), Alo (R2 = 0.64, 0.74), Fed (R2 = 0.48, 0.41), Feo (R2 = 0.43, 0.72), and clay content (R2 = 0.48, 0.36). Stepwise regression indicated that 81% of the variability in P sorption by these soils could be explained by a combination of dithionite and oxalate Fe and Al, however, Ald alone is almost as effective in predicting the P sorption capacity of Thai soils.

Sorption and desorption of orthophosphate and pyrophosphate by mineral fractions of soils, goethite, and kaolinite

1991 ◽  
Vol 71 (3) ◽  
pp. 327-338 ◽  
Author(s):  
T. Al-Kanani ◽  
A. F. MacKenzie
Keyword(s):  
Ammonium Oxalate ◽  
Sorption Isotherms ◽  
Parent Material ◽  
Langmuir Equation ◽  
Particle Sizes ◽  
Sorption Data ◽  
Freundlich Equation ◽  
P Release ◽  
P Fertilizer ◽  
Degree Of Sorption

Sorption-desorption reactions of orthophosphate (OP) and pyrophosphate (PP) were studied in two size fractions of Quebec soils (St. Bernard and Dalhousie) and minerals (goethite and kaolinite). Soil and mineral samples were fractionated into two separates (20.0–2.0 μm and 2.0–0.2 μm). The soils had similar mineral suites, but the St. Bernard have more vermiculite, chlorite, and quartz in the coarser fraction than the Dalhousie soil, perhaps an indication of different origin of parent material. Soil and goethite samples sorbed more OP than PP whereas kaolinite sorbed small but similar amounts of PP and OP. The PP and OP sorption was found to be significantly correlated with acid ammonium oxalate extractable Fe, but not with dithionite extractable Fe. Kaolinite desorbed similar amounts of OP and PP whereas more OP than PP was desorbed from soil and goethite samples. The degree of subsequent desorption seemed to be related to degree of sorption. The lack of similarity between sorption and desorption isotherms may indicate that sorption isotherms are of limited value in P fertilizer studies especially with regard to the estimation of subsequent P release in fertilized soils. Smaller particle sizes and their larger specific surface area resulted in higher OP and PP sorption compared with the coarser particle sizes. For OP sorption, the Langmuir equation yielded the closest fit in comparison to Freundlich and Temkin equations; the Freundlich equation gave the closest fit for PP sorption data. The Langmuir equation failed to fit desorption data. Key words: Orthophosphate, pyrophosphate, sorption, desorption

Take-off control and characteristics of FanWing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lin Meng ◽  
Yang Gao ◽  
Yangyang Liu ◽  
Shengfang Lu
Keyword(s):  
Control System ◽  
Control Systems ◽  
Design Methodology ◽  
Control System Design ◽  
Control Methods ◽  
Force Analysis ◽  
Close Attention ◽  
Content Type ◽  
Vehicle Load ◽  
Practical Implications

Purpose As a short take-off and landing aircraft, FanWing has the capability of being driven under power a short distance from a parking space to the take-off area. The purpose of this paper is to design the take-off control system of FanWing and study the factors that influence the short take-off performance under control. Design/methodology/approach The force analysis of FanWing is studied in the take-off phase. Two take-off control methods are researched, and several factors that influence the short take-off performance are studied under control. Findings The elevator and fan wing control systems are designed. Although the vehicle load increases under the fan wing control, the fan wing control is not a recommended practice in the take-off phase for its sensitivity to the pitch angle command. The additional pitch-down moment has a significant influence on the control system and the short take-off performance that the barycenter variation of FanWing should be considered carefully. Practical implications The presented efforts provide a reference for the location of the center of gravity in designing FanWing. The traditional elevator control is more recommended than the fan wing control in the take-off phase. Originality/value This paper offers a valuable reference on the control system design of FanWing. It also proves that there is an additional pith-down moment that needs to be paid close attention to. Four factors that influence the short take-off performance are compared under control.

scholarly journals Properties, processes and regimes of soil solutions and surface waters

2020 ◽  
Vol 175 ◽  
pp. 12022
Author(s):  
Guriyat Podvolotskaya ◽  
Sergey Belopukhov ◽  
Vitaly Savich ◽  
Andrey Sorokin ◽  
Nikolay Tyutrin
Keyword(s):  
Biological Activity ◽  
Surface Water ◽  
Surface Waters ◽  
Pair Correlation ◽  
Rate Of Change ◽  
Water Soluble ◽  
Soil Solutions ◽  
Different Depths ◽  
Different Soils

