scholarly journals Comparative analysis of linear and nonlinear equilibrium models for the removal of metronidazole by tea waste activated carbon

2020 ◽  
Vol 82 (7) ◽  
pp. 1484-1494
Author(s):  
Peter Emmanuel Ebili ◽  
Manase Auta ◽  
Kehinde Shola Obayomi ◽  
Joseph Onyebuchi Okafor ◽  
Muibat Diekola Yahya ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Adsorption Isotherm ◽  
Active Sites ◽  
Linear Models ◽  
Physical Adsorption ◽  
Freundlich Isotherm ◽  
Cost Effective ◽  
Chi Square ◽  
Tea Waste ◽  
Non Linear

Abstract Tea waste was carbonized at 400 °C for 45 min and modified with potassium hydroxide (KOH), to enhance the active sites for the adsorption of antibiotics. The developed tea waste activated carbon (TWAC) was used as a novel eco-friendly and cost-effective adsorbent for metronidazole (MZN) removal from aqueous solution. The textural and surface properties of the adsorbent were determined using Brunauer-Emmett-Teller (BET) and FT-Raman analysis. The BET surface was found to have increased from 24.670 to 349.585 after carbonization and KOH modification. The batch experimental parameters were optimized and equilibrium time was found to be 75 min. Linear and non-linear models were carried out on the adsorption isotherm and kinetics to determine the best fit for the adsorption data. The adsorption equilibrium data were well fitted by the Freundlich isotherm and pseudo-second order models, with higher regression correlation (R2) and smaller chi-square (χ2), as predicted by the non-linear model. The thermodynamic results revealed the adsorption of MZN as spontaneous, physical, and consistently exothermic in character. The activation energy value of 7.610 kJ/mol further revealed that the adsorption process is dominated majorly by physical adsorption. The removal of MZN onto TWAC was best described by the non-linear adsorption isotherm and kinetics model.

The study of non-linear kinetics and adsorption isotherm models for Acid Red 18 from aqueous solutions by magnetite nanoparticles and magnetite nanoparticles modified by sodium alginate

2016 ◽  
Vol 74 (5) ◽  
pp. 1235-1242 ◽  
Author(s):  
Zohre Berizi ◽  
Seyed Yaser Hashemi ◽  
Mahdi Hadi ◽  
Ali Azari ◽  
Amir Hosein Mahvi
Keyword(s):  
Adsorption Isotherm ◽  
Sodium Alginate ◽  
Magnetite Nanoparticles ◽  
Linear Models ◽  
Freundlich Isotherm ◽  
Precipitation Method ◽  
Isotherm Models ◽  
Residual Concentration ◽  
Adsorption Isotherm Models ◽  
Non Linear

Azo dyes are widely used in various industries. These substances produce toxic byproducts in aquatic environments in addition to their mutagenic and carcinogenic potential effects. In this study, the effect of magnetite nanoparticles and magnetite nanoparticles modified by sodium alginate in batch systems and nonlinear kinetic and adsorption isotherm models were investigated. Magnetite nanoparticles were synthesized by chemical co-precipitation method and then modified and used as adsorbent to adsorb Acid Red 18. After determining the optimum pH and adsorbent dose, non-equilibrium models for kinetic adsorption were tested with concentrations (25–100 mg/L) and at eight different periods of time (1–15 min) and the pseudo-first-order and pseudo-second-order non-linear models were used to describe the results. For adsorption isotherm, a contact time of 120 min was studied in different concentrations (25–100 mg/L) and the residual concentration of Acid Red 18 was obtained. The results are described by non-linear Langmuir, Freundlich and Dubinin–Radushkevich isotherm models. The optimum amounts of pH for magnetite nanoparticles and for modified ones were 3 and 5, respectively, the efficiencies were 0.75 and 0.2 g/L, respectively. According to the results sodium alginate has a high performance in adsorption of Acid Red 18. Adjusted correlation coefficients and chi-square test showed that Freundlich isotherm and then Langmuir isotherm can well describe the experimental results. In Freundlich, the value of (Kf) was 3.231 (L/g) for magnetite nanoparticles and 21.615 (L/g) for modified adsorbent. In Langmuir, the value of (qm) was 16.259 (mg/g) for magnetite nanoparticles and 73.464 (mg/g) for modified adsorbent. Comparing the Langmuir maximum calculated adsorption capacity indicated that modified adsorbent can adsorb the pollutants 6.5 times more than the other one.

