scholarly journals A new adsorbent for fluoride removal: The utilization of sludge waste from electrocoagulation as adsorbent

2015 ◽  
Vol 17 (1) ◽  
pp. 186-197 ◽  
Keyword(s):  
Particle Size ◽  
Contact Time ◽  
Fluoride Concentration ◽  
Freundlich Isotherm ◽  
Solution Temperature ◽  
Fluoride Removal ◽  
Maximum Adsorption Capacity ◽  
Batch Mode ◽  
Adsorption Removal ◽  
Adsorbent Dose

<div> <p>This work investigated the potential of calcined electrocoagulation sludge (CES) within metals hydroxide generated during removal of boron using Al electrode for adsorption of fluoride from aqueous solution. The effects of contact time, pH of the solution (2-10), stirrer speed (50-450 rpm), initial concentration (5-100<br /> mg l<sup>-1</sup>), adsorbent dose (1-4 mg l<sup>-1</sup>), solution temperature (293-333 K) and particle size (0.125-1000 &micro;m) on fluoride removal were investigated. All the experiments were carried out by batch mode. It was found that the maximum adsorption takes place within 2 h at pH 6.0. The adsorption removal increased with increase in the adsorbent dose, but decreased with increase in fluoride concentration. It was found that the adsorption removal decreases with increase in temperature, which showed that the adsorption process was exothermic in nature. The decrease in particle size increased fluoride removal efficiency. The maximum adsorption capacity (q<sub>m</sub>) increased from 45.5 to 124.6 mg g<sup>-1</sup> when the adsorbent dosage was adjusted to 1 instead of 4 g l<sup>-1</sup>. The Freundlich isotherm and Langmuir isotherm were used to fit the data of equilibrium experiments. The adsorption data fitted well into the linearly transformed Langmuir equation. The efficiency of CES to remove fluoride was found to be 99.99% at pH 6, contact time for 2 h, dose of 4 g l<sup>-1</sup>, when 25 mg l<sup>-1</sup> of fluoride was present in 100 ml of water. Comparison with literature reported values of q<sub>m</sub>, it was found that CES was an attractive adsorbent.</p> </div> <p>&nbsp;</p>

scholarly journals Removal of Fluoride from Drinking Water by Sorption Using Diatomite Modified with Aluminum Hydroxide

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Tesfaye Akafu ◽  
Achalu Chimdi ◽  
Kefyalew Gomoro
Keyword(s):  
Aluminum Hydroxide ◽  
Contact Time ◽  
Fluoride Concentration ◽  
Freundlich Isotherm ◽  
Intraparticle Diffusion ◽  
Fluoride Removal ◽  
Contaminated Water ◽  
Optimum Conditions ◽  
Intraparticle Diffusion Model ◽  
Adsorbent Dose

Exposure to fluoride beyond the recommended level for longer duration causes both dental and skeletal fluorosis. Thus, the development of cost-effective, locally available, and environmentally benign adsorbents for fluoride removal from contaminated water sources is absolutely required. In the present study, diatomaceous earth (diatomite) locally available in Ethiopia, modified by treating it with an aluminum hydroxide solution, was used as an adsorbent for fluoride removal from aqueous solutions. Adsorption experiments were carried out by using batch contact method. The adsorbent was characterized using FT-IR spectroscopy. Effects of different parameters affecting efficiency of fluoride removal such as adsorbent dose, contact time, initial fluoride concentration, and pH were investigated and optimized. The optimum adsorbent dose, contact time, initial fluoride concentration, and pH values were 25 g/L, 180 min, 10 mg/L, and 6.7, respectively. The performance of the adsorbent was also tested under optimum conditions using groundwater samples taken from Hawassa and Ziway. Langmuir and Freundlich isotherm models were applied to describe the equilibrium data. Compared to Langmuir isotherm (R2 = 0.888), the Freundlich isotherm (R2 = 0.985) model was better fitted to describe the adsorption characteristics of fluoride on Al-diatomite. The Langmuir maximum adsorption capacity was 1.67 mg/g. The pseudosecond-order model was found to be more suitable than the pseudofirst-order to describe the adsorption kinetics. The low correlation coefficient value of R2 = 0.596 for the intraparticle diffusion model indicates that the intraparticle diffusion model does not apply to the present studied adsorption system. The maximum fluoride removal was observed to be 89.4% under the optimum conditions which indicated that aluminum hydroxide-modified diatomite can be used as efficient, cheap, and ecofriendly adsorbents for the removal of fluoride from contaminated water.

