Freundlich isotherm model

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Studies on potassium requirements for maize in Nyamira County, Kenya.

Studies on potassium requirements for maize in Nyamira County, Kenya.

In Kenya, maize is a key cereal crop and a major staple food in most Kenyan families. Most maize farmers mainly apply nitrogenous and phosphorus fertilizers to improve on maize yields in the country and Nyamira County in particular. However, acreage yields have been declining yearly despite their use. Application of potassium (K) fertilizers in the region is limited yet it is the third major nutrient required by maize crop in large quantities for optimum growth and yields. Consequently, it is no longer wise to assume that the soils in the region have enough K levels for good maize growth and yields. The present study was planned to determine the soils nutrient status and evaluate whether K fertilizers use can play a role to improve maize yield in the region. The field experiments were set and conducted in Gachuba location in Nyamira County. Equilibria K concentrations were determined by flame photometry from filtrate of 2.5 g soil in 25 mL solutions of various potassium concentrations (0, 25, 50, 75, 100, 125, 150, 175, 200, 225 and 250 mgL -1 ) after stirring the mixtures for 24 hours to achieve steady state condition. Adsorption data obtained from the various soil solutions of K were fitted into Langmuir, Freundlich, Temkin and Van Hauy equations. The data fitted best in Freundlich isotherm model and was farther used to calculate acreage doses. Maize was grown under same doses of nitrogenous and phosphorus fertilizer and ten different doses of potassium in plots of 6 m by 5 m at two farm sites, that is, Gachuba (farm site 1) and (Kiang’ende farm site 2). Maize performances with site and dosage application were determined and growth parameters as well as yield parameters recorded. The study found that maize growth parameters of plant height and stem girth and its yield parameters of ear weight, ear length, ear girth and grain yields increased steadily as potassium doses were increased and reached their optimum values at potassium doses of 155.84 and 144.76 kg ha -1 giving yields of 3315.27 kg ha -1 and 3340.50 kg ha -1 for farm sites 1 and 2 respectively. The concentration levels of available potassium in the soils ranged from 57 to 70 mg kg -1 and with a mean value of 60±5.542 mg kg -1 . The water soluble potassium ranged from 1.8 to 2.2 mg kg -1 and gave a mean of 2.02±0.16 mg kg -1 . Nitric acid extracted potassium had a mean of 149±2.306 mg kg -1 . The mean value of energy of replacement, Δ𝐹, was found as −3572±44.98 cal mol -1
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Chemical modification and characterization of
clinoptilolite by
1,3-Phenylenediamine as a sorbent for the removal
of NO2

Chemical modification and characterization of clinoptilolite by 1,3-Phenylenediamine as a sorbent for the removal of NO2

Where, 1/n is the heterogeneity factor and is the Freundlich constant .Therefore, a plot of as a functionof (Fig. 6)allows the 1/n and constant to be determined.1/n value below unity implies a chemisorption process while1/n value above unity is indicative of cooperative adsorption [12]. As can be seen from the results of Freundlich isotherm model presented in Table 2, 1/n value for NO 2 adsorption onto modified zeolite is below unity and

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State of the art of the environmental behaviour and removal techniques of the endocrine disruptor 3,4-dichloroaniline

State of the art of the environmental behaviour and removal techniques of the endocrine disruptor 3,4-dichloroaniline

The irreversible sorption observed in these systems was described 118 using a Freundlich isotherm model: Cs = K f Cen suggesting an initially quick process, which then plateaus and requi[r]

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Adsorption mechanism of low concentration pollutants in water on modified zeolite

Adsorption mechanism of low concentration pollutants in water on modified zeolite

(2) The modified zeolite adsorption isotherm shows, to nitrate nitrogen and COD adsorption, modified zeolite was fit with Langmuir isotherm model, and the main type of modified zeolite is chemisorption; to ammonia nitrogen adsorption, modified zeolite was fit with Freundlich isotherm model, and the main type of modified zeolite is multilayer absorption;

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Study on Adsorption of Malachite Green by Date Palm Fiber

Study on Adsorption of Malachite Green by Date Palm Fiber

In this study, the adsorption of malachite green (MG) onto date palm fibers (DPF) was examined in aqueous solutions. The Langmuir and Freundlich adsorption isotherm models were employed to describe the equilibrium adsorption data. The Freundlich isotherm model was found to fit the adsorption data The removal percentage of MG dye from aqueous solutions via adsorption onto DPF adsorbent varied with pH and temperature, showing that these factors play a key role in the adsorption process. The removal percentage was found to increase with decrease in the solution temperature and in alkaline media. The adsorption kinetic data were fitted with a pseudo-second- order model.
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REMOVAL OF METHYLENE BLUE BY ADSORPTION ONTO  RETAMA RAETAM PLANT: KINETICS AND EQUILIBRIUM STUDY

