Fluoride removal by a hybrid fluoride-selective adsorbent

2014 ◽  
Vol 14 (6) ◽  
pp. 1133-1141 ◽  
Author(s):  
Geetanjali Tomar ◽  
Arushi Thareja ◽  
Sudipta Sarkar
Keyword(s):  
Adsorption Capacity ◽  
Hydraulic Properties ◽  
Mechanical Stability ◽  
Fluoride Removal ◽  
Maximum Adsorption Capacity ◽  
Activated Alumina ◽  
Fluoride Adsorption ◽  
Effective Removal ◽  
Synthetic Solution ◽  
High Concentrations

High concentrations of fluoride in groundwater have become a global environmental challenge. Out of the various methods developed for effective removal of fluoride adsorption using activated alumina (AA) is popular as it has a low initial cost. AA offers excellent chemical and mechanical stability, selectivity for fluoride, favorable hydraulic properties, regenerability but offers lower adsorption capacity as there is reduction in material and capacity with an increased presence of aluminum. Hydroxyapatite nanoparticles have been found to possess high adsorption capacity for fluoride but they lack mechanical stability and favorable hydraulic properties. In this study, we synthesized a hybrid adsorbent, modified activated alumina, prepared by dispersing nanoparticles of hydroxyapatite inside AA granules. The hybrid adsorbent possesses a maximum adsorption capacity of 14.4 mg F/g which is at least five times higher than that of the virgin AA which has been used extensively for fluoride removal. A column run carried out on the hybrid adsorbent with a synthetic solution containing 3 mg/L fluoride lasted for 450 bed volumes before a breakthrough of 1.5 mg/L was observed. The exhausted adsorbent could be fully regenerated in a column within six bed volumes using commonly available innocuous chemicals. The study will contribute to the field of effective removal of fluoride from contaminated drinking water.

scholarly journals Synthesis of a Novel Ce-bpdc for the Effective Removal of Fluoride from Aqueous Solution

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Changqing Zhao ◽  
Yanwei Cui ◽  
Fang Fang ◽  
Si Ok Ryu ◽  
Jiarui Huang
Keyword(s):  
Adsorption Capacity ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Ph Value ◽  
Binding Capacity ◽  
Fluoride Removal ◽  
Maximum Adsorption Capacity ◽  
Fluoride Ions ◽  
X Ray ◽  
Fluoride Adsorption

Ce-1,1′-biphenyl-4,4′-dicarboxylic acid (Ce-bpdc), a novel type of metal organic framework, was synthesized and applied to remove excessive fluoride from water. The structure and morphology of Ce-bpdc were measured by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The effects, such as saturated adsorption capacity, HCO3-, and pH, were investigated. The optimal pH value for fluoride adsorption was the range from 5 to 6. The coexisting bicarbonate anions have a little influence on fluoride removal. The fluoride adsorption over the Ce-bpdc adsorbent could reach its equilibrium in about 20 min. The Ce-bpdc coordination complex exhibited high binding capacity for fluoride ions. The maximum adsorption capacity calculated from Langmuir model was high up to 45.5 mg/g at 298 K (pH = 7.0) and the removal efficiency was greater than 80%. In order to investigate the mechanism of fluoride removal, various adsorption isotherms such as Langmuir and Freundlich were fitted. The experimental data revealed that the Langmuir isotherm gave a more satisfactory fit for fluoride removal. Finally, the tested results of ground water samples from three places, Yuefang, Jiangji, and Sanyi which exhibited high removal efficiency, also demonstrate the potential utility of the Ce-bpdc as an effective adsorbent.

scholarly journals FLUORIDE REMOVAL USING ACTIVATED ALUMINA: A CASE STUDY OF BHOOMA CHOTA WATER

2013 ◽  
Vol 21 (21) ◽  
pp. 61-77
Author(s):  
R. AGRAWAL ◽  
M. K. MISHRA ◽  
K. MARGANDAN ◽  
K. SINGH ◽  
R. ACHARYA ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Absorption Capacity ◽  
Intraparticle Diffusion ◽  
Second Order ◽  
Least Square ◽  
Fluoride Removal ◽  
Activated Alumina ◽  
Surface Absorption ◽  
Fluoride Adsorption ◽  
Pseudo Second Order