scholarly journals An Experimental Study on Biosorption of Fluoride from Water Using LocallyObtained Moringa Oleifera Seeds

2021 ◽  
Vol 19 (1) ◽  
pp. 35-39
Author(s):  
Faheem Akhter ◽  
Arsalan A. Jokhio ◽  
Javed A. Noonari
Keyword(s):  
Aqueous Solution ◽  
Removal Efficiency ◽  
Contact Time ◽  
Moringa Oleifera ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Engineering Science ◽  
Environment Friendly ◽  
Experimental Facilities ◽  
Adsorbent Dose

Moringa Oleifera is considered to be a natural bio-adsorbent. Unlike chemical coagulants, Moringa Oleifera seeds are environment friendly with various other advantages. The present study investigated the fluoride removal efficiency of Moringa Oleifera from water. Influence of adsorbent dose (1, 2, 4 g/L), contact time (20, 40 and 60 min) and initial fluoride concentration (2 and 5 mg/L) over removal efficiency were determined and optimized. It was found that increased adsorbent dose and contact time enhanced the removal efficiency which is in agreement with the previous studies. The highest removal of 88.1% was achieved when the adsorbent dose and contact time were optimized to 4 g/L and 60 minutes with an initial fluoride concentration of 2 mg/L. The results showed that Moringa Oleifera can be used as an environment friendly, cheap and effective bio-adsorbent for fluoride removal from aqueous solution. All the experimental facilities were provided by Bio-Fuel Lab, Energy & Environment Department, Quaid-e-Awam University of Engineering, Science and Technology, Nawabshah, Pakistan. The samples were analyzed at the Pakistan Council of Research in Water Resources (PCRWR), Tando Jam, Pakistan.

scholarly journals Experimental and modeling study of water defluoridation using waste granular brick in a continuous up-flow fixed bed

2020 ◽  
Vol 26 (2) ◽  
pp. 190506-0
Author(s):  
Ziad T. Abd Ali ◽  
Zainab Z. Ismail
Keyword(s):  
Health Hazard ◽  
Economic Value ◽  
Fixed Bed ◽  
Freundlich Isotherm ◽  
Fluoride Removal ◽  
Maximum Adsorption Capacity ◽  
Continuous Mode ◽  
Batch Mode ◽  
Initial Ph ◽  
Modeling Study

Contamination of surface and groundwater with excessive concentrations of fluoride is of significant health hazard. Adsorption of fluoride onto waste materials of no economic value could be a potential approach for the treatment of fluoride-bearing water. This experimental and modeling study was devoted to investigate for the first the fluoride removal using unmodified waste granular brick (WGB) in a fixed bed running in continuous mode. Characterization of WGB was carried out by FT-IR, SEM, and EDX analysis. The batch mode experiments showed that they were affected by several parameters including contact time, initial pH, and sorbent dosage. The best values of these parameters that provided maximum removal percent (82%) with the initial concentration of F-1 ions (10 mg/L) and agitation speed (200 rpm) were 90 min, 8, and 3 g/100 mL, respectively. The experimental data were found to fit the Freundlich isotherm model. The maximum adsorption capacity of fluoride on WGB was 1.1 mg/g. The continuous mode experiments clearly confirmed the important role of WGB bed in hindering and confining the propagation of the fluoride-loaded plume as well as there was a very good matching (RMSE ≤ 0.0398) with the predicted results obtained by the simulated mathematical model using COMSOL Multiphysics 3.5a software.

scholarly journals Synthesis and characterization of aluminum-based adsorbent and application in fluoride removal from aqueous solution

