Adsorbent For Fluoride Removal Research Articles

Simultaneous removal of fluoride and nitrate from an aqueous mixture and semiconductor wastewater by sodium chloride mediated electro-generated aluminas (EGAs): Conversion of recovered fluoride into fluorapatite using plasterboard waste

Electro-generated aluminas (EGAs) were synthesized using sodium chloride electrolyte of 100 mM with Al/Al and Al/Fe electrodes operated at 800 mA for 1.5 h. The synthesized mesoporous EGAs, EGA (Al) and EGA (Fe) belonging to H2 type hysteresis contain the boehmite and bayerite phases as confirmed by XRD analysis and whose proportions are estimated to be 49.6 ± 0.3% and 50.4 ± 0.3% respectively by thermo-gravimetric study. The batch adsorption studies were conducted using the binary (F−/NO3−) mixture from which the adsorption efficiency was studied as a function of time (0–60 min), pH (3–10), initial concentration of fluoride or nitrate (100, 300, 500 and 1000 mgL−1) and temperature (15 °C, 25 °C, 35 °C and 45 °C) using EGA (Al) and EGA (Fe) adsorbents. The adsorptive removal of fluoride and nitrate from real effluent samples using EGAs was significant particularly in effluents E1 and E3 with residual concentrations within the safe limit of World Health Organization (WHO). Regeneration using 100 mM NaOH was quite consistent up to five consecutive cycles and the recovered fluoride was converted into fluorapatite. Taking into account the regeneration aspect, the cost analysis showed that 1 g EGA (Al) and EGA (Fe) was 0.464 USD and 0.508 USD respectively. The endothermic nature of adsorption through chemical forces was confirmed by the compliance of pseudo – second – order (kinetic), Langmuir and DKR (isotherm) models (R2 ≈ 0.99) along with thermodynamic parameters. Characterization of EGAs using FTIR, FESEM, XRD, XPS and BET was done to understand the adsorptive behavior between EGAs and the adsorbate (F−/NO3−) ions. The exhausted EGAs after fifth cycle of regeneration was mixed with ariake clay, plasterboard waste and cement in proper proportions and, made as specimens for the construction of bank bodies.

Unveiling the presence of fluoride in commercial tea infusion: Factors influencing its release and its adsorptive elimination by indigenously developed nanoadsorbents

Drinking tea, which is globally one of the most widely consumed beverages, is a potential source of fluoride toxicity. This research aimed at fluoride estimation in the infusions of commercial black tea and green tea samples, purchased from the local Indian market, systematic evaluation of the factors influencing the fluoride release and the adsorptive removal of fluoride using the indigenously developed nanoadsorbents. All the prepared infusions had fluoride content above the permissible WHO limits. Various factors, which affect the release of fluoride from tea leaves into the infusion include type of water, tea dosage and brewing time. The investigations revealed that, the fluoride content in the black tea infusions was much higher than the green tea infusions. Further, it also depended on the amount of tea leaves used for brewing. The fluoride, present in tea leaves, is released gradually and within just 1 min of brewing, the concentration of fluoride in the infusions was well above the permissible WHO limits. It was also observed that, the dried unprocessed tea leaves, when brewed in water, had high fluoride content. This further confirmed the presence of fluoride in tea infusion, which demands an efficient remediation technique. The developed nanoadsorbents exhibited efficient defluoridation of groundwater, and were therefore tested for their efficiency in defluoridating tea infusions as well. These nanoadsorbents could efficiently eliminate fluoride from both green and black tea infusions, bringing down the fluoride content below the WHO limits, thereby rendering the infusions safe. They exhibited rapid kinetics with high efficiency in adsorbing fluoride from tea infusions. These properties make them potential adsorbents for defluoridating tea infusion, which provides a probable solution to the problem of fluoride toxicity from drinking tea. This is one of the first reports on a technique for eliminating fluoride from tea infusions.