The adsorption of fluoride, from a fluoride, contaminated groundwater sample from the village, Bhooma Chota, District Sikar, in the State of Rajasthan, India, has been studied using alumina grade DF-101. The fluoride adsorption capacity (q1) has been fitted into the pseudo-first-order adsorption, pseudo-second-order adsorption, Elovich, and intraparticle diffusion models. It has been found that the kinetic data fits best in the pseudo-second-order rate equation giving a very high correlation coefficient (R2 = 0.991). the modeled fluoride absorption capacity (q1) has been calculated from the various equations using the constants derived from the least square regression plots. The calculated q1 values, model the experimental data very well, for the pseudo-second-order and Elovich equations, as is evident from the sum of square error calculations. Fluoride removal is through a combination of surface absorption and intraparticle diffusion. A study of the fluoride removal process with increasing dosage of activated alumina reveals that though the percentage of fluoride removal increases with activated alumina, the adsorption capacity at equilibrium decreases. The minimum dosage of activated alumina which causes the maximum percentage removal of fluoride from water, while at the same time brings forth its highest equilibrium absorption capacity has been determined.

scholarly journals Application of spheroidal agglomerates of γ-Al2O3 in the fluoride removal from aqueous medium

2019 ◽  
Vol 29 ◽  
pp. 1-16
Author(s):  
Rafael Romero Toledo ◽  
Víctor Ruiz Santoyo ◽  
Ulises Zurita Luna ◽  
Gustavo Rangel Porras ◽  
Merced Martínez Rosales
Keyword(s):  
Aqueous Medium ◽  
Fluoride Removal ◽  
Batch Experiments ◽  
Activated Alumina ◽  
27Al Nmr ◽  
First Order ◽  
First Order Kinetics ◽  
Effective Removal ◽  
Adsorption Processes ◽  
Ft Ir

A spheroidal agglomerate γ-Al2O3 adsorbent obtained from pseudoboehmite for effective removal of fluoride from aqueous medium was investigated in the present study. The surface properties were characterized by several techniques: XRD, physisorption of N2, FE-SEM/EDS, 27Al NMR, FT-IR Pyridine adsorption, PZ and particle size. Batch experiments were conducted and they were compared with a commercial activated alumina (AA). The process was carried out at pH 5, 7, and 9, then at 25 and 35 ºC. Batch experimental results indicated that the spheroidal agglomerates of γ-Al2O3 remove up to 15 mg/g with a higher adsorption capacity than AA of 13 mg/g, at pH 5, studied at 25 and 35 °C. The F− adsorption processes in γ-Al2O3 and AA followed the pseudo-first-order kinetics and the Langmuir isotherm. The results showed an adsorbent effective for removal of F−.

Regeneration Effect of Fluoride-Rich Granular Activated Alumina on Desorption Regent NaOH Solution

2013 ◽  
Vol 316-317 ◽  
pp. 653-656
Author(s):  
Bai Jie Niu ◽  
Wen Ming Ding ◽  
Dan Dang
Keyword(s):  
Adsorption Capacity ◽  
Sodium Hydroxide Solution ◽  
Fluoride Concentration ◽  
Column Experiment ◽  
Fluoride Removal ◽  
Activated Alumina ◽  
Optimal Method ◽  
Column Adsorption ◽  
Naoh Solution ◽  
Regeneration Effect

As an effective adsorbent, granular activated alumina (GAA) has been widely used in defluoridation. In order to reduce cost and operate environment-friendly, the adsorbent should be regenerated. In this paper, column experiment was done to characterize the fluoride removal properties and to develop an optimal method to regenerate fluoride-rich modified activated alumina (MGAA). The MGAA can be regenerated by utilizing sodium hydroxide solution desorption, deionized water washing and ferric sulfate reactivation and then used for futher defluoride operation. The influence of the concentration of desorption agent (NaOH solution) and desorbing time on desorption rate and the adsorption capacity of regenerated MGAA were studied. The optimal desorption condition was: 1% NaOH solution for desorption agent, desorbing time in 1.5h.In addition, when the regenerated MGAA was used again for column adsorption test, its adsorption capacity reached 94% of that of original sorbent in 1mg/L outlet fluoride concentration.