Machine Learning Techniques on Multidimensional Curve Fitting Data Based on R- Square and Chi-Square Methods

2016 ◽  
Vol 6 (3) ◽  
pp. 974 ◽  
Author(s):  
Vidyullatha P ◽  
D. Rajeswara Rao
Keyword(s):  
Machine Learning ◽  
Linear Model ◽  
Curve Fitting ◽  
Linear Models ◽  
Machine Learning Techniques ◽  
Chi Square ◽  
Curve Fit ◽  
Learning Techniques ◽  
Non Linear ◽  
Data Points

<p>Curve fitting is one of the procedures in data analysis and is helpful for prediction analysis showing graphically how the data points are related to one another whether it is in linear or non-linear model. Usually, the curve fit will find the concentrates along the curve or it will just use to smooth the data and upgrade the presence of the plot. Curve fitting checks the relationship between independent variables and dependent variables with the objective of characterizing a good fit model. Curve fitting finds mathematical equation that best fits given information. In this paper, 150 unorganized data points of environmental variables are used to develop Linear and non-linear data modelling which are evaluated by utilizing 3 dimensional ‘Sftool’ and ‘Labfit’ machine learning techniques. In Linear model, the best estimations of the coefficients are realized by the estimation of R- square turns in to one and in Non-Linear models with least Chi-square are the criteria. </p>

Adsorption of chromium (VI) from aqueous solutions on activated carbon

1994 ◽  
Vol 30 (9) ◽  
pp. 191-197 ◽  
Author(s):  
R. Leyva Ramos ◽  
A. Juarez Martinez ◽  
R. M. Guerrero Coronado
Keyword(s):  
Activated Carbon ◽  
Adsorption Isotherm ◽  
Adsorption Capacity ◽  
Ph Effect ◽  
Freundlich Isotherm ◽  
Maximum Adsorption Capacity ◽  
Experimental Adsorption ◽  
Ph Values ◽  
Chromium Vi ◽  
Adsorption Data

The adsorption isotherm of chromium (VI) on activated carbon was obtained in a batch adsorber. The experimental adsorption data were fitted reasonably well to the Freundlich isotherm. The effect of pH on the adsorption isotherm was investigated at pH values of 4, 6, 7, 8, 10 and 12. It was found that at pH &lt; 6, Cr(VI) was adsorbed and reduced to Cr(III) by the catalytic action of the carbon and that at pH ≥ 12, Cr(VI) was not adsorbed on activated carbon. Maximum adsorption capacity was observed at pH 6 and the adsorption capacity was diminished about 17 times by increasing the pH from 6 to 10. The pH effect was attributed to the different complexes that Cr(VI) can form in aqueous solution. The adsorption isotherm was also affected by the temperature since the adsorption capacity was increased by raising the temperature from 25 to 40°C. It was concluded that Cr(VI) was adsorbed significantly on activated carbon at pH 6 and that the adsorption capacity was greatly dependent upon pH.

