scholarly journals Adsorption and desorption characteristics and mechanism of Cd in reclaimed soil under the influence of dissolved organic carbon

2021 ◽  
Author(s):  
Yonghong Zheng ◽  
Zhiguo Zhang ◽  
Yongchun Chen ◽  
Shikai An ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Organic Acids ◽  
Organic Acid ◽  
Mining Area ◽  
Adsorption And Desorption ◽  
Reaction Stage ◽  
Reclaimed Soil ◽  
Cd Adsorption ◽  
And Migration ◽  
Two Stages ◽  
Adsorption Desorption

Abstract Organic acids are widespread in the environment and play an important role in the adsorption, desorption, and migration of soil Cd. This study evaluated the characteristics and mechanism of Cd adsorption and desorption in reclaimed soil from Panyi Mine in the Huainan mining area under the influence of humic acid (HA) and citric acid (CA). The addition of HA and CA inhibited the adsorption and enhanced the desorption of Cd in reclaimed soil, with HA having a stronger effect than CA. As the concentration of added HA or CA increased, the adsorption capacity of Cd in the reclaimed soil gradually decreased, while the desorption capacity gradually increased. That is, the adsorption inhibition/desorption promotion effect was stronger for higher concentrations of organic acid. Cd adsorption and desorption could be described as a logarithmic function of organic acid concentration. The kinetic curves of Cd adsorption and desorption in reclaimed soil under the influence of organic acids show that both adsorption and desorption involved two stages: a fast reaction stage followed by a slow reaction stage.

scholarly journals Adsorption and Desorption of Cd: Characteristics and Mechanisms in Reclaimed Soil Under the Influence of Dissolved Organic Carbon

2021 ◽  
Author(s):  
Yonghong Zheng ◽  
Zhiguo Zhang ◽  
Yongchun Chen ◽  
Shikai An ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Organic Acid ◽  
Rank Order ◽  
Linear Regression Analysis ◽  
Functional Model ◽  
Mining Area ◽  
Adsorption And Desorption ◽  
Reaction Stage ◽  
Reclaimed Soil ◽  
Cd Adsorption ◽  
And Migration

Abstract Organic acids are widespread in the environment, where they play an important role in the adsorption, desorption, and migration of Cd in soil. This study evaluated the characteristics and mechanisms of Cd adsorption and desorption in reclaimed soil from the Panyi Mine, in the Huainan mining area (China), under the influence of humic acid (HA). The addition of HA inhibited the adsorption of Cd but enhanced its desorption in reclaimed soil. With an increasing concentration of added HA, the adsorption capacity of Cd in the reclaimed soil gradually decreased, while the desorption capacity gradually increased. That is, the adsorption inhibition/desorption promotion effect was stronger under higher concentrations of organic acid. Cd adsorption and desorption dynamics could be described as a logarithmic function of organic acid concentration. Kinetic curves for Cd adsorption and desorption in reclaimed soil under the influence of organic acid showed that both adsorption and desorption involved two stages: a fast reaction stage, followed by a slow reaction stage. The factors influencing the capacity of Cd adsorption and desorption in soil were analyzed by gray correlation analysis, and their resulting rank order was as follows: Cd concentration > HA concentration > pH > temperature. Using linear regression analysis, a multi-factor coupling functional model of soil Cd adsorption and desorption under the influence of DOC was established, in the form of Y = a + bXHA + cXT + dXPH + eXCd.

scholarly journals Mechanism and Influencing Factors of REY Enrichment in Deep-Sea Sediments

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 196
Author(s):  
Jiangbo Ren ◽  
Yan Liu ◽  
Fenlian Wang ◽  
Gaowen He ◽  
Xiguang Deng ◽  
...  
Keyword(s):  
Deep Sea ◽  
Research Progress ◽  
Bottom Current ◽  
Knowledge Map ◽  
P2o5 Content ◽  
Deep Sea Sediments ◽  
Potential Resource ◽  
And Migration ◽  
Adsorption Desorption ◽  
Sediment Interface

Deep-sea sediments with high contents of rare-earth elements and yttrium (REY) are expected to serve as a potential resource for REY, which have recently been proved to be mainly contributed by phosphate component. Studies have shown that the carriers of REY in deep-sea sediments include aluminosilicate, Fe-Mn oxyhydroxides, and phosphate components. The ∑REY of the phosphate component is 1–2 orders of magnitude higher than those of the other two carriers, expressed as ∑REY = 0.001 × [Al2O3] − 0.002 × [MnO] + 0.056 × [P2O5] − 32. The sediment P2O5 content of 1.5% explains 89.1% of the total variance of the sediment ∑REY content. According to global data, P has a stronger positive correlation with ∑REY compared with Mn, Fe, Al, etc.; 45.5% of samples have a P2O5 content of less than 0.25%, and ∑REY of not higher than 400 ppm. The ∑REY of the phosphate component reaches n × 104 ppm, much higher than that of marine phosphorites and lower than that of REY-phosphate minerals, which are called REY-rich phosphates in this study. The results of microscopic observation and separation by grain size indicate that the REY-rich phosphate component is mainly composed of bioapatite. When ∑REY > 2000 ppm, the average CaO/P2O5 ratio of the samples is 1.55, indicating that the phosphate composition is between carbonate fluoroapatite and hydroxyfluorapatite. According to a knowledge map of sediment elements, the phosphate component is mainly composed of P, Ca, Sr, REY, Sc, U, and Th, and its chemical composition is relatively stable. The phosphate component has a negative Ce anomaly and positive Y anomaly, and a REY pattern similar to that of marine phosphorites and seawater. After the early diagenesis process (biogeochemistry, adsorption, desorption, transformation, and migration), the REY enrichment in the phosphate component is completed near the seawater/sediment interface. In the process of REY enrichment, the precipitation and enrichment of P is critical. According to current research progress, the REY enrichment is the result of comprehensive factors, including low sedimentation rate, high ∑REY of the bottom seawater, a non-carbonate depositional environment, oxidation conditions, and certain bottom current conditions.

