Adsorption-desorption of chlorpyrifos in soils and sediments from the Rufiji Delta, Tanzania

Batch adsorption-desorption equilibrium techniques were used to investigate the adsorption capacity and influence of salinity on partitioning of the insecticide chlorpyrifos between water and soil or water and sediments from the Rufiji Delta. The data were fitted to different adsorption-desorption models and the hysteresis index was calculated using the ratio between the Freundlich exponents for desorption and adsorption, and secondly, the difference in area under the normalized adsorption and desorption isotherms using the maximum adsorbed and solution concentrations. The data showed non-linear adsorption and that chlorpyrifos was strongly adsorbed to soil and sediments from the Rufiji Delta. The linearized adsorption coefficient (KD) and Freundlich adsorption coefficient (Kf) correlated significantly with organic carbon content. Chlorpyrifos adsorption as well as hysteresis calculated by both methods decreased with salinity (i.e. the sediment adsorbs increasing amounts of chlorpyrifos with decreasing salinity). This indicates that settling of freshwater sediments is among the major removal pathways of the chemical from the water column, but increased turbulence during high tides may resuspend settled sediment simultaneously increasing salinity and re-dissolve chlorpyrifos. However, discharge of fresh water, particularly during heavy rains, increases the trapping efficiency of the sediments. The theoretical approach developed showed that the Langmuir model describes the desorption data better than the Freundlich model, and that a better index of hysteresis is one that considers areas under the adsorption and desorption isotherms, provided the desorption isotherm is described by the normalized Langmuir isotherm and the adsorption isotherm by the normalized Freundlich isotherm.

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Adsorption and desorption of perchloroethylene in soils, peat moss, and granular activated carbon

Canadian Journal of Civil Engineering ◽

10.1139/l89-123 ◽

1989 ◽

Vol 16 (6) ◽

pp. 798-806 ◽

Cited By ~ 7

Author(s):

Richard Zytner ◽

Nihar Biswas ◽

Jatinder K. Bewtra

Keyword(s):

Activated Carbon ◽

Granular Activated Carbon ◽

Freundlich Isotherm ◽

Peat Moss ◽

Organic Carbon Content ◽

Dry Cleaning ◽

Desorption Process ◽

The Media ◽

Desorption Isotherms ◽

Adsorption Desorption

Studies were conducted to evaluate the adsorption–desorption isotherms of a common dry cleaning solvent, perchloroethylene (PCE), in soils, peat moss, and granular activated carbon. The results obtained followed the Freundlich Isotherm, and the organic carbon content of the media was the most significant controlling factor in the adsorption–desorption process. The peat moss exhibited the highest residual saturation concentration for pure PCE amongst all the media tested. The desorption studies indicated that PCE had medium mobility in soil and was not significantly affected by moderate changes in pH. Key words: adsorption, desorption, Freundlich Isotherm, granular activated carbon, peat moss, perchloroethylene, soils.

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Sorption of Metribuzin and Metolachlor in Alaskan Subarctic Agricultural Soils

Weed Science ◽

10.1017/s004317450005712x ◽

1992 ◽

Vol 40 (1) ◽

pp. 155-160 ◽

Cited By ~ 20

Author(s):

Jeff S. Graham ◽

Jeffery S. Conn

Keyword(s):

Organic Carbon ◽

Carbon Content ◽

Soil Type ◽

Surface Soil ◽

Agricultural Soils ◽

Freundlich Isotherm ◽

Organic Carbon Content ◽

Surface Soils ◽

Adsorption And Desorption ◽

Equilibration Temperature

Adsorption and desorption of metribuzin and metolachlor were studied for 0- to 15- and 30- to 45-cm soil depths and at 5 and 28 C temperatures for two subarctic Alaskan agricultural soils. Surface soils had five to eight times the organic carbon content of deeper soils and had lower Freundlich isotherm slopes (1/n) for both herbicides. Surface soil Freundlich coefficients (Kf) were affected by both soil type and equilibration temperature, with soil type accounting for greater than 80% of the variation in Kf. Surface soil mean Kfvalues ranged from 1.5 to 2.4 for metribuzin and 4.4 to 9.2 for metolachlor. For soils from the 30- to 45-cm depth, neither soil type nor temperature affected Kf. Isotherm slopes for desorption were less than adsorption, indicating hysteresis. Regressions between desorption Kfand maximum herbicide adsorbed prior to desorption were highly significant with coefficients of determination (r2) between 0.50 and 0.99.