Modeling of phenol adsorption isotherm onto activated carbon by non-linear regression methods: models with three and four parameters

2018 ◽  
Vol 136 ◽  
pp. 199-206
Author(s):  
Donald Raoul Tchuifon Tchuifon ◽  
George Nche Ndifor-Angwafor ◽  
Aurelien Bopda ◽  
Solomon Gabche Anagho
Keyword(s):  
Activated Carbon ◽  
Adsorption Isotherm ◽  
Linear Regression ◽  
Phenol Adsorption ◽  
Regression Methods ◽  
Non Linear

Adsorption of cadmium(II) from aqueous solution onto activated carbon

1997 ◽  
Vol 35 (7) ◽  
pp. 205-211 ◽  
Author(s):  
R. Leyva-Ramos ◽  
J. R. Rangel-Mendez ◽  
J. Mendoza-Barron ◽  
L. Fuentes-Rubio ◽  
R. M. Guerrero-Coronado
Keyword(s):  
Activated Carbon ◽  
Adsorption Isotherm ◽  
Adsorption Capacity ◽  
Freundlich Isotherm ◽  
Carbon Surface ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Ph Values ◽  
Average Percent Deviation ◽  
Initial Ph

The adsorption isotherm of cadmium on activated carbon was measured in a batch adsorber. Effects of temperature and solution pH on the adsorption isotherm were investigated by determining the adsorption isotherm at temperatures of 10, 25, and 40°C and at initial pH values from 2 to 8. Langmuir isotherm better fitted the experimental data since the average percent deviation was lower than with the Freundlich isotherm It was noticed that the amount of Cd2+ adsorbed was reduced about 3 times by increasing the temperature from 10 to 40°C. It was found that Cd2+ was not adsorbed on activated carbon at pH of 2 or lower and that Cd2+ was precipitated out as Cd(OH)2 at pH values above 9. Maximum adsorption capacity was observed at pH of 8 and the adsorption capacity was decreased about 12 times by reducing the initial pH from 8 to 3. According to the cadmium speciation diagram the predominant species below pH of 8 is Cd2+. Thus, cadmium was adsorbed on the activated carbon surface as Cd2+. It was concluded that the adsorption capacity is a strong function of pH and temperature.

scholarly journals The assessment of efficient representation of drug features using deep learning for drug repositioning

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Mahroo Moridi ◽  
Marzieh Ghadirinia ◽  
Ali Sharifi-Zarchi ◽  
Fatemeh Zare-Mirakabad
Keyword(s):  
Deep Learning ◽  
Linear Models ◽  
De Novo ◽  
Drug Repositioning ◽  
Linear Method ◽  
Cost Effective ◽  
Biological Data ◽  
Non Linear ◽  
Disease Associations ◽  
Efficient Representation

Abstract Background De novo drug discovery is a time-consuming and expensive process. Nowadays, drug repositioning is utilized as a common strategy to discover a new drug indication for existing drugs. This strategy is mostly used in cases with a limited number of candidate pairs of drugs and diseases. In other words, they are not scalable to a large number of drugs and diseases. Most of the in-silico methods mainly focus on linear approaches while non-linear models are still scarce for new indication predictions. Therefore, applying non-linear computational approaches can offer an opportunity to predict possible drug repositioning candidates. Results In this study, we present a non-linear method for drug repositioning. We extract four drug features and two disease features to find the semantic relations between drugs and diseases. We utilize deep learning to extract an efficient representation for each feature. These representations reduce the dimension and heterogeneity of biological data. Then, we assess the performance of different combinations of drug features to introduce a pipeline for drug repositioning. In the available database, there are different numbers of known drug-disease associations corresponding to each combination of drug features. Our assessment shows that as the numbers of drug features increase, the numbers of available drugs decrease. Thus, the proposed method with large numbers of drug features is as accurate as small numbers. Conclusion Our pipeline predicts new indications for existing drugs systematically, in a more cost-effective way and shorter timeline. We assess the pipeline to discover the potential drug-disease associations based on cross-validation experiments and some clinical trial studies.

scholarly journals Bentonite and Magnetite Filler-Modified Polyurethane Foam in Fixed Bed Column for the Adsorption of Mercury(II) Ions from Aqueous Solution