Soil solutions and the surface waters are characterized by properties, processes and regimes. Soil solutions of different soils and their surface water have different biological activity and change the activity of dissolved stimulants and inhibitors. The object of the study are soil solutions of the main types of soils obtained in the model experiments with the ratio of soils: water equal to 1:1 and 1: 2, soil solutions and surface water in the flooding of soils with water for 1 week – 3 months. The research method consisted in the assessment of pH, Eh, activity of K, NO3, NH4, Ca, Mg by conventional methods, assessment of concentrations of water-soluble compounds extracted from soils by ionite membranes, in the assessment of biological activity of solutions using biotests. The following is suggested for additional evaluation: the using of cation and anion membranes, determination of interrelation between the properties of waters, equation of pair correlation and multiply regression. The informative value of the gradient of surface water concentrations at different distances from the floor of the reservoir, at different depths of the overwatered soils is shown. The mobility of Ca, Mg, Fe, Mn in soils and the content of their water-soluble forms depends on both pH and Eh, whose influence on the content of water-soluble forms of the considered cations shows the effects of synergy and antagonism. The rate of change in the composition of soil solutions during soil flooding depends on a combination of soil properties, temperature, and duration of flooding. Soil solutions of different soils and their surface waters have differentrates.

Effects of the actively morphing root chord and taper on helicopter energy

2019 ◽  
Vol 92 (2) ◽  
pp. 264-270
Author(s):  
Firat Sal
Keyword(s):  
Control System ◽  
Energy Consumption ◽  
Flight Control ◽  
Design Methodology ◽  
Chord Length ◽  
Flight Control System ◽  
Content Type ◽  
Helicopter Blade ◽  
Blade Root ◽  
Practical Implications

Purpose The purpose of this paper presents the effects of actively morphing root chord and taper on the energy of the flight control system (i.e. FCS). Design/methodology/approach Via regarding previously mentioned purposes, sophisticated and realistic helicopter models are benefitted to examine the energy of the FCS. Findings Helicopters having actively morphing blade root chord length and blade taper consume less control energy than the ones having one of or any of passively morphing blade root chord length and blade taper. Practical implications Actively morphing blade root chord length and blade taper can be used for cheaper helicopter operations. Originality/value The main originality of this paper is applying active morphing strategy on helicopter blade root chord and blade taper. In this paper, it is also found that using active morphing strategy on helicopter blade root chord and blade taper reasons less energy consumption than using either passively morphing blade root chord length plus blade taper or not any. This causes also less fuel consumption and green environment.

scholarly journals Zn sorption on Ca-illite and Ca-smectite: experiment and modelling

2019 ◽  
Vol 98 ◽  
pp. 04008
Author(s):  
Christelle Latrille ◽  
Aubéry Wissocq ◽  
Catherine Beaucaire
Keyword(s):  
Ion Exchange ◽  
Clay Minerals ◽  
Sorption Isotherms ◽  
Ion Exchanger ◽  
Natural Environments ◽  
Sorption Site ◽  
Batch Experiments ◽  
Sorption Data ◽  
Relevant Role ◽  
Site Types

To predict Zn behaviour in soil, the retention properties of clay minerals plays a relevant role. In a continental environment, Ca is the main cation in solution. Soil reactivity may be reduced to sorption properties of Zn and Ca on illite and smectite, the major clay minerals in soil. With this assumption, a multi-site ion exchanger model has successfully been applied to the Zn sorption on Ca-illite and Ca-smectite. New batch experiments performed in this study enabled to collect sorption data for Zn on Ca-illite by concentration and pH isotherms. Zn sorption reversibility was then verified. These sorption data were modelled successfully with a multi-site ion exchanger (MSIE) formalism by using four sorption site types. Zn sorption isotherms on smectite were retrieved from literature and interpreted following the MSIE formalism. The obtained selectivity coefficients may be thereafter put into ion exchange models to describe the Zn sorption in natural environments.

