scholarly journals Zn–Al Layered Double Hydroxides Synthesized on Aluminum Foams for Fluoride Removal from Water

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2109
Author(s):  
Yuliu Li ◽  
Riccardo Narducci ◽  
Alessandra Varone ◽  
Saulius Kaciulis ◽  
Eleonora Bolli ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Fluoride Concentration ◽  
Threshold Value ◽  
Absorption Efficiency ◽  
Polluted Water ◽  
Fluoride Removal ◽  
Synthesis Methods ◽  
Aluminum Foams ◽  
Fluoride Ions ◽  
Double Hydroxides

Fluoride excess in water represents an environmental issue and a risk for human health since it can cause several diseases, such as fluorosis, osteoporosis, and damage of the nervous system. Layered double hydroxides (LDHs) can be exploited to remove this contaminant from water by taking advantage of their high ion-exchange capability. LDHs are generally mixed with polluted water in the form of powders, which then cause the problem of uneasy separation of the contaminated LDH sludge from the purified liquid. In this work, Zn–Al LDH films were directly grown in situ on aluminum foams that acted both as the reactant and substrate. This method enabled the removal of fluoride ions by simple immersion, with ensuing withdrawal of the foam from the de-contaminated water. Different LDH synthesis methods and aluminum foam types were investigated to improve the adsorption process. The contact time, initial fluoride concentration, adsorbent dosage, and pH were studied as the parameters that affect the fluoride adsorption capacity and efficiency. The highest absorption efficiency of approximately 70% was obtained by using two separate growth methods after four hours, and it effectively reduced the fluoride concentration from 3 mg/L to 1.1 mg/L, which is below the threshold value set by WHO for drinking water.

scholarly journals LAYERED DOUBLE HYDROXIDES: NANOMATERIALS FOR APPLICATIONS IN AGRICULTURE

2015 ◽  
Vol 39 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Luíz Paulo Figueredo Benício ◽  
Rejane Alvarenga Silva ◽  
Júnia Aparecida Lopes ◽  
Denise Eulálio ◽  
Rodrigo Morais Menezes dos Santos ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Layered Double Hydroxides ◽  
Slow Release ◽  
Structural Characteristics ◽  
Synthesis Methods ◽  
Double Hydroxides ◽  
Near Future

The current research aims to introduce Layered Double Hydroxides (LDH) as nanomaterials to be used in agriculture, with particular reference to its use as storage and slow release matrix of nutrients and agrochemicals for plant growing. Structural characteristics, main properties, synthesis methods and characterization of LDH were covered in this study. Moreover, some literature data have been reported to demonstrate their potential for storage and slow release of nitrate, phosphate, agrochemicals, besides as being used as adsorbent for the wastewater treatment. This research aims to expand, in near future, the investigation field on these materials, with application in agriculture, increasing the interface between chemistry and agronomy.

scholarly journals Biosorption of Fluoride from Synthetic and Ground Water Using Chlorella vulgaris Immobilized in Calcium Alginate Beads in an Upflow Packed Bed Column

2017 ◽  
Vol 61 (3) ◽  
pp. 188 ◽  
Author(s):  
Poornima G. Hiremath ◽  
Thomas Theodore
Keyword(s):  
Experimental Data ◽  
Ground Water ◽  
Chlorella Vulgaris ◽  
Water Samples ◽  
Packed Column ◽  
Fluoride Concentration ◽  
Fixed Bed ◽  
Fluoride Removal ◽  
Fluoride Ions ◽  
Fluoride Adsorption

The potential of immobilized Chlorella vulgaris to remove fluoride from synthetic and real ground water samples in a fixed bed was investigated. The effect of important kinetic parameters including column bed height, feed flow rate and influent fluoride concentration of solution on fluoride removal was studied. Thomas, Yoon-Nelson, and BDST models were used to analyze the experimental data and understand the influence on biosorption performance. The models’ predictions were in good agreement with the experimental data for all the process parameters studied, indicating that the models were suitable for fixed-bed column design. Fluoride adsorption was reversible. Desorption of fluoride ions was accomplished by pumping 0.1 N HCl solution. The reusability of adsorbent was studied by subjecting column to repeated cycles of fluoride adsorption and desorption. The suitability of immobilized C. vulgaris adsorbent for fluoride removal from ground water samples of Pavagada taluk, Tumakuru district was studied in the packed column.

Effect of Doped Iron on Fluoride Sorption by Calcined MgAlFe-CO3 Layered Double Hydroxides

2013 ◽  
Vol 681 ◽  
pp. 21-25
Author(s):  
Yu Bing Pu ◽  
Jia Rui Wang ◽  
Hong Zheng ◽  
Peng Cai ◽  
Si Yuan Wu
Keyword(s):  
Layered Double Hydroxides ◽  
Synthetic Wastewater ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Fluoride Removal ◽  
Maximum Sorption Capacity ◽  
Fluoride Adsorption ◽  
Maximum Sorption ◽  
Co Precipitation ◽  
Double Hydroxides

A series of MgAlFe-CO3 layered double hydroxides (LDHs) were successfully prepared by co-precipitation method. With synthetic wastewater, the effect of doped iron on fluoride sorption by calcined MgAlFe-CO3 layered double hydroxides (CLDH) under different pH and contact time conditions was investigated. The sorption isotherm data were fitted well to Langmuir isotherm at 25 °C. The maximum sorption capacity of fluoride on CLDH increases first and then decreases with the increase of Fe/Al molar ratio and attains maximum of 71.94 mg/g when Fe/Al molar ratio is 1:2, although doped iron is unfavorable to the regeneration of original layered structure for CLDH after fluoride adsorption. No aluminium in the solution after fluoride adsorption was detected when Fe/Al molar ratio is equal to or larger than 1:2. The results indicate that CLDH with proper Fe/Al molar ratio is a promising candidate as an adsorbent material for fluoride removal from aqueous solutions.