scholarly journals Mechanochemically Activated Aluminosilicate Clay Soils and their Application for Defluoridation and Pathogen Removal from Groundwater

2019 ◽  
Vol 16 (4) ◽  
pp. 654 ◽  
Author(s):  
Olumuyiwa Obijole ◽  
Mugera Gitari ◽  
Patrick Ndungu ◽  
Amidou Samie
Keyword(s):  
Clay Soils ◽  
Diffusion Method ◽  
Fluoride Removal ◽  
Particle Diffusion ◽  
Maximum Adsorption Capacity ◽  
Bacterial Strains ◽  
Pathogen Removal ◽  
X Ray ◽  
Fluoride Adsorption ◽  
Bet Analysis

In this study, aluminosilicate rich clay soils were prepared through mechanochemical activation. The chemical and mineralogical properties were investigated using X-Ray Fluorescence (XRF) and X-ray diffraction (XRD). The functional groups, morphology and surface area were evaluated using Fourier Transform Infra-Red (FTIR), Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. Batch experiments were used to evaluate its defluoridation efficiency while antibacterial activities were assessed using well diffusion method. Maximum adsorption capacity was found to be 1.87 mg/g with 32% fluoride removal. Fluoride adsorption was found to reduce in the presence of Cl−, PO42− and CO32− while it increased in the presence of SO42− and NO3−. Adsorption data fitted well to Freundlich isotherms, hence, confirming heterogeneous multilayer adsorption. Kinetic studies revealed that fluoride adsorption fitted well to pseudo-second order model. The sorption of F− onto the clays’ surface followed intra-particle diffusion mode. High correlation coefficient indicates that the sorption process was greatly controlled by particle diffusion while it is minimal in pore diffusion model. Antibacterial studies revealed no zone of inhibition for all the activated clays, hence indicating that they are not active against the bacterial strains of Escherichia coli used in this study. The results showed activated clays’ potential for defluoridation. Its effectiveness in pathogen removal is limited. Hence further modifications of the clays’ surfaces are hereby recommended.

scholarly journals Fluoride adsorption properties of three modified forms of activated alumina in drinking water

2014 ◽  
Vol 12 (4) ◽  
pp. 715-721 ◽  
Author(s):  
Ying Duan ◽  
Chenchen Wang ◽  
Xuede Li ◽  
Wei Xu
Keyword(s):  
Drinking Water ◽  
Surface Area ◽  
Adsorption Properties ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Activated Alumina ◽  
Fluoride Ions ◽  
Fluoride Adsorption ◽  
Order Kinetic Model ◽  
Chlorine Ions

The study describes the removal of fluoride from drinking water using activated alumina (AA). AA was modified with H2SO4, FeCl3 and a combination of the two to enhance fluoride adsorption. The AA adsorbents were characterized using Brunauer–Emmett–Teller surface area analysis and X-ray fluorescence. The maximum adsorption capacity of H2SO4- and FeCl3-modified AA adsorbents was 4.98 mg/g, which is 3.4 times higher compared with that of normal AA. The results showed that the surface area of AA increased when modified with H2SO4. AA modified with FeCl3 enhanced fluoride adsorption ability through ion-exchange between chlorine ions and fluoride ions. The fluoride adsorption properties of AA modified with both H2SO4 and FeCl3 were consistent with the Langmuir model. The fluoride adsorption kinetics of the adsorbents were well described by the pseudo-second-order kinetic model.

scholarly journals Development of a small scale water treatment system for fluoride removal for rural areas