2021 ◽  
Vol 10 (1) ◽  
pp. 27-36
Author(s):  
Siti Sarah ◽  
Adisalamun Adisalamun ◽  
Darmadi Darmadi ◽  
Suraiya Kamaruzzaman ◽  
Abrar Muslim ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Adsorption Isotherm ◽  
Adsorption Capacity ◽  
Polyurethane Foam ◽  
Pore Volume ◽  
Linear Models ◽  
Removal Rate ◽  
Fixed Bed ◽  
Simple Method ◽  
Non Linear

This paper proposed adsorbent development by synthesizing polyurethane foam (PUF) using a simple method, mixing polyol with isocyanate and adding fillers of bentonite and magnetite to the PUF matrix. The study's main objective was to produce a PUF-based adsorbent with high reactivity to remove Hg2+ in wastewater. This bentonite and magnetite filler-modified polyurethane foam (BMPUF) adsorbent was fixed in a bed column for the adsorption of mercury (II) ions from an aqueous solution. The effect of initial Hg2+ concentration on the removal rate and the effect of contact time on adsorption efficiency was investigated. Langmuir, Freundlich, and BET non-linear models were taken into account to determine the best adsorption isotherm fitting and obtain adsorption capacity, intensity, and pore volume. As a result, it followed the non-linear Freundlich model, and the average adsorption capacity and intensity were 0.466 mg/g and 0.923, respectively. The average BET-based pore volume obtained was 0.782 L/mg. The kinetics study showed that the non-linear pseudo-first-order kinetics model was more suitable for describing the Hg2+ adsorption kinetics. The maximum equilibrium adsorption capacity was 1.770 mg/g with the adsorption rate of 0.0013 min-1 based on the non-linear model. The effect of varying bentonite and magnetite ratio on adsorption isotherm and kinetics was also investigated. Overall, the potential application of BMPUF adsorbent in the adsorption of mercury (II) ions was demonstrated in the current study. 

scholarly journals The removal of anionic and cationic dyes from an aqueous solution using biomass-based activated carbon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nurul Umairah M. Nizam ◽  
Marlia M. Hanafiah ◽  
Ebrahim Mahmoudi ◽  
Azhar A. Halim ◽  
Abdul Wahab Mohammad
Keyword(s):  
Aqueous Solution ◽  
Activated Carbon ◽  
Active Sites ◽  
Adsorption Process ◽  
Removal Rate ◽  
Cost Effective ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Rubber Seed ◽  
Morphological Studies

AbstractIn this study, two biomass-based adsorbents were used as new precursors for optimizing synthesis conditions of a cost-effective powdered activated carbon (PAC). The PAC removed dyes from an aqueous solution using carbonization and activation by KOH, NaOH, and H2SO4. The optimum synthesis, activation temperature, time and impregnation ratio, removal rate, and uptake capacity were determined. The optimum PAC was analyzed and characterized using Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), a field emission scanning electron microscope (FESEM), Zeta potential, and Raman spectroscopy. Morphological studies showed single-layered planes with highly porous surfaces, especially PAC activated by NaOH and H2SO4. The results showed that the experimental data were well-fitted with a pseudo-second-order model. Based on Langmuir isotherm, the maximum adsorption capacity for removing methylene blue (MB) was 769.23 mg g−1 and 458.43 mg g−1 for congo red (CR). Based on the isotherm models, more than one mechanism was involved in the adsorption process, monolayer for the anionic dye and multilayer for the cationic dye. Elovich and intraparticle diffusion kinetic models showed that rubber seed shells (RSS) has higher α values with a greater tendency to adsorb dyes compared to rubber seed (RS). A thermodynamic study showed that both dyes’ adsorption process was spontaneous and exothermic due to the negative values of the enthalpy (ΔH) and Gibbs free energy (ΔG). The change in removal efficiency of adsorbent for regeneration study was observed in the seventh cycles, with a 3% decline in the CR and 2% decline in MB removal performance. This study showed that the presence of functional groups and active sites on the produced adsorbent (hydroxyl, alkoxy, carboxyl, and π − π) contributed to its considerable affinity for adsorption in dye removal. Therefore, the optimum PAC can serve as efficient and cost-effective adsorbents to remove dyes from industrial wastewater.