RESIDUAL PHOSPHORUS SOLUBILITY FOR AN ACID, CLAYEY, FORESTED SOIL IN THE PRESENCE OF OXALATE AND CITRATE

1989 ◽  
Vol 69 (1) ◽  
pp. 111-117 ◽  
Author(s):  
N. B. COMERFORD ◽  
M. F. SKINNER
Keyword(s):  
Key Words ◽  
Pinus Radiata ◽  
Clayey Soil ◽  
Organic Anion ◽  
Sorption Isotherms ◽  
Organic P ◽  
Soil Material ◽  
Residual P ◽  
Residual Phosphorus ◽  
P Sorption

A highly weathered, clayey soil was sampled 14 yr after a Pinus radiata stand was broadcast fertilized with 0, 50 and 200 kg P ha−1 as ordinary superphosphate. Incremental loadings of oxalate and citrate anions from 10 to 100 μmol of anion g−1 soil were evaluated for increased soluble, reactive P (SRP) and soluble, nonreactive (SNP) P. Sorption isotherms were compared to evaluate the effect of the previous fertilization on P sorption by the soil material sampled, and also to measure SNP displacement by orthophosphate-P. A portion of the SNP pool was more readily released than SRP and orthophosphate displaced a significant amount of SNP. After 14 yr the effect of fertilization was still obvious in the sampled soil material. Much of the organic anion-soluble P was in the SRP form. Key words: Citrate, organic P, orthophosphate, oxalate, Pinus radiata, residual P

scholarly journals Engineering Functionalized Chitosan-Based Sorbent Material: Characterization and Sorption of Toxic Elements

2019 ◽  
Vol 9 (23) ◽  
pp. 5138 ◽  
Author(s):  
Adnan Khan ◽  
Nisar Ali ◽  
Muhammad Bilal ◽  
Sumeet Malik ◽  
Syed Badshah ◽  
...  
Keyword(s):  
Experimental Data ◽  
Sorption Isotherms ◽  
Analytical Techniques ◽  
Aqueous Environment ◽  
X Ray Diffraction ◽  
Sorption Data ◽  
Regression Methods ◽  
Sorbent Material ◽  
Lead And Cadmium ◽  
Cadmium And Lead

The present study reports the engineering of functionalized chitosan (CH)-based biosorbent material. Herein, a two-step reaction was performed to chemically modify the CH using 1,4-bis(3-aminopropyl) piperazine to incorporate nitrogen basic centers for cations sorption from the aqueous environment. The resultant functionalized chitosan-based sorbent material was designated as CH-ANP and characterized using various analytical techniques, including elemental analysis, Fourier-transform infrared spectroscopy (FTIR), 13C NMR (in solid-state), X-ray diffraction, and thermal analysis. Then, the newly engineered CH-ANP was employed for the removal of copper, lead, and cadmium in the aqueous medium. Langmuir sorption isotherm analysis revealed that the highest sorption abilities achieved were 2.82, 1.96, and 1.60 mmol g−1 for copper, cadmium, and lead, respectively. Linear and nonlinear regression methods were deployed on the sorption data to study the behavior of the Langmuir, the Freundlich, and the Temkin sorption isotherms. Among the four different forms, the Langmuir isotherm type 1 fit well to the experimental data as compared to the other models. It also showed the lowest values of error, and a higher correlation coefficient than the Freundlich and Temkin models; thus it was the best fit with the experimental data compared to the latter two models. In conclusion, the findings suggest that chemically modified novel materials with enhanced Lewis basic centers are useful and promising candidates for the sorption of various toxic cations in aqueous solution.

scholarly journals New carbon from low cost vegetal precursors: acorn and cypress cone

2013 ◽  
Vol 11 (12) ◽  
pp. 2012-2021
Author(s):  
Giovanni Toscano ◽  
Giuseppe Cimino
Keyword(s):  
Methylene Blue ◽  
Low Cost ◽  
Chemical Properties ◽  
Sorption Isotherms ◽  
Surface Chemical ◽  
Sodium Dodecylbenzenesulfonate ◽  
Sorption Data ◽  
Treatment Changes ◽  
Mass Titration ◽  
Minor Extent

AbstractThermal-treated carbons from acorn and cypress cone were prepared and characterized. The uptakes of heavy metal ions (Ag+, Cd2+ and Cr+3) and organics (phenol, methylene blue and sodium dodecylbenzenesulfonate) from aqueous solution have been studied. Effects of activation by HCl and HNO3 acids on the sorption properties of these carbons were investigated by mass titration, sorption isotherms, IRS, SEM and XRS. The models of Langmuir and Freundlich do not represent our sorption data very well. An earlier proposed empirical correlation is applied successfully to carry out a parameter of comparison between the studied carbons. The acidic treatment changes the surface chemical properties of the two thermal-treated carbons lowering their sorption performances. The carbons show good capacities to uptake metals, phenol and methylene blue, but sodium dodecylbenzenesulfonate is removed from its solutions to minor extent. The up-taking properties are found similar to those of two worldwide used commercial grade carbons.

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