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Adsorption-desorption processes of azo dye on natural bentonite: batch experiments and modelling

Clay Minerals ◽

10.1180/claymin.2014.049.5.10 ◽

2014 ◽

Vol 49 (5) ◽

pp. 747-763 ◽

Cited By ~ 8

Author(s):

A. Berez ◽

F. Ayari ◽

N. Abidi ◽

G. Schäfer ◽

M. Trabelsi-Ayadi

Keyword(s):

Azo Dye ◽

Physical Adsorption ◽

Raw Material ◽

Coefficient Of Determination ◽

Batch Adsorption ◽

Desorption Kinetics ◽

Desorption Process ◽

Non Linear ◽

Desorption Isotherms ◽

Adsorption Desorption

AbstractThe purpose of this study was to determine whether a bentonite from the Gafsa deposit (western Tunisia) could be used to remove the Foron Blue 291 (FB) azo dye from wastewater. Batch adsorption and desorption experiments were conducted using untreated and purified bentonite and the influence of contact time, pH, adsorbent mass and temperature of the dye solution on the adsorption of FB was evaluated. Kinetic and isotherm data were fitted using two non-linear kinetic and two non-linear isotherm equations. In addition, the fits were evaluated using the coefficient of determination (R2) and the RMSE. The percentage of dye removal increased with increasing amount of adsorbent until total discolouration was achieved. The adsorption isotherms followed the Langmuir model, with the purified bentonite having a higher adsorption capacity than the raw material due to its higher specific surface area. In addition, the FB molecules were removed from the liquid medium by physical adsorption. Batch desorption experiments were conducted to study the desorption kinetics and the characteristics of the desorption isotherms as well as to quantify the portion of the FB (by mass) that was irreversibly fixed on the solid. Overall, the desorption kinetics were similar to the adsorption kinetics, which indicated that the adsorption-desorption process of azo dye is non-singular; irreversibility occurred that was underlined by an observed thermodynamic index of irreversibility (TII) of 0.69–0.94. The desorption isotherms of the FB depended on the mass of the FB that was initially adsorbed on the bentonite sample, suggesting hysteresis. The amount of irreversibly retained FB was between 46 and 68% of the initial adsorbed mass.

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Plant Available Zinc Is Influenced by Landscape Position in the Amhara Region, Ethiopia

Plants ◽

10.3390/plants10020254 ◽

2021 ◽

Vol 10 (2) ◽

pp. 254

Author(s):

Mesfin K. Desta ◽

Martin R. Broadley ◽

Steve P. McGrath ◽

Javier Hernandez-Allica ◽

Kirsty L. Hassall ◽

...

Keyword(s):