2015 ◽  
Author(s):  
◽  
Thulani Dlamini
Keyword(s):  
Water Treatment ◽  
Pressure Drop ◽  
Adsorption Capacity ◽  
Rural Areas ◽  
Contact Time ◽  
Treatment System ◽  
Fluoride Removal ◽  
Activated Alumina ◽  
Water Treatment System ◽  
Small Water

Several areas in the world such as the United States of America, Sri Lanka, China, Argentina, Canada, Tanzania, Kenya, South Africa and many others have a problem of high fluoride content in drinking water. Generally fluoride levels above 1.5 ppm in water may result in dental and skeletal fluorosis in humans depending on quantity consumed (Fan et al., 2003; Meenakshi, 2004). Remote rural areas where there are no water treatment facilities are more vulnerable to this problem. Adsorbents such as activated alumina and FR-10 resin seem to have a potential for successful application in rural areas. These methods however require pre-treatment if the feed has high turbidity. A membrane based system called woven fabric microfiltration gravity filter (WFMFGF) developed by Durban University of Technology proved to be suitable for turbidity removal. The main objective of this research was to develop a small water treatment system for fluoride removal. The small water treatment system developed in this study consists of WFMFGF for pre-treatment and an adsorption column. The WFMFGF is made up of a 40 L container packed with 15 immersed flat sheet membrane elements. The operation of the WFMFGF is in batch mode, driven by varying static head. The static head variation results in flow rate variation through the system. This in turn result in variation of contact time, velocity as well as pressure drop in the fluoride removal unit. Specific objectives of the study were: (1) to establish the maximum and minimum flow rates through the WFMFGF system, the total run time before cleaning is required and the best cleaning method for this particular membrane system. (2) to evaluate and compare the performance of activated alumina and FR-10 resin on varying contact time, velocity and pressure drop on the fluoride removal unit. The adsorbents were also compared on adsorption capacity, cost and ease of operation. The minimum and maximum flow rates through the WFMFGF were found to be 5 l/hr and 100 l/hr respectively. It was found that the system can be run for more than a month before requiring cleaning. The suitable cleaning method was found to be soaking the membranes in 0.0225 percent sodium hypochlorite solution overnight and brushing them using a plastic brush. The comparison of the performance of FR-10 resin to activated alumina found that the adsorbents gave equal performance based on the given criteria. FR-10 resin had higher adsorption capacity, gave good quality treated water even with shorter contact time and operated at wider velocity range. Activated alumina on the other hand had an advantage of lower costs, lower pressure drop and ease of use. According to Pontius (1990), the performance of activated alumina can be improved by intermittent operation. Point of use (POU) systems are generally operated intermittently. This improves the fluoride removal efficiency of activated alumina giving it more advantage over FR-10 resin. Based on this activated alumina was selected as the best adsorbent for the system. After the adsorbent was selected, the adsorption column was designed. The column operation regime was 3.5 minutes minimum contact time and 1.17 to 7.8 m/hr velocity range. The activated alumina adsorption capacity was 1.53mg/g. The column had an inside diameter of 70 mm. It was packed with activated alumina to a bed height of 400 mm. The column inlet and outlet pipes were made of PVC with a standard pipe size of 20 mm outside diameter. A valve at the column inlet pipe allowed water to flow through the system.

scholarly journals Investigation of kinetics and adsorption isotherm for fluoride removal from aqueous solutions using mesoporous cerium–aluminum binary oxide nanomaterials

RSC Advances ◽  
2021 ◽  
Vol 11 (46) ◽  
pp. 28744-28760
Author(s):  
Rumman Zaidi ◽  
Saif Ullah Khan ◽  
I. H. Farooqi ◽  
Ameer Azam
Keyword(s):  
Adsorption Isotherm ◽  
Aqueous Solutions ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Removal Efficiency ◽  
Small Dose ◽  
Binary Oxide ◽  
Fluoride Removal ◽  
Maximum Adsorption Capacity

Mesoporous Ce–Al binary oxide nanomaterials prepared with a surface area of 110.32 m2 g−1 showed defluoridation capacity at pH 2.4, exhibited maximum adsorption capacity of 384.6 mg g−1 and a removal efficiency of 91.5% at a small dose of nanoadsorbent.