REMOVAL OF METHYLENE BLUE BY ADSORPTION ONTO RETAMA RAETAM PLANT: KINETICS AND EQUILIBRIUM STUDY

by non linear Freundlich isotherm model. Thermodynamic studies show that adsorption was spontaneous and exothermic. For determining the best-fi t-kinetic adsorption model, the experimental data were analyzed by using pseudo-fi rst-order, pseudo-second-order, pseudo-third-order, Esquivel, and Elovich models. Linear regressive and non-linear regressive method was used to obtain the relative parameters. The statistical functions were estimated to fi nd the suitable method that fi t better the experimental data. Both methods were appropriate for obtaining the parameters. The linear pseudo-second-order (type 9 and type 10) models were the best to fi t the equilibrium data. The present work showed that plant Retama raetam can be used as a low cost adsorbent for the removal of methylene blue from water.
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Adsorption of Zn (II) from aqueous solution by using chitin extraction from crustaceous shell

Adsorption of Zn (II) from aqueous solution by using chitin extraction from crustaceous shell

Removal of toxic heavy metals from wastewater is an important environmental challenge. In this Study, Zn (II) removal from aqueous solution by chitin extraction from crustaceous shells (shrimp and crab) was investigated. The biosorption studies were determined as a function of contact time, pH, initial metal concentration, and the amount of adsorbent. Adsorption of Zn (II) increased with decreasing concentration of the adsorbents and reached maximum uptake at 0.5 g. Effect of pH was studied in the range of 3-7 and the optimum conditions for both adsorbents were found in the range of 5-7. Zn (II) adsorption for both adsorbent was evaluated by Langmuir and Freundlich Isotherms. Results indicated that the Freundlich isotherm model was the most suitable one for the adsorption process using chitin extracted of shrimp and crab shells. The pseudo-first order and pseudo second order kinetic models were used to describe the kinetic data. The adsorption capacity (q max ) calculated from
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Adsorption properties of As, Pb AND Cd in soft soil and meta sedimentary residual soil

Adsorption properties of As, Pb AND Cd in soft soil and meta sedimentary residual soil

Arsenic, Lead and Cadmium were commonly found at industrial sites and turn out to be toxic at high concentrations. Two types of soil commonly found in Malaysia, namely meta sedimentary residual soil (RS) and soft soil (SS) were studied as an adsorbent for the removal of As, Pb and Cd. The physico-chemical properties and batch adsorption tests were conducted in order to evaluate the capability of these soils. The physico-chemical properties tested in this study include particle size distribution, Atterberg limit, pH of soils, surface area and pore size determination, soil mineralogy, soil composition and cation exchange capacity. Batch adsorption tests were performed by shaking 6g of soil in 30ml of solution. The concentration were fixed at 10mg/L while the contact time varies at 0.5, 1, 2, 4, 8, 12, 16, 20, 24, 48, 72, 96, 120, and 168 hours. The filtrates were then tested using Atomic Absorption Spectrometer (AAS) and the adsorption data have been correlated with both Freundlich and Langmuir isotherms. The results showed that the RS successfully adsorbed Pb and Cd while soft soil was effective in the removal of As. Both soils fitted well to Freundlich adsorption isotherm in the adsorption of As and Cd while Langmuir was best fitted in the removal of Pb.
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The kinetics of the removal of copper ions from aqueous solutions using magnetic nanoparticles supported on activated carbon

The kinetics of the removal of copper ions from aqueous solutions using magnetic nanoparticles supported on activated carbon

it was 61.52% for AC. Langmuir, Freundlich, and Temkin isotherm models were also used in equilibrium studies. According to the findings, Temkin isotherm was well-fitted with the experimental data. In the kinetic studies, pseudo-first-order and pseudo-second-order models were assessed, and the pseudo-first-order equation provided the optimal correlation with the obtained data. Keywords: Kinetics, Copper Ions, Magnetic Nanoparticles, Activated Carbon

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Adsorption thermodynamics of phenobarbital sodium on powdered  garcinia kola seeds

Adsorption thermodynamics of phenobarbital sodium on powdered garcinia kola seeds