Efficient fluoride removal from aqueous solution by sorption using natural adsorbent - Eugenia Jambolana: Equilibrium isotherm analysis and influence of anions

Commercial industries which employ metallurgical extraction, cement manufacturing and fuel cells expulse heavy volumes of fluoride-containing wastewater into the natural environment posing grave threats to public health. In the current study, a locally available plant known as Jamun (Eugenia Jambolana), was used as an adsorbent for fluoride removal from aqueous solutions. Physico-chemical experiments were conducted to reveal the size and surface distribution of natural fluoride adsorption on the adsorbent surface using SEM, XRD, and FT- IR. Effects of different parameters such as solution pH, adsorbent dosage (m), co-ions contact time (t), fluoride concentration, and flow rates were investigated. Additionally, the adsorption efficiency of competing ions like Cl-, NO3-, SO42-, PO43-, Ca2+, and Mg2+ and their physiological effects were studied under different solution concentrations ranging from 20 – 200 mg / L at pH 6.90±0.10 for 1 hour. Results showed that the adsorption equilibrium and kinetic data were matched with the isotherm Langmuir model (R2 = 0.98) and Freundlich model (R2 = 0.97). Also, we could conclude that the adsorption process of fluoride using the natural adsorbent resu bivalve shells was an endothermic reaction and resulted in a spontaneous adsorption process. Adsorption kinetic models revealed a swift adsorption rate with minimum and maximum fluoride concentrations as 100 mg / L and 500 mg / L with contact time (t) = 60 minutes at adsorbent dosage (m) = 1 g / L.

Synthesis and application of lanthanum-doped magnetic biochar composite adsorbent for removal of fluoride from water.

Fluoride levels greater than 1.5mg/L in drinking water are a global environmental issue that can seriously harm the health of humans. One of the most effective techniques for defluoridating water is adsorption. The main drawbacks of many adsorbent materials include their poor adsorption capabilities, prolonged contact times, excessively low or high pH levels, and high dosages. The biochar-based magnetic nanocomposite adsorbent was synthesized in the current study and used as an adsorbent for water defluoridation. Through slow pyrolysis, coffee husk waste was converted to biochar. The composite was created by chemically co-precipitating iron and lanthanum oxide nanoparticles onto the surface of biochar. By using X-ray diffraction analysis (XRD), Fourier transform infrared spectrometry (FTIR), Brunauer-Emmett-Teller (BET), and pHPZC values, researchers were able to describe the magnetic biochar nanocomposite material. The Central Composite Design (CCD), which uses four input variables including dosage (2-5g/L), solution pH (4-8), contact time (30-70min), and initial concentration (10-20mg/L), was used to design the experiments. The quadratic model indicated that the ideal conditions for removing 98.994% of the fluoride from water (adsorbent dosage of 5g L-1, pH 5.74, contact period of 60min, and initial concentration of 12.245mg/L) would be attained. The average triplicate value in ideal circumstances produced a removal effectiveness of 98.51%, demonstrating the proposed response surface's capacity for prediction. The findings of this investigation showed that the magnetic biochar nanocomposite that was created is an effective fluoride adsorbent.

Dual network nano-Zr@chitosan-ĸ-carrageenan hydrogel beads as an adsorbent for fluoride removal from aqueous solution: equilibrium, kinetic and thermodynamic studies

The occurrence of a high concentration of fluoride ions in drinking possess serious issues related to human health. The present study aims to develop a potent adsorbent from the nano-zirconium prepared from the leaf extract of Azolla pinnata. Nanoparticles were embedded into chitosan-κ-carrageenan beads and used for defluoridation from an aqueous solution. The prepared adsorbent was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), selected area electron diffraction, and Fourier-transform infrared spectroscopy (FTIR) analysis. Various parameters, for example, adsorbent dosages, pH, contact time, and temperature affecting adsorption of fluoride were examined. The results of the batch adsorption study for the designed dual network, Zr@chitosan-κ-carrageenan beads showed the highest removal efficiency of 97.5% at 6.5. The Langmuir model yielded a better representation of the experimental results where the maximum removal capacity was reported to be 22.9 mgg−1. Thus, prepared hydrogel beads can be considered a good defluoridating agent.