Management Strategies ◽

Freundlich Isotherm ◽

Farming Systems ◽

Exchange Capacity ◽

Soil Parameters ◽

Amhara Region ◽

Adsorption And Desorption ◽

Organic Carbon Concentration ◽

Cropping Season ◽

Adsorption Desorption

Zinc (Zn) is an important element determining the grain quality of staple food crops and deficient in many Ethiopian soils. However, farming systems are highly variable in Ethiopia due to different soil types and landscape cropping positions. Zinc availability and uptake by plants from soil and fertilizer sources are governed by the retention and release potential of the soil, usually termed as adsorption and desorption, respectively. The aim of this study was to characterize the amount of plant available Zn at different landscape positions. During the 2018/19 cropping season, adsorption-desorption studies were carried out on soil samples collected from on-farm trials conducted at Aba Gerima, Debre Mewi and Markuma in the Amhara Region. In all locations and landscape positions, adsorption and desorption increased with increasing Zn additions. The amount of adsorption and desorption was highly associated with the soil pH, the soil organic carbon concentration and cation exchange capacity, and these factors are linked to landscape positions. The Freundlich isotherm fitted very well to Zn adsorption (r2 0.87–0.99) and desorption (r2 0.92–0.99), while the Langmuir isotherm only fitted to Zn desorption (r2 0.70–0.93). Multiple regression models developed by determining the most influential soil parameters for Zn availability could be used to inform Zn fertilizer management strategies for different locations and landscape positions in this region, and thereby improve plant Zn use efficiency.

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Adsorption-Desorption Mechanism of Synthesized Benzimidazole Based Fungicide 2-(3’-Pyridyl) on Selected Soil Minerals

International Journal of Economic and Environmental Geology ◽

10.46660/ijeeg.vol10.iss2.2019.260 ◽

2019 ◽

Vol 10 (2) ◽

pp. 38-44 ◽

Cited By ~ 1

Author(s):

Khuram Shahzad Ahmad ◽

Shaan Bibi Jaffri ◽

Saba Gul ◽

Khadija Ikhlaq ◽

Maryam Javaid ◽

...

Keyword(s):

Surface Area ◽

Physicochemical Characteristics ◽

Soil Profiles ◽

Adsorption Coefficient ◽

Soil Minerals ◽

Adsorption And Desorption ◽

Desorption Mechanism ◽

Adsorption Desorption ◽

Residual Plots ◽

Research Show

The adsorption and desorption phenomenon of synthesized Benzimidazole based fungicide, 2-(3’-pyridyl)benzimidazole (PyBlm), was investigated by batch equilibrium method. Four soil minerals were utilized for thesorption studies including; alumina, silica, muscovite and montmorillonite. Highest value of adsorption coefficient(Kd(ads)), obtained for montmorillonite mineral (Mx (Al, Fe, Mg4) Si8O20 (OH4)) was 2779 µg ml-1. Highest rate ofadsorption is attributable to its considerably large surface area of 628 m2g-1 and highest inter-lattice d-spacing, 10 Å.Highest desorption (Kd(des)) was also observed in montmorillonite mineral (21.45 µg ml-1). Montmorillonite thusdisplayed increased sorption capacity for PyBlm among all tested minerals. Hysteresis coefficient ranged from 0.58 to3. The results were statistically evaluated by using one-way analysis of variance (ANOVA). Furthermore, statisticalevaluation done with the help of Minitab 17 expressed the good fitting of the obtained results, which was shown bymeans of residual plots. Current research which suggests the variable adsorption and desorption of PyBlm expresses theprofound dependence of PyBlm interaction on the physicochemical characteristics of the selected minerals. Allminerals except montmorillonite expressing poor adsorption signifying the percolation of PyBlm through them towardsthe lower soil profiles. Results obtained in the present research show of that montmorillonite in firmly interacting withthe PyBlm molecules and thus alleviating the possibility of PyBlm percolation to lower soil profiles.

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Biodegradation of 2,4-D herbicide as affected by Its adsorption-desorption behaviour and microbial activity of soils

Soil Research ◽

10.1071/sr9961041 ◽

1996 ◽

Vol 34 (6) ◽

pp. 1041 ◽

Cited By ~ 52

Author(s):