2020 ◽  
Vol 10 (1) ◽  
pp. 46-61 ◽  
Author(s):  
Jihane Assaoui ◽  
Zineb Hatim ◽  
Abdelmoula Kheribeche
Keyword(s):  
Aqueous Solution ◽  
Contact Time ◽  
Fluoride Concentration ◽  
Infrared Spectrometry ◽  
Fluoride Removal ◽  
Batch Adsorption ◽  
X Ray ◽  
Wide Range ◽  
Adsorbent Dose

A novel adsorbent was obtained by a facile precipitation method and was used for fluoride removal from aqueous solution. Mineralogical and physicochemical characterization of the adsorbent was carried out by X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Energy Dispersive X-Ray attached to Scanning Electron Microscopy (SEM-EDX), BET Specific Surface Area(SSAN2BET) analysis and Fourier-Transform Infrared Spectrometry (FTIR). The effect of various operational parameters such as contact time, initial fluoride concentration, (20-160 mg L-1) adsorbent dose (1-6 g L-1) and initial pH solution (3-11) was evaluated in batch procedures at room temperature (25±2°C). The results of the batch adsorption experiments proved that 24 h of contact time was sufficient for attaining equilibrium. The maximum wastewater defluoridation (84.91%) was obtained for 40 mg L-1 and 3 g L-1 of initial fluoride concentration and adsorbent dose, respectively. It appears that there was no significant effect on the F- removal over a wide range of pH 3-11. Kinetic studies revealed that fluoride adsorption fitted well to pseudo-second-order. The adsorption isotherm of fluoride sorption indicated that the maximum adsorption capacity was noted to be 43.29 mg g-1. Batch adsorption data was better described by Langmuir isotherm confirming monolayer adsorption with homogenous distribution of active sites and without interaction between adsorbed molecules. The obtained results indicated that the ion exchange is probably the main mechanism involved in the F- adsorption by the aluminium-based adsorbent.

Effect of Oxalic Acid on the Adsorption of Fluoride by Phosphate Rock from Aqueous Solution

2012 ◽  
Vol 610-613 ◽  
pp. 390-393
Author(s):  
Yu Wang ◽  
Xiao Qing Dong ◽  
Bao Hua Zhou ◽  
Zhi Bing Xu
Keyword(s):  
Aqueous Solution ◽  
Oxalic Acid ◽  
Adsorption Capacity ◽  
Contact Time ◽  
Phosphate Rock ◽  
Fluoride Concentration ◽  
Maximum Adsorption Capacity ◽  
Batch Experiments ◽  
Fluoride Uptake ◽  
Adsorbent Dose

The defluoridation capacity of phosphate rock in the presence of oxalic acid was investigated using batch experiments. Defluoridation capacity of phosphate rock was enhanced in the presence of oxalic acid, removing fluoride from 22.46% up to 57.98% with 2.5 mmol/L oxalic acid. The contact time and pH for maximum fluoride uptake were found 2 h and 5, respectively. Maximum adsorption capacity (0.36 mg/g) of fluoride on phosphate rock was observed at 50 mg/L initial fluoride concentration using 2 g adsorbent dose.

scholarly journals Efficient Fluoride Removal from Aqueous Solution Using Zirconium-Based Composite Nanofiber Membranes

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 147
Author(s):  
Alaa Mohamed ◽  
Elvia P. Valadez Sanchez ◽  
Evgenia Bogdanova ◽  
Britta Bergfeldt ◽  
Ammar Mahmood ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Ph Value ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Regeneration Ability ◽  
Maximum Adsorption Capacity ◽  
Fluoride Adsorption ◽  
Composite Nanofiber ◽  
Nanofiber Membranes ◽  
Adsorbent Dose