Lanthanum cholate fibres: A novel adsorbent for fluoride removal

Lanthanum cholate fibres: A novel adsorbent for fluoride removal

Facile synthesis and characterization of multi-walled carbon nanotubes decorated with hydroxyapatite from cattle horns for adsorptive removal of fluoride

Developing a new adsorbent for fluoride removal from cattle horn waste materials by a facile chemical method has shown great potential for fluoride removal. This paper reports the synthesis of multi-walled carbon nanotubes decorated with hydroxyapatite from cattle horns (MWCNT-CH) using a facile chemical method. Characterization studies using standard techniques showed that the composite is mesoporous with a rough morphology and contained MWCNTs uniformly encapsulated by the hydroxyapatite forming a crystalline MWCNT-CH composite. Optimization of fluoride adsorption by the as-synthesized composite using Response Surface Methodology (RSM) showed that a maximum fluoride removal efficiency of 80.21% can be attained at initial fluoride concentration = 10 mg/L, pH = 5.25, adsorbent dose = 0.5 g and a contact time of 78 min. ANOVA indicates contribution of the process variables in descending order as pH > contact time > adsorbent dose > initial fluoride concentration. Langmuir isotherm (R2 = 0.9991) best described the process, and the maximum adsorption capacity of fluoride onto the as-synthesized MWCNT-CH composite was 41.7 mg/g. Adsorption kinetics data were best fitted in the pseudo-second-order kinetic model (R2 = 0.9969), indicating chemisorption. The thermodynamic parameter (Δ H = 13.95 J/mol and Δ S = 65.76 J/mol/K) showed that fluoride adsorption onto the MWCNT-CH composite was a spontaneous, endothermic, and entropy-driving process. Moreover, the adsorption mechanism involves ion exchange, electrostatic interaction, and hydrogen bonding. Fluoride was successfully desorbed (using 0.1 M NaOH) from the composite in four cycles, retaining fluoride removal efficiency in the fourth cycle of 57.3%.

Coal mine waste characterization and defluoridation property

Fluoride contamination has been addressed as a major problem worldwide, along with the scarcity of water. This attracts researchers to do more research in the field of fluoride contamination and mitigation of high fluoride content in water. There are various studies, that used a variety of adsorbents for the removal of fluoride from contaminated water. But none of them utilized the vast number of waste, that is generated from the coal mining industries. In this paper, Shale, which is a common coal mine waste, has been used as an adsorbent for fluoride removal from aqueous solution. Along with the defluoridation property of shale, the effect of weathering on the adsorption property of shale was also analyzed using different characterization tests, such as XRD (X-ray powder diffraction), SEM (Scanning Electron Microscope), and FTIR (Fourier Transform Infrared spectroscopy). Two types of shale samples were collected, crushed, and used in the adsorption process in the lab using synthetic fluoride solution. The maximum efficiency of type I (weathered) shale was obtained as 47.05% compared to type II (fresh) shale as 40.02% for 3 ppm initial fluoride solution for 60 min of contact time in pH range 5–7 using batch adsorption process. Other parameters such as shale particle size, pH, and total suspended solid present before and after the adsorption process were also taken into consideration. The adsorption followed pseudo-second kinetics and Freundlich isotherm with an adsorption capacity of 23.66 mg/g, and 21.33 mg/g for weathered and fresh shale respectively. The characterization test showed more clayey content in the weathered shale compared to fresh shale, making it more porous and suitable as a fluoride adsorbent. XRD showed the F− containing minerals such as Villiaumite (5.1%) and Fluorite (4.3%) in F− loaded weathered shale, confirming the F− adsorption onto the shale surface. The major advantage of shale over other existing adsorbents is, it removes the fluoride without significant change in pH, and there are no or very less suspended ions that can be found in treated water. This means the water may not need any secondary treatment after the adsorption process. Shale is a very common and readily available mine waste, that is used for the ceramic industry, building materials, and road construction, making it a no-cost material to be used as an adsorbent for fluoride removal.

Preparation of alumina-supported Fe-Al-La composite for fluoride removal from an aqueous matrix.

Using groundwater for human consumption is an alternative for places with no nearby surface water resources. Fluoride is commonly found in groundwater, and the consumption of this water for a prolonged time in concentrations that exceed established limits by WHO and Brazilian legislation on water potability (1.5mg L-1) can cause harmful problems to human health. For this reason, fluoride removal is an important step before water consumption. In this work, activated alumina was impregnated with Fe-Al-La composite and employed for the first time as an adsorbent for fluoride removal from an aqueous environment. XRD, SEM/EDS, FT-IR, and point of zero charge were used to characterize the prepared adsorbent. The adsorptive performance of adsorbent material was investigated by employing a 23-central composite design (CCD), and the obtained experimental conditions were pH = 6.5 and adsorbent dosage = 3.0g L-1. A maximum adsorption capacity of 8.17mgg-1 at 298K and pH = 6.5 was achieved by Langmuir isotherm to describe the adsorption. The kinetic model that better described experimental data was Avrami, with the kav parameter increasing with the initial concentration from 0.076 to 0.231 (min-1)nav. The nature of adsorption was found to be homogeneous, and it occurs in a monolayer. The fluoride removal performance for the prepared adsorbent was higher than granular activated alumina, showing that supporting Fe-Al-La at the alumina surface increased its fluoride adsorption capacity from 16 to 42% at the same experimental conditions. Finally, the influence of co-existing ions Cl-, SO42-, and NO3- was evaluated in fluoride adsorption, and the material presented great selectivity to fluoride. Thus, Fe-Al-La/AA adsorbent is a promising material for fluoride removal from water.