scholarly journals PSVIII-16 The effects of adding two organic acid blends with or without high levels of zinc or copper, on post-weaning pig performance

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 209-210
Author(s):  
Casey L Bradley ◽  
Jon Bergstrom ◽  
Jeremiah Nemechek ◽  
J D Hahn
Keyword(s):  
Phosphoric Acid ◽  
Benzoic Acid ◽  
Organic Acids ◽  
Organic Acid ◽  
Factorial Design ◽  
Sodium Butyrate ◽  
Weaned Pigs ◽  
Weaning Pig ◽  
Pig Performance ◽  
Dietary Treatments

Abstract A subset of 720 weaned pigs (6.44 ± 0.1 kg, PIC genetics, approximately 21-d of age) were used in a 42-d trial with a 2x3 factorial design evaluating the effects of adding organic acid (OA) blends [factor 1 = no organic acid (NO), Acid Pak 1 (AP1), Acid Pak 2 (AP2)] to diets with or without higher levels of Zn or Cu [factor 2 = +/-PZC] on pig performance. Pigs were allotted 10 pigs/pen to 12 weight blocks and randomly assigned the six dietary treatments. The +PZC diets contained 3000 ppm Zn (d 0-7), 2000 ppm Zn (d 8-21), and 250 ppm Cu (d 21-42) and -PZC diets contained 95 ppm Zn and 20 ppm Cu (d 0-42). The AP1 and AP2 diets used 0.9% of 2 acid premixes (d 0-21), and 0.45% of the premixes (day 22-42). AP1 provided 0.5% benzoic acid, 0.07% sodium butyrate, and 0.025% phosphoric acid (day 0-21) and half those levels (day 22-42). AP2 included the same acids as AP1 but at half the rate and combined with 7 other organic acids and carvacrol. From d 0-21, ADG, ADFI, and G:F were improved (P< 0.01) by +PZC compared to -PZC and by AP1 or AP2 compared to NO (P< 0.02). Overall (d 0-42), ADG and G:F were improved (P< 0.01) by +PZC compared to -PZC and by AP1 or AP2 compared to NO (P< .010). Data from this trial indicate that performance was improved by the addition of both OA and PZC. However, pigs fed OA and -PZC performed similarly to those fed NO and +PZC in the post-weaning period. In summary, regardless of the acid combination, organic acid supplementation has the potential to improve growth performance in weaned pigs.

The Xylem Sap of Maize Roots: Its Collection, Composition and Formation

1988 ◽  
Vol 15 (4) ◽  
pp. 557 ◽  
Author(s):  
MJ Canny ◽  
ME Mccully
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Organic Acid ◽  
Aspartic Acid ◽  
Xylem Sap ◽  
Great Variability ◽  
Reduced Pressure ◽  
Transpiration Stream ◽  
Maize Roots ◽  
Total Amino Acids

Three methods of sampling xylem sap of maize roots were compared: sap bleeding from the stem cut just above the ground; sap bleeding from the cut tops of roots still undisturbed in the ground; and sap aspirated from excavated roots under reduced pressure. The bleeding saps were often unobtainable. When their composition was measured with time from cutting, the concentrations of the major solutes approximately doubled in 2 h. Aspirated sap was chosen as the most reliable sample of root xylem contents. Solute concentrations of the saps showed great variability between individual roots for all solutes, but on average the concentrations found (in �mol g-1 sap) were: total amino acids, 1.8; nitrate, 1.8; sugars (mainly sucrose), 5.4; total organic acids, 18.3. Individual amino acids also varied greatly between roots. Glutamine, aspartic acid and serine were generally most abundant. The principal organic acid found was malic, approximately 8 �mol g-1. From these analyses the ratios of carbon in the fractions (sugars : amino acids : organic acids) = (44 : 6 : 50). 14Carbon pulse fed to a leaf appeared in the root sap within 30 min, rose to a peak at 4-6 h, and declined slowly over a week. During all this time the neutral, cation and anion fractions were sensibly constant in the proportions 86 : 10 : 4. The 14C therefore did not move towards the equilibrium of 12C-compounds in the sap. It is argued that the results do not support a hypothesis of formation of amino carbon from recent assimilate and reduced nitrate in the roots and an export of this to the shoot in the transpiration stream.