NS Bolan ◽

S Baskaran

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Content ◽

Microbial Activity ◽

Clay Content ◽

Freundlich Isotherm ◽

Surface Concentration ◽

Initial Increase ◽

Organic Carbon Content ◽

Adsorption Desorption

The adsorption-desorption behaviour and the degradation of an ionic herbicide (2,4-D) were examined using 10 soils from New Zealand that differed in their organic matter and clay content. Adsorption isotherms for 2,4-D were adequately described by the Freundlich isotherm and the values of the exponent N of the Freundlich isotherm were close to 1 (0.92-0.98), indicating that the adsorption isotherm tended to become linear. The extent of adsorption, as measured by the distribution coefficient (Kd), increased with an increase in soil organic carbon. The rate of desorption of 2,4-D followed first-order reaction kinetics with respect to surface concentration, and decreased with an increase in the organic carbon content of the soils. The rate of degradation of 2,4-D, as measured by the half-life (t1/2), decreased with an initial increase in soil organic carbon, which is attributed to the increase in adsorption. With increasing adsorption, the rate of desorption decreased, resulting in a low concentration of 2,4-D in the soil solution that is available for microbial degradation. When the organic carbon content was more than 12%, however, both the adsorption and rate of degradation increased. The enhanced degradation of 2,4-D at these levels of organic carbon may be related to the increased biological activity of the soil, as measured by substrate-induced respiration, and the decreased 2,4-D-induced inhibitory effect on microbial activity.

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Adsorption and Desorption Properties of Polyethylenimine/Polyvinyl Chloride Cross-Linked Fiber for the Treatment of Azo Dye Reactive Yellow 2

Molecules ◽

10.3390/molecules26061519 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1519

Author(s):

Zhuo Wang ◽

Ha Neul Park ◽

Sung Wook Won

Keyword(s):

Polyvinyl Chloride ◽

Adsorption Process ◽

Model Fit ◽

Batch Adsorption ◽

Optimal Conditions ◽

Order Model ◽

Adsorption And Desorption ◽

Adsorption Data ◽

Pseudo Second Order ◽

Adsorption Desorption

In this study, the optimal conditions for the fabrication of polyethylenimine/polyvinyl chloride cross-linked fiber (PEI/PVC-CF) were determined by comparing the adsorption capacity of synthesized PEI/PVC-CFs for Reactive Yellow 2 (RY2). The PEI/PVC-CF prepared through the optimal conditions was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analyses. Several batch adsorption and desorption experiments were carried out to evaluate the sorption performance and reusability of PEI/PVC-CF for RY2. As a result, the adsorption of RY2 by PEI/PVC-CF was most effective at pH 2.0. A pseudo-second-order model fit better with the kinetics adsorption data. The adsorption isotherm process was described well by the Langmuir model, and the maximum dye uptake was predicted to be 820.6 mg/g at pH 2.0 and 25 °C. Thermodynamic analysis showed that the adsorption process was spontaneous and endothermic. In addition, 1.0 M NaHCO3 was an efficient eluent for the regeneration of RY2-loaded PEI/PVC-CF. Finally, the repeated adsorption–desorption experiments showed that the PEI/PVC-CF remained at high adsorption and desorption efficiencies for RY2, even in 17 cycles.

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Adsorption and desorption of crystal violet and basic red 9 by multi-walled carbon nanotubes

Water Science & Technology ◽

10.2166/wst.2019.157 ◽

2019 ◽

Vol 79 (8) ◽

pp. 1541-1549

Author(s):

Xian Chen ◽

Ching-Ju Monica Chin

Keyword(s):