Thermal plasma processing of Moringa oleifera biochars: adsorbents for fluoride removal from water.

Anthropogenic activities accelerate fluoride contamination in groundwater, which largely affects public health. Though biochars have been explored for defluoridation, the plasma technology-based production of biochars has not received as considerable attention as other methods and it is also important that biochars be tested on groundwater samples. In the present study, for the first time, we report the preparation of biochars from different parts of Moringa oleifera using thermal plasma processing and demonstrate fluoride adsorption in both synthetic and contaminated groundwater. Water samples were collected from different locations in Nuapada district of Odisha such as Kotamal-Makardampada (20°24'46''N 82°37'19''E), Pandrapathar (20°34'41''N 82°39'25''E), Karlakot-Kadobhata (20°22'52''N 82°37'24''E), Kotamal-Jhakarpada (20°24'35''N 82°37'20''E), and Dohelpada (20°33'50''N 82°38'57''E). The Moringa leaf samples are processed at 1600 °C for 3 min in an inert atmosphere under a continuous flow of argon to get suitable biochars. The plasma-synthesized biochars contain larger exposed surfaces, which are efficient for the adsorption of fluoride. The prepared biochars were highly porous, amorphous, and contain > 72% carbon, which increases the efficiency of defluoridation due to the surface adsorbate site exposed. XRD of the samples showed the presence of calcium hydroxide, magnesium oxide, and calcium oxide, and large peaks of carbon. Raman data showed the double bond of carbon with oxygen in the form of carbonyl bonds, thioether, and sulfhydryl bonds, which contribute to the protonated site for the adsorption of fluoride, and assist in water penetration and swelling of biochars. The biochar of Moringa oleifera is very efficient for the adsorption of fluoride from standard samples as well as groundwater samples up to a concentration of 6 ppm. Conclusively, the present investigation shows that Moringa oleifera leaves are a good alternative adsorbent that could be used for the removal of fluoride from groundwater samples with > 85% removal in 18 h using 1 g biochar for 100 mL or 10 g biochar for 1 L water containing 4 ppm fluoride. To our knowledge, this is the first report on the thermal plasma-based production of Moringa biochars for the removal of fluoride from drinking water.

Feasibility of fluoride removal using calcined Mactra veneriformis shells: Adsorption mechanism and optimization study using RSM and ANN

In this study, Mactra veneriformis shells (MVS), a seafood by-product with high Ca content, was assessed as an adsorbent for fluoride removal from contaminated water. MVS was calcined at various temperatures (100–900 °C), and MVS calcined at 800 and 900 °C (MVS-800 and MVS-900) had the highest adsorption capacity. The high fluoride adsorption of MVS-800 and MVS-900 originated from the conversion of CaCO3 present in the raw MVS to CaO and Ca(OH)2 by calcination at high temperatures. The kinetic and equilibrium adsorption of fluoride by MVS-800 were accurately described by the pseudo-second-order and Langmuir models, respectively. The maximum fluoride adsorption capacity was 244.61 mg/g, which is comparable to that of other adsorbents reported in the literature. The enthalpy and entropy of adsorption were 7.42 kJ/mol and 56.48 J/mol‧K, respectively, and the Gibbs free energy was negative at all reaction temperatures. The interactive effects of pH, reaction time, dosage, and temperature and the optimal values for fluoride removal by MVS-800 were explored using response surface methodology (RSM) and artificial neural networks (ANN). The RSM results demonstrated that reaction time, dosage, and temperature significantly influenced fluoride removal; however, pH was an insignificant term. The accuracy of the ANN model (R2 = 0.9932) for predicting fluoride removal was higher than that of RSM (R2 = 0.9347). The optimal fluoride removal at a dosage of 3.3 g/L under optimized conditions (pH 5; reaction time 9 h; temperature 35 °C) was predicted to be 98.5% by the ANN model.