Herein, composite nanofiber membranes (CNMs) derived from UiO-66 and UiO-66-NH2 Zr-metal-organic frameworks (MOFs) were successfully prepared, and they exhibited high performance in adsorptive fluoride removal from aqueous media. The resultant CNMs were confirmed using different techniques, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and Brunauer–Emmett–Teller (BET) in addition to Fourier-transform infrared spectroscopy (FTIR). The parameters that govern the fluoride adsorption were evaluated, including adsorbent dose, contact time, and pH value, in addition to initial concentration. The crystalline structures of CNMs exhibited high hydrothermal stability and remained intact after fluoride adsorption. It could also be observed that the adsorbent dose has a significant effect on fluoride removal at high alkaline values. The results show that UiO-66-NH2 CNM exhibited high fluoride removal due to electrostatic interactions that strongly existed between F− and metal sites in MOF in addition to hydrogen bonds formed with MOF amino groups. The fluoride removal efficiency reached 95% under optimal conditions of 20 mg L−1, pH of 8, and 40% adsorbent dose at 60 min. The results revealed that UiO-66-NH2 CNM possesses a high maximum adsorption capacity (95 mg L−1) over UiO-66 CNM (75 mg L−1), which exhibited better fitting with the pseudo-second-order model. Moreover, when the initial fluoride concentration increased from 20 to 100 mg/L, fluoride adsorption decreased by 57% (UiO-66 CNM) and 30% (UiO-66-NH2 CNM) after 60 min. After three cycles, CNM revealed the regeneration ability, demonstrating that UiO-66-NH2 CNMs are auspicious adsorbents for fluoride from an aqueous medium.

scholarly journals Characterisation of smectite-rich clay soil: Implication for groundwater defluoridation

2016 ◽  
Vol Volume 112 (Number 11/12) ◽  
Author(s):  
Rabelani Mudzielwana ◽  
Mugera W. Gitari ◽  
Titus A.M. Msagati ◽  
◽  
◽  
...  
Keyword(s):  
South Africa ◽  
Rural Areas ◽  
Contact Time ◽  
Clay Soil ◽  
Dental Fluorosis ◽  
Fluoride Concentration ◽  
Limpopo Province ◽  
World Health ◽  
Fluoride Removal ◽  
X Ray

Abstract Groundwater is a widely used and affordable source of drinking water in most of the rural areas of South Africa. Several studies have indicated that groundwater in some boreholes in South Africa has a fluoride concentration above the level recommended by the World Health Organization (1.5 mg/L). Fluoride concentrations above the permissible limit (>1.5 mg/L) lead to dental fluorosis, with even higher concentrations leading to skeletal fluorosis. In the present work, we evaluate the application of smectite-rich clay soil from Mukondeni (Limpopo Province, South Africa) in defluoridation of groundwater. The clay soil was characterised by mineralogy using X-ray diffraction, by elemental composition using X-ray fluorescence and by morphology using scanning electron microscopy. Surface area and pore volume was determined by the Brunauer–Emmett–Teller surface analysis method. Cation exchange capacity and pHpzc of the soil were also evaluated using standard laboratory methods. Batch experiments were conducted to evaluate and optimise various operational parameters such as contact time, adsorbent dose, pH and initial adsorbate concentration. It was observed that 0.8 g/100 mL of smectite-rich clay soil removed up to 92% of fluoride from the initial concentration of 3 mg/L at a pH of 2 with a contact time of 30 min. The experimental data fitted well to a Langmuir adsorption isotherm and followed pseudo second order reaction kinetics. Smectite-rich clay soil showed 52% fluoride removal from field groundwater with an initial fluoride concentration of 5.4 mg/L at an initial pH of 2 and 44% removal at a natural pH of 7.8. Therefore smectite-rich clay soil from Mukondeni has potential for application in defluoridation of groundwater. Chemical modification is recommended to improve the defluoridation capacity.

scholarly journals Ricinus CommunisPericarp Activated Carbon Used as an Adsorbent for the Removal of Ni(II) From Aqueous Solution

2008 ◽  
Vol 5 (4) ◽  
pp. 761-769 ◽  
Author(s):  
S. Madhavakrishnan ◽  
K. Manickavasagam ◽  
K. Rasappan ◽  
P. S. Syed Shabudeen ◽  
R. Venkatesh ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Activated Carbon ◽  
Contact Time ◽  
Metal Ion ◽  
Ricinus Communis ◽  
Ion Concentration ◽  
Batch Mode ◽  
Adsorption Data ◽  
Initial Ph