Carbon Nanotubes ◽

Chemical Reactions ◽

Crystal Violet ◽

Steric Hindrance ◽

Batch Adsorption ◽

Adsorption And Desorption ◽

Multi Walled Carbon Nanotubes ◽

Desorption Hysteresis ◽

Adsorption Desorption ◽

Walled Carbon Nanotubes

Abstract Batch adsorption and desorption of crystal violet (CV) and basic red 9 (BR9) on multi-walled carbon nanotubes (MWCNTs) were conducted. To investigate the possible mechanisms of adsorption/desorption hysteresis, oxidized MWCNTs (O-MWCNTs) with more oxygen-containing groups were obtained by oxidizing as-purchased MWCNTs (A-MWCNTs) using nitric acid. The adsorption kinetics could be described by the pseudo-second-order model, suggesting that chemical reactions are the rate-limiting steps. The adsorption isotherms were fitted well by the Langmuir model, which suggests that, in addition to π–π interactions, chemical reactions significantly affect the adsorption. The adsorption capacity decreased in the order of CV on A-MWCNTs, BR9 on A-MWCNTs, and BR9 on O-MWCNTs, possibly because the amidation between BR9 and the surface groups of MWCNTs results in steric hindrance, which limits the adsorption of BR9 to inner grooves between CNT bundles. Adsorption/desorption hysteresis was observed for BR9 but not for CV. It was found that the π–π interaction and molecular entrapment were not responsible for the adsorption/desorption hysteresis. The hysteresis might be caused by the irreversible amide bonds between BR9 and MWCNTs. The results indicate that the steric hindrance due to the three-dimensional structure of organic compounds plays an important role in both adsorption/desorption kinetics and equilibria.

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Removal Performance and Mechanism of Benzo(b)Fluorathene Using MnO2 Nanoflower/Graphene Oxide Composites

Materials ◽

10.3390/ma14164402 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4402

Author(s):

Qingqing Cao ◽

Siqi Lu ◽

Wenjun Yin ◽

Yan Kang ◽

Naihao Yang ◽

...

Keyword(s):

Graphene Oxide ◽

Water Environment ◽

Freundlich Isotherm ◽

Batch Adsorption ◽

Order Kinetic ◽

Acceptor Interaction ◽

Order Kinetic Model ◽

Polycyclic Aromatic ◽

Donor Acceptor ◽

Adsorption Desorption

High-ring polycyclic aromatic hydrocarbons (PAHs, Benzo[b]fluorathene (BbFA), etc.) are difficult to biodegrade in the water environment. To address this issue, an innovative method for the preparation of MnO2 nanoflower/graphene oxide composite (MnO2 NF/GO) was proposed for adsorption removal of BbFA. The physicochemical properties of MnO2 NF/GO were characterized by SEM, TEM, XRD, and N2 adsorption/desorption and XPS techniques. Results show that the MnO2 NF/GO had well-developed specific surface area and functional groups. Batch adsorption experiment results showed that adsorption capacity for BbFA was 74.07 mg/g. The pseudo-second-order kinetic model and Freundlich isotherm model are fitted well to the adsorption data. These show electron-donor-acceptor interaction; especially π-π interaction and π complexation played vital roles in BbFA removal onto MnO2 NF/GO. The study highlights the promising potential adsorbent for removal of PAHs.

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Characterization of Alachlor and Atrazine Desorption from Soils

Weed Science ◽

10.1017/s0043174500056149 ◽

1990 ◽

Vol 38 (1) ◽

pp. 74-80 ◽

Cited By ~ 61

Author(s):

Sharon A. Clay ◽

William C. Koskinen

Keyword(s):

Silt Loam ◽

Clay Loam ◽

Adsorption And Desorption ◽

Methanol Extraction ◽

Application Rates ◽

Desorption Isotherms ◽

The Difference

Herbicide desorption isotherms may be affected by the amount of nondesorbable herbicide present in soil. Nondesorbable alachlor (as determined after methanol extraction) generally increased on a Waukegan silt loam (Typic Hapludolls) and a Ves clay loam (Udic Haplustolls) during five 0.01 M CaCl2desorptions. Atrazine was totally extracted with methanol from the Waukegan soil after one desorption using 0.01 M CaCl2. However, after five desorptions with 0.01 M CaCl2an average of 5.5 and 15.5% of the total recovered atrazine from two atrazine application rates was methanol nondesorbable from the Waukegan and Ves soils, respectively. Freundlich desorption isotherms adjusted for nondesorbable herbicide accounted for as much as 71 % of the difference between adsorption and desorption isotherms. Only a portion of the hysteresis observed can be attributable to nondesorbable herbicide.

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