scholarly journals Recent Advances in Self-Supported Layered Double Hydroxides for Oxygen Evolution Reaction

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Libo Wu ◽  
Luo Yu ◽  
Xin Xiao ◽  
Fanghao Zhang ◽  
Shaowei Song ◽  
...  
Keyword(s):  
Water Splitting ◽  
Oxygen Evolution ◽  
Layered Double Hydroxides ◽  
Oxygen Evolution Reaction ◽  
Influential Factors ◽  
Future Research ◽  
Limiting Factor ◽  
Synthesis Methods ◽  
High Catalytic Activity ◽  
Double Hydroxides

Electrochemical water splitting driven by clean and sustainable energy sources to produce hydrogen is an efficient and environmentally friendly energy conversion technology. Water splitting involves hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in which OER is the limiting factor and has attracted extensive research interest in the past few years. Conventional noble-metal-based OER electrocatalysts like IrO2 and RuO2 suffer from the limitations of high cost and scarce availability. Developing innovative alternative nonnoble metal electrocatalysts with high catalytic activity and long-term durability to boost the OER process remains a significant challenge. Among all of the candidates for OER catalysis, self-supported layered double hydroxides (LDHs) have emerged as one of the most promising types of electrocatalysts due to their unique layered structures and high electrocatalytic activity. In this review, we summarize the recent progress on self-supported LDHs and highlight their electrochemical catalytic performance. Specifically, synthesis methods, structural and compositional parameters, and influential factors for optimizing OER performance are discussed in detail. Finally, the remaining challenges facing the development of self-supported LDHs are discussed and perspectives on their potential for use in industrial hydrogen production through water splitting are provided to suggest future research directions.

scholarly journals Fluoride removal by Ca-Al-CO3 layered double hydroxides at environmentally-relevant concentrations

Chemosphere ◽  
2020 ◽  
Vol 243 ◽  
pp. 125307 ◽  
Author(s):  
Liangfu Wei ◽  
Frederik Zietzschmann ◽  
Luuk C. Rietveld ◽  
Doris van Halem
Keyword(s):  
Layered Double Hydroxides ◽  
Fluoride Removal ◽  
Double Hydroxides

Enhanced fluoride removal from water by non-thermal plasma modified CeO2/Mg–Fe layered double hydroxides

2013 ◽  
Vol 72 ◽  
pp. 117-123 ◽  
Author(s):  
Tao Zhang ◽  
Qiurong Li ◽  
Haiyan Xiao ◽  
Zhenyu Mei ◽  
Hongxiao Lu ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Thermal Plasma ◽  
Fluoride Removal ◽  
Non Thermal Plasma ◽  
Double Hydroxides

scholarly journals Water defluoridation by carbonate calcined and uncalcined Layered Double Hydroxides (LDHs)

2019 ◽  
Vol 98 ◽  
pp. 09005
Author(s):  
Elisabetta Dore ◽  
Franco Frau
Keyword(s):  
Anion Exchange ◽  
Sorption Capacity ◽  
Layered Double Hydroxides ◽  
Lamellar Structure ◽  
Ph Value ◽  
Molar Ratio ◽  
Fluoride Removal ◽  
Cationic Composition ◽  
Removal Capacity ◽  
Double Hydroxides

Carbonate Layered Double Hydroxides (LDHs) with different cationic composition and M2+/M3+ molar ratio were tested, both untreated and calcined, for water defluoridation. The defluoridation capacity of calcined LDHs, produced by intercalation during the reconstruction of lamellar structure, is more effective than the anion exchange of untreated LDHs. Among the calcined LDHs tested, that with 3Mg/(0.5Al+0.5Fe) molar ratio yields a maximum fluoride sorption capacity up to 92.3 mg/g, in spite of the high pH value (up to 12) of the experiments. After four cycles of regeneration by calcination and subsequent water defluoridation, this LDH composition maintains more than 80% of its fluoride removal capacity.

Adsorption of fluoride from aqueous solution by enhanced chitosan/bentonite composite

2013 ◽  
Vol 68 (9) ◽  
pp. 2074-2081 ◽  
Author(s):  
Qian Liu ◽  
Ruihua Huang ◽  
Bingchao Yang ◽  
Yanping Liu
Keyword(s):  
Aqueous Solution ◽  
Ph Value ◽  
Fluoride Concentration ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Fluoride Removal ◽  
Fluoride Ions ◽  
Adsorbent Dosage ◽  
Batch System ◽  
Monolayer Adsorption

In this work, enhanced chitosan/bentonite composite was prepared by treating chitosan/bentonite composite with concentrated hydrochloric acid (HCl). The adsorption of fluoride ions from aqueous solution onto the enhanced chitosan/bentonite composite was investigated. Adsorption studies were performed in a batch system, and the effects of various parameters, such as the pH value of the solution, adsorbent dosage and initial fluoride concentration, were evaluated. The optimum operating conditions for fluoride removal by the enhanced chitosan/bentonite composite were pH = 7 or so, and adsorbent dosage =1.2 g. Increasing initial fluoride concentration reduced the adsorption of fluoride onto the enhanced chitosan/bentonite composite. Furthermore, the presence of other co-anions weakened the adsorption of fluoride onto this adsorbent. The equilibrium adsorption isotherms were well described by both the Freundlich and Langmuir models. The maximum monolayer adsorption capacity was 2.95 mg/g at 293 K.

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