The adsorption equilibrium isotherm was carried out to demonstrate the relationship between the concentration of PBT sodium in bulk solution and that adsorbed to the interface or removed from the bulk solution. Freundlich, Langmuir and D- R equilibrium isotherm models were applied to investigate the adsorption isotherm. The Langmuir model assumes that maximum adsorption corresponds to a saturated monlayer of solute molecules on the adsorbent surface with no lateral interaction between the sorbed molecules (Eastoe and Dalton, 2000). The linear plot of (1/q e ) verses (1/C e ) shows that the
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Adsorption Characteristics of Leonardite for Removal of Cd(II) and Zn(II) from Aqueous Solutions

Adsorption Characteristics of Leonardite for Removal of Cd(II) and Zn(II) from Aqueous Solutions

adsorption of metal ions on leonardite was fast and reached the equilibrium within 60 min. Pseudo-second-order can be used to describe the kinetic adsorption of Cd(II) and Zn(II). The intra-particle diffusion was not the only rate-controlling step for adsorption of metals ions. Adsorption mechanisms of both metals were controlled by film and intra-particle diffusions. Adsorption of Cd(II) was found to be fitted to Freundlich isotherm whereas the adsorption of Zn(II) was agree well with both Langmuir and Freundlich isotherms. The maximum adsorbed amount of Cd(II) and Zn(II) were 37.0 and 21.5 mg g -1 , respectively. Leonardite is a low-cost material which has a good efficiency for metal ions adsorption. It can be an alternative adsorbent for the treatment of metal-contaminated water.
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Further Study of Adsorption of Crude Oils onto Acetylated Corn Silk and its Kinetics and Equilibrium Isotherm

Further Study of Adsorption of Crude Oils onto Acetylated Corn Silk and its Kinetics and Equilibrium Isotherm

from to the qe experimental, the Freundlich model was therefore considered as the better model for the sorption of oils by corn silk. For all experimental data of adsorption of crude oil onto the corn silk which are agreed with Freundlich isotherm implied that stronger binding sites are engaged for sorption firstly and with the increase in degree of site occupation, the binding force decrease. Freundlich model incorporates the heterogeneity of the surface sustaining sites of extensive affinities. This model is derived by assuming a heterogeneous surface with a non-uniform distribution of heat of adsorption over the surface.
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Separation of lead (II) ions from aqueous solutions by adsorption on kaoline

Separation of lead (II) ions from aqueous solutions by adsorption on kaoline

The presence of heavy metals in the environment has adverse effects on plants, animals and humans. Even a low concentration of lead in water is toxic to aquatic life. Lead affects the central nervous system, cardiovascular system and kidney function. The present study was aimed at the development of Kaoline, a carbonate mineral, as the adsorbent for the removal of lead(II) ions by adsorption. Separation of lead(II) ions from aqueous solutions containing 10 to 200 mg dm-3 of lead was studied. The effects of change in pH, adsorbent dosage, initial concentration of lead(II) ions, temperature and contact time were studied using batch method. The data were fed into various isotherm equations – Langmuir, Freundlich, Redlich Peterson and Dubinin- Radushkevich and the best fit was envisaged. Thermodynamic parameters like changes in enthalpy, entropy and Gibbs free energy for the adsorption process were evaluated. Kinetics of the adsorption process was studied using Lagergren’s first order, pseudo-second order, Elovich and Inter particle diffusion model rate equations and the rate constants and other parameters were deduced. Spectral studies (FTIR, XRD and SEM) were conducted on the adsorbent before and after the adsorption process and the data were analysed. Results show that the adsorption of lead(II) ions on kaoline is a spontaneous, endothermic process proceeding with increase in entropy.
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Coconut fronds as adsorbent in the removal 
		of malachite green dye

Coconut fronds as adsorbent in the removal of malachite green dye

This study represents the used of coconut frond (CF) to remove malachite green dye. This dye is toxic and will cause severe problems to environment. To investigate the potential of CF as adsorbent, a few parameters were studied such as adsorbent size, adsorbent dosage, initial dye concentration, contact time and pH. The results showed that the CF has the highest percentage of dye removal which is up to 99.91 % under optimum condition. The experimental data was analyzed with the Langmuir and Freundlich adsorption isotherm equations. The Langmuir isotherm model has given a better conformity than the Freundlich model with adsorption capacity of 18.98 mg/g. This study indicates that CF could be employed as a low cost adsorbent for the removal of malachite green dye.
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Adsorption of copper (II) on mesoporous silica: the effect of nano-scale confinement