scholarly journals Characterization of Aerosol Composition, Aerosol Acidity and Organic Acid Partitioning at an Agriculture-Intensive Rural Southeastern U.S. Site

2018 ◽  
Author(s):  
Theodora Nah ◽  
Hongyu Guo ◽  
Amy P. Sullivan ◽  
Yunle Chen ◽  
David J. Tanner ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Organic Acids ◽  
Organic Acid ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Molar Concentration ◽  
Particle Phase ◽  
Aerosol Composition ◽  
Phase Water ◽  
Acetic Acids

Abstract. The implementation of stringent emission regulations has resulted in the decline of anthropogenic pollutants including sulfur dioxide (SO2), nitrogen oxides (NOx) and carbon monoxide (CO). In contrast, ammonia (NH3) emissions are largely unregulated, with emissions projected to increase in the future. We present real-time aerosol and gas measurements from a field study conducted in an agricultural-intensive region in the southeastern U.S. during the fall of 2016 to investigate how NH3 affects particle acidity and SOA formation via the gas-particle partitioning of semi-volatile organic acids. Particle water and pH were determined using the ISORROPIA-II thermodynamic model and validated by comparing predicted inorganic HNO3-NO3− and NH3-NH4+ gas-particle partitioning ratios with measured values. Our results showed that despite the high NH3 concentrations (study average 8.1 ± 5.2 ppb), PM1 were highly acidic with pH values ranging from 0.9 to 3.8, and a study-averaged pH of 2.2 ± 0.6. PM1 pH varied by approximately 1.4 units diurnally. Formic and acetic acids were the most abundant gas-phase organic acids, and oxalate was the most abundant particle-phase water-soluble organic acid anion. Measured particle-phase water-soluble organic acids were on average 6 % of the total non-refractory PM1 organic aerosol mass. The measured molar fraction of oxalic acid in the particle phase (i.e., particle-phase oxalic acid molar concentration divided by the total oxalic acid molar concentration) ranged between 47 and 90 % for PM1 pH 1.2 to 3.4. The measured oxalic acid gas-particle partitioning ratios were in good agreement with their corresponding thermodynamic predictions, calculated based on oxalic acid’s physicochemical properties, ambient temperature, particle water and pH. In contrast, gas-particle partitioning of formic and acetic acids were not well predicted for reasons currently unknown. For this study, higher NH3 concentrations relative to what has been measured in the region in previous studies had minor effects on PM1 organic acids and their influence on the overall organic aerosol and PM1 mass concentrations.

STUDIES ON INFANT DIARRHEA. III. CHANGES IN COMPOSITION OF SALINE AND GLUCOSE-SALINE SOLUTIONS INSTILLED INTO THE COLON

PEDIATRICS ◽  
1968 ◽  
Vol 42 (2) ◽  
pp. 303-311
Author(s):  
R. Torres-Pinedo ◽  
E. Conde ◽  
G. Robillard ◽  
M. Maldonado
Keyword(s):  
Organic Acids ◽  
Organic Acid ◽  
The Body ◽  
Hydrogen Ion ◽  
Sodium Absorption ◽  
Infectious Diarrhea ◽  
Subsequent Formation ◽  
Clear Cut ◽  
Compositional Changes ◽  
Saline Solutions

Saline and glucose-saline solutions were instilled into the distal colons of infants with acute infectious diarrhea. Samples of the fluid were obtained at hourly intervals. Clear-cut differences in compositional changes were observed with the saline and glucose-saline solutions. The net effects induced by glucose were: (1) generation of organic acids and subsequent formation of poorly absorbable organic acid salts, and (2) osmotic inflow of water. The overall process led to a net gain of hydrogen ion by the body fluids, decrease in sodium absorption, augmented potassium loss, and net increase in volume of the colonic fluid.

Thermo-kinetic investigation of heavy metal ions adsorption onto lignin considering coupled adsorption–desorption mechanisms: Modeling and experimental validation

2018 ◽  
Vol 09 (02) ◽  
pp. 1850014
Author(s):  
Farnaz Seyedvakili ◽  
Mohammad Samipoorgiri
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Individual Characteristics ◽  
Adsorption And Desorption ◽  
Isotherm Equation ◽  
Proposed Model ◽  
Isotherm And Kinetic Models ◽  
The Individual ◽  
Adsorption Desorption

A coupled adsorption–desorption thermo-kinetic model is developed incorporating both adsorption and desorption reactions. A local pseudo-equilibrium condition at the interface of adsorbent and adsorbate bulk phases was used as isotherm equation which can even be applied for multi-pollutants scenarios. The developed model is then validated using collected experimental data of heavy metal ions (Pb, Cu, Cd, Zn, and Ni). Comparisons were made for a number of isotherm and kinetic models to examine the performance of the proposed model. The developed model revealed desirable accuracy and superiority over other models in predicting the adsorption behavior and can be used for other systems of concern. The model correlates the adsorption kinetic with an [Formula: see text] value of 0.9391 and desorption kinetic with an [Formula: see text] value of 0.9383. By application of the proposed model to any available adsorption datasets, the individual characteristics of adsorption and desorption can be determined.

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