A Study of Isotherms and Kinetics of Mangifera Indica Bark Adsorbent Used for Fluoride Removal form Drinking Water

In this paper, we have investigated the bark of mango (Mangifera Indica) as an adsorbent for fluoride removal. Chemical treatment and aluminum hydroxide coating increased the adsorption capacity of the adsorbent from 0 to 15mg/g. Aluminum hydroxide-coated adsorbent (Al-MIBAC) was subjected to a batch study by considering different operational parameters such as adsorbent dose, reaction time, and pH. The kinetics of the adsorbent strongly followed second-order behavior, indicating the chemo-sorption adsorption process. The R2 value for Langmuir isotherm is 0.999 and it was found to be fitted well with the experimental data. It is hence assumed that the adsorption of fluoride is homogeneous and monolayer. The maximum fluoride adsorption amount of Al-MIBAC was 56.81mg/g, which was superior to those of other adsorbents derived from bark. Al-MIBAC was highly effective in reducing the fluoride concentration from 20mg/L to less or equal to 1.5mg/L which is safe for drinking purposes.

Nanoalumina-supported Mn2O3 as efficient adsorbent for removal of fluoride and arsenic from water: a study from lab to field

Nanoalumina-supported Mn2O3 as efficient adsorbent for removal of fluoride and arsenic from water: a study from lab to field

Conversion of Organic Waste to Novel Adsorbent for Fluoride Removal: Efficacy and Mechanism of Fluoride Adsorption by Calcined Venerupis philippinarum Shells

Conversion of Organic Waste to Novel Adsorbent for Fluoride Removal: Efficacy and Mechanism of Fluoride Adsorption by Calcined Venerupis philippinarum Shells

Adsorption Characteristics and Charge Transfer Kinetics of Fluoride in Water by Different Adsorbents

Water containing high concentrations of fluoride is widely distributed and seriously harmful, largely because long-term exposure to fluoride exceeding the recommended level will lead to fluorosis of teeth and bones. Therefore, it is imperative to develop cost-effective and environmentally friendly adsorbents to remove fluoride from polluted water sources. In this study, diatomite (DA), calcium bentonite (CB), bamboo charcoal (BC), and rice husk biochar (RHB) were tested as adsorbents to adsorb fluoride (F‐) from water, and this process was characterized by scanning electron microscopy (FEI-SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The effects of pH, dosage, and the initial mass concentration of each treatment solution upon adsorption of F‐ were determined. Kinetic and thermodynamic models were applied to reveal the mechanism of defluoridation, and an orthogonal experiment was designed to obtain the optimal combination of conditions. The results show that the surfaces of CB, BC, and RHB have an irregular pore structure and rough surface, whereas DA has a rich pore structure, clear pores, large specific surface area, and high silica content. With regard to the adsorption process for F‐, DA has an adsorption complex electron interaction; that of CB, BC, and RHB occur mainly via ion exchange with positive and negative charges; and CB on F‐ relies on chemical electron bonding adsorption. The maximum adsorption capacity of DA can reach 32.20 mg/g. When the mass concentration of fluoride is 100 mg/L, the pH value is 6.0 and the dosage is 4.0 g/L; the adsorption rate of F‐ by DA can reach 91.8%. Therefore, we conclude that DA soil could be used as an efficient, inexpensive, and environmentally friendly adsorbent for fluoride removal, perhaps providing an empirical basis for improving the treatment of fluorine-containing water in the future.

Adsorptive removal of fluoride using ionic liquid-functionalized chitosan – Equilibrium and mechanism studies