scholarly journals Nonlinear Kinetic and Equilibrium Adsorption Isotherm Study of Cadmium (II) Sorption by Dacryodes edulis Biomass

2021 ◽  
Vol 28 (2) ◽  
pp. 10-19
Author(s):  
L.C. Overah
Keyword(s):  
Adsorption Isotherm ◽  
Active Sites ◽  
Freundlich Isotherm ◽  
Equilibrium Adsorption ◽  
Isotherm Study ◽  
Freundlich Adsorption Isotherm ◽  
Seed Biomass ◽  
Good Potential ◽  
Equilibrium Adsorption Isotherm ◽  
Dacryodes Edulis

The kinetics and equilibrium adsorption isotherm of cadmium (II) adsorption onto Dacryodes edulis (native peer seed) biomass was studied using a nonlinear approach, which is unpopular but proven in some literature to be more reliable and easier. In optimizing the process, about 98% removal of the cadmium ion was achieved within five minutes at pH 7 by contacting just 30 mg of the Dacryodes edulis seed biomass with the adsorbate solution of a concentration of 100 mg/L. Non-linear investigation of the kinetics and adsorption isotherms of the process was done using the R console statistical and computing software. The results indicated that the Elovich mechanism and the Freundlich adsorption isotherm most suitably described the kinetics and adsorption isotherm, respectively, of the process as provided by their least values of the sum of squared residuals (SSR). This outcome implied a chemical adsorption  (chemisorption) mechanism and a multi-layer coverage by the cadmium ions on heterogeneous active sites of the biomass surface with a Freundlich constant or capacity factor, Kf of 27.83 mg g-1, heterogeneity factor, 1/n of 0.2614 and Elovich constants, α and β of 7.0 mg g−1 s−1 and 1.0 g mg-1, respectively. These findings indicate that Dacryodes edulis seed biomass has a good potential for cadmium (II) adsorption. Keywords: Dacryodes edulis, Elovich kinetic model, Freundlich isotherm, Langmuir isotherm, Nonlinear 

scholarly journals Preparation and characterization of activated carbon from wheat straw to remove2, 4-dichlorophenoxy acetic acid from aqueous solutions

2021 ◽  
pp. 175-186
Author(s):  
Molla Tefera ◽  
Mengistu Tulu
Keyword(s):  
Aqueous Solution ◽  
Acetic Acid ◽  
Activated Carbon ◽  
Wheat Straw ◽  
Freundlich Isotherm ◽  
Cost Effective ◽  
Volatile Matter ◽  
Adsorption Sites ◽  
Adsorptive Behavior ◽  
Dichlorophenoxy Acetic Acid

This study was focused to investigate the adsorptive behavior of activated carbon prepared from wheat straw treated with acid and base for the removal of 2, 4-dichlorophenoxy acetic acid (2,4-D). The morphology of the adsorbent was characterized using infrared spectroscopy and scanning electron microscopy. Compared with acid activated wheat straw, base activated wheat straw has provided lower ash content, moisture and volatile matter. However, it has higher iodine number than acid activated wheat straw. The removal of 2,4-D from aqueous solution was investigated at various physicochemical parameters such as pH (2–10), contact time (5–60 min), temperature (20-80 oC), amount of adsorbent (0.1-1.4 g) and initial concentration of 2,4-D (1.0-25 mg/L). The removal efficiency of 2,4-D in aqueous solution was found to be 92.02%. The equilibrium data were analyzed using Langmuir and Freundlich isotherm and the Langmuir model better describes that the active adsorption sites were homogeneously distributed on the surface of the adsorbent. Therefore, the activated carbon prepared from wheat straw treated with base can be used as efficient and cost-effective method to remove 2,4-D from aqueous solution.

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