scholarly journals Adsorption of Cu(II) ions from synthetic solution by sunflower seed husks

2019 ◽  
pp. 268-277
Author(s):  
Srdjan Stankovic ◽  
Tatjana Sostaric ◽  
Mladen Bugarcic ◽  
Aleksandra Janicijevic ◽  
Katarina Pantovic-Spajic ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Functional Groups ◽  
Vegetable Oil ◽  
Sunflower Seed ◽  
Active Sites ◽  
Animal Feed ◽  
Added Value ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Synthetic Solution

Annual production of the sunflower seed in Serbia is between 650,000-720,000 tons. Most of this amount is used in vegetable oil industry. Abundant by-products from this processing are sunflower seed husks. Husks are usually incinerated by vegetable oil producers in order to obtain energy, used as an animal feed, or, unfortunately, landed up at some landfills. In order to promote new, added value for this abundant, renewable resource, the investigation presented in this paper was conducted. For that purpose, adsorption of Cu(II) ions from synthetic solution by unmodified sunflower seed husks was examined. ATR-FTIR was used to identify functional groups as potential active sites for Cu(II) sorption. Zeta potential values were determined to reveal the surface charge, while the cation exchange capacity (CEC) was determined to reveal the amount of exchangeable ions on its surface. ATR-FTIR analysis revealed the presence of specific functional groups (hydroxyl, carboxyl, carbonyl, and amine) responsible for removal of Cu(II) ions. The total CEC of sunflower husk is 47.74 meq/100g and Ca(II) and Mg(II) ions are in dominant exchangeable positions. The study of ion-exchange mechanism involvement was done and results confirmed that this mechanism is not the only mechanism which is involved in copper sorption. Also, the results show that the Cu(II) ions have preference for Mg(II) ions substitution. Sorption experiments were conducted in batch system. The effect of operating parameters (pH, contact time, initial concentration of Cu(II) ions and adsorbent dosage) on the adsorption capacity were investigated. The obtained experimental data were fitted by Langmuir and Freundlich isotherm models. The maximum adsorption capacity for Cu(II) ions calculated from Langmuir adsorption isotherm was 34.89 mg/g which is 15 to 35% higher than the capacity that other researchers reported previously for the same material and pollutant. These results are suggesting that sunflower seed husks have a potential to be applied as an effective adsorbent of copper ions from contaminated waters.

scholarly journals Radiation Synthesis of Pentaethylene Hexamine Functionalized Cotton Linter for Effective Removal of Phosphate: Batch and Dynamic Flow Mode Studies

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3393 ◽  
Author(s):  
Jifu Du ◽  
Zhen Dong ◽  
Zhiyuan Lin ◽  
Xin Yang ◽  
Long Zhao
Keyword(s):  
Adsorption Capacity ◽  
Fixed Bed ◽  
Column Experiment ◽  
Flow Mode ◽  
Maximum Adsorption Capacity ◽  
Cotton Linter ◽  
Ring Opening Reaction ◽  
Effective Removal ◽  
Pseudo Second Order ◽  
Epoxy Groups

A quaternized cotton linter fiber (QCLF) based adsorbent for removal of phosphate was prepared by grafting glycidyl methacrylate onto cotton linter and subsequent ring-opening reaction of epoxy groups and further quaternization. The adsorption behavior of the QCLF for phosphate was evaluated in a batch and column experiment. The batch experiment demonstrated that the adsorption process followed pseudo-second-order kinetics with an R2 value of 0.9967, and the Langmuir model with R2 value of 0.9952. The theoretical maximum adsorption capacity reached 152.44 mg/g. The experimental data of the fixed-bed column were well fitted with the Thomas and Yoon–Nelson models, and the adsorption capacity of phosphate at 100 mg/L and flow rate 1 mL/min reached 141.58 mg/g. The saturated QCLF could be regenerated by eluting with 1 M HCl.

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