In this study, novel biosorbents, based on chitosan and imidazolium ionic liquid, were prepared for the removal of fluoride from aqueous solutions. The adsorbents were characterized by FTIR, SEM-EDS and low-temperature nitrogen adsorption-desorption. To investigate the adsorption mechanism and behavior of chitosan adsorbents, batch experiments were conducted under different adsorbent dosages (2, 4, 10 g/L), pH (4, 7, 9) and initial concentration (0.5–25.0 mg/L). The influence of the method of synthesis of ionic liquid on the adsorption performance were also studied. Experimental data were evaluated by Freundlich, Langmuir and Sips models. The introduction of ionic liquid significantly improved the uptake of fluoride compared to pure chitosan. The adsorption was influenced by the experimental conditions, as well as the method of ionic liquid synthesis. The highest fluoride removal was observed at pH 4 and found to decrease with increasing pH. The removal efficiency and adsorption capacity values indicated that the dose of 4 g/L was the optimum adsorbent dosage. The equilibrium data fitted best with the Sips isotherm and the maximum adsorption capacity reached 8.068 mg/g for modified chitosan beads. The mechanism of fluoride adsorption onto ionic liquid-modified chitosan involves electrostatic attraction, ion exchange and ion pair interaction.

Modified mine waste as an adsorbent for fluoride removal from contaminated water

Shale is a coal mine waste belongs to sedimentary type of rocks. These wastes are generated in tons per year from various mine sectors. In this study shale samples collected from Samleshwari open cast mine were used as an adsorbent for defluoridation of mine waste water. The two types of shale samples, that is, old shale sample (OSS) and new shale sample (NSS) were collected from Samleshwari open cast mine located in IB valley coalfields of MCL mine, Odisha. The fluoride removal efficiency of the samples were increased by using heat activation (100 °C, 500 °C, and 800 °C) and chemical activation using different chemicals (KOH, NaOH, K2CO3, H2SO4, and ZnCl2). The effect of different parameters were also taken in to consideration during the batch adsorption process. The pH of the resulting water decreased slightly but maintained in between 4.5 and 7.5 confirms it’s applicability for drinking purpose. Maximum fluoride Removal obtained using OSS 800 and OSS KOH (heat) were 85.01% and 92.23%, respectively, at initial concentration of 3 ppm, contact time 60 min, dose 10 mg and pH 4.9. The process followed Freundlich isotherm and data were well fitted to pseudo second order kinetics upon analysis with adsorption capacity 42.66 mg/gm and 45.16 mg/gm for OSS 800 and OSS KOH (heat), respectively.

Evaluation of Scales of Tilapia Sp. and Sciaenops ocellatus as Low Cost and Green Adsorbent for fluoride Removal From Water.

Water containing more than 1.5 mg/L of fluoride is considered toxic as it causes dental, kidney, and other health problems. With the purpose of helping alleviate these problems by exploring a treatment method for fluoride contamination, this study was to assess the suitability of scales of Tilapia Sp. and Sciaenops ocellatus as a cheaper source of adsorbent for the removal of fluoride from drinking water. The samples which were obtained from the Lapaz Market in Accra, Ghana, underwent treatment to eliminate any impurities. They were then ground into powder and treated with aluminum hydroxide [Al(OH)3]. The treated samples were used for the removal of fluoride from spiked solutions prepared in the laboratory. Batch adsorption was performed by varying parameters such as adsorbent dose (1–8 g/L), initial concentration (2 mg/L to 10 mg/L), and contact time (30–300 min) at pH of 7. A one-way ANOVA was used to validate the significance of the defluoridation process with respect to the different experimental conditions. The optimum adsorbent dose, initial concentration, and contact time were found to be 4 g/L, 10 mg/L, and 300 min, respectively. The results revealed that the maximum percentage removal of fluoride was 76% by Tilapia Sp. and 70% by Sciaenops ocellatus at the optimum conditions. This is an indication that both Tilapia Sp. And Sciaenops ocellatus scales are suitable adsorbents for the removal of fluoride from water. The fluoride adsorption kinetics followed the pseudo-second-order model, and the adsorption isotherm fitted the Freundlich Isotherm model better than the Langmuir Isotherm model. The adsorption intensity and adsorption capacity for Tilapia Sp. were 3.484 L/mg and 0.065 mg/g, and that of Sciaenops ocellatus 3.195 L/mg and 0.045 mg/g respectively.

Synthesis and characterization of cross linked N-methylene phosphonic chitosan resin chelated with Al(III) for use as adsorbent for fluoride removal from aqueous solutions

Synthesis and characterization of cross linked N-methylene phosphonic chitosan resin chelated with Al(III) for use as adsorbent for fluoride removal from aqueous solutions

Zirconium loaded on tannin foam for efficient adsorptive removal of fluoride at low concentration in a wide pH range

Zirconium loaded on tannin foam for efficient adsorptive removal of fluoride at low concentration in a wide pH range