Adsorption of copper (II) on mesoporous silica: the effect of nano-scale confinement

first, to our knowledge, study quantifying nano-scale con- finement effects on the adsorption of Cu on mesoporous silica. Through an analysis of the surface area normalized adsorption isotherms and adsorption kinetics of Cu on SBA-15-8, SBA-15-6, ad SBA-15-4, we concluded that nano-scale confinement enhances both the adsorption maximum, and Cu adsorption reaction rate. Evidence of this is shown in the significant increase in the surface area normalized adsorption maximum of Cu on SBA- 15-4 compared to both SBA-15-6 and SBA-15-8 across all isotherm models. Further, the pseudo-first-order reac- tion rate constant increased with decreasing pore size. The intraparticle diffusion model was applied, and it illustrates that external mass transfer diffusion constant increases with decreasing pore size, and we postulate that this rapid film diffusion in 4  nm pores was responsible for the observed increase in reaction rate. Future work should address molecular-scale speciation of Cu associ- ated with mesoporous silica surfaces, using spectroscopic approaches.
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A comparative study on the removal of thorium ions from artificially enriched
radioactive waters using Moroccan clays and oil shales

A comparative study on the removal of thorium ions from artificially enriched radioactive waters using Moroccan clays and oil shales

The adsorption behaviour of thorium from aqueous solutions by natural adsorbents (clays and oil shales) has been investigated by a batch technique. The natural samples were characterized by X-ray powder diffraction and X-ray fluorescence. The thorium adsorption on natural adsorbents was studied as a function of shaking time (adsorption kinetics). The adsorption data from experiments were fitted with Langmuir (forms I, II and III), Freundlich, Elovich and Temkin isotherms. The equilibrium process was described by the Langmuir model very well. Comparison of the oil schales adsorption capacity and the clays adsorption capacity indicated that the oil schales had a higher selectivity for thorium removal.
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Investigation of Langmuir and Freundlich Adsorption Isotherm of Co2+ Ion by Micro Powder of Cedar Leaf

Investigation of Langmuir and Freundlich Adsorption Isotherm of Co2+ Ion by Micro Powder of Cedar Leaf

Then Langmuir and Freundlich models were fitted on experimental data. The Freundlich isotherm is appropriate to both monolayer and multilayer adsorption and is based on the assumption that the adsorbates are adsorbed onto the heterogeneous surface of an adsorbent 14 . The Langmuir isotherm

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Langmuir, Freundlich and BET Adsorption
Isotherm Studies for Zinc ions onto coal fly ash

Langmuir, Freundlich and BET Adsorption Isotherm Studies for Zinc ions onto coal fly ash

metal ion solution and 10 g fly ash was placed in a stoppered Pyrex glass round bottom vessel and stirred at constant speed for 3 hours using a magnetic stirrer (Remi Make, India). The solution was centrifuged at a speed of 3000 rpm for 5 minutes and the supernant liquid sample was used for the determination of residual metal ion concentrations. The metal ion concentrations were obtained by using atomic absorption spectroscopy (Model – GBC 932 AA).

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Comparative Study of Isotherms Adsorption of B12 By Single-wall Carbon Nanotube and Multi-wall Carbon Nanotube

Comparative Study of Isotherms Adsorption of B12 By Single-wall Carbon Nanotube and Multi-wall Carbon Nanotube

In this study we compare the adsorption isotherms of B 12 by carbon nanotube Single and multi wall. Base on obtained results we conclude that MWCNTs has more efficiency in removal of B 12 rather than SWCNTs.Therefore, in total, it is concludedthat correlation coefficient, (n and Kf) in Table 1: Parameters of Langmuir, Freundlich and Temkin

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Biosorption of Fe+3 and Mn+2 ions from aqueous solution by a Pleurotus mutilus fungal biomass

Biosorption of Fe+3 and Mn+2 ions from aqueous solution by a Pleurotus mutilus fungal biomass

Five correlation isotherms were used to model the experimental data for Fe 3+ and Mn 2+ biosorption on the Pleurotus mutilus fungal biomass. However regarding the correlation coefficient R 2 for the Fe 3+ ions adsorption Langmuir (R 2 =0.98) and Redlich –Peterson (R 2 =0.98) isotherms were found to represent the equilibrium adsorption data. For Mn +2 biosorption Langmuir isotherm (R 2 =0.98) was found to represent the equilibrium adsorption data.

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