Activated carbon prepared from Ricinus communis Pericarp was used to remove Ni(II) from aqueous solution by adsorption. Batch mode adsorption experiments are carried out by varying contact time, metal-ion concentration, carbon concentration and pH to assess kinetic and equilibrium parameters. The adsorption data were modeled by using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacity (Qo) calculated from the Langmuir isotherm was 31.15 mg/g of activated carbon at initial pH of 5.0±0.2 for the particle size 125-250 µm.

scholarly journals Modified/Unmodified Nanoparticle Adsorbents of Cellulose Origin With High Adsorptive Potential for Removal of Pb(II) From Aqueous Solution

2017 ◽  
Vol 13 (27) ◽  
pp. 425
Author(s):  
Azeh Yakubu ◽  
Gabriel Ademola Olatunji ◽  
Folahan Amoo Adekola
Keyword(s):  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Contact Time ◽  
Adsorption Process ◽  
Correlation Coefficients ◽  
Solution Temperature ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Kinetics Of Adsorption ◽  
Kinetics Of

This investigation was conducted to evaluate the adsorption capacity of nanoparticles of cellulose origin. Nanoparticles were synthesized by acid hydrolysis of microcrystalline cellulose/cellulose acetate using 64% H3PO4 and characterized using FTIR, XRD, TGA-DTGA, BET and SEM analysis. Adsorption kinetics of Pb (II) ions in aqueous solution was investigated and the effect of initial concentration, pH, time, adsorbent dosage and solution temperature. The results showed that adsorption increased with increasing concentration with removal efficiencies of 60% and 92.99% for Azeh2 and Azeh10 respectively for initial lead concentration of 3 mg/g. The effects of contact time showed that adsorption maximum was attained within 24h of contact time. The maximum adsorption capacity and removal efficiency were achieved at pH6. Small dose of adsorbent had better performance. The kinetics of adsorption was best described by the pseudo-second-Order model while the adsorption mechanism was chemisorption and pore diffusion based on intra-particle diffusion model. The isotherm model was Freundlich. Though, all tested isotherm models relatively showed good correlation coefficients ranging from 0.969-1.000. The adsorption process was exothermic for Azeh-TDI, with a negative value of -12.812 X 103 KJ/mol. This indicates that the adsorption process for Pb by Azeh-TDI was spontaneous. Adsorption by Azeh2 was endothermic in nature.

scholarly journals Application of treated eggplant peel as a low-cost adsorbent for water treatment toward elimination of Pb2+: Kinetic modeling and isotherm study

2018 ◽  
Vol 36 (3-4) ◽  
pp. 1112-1143 ◽  
Author(s):  
Mohammad Hossein Karimi Darvanjooghi ◽  
Seyyed Mohammadreza Davoodi ◽  
Arzu Y Dursun ◽  
Mohammad Reza Ehsani ◽  
Iman Karimpour ◽  
...  
Keyword(s):  
Contact Time ◽  
Low Cost ◽  
Standard Free Energy ◽  
Chemical Properties ◽  
Entropy Change ◽  
Batch Adsorption ◽  
Maximum Adsorption Capacity ◽  
Standard Entropy ◽  
Adsorption Parameters ◽  
Adsorbent Dose

In this study, treated eggplant peel was used as an adsorbent to remove Pb2+ from aqueous solution. For this purpose batch adsorption experiments were performed for investigating the effect of contact time, pH, adsorbent dose, solute concentrations, and temperature. In order to assess adsorbent’s physical and chemical properties, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were used. The results showed that the adsorption parameters for reaching maximum removal were found to be contact time of 110 min, adsorbent dose of 0.01 g/ml, initial lead(II) concentration of 70 ppm, pH of 4, and temperature of 25°C. Moreover, for the experiments carried out at pH > 4 the removal occurred by means of significant precipitation as well as adsorption. Furthermore, these results indicated that the adsorption followed pseudo-second-order kinetics model implying that during the adsorption process strong bond between lead(II) and chemical functional groups of adsorbent surface took place. The process was described by Langmuir model (R2 = 0.99; maximum adsorption capacity 88.33 mg/g). Also thermodynamics of adsorption was studied at various temperatures and the thermodynamic parameters including equilibrium constant (K), standard enthalpy change, standard entropy change, and standard free energy changes were obtained from experimental data.

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