Study of a New Adsorbent for Fluoride Removal from Waters

1995 ◽  
Vol 30 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Wang Rongshu ◽  
Li Haiming ◽  
Na Ping ◽  
Wang Ying
Keyword(s):  
High Temperature ◽  
High Selectivity ◽  
Adsorption Process ◽  
Field Tests ◽  
Neutral Medium ◽  
Fluoride Removal ◽  
Removal Mechanism ◽  
Activated Alumina ◽  
High Fluoride ◽  
The One

Abstract A new adsorbent for fluoride removal is reported in this study. The process and mechanism of removing fluoride are also reported. The adsorbent was characterized as having high selectivity for fluoride, large adsorption capacity, applicability to neutral medium and much better adsorption at high temperature. The floride removal mechanism is a typical chemisorption which is different from the one used for activated alumina. Adsorption rate was considerably faster at the beginning of the adsorption process, followed by a much slower porous diffusion process. Results of field tests showed that the adsorbent was much more suitable for treating high temperature geothermal water with high fluoride content. It also had the advantages of reducing turbidity, decolorizing, dealkalizing, and removing iron from drinking water.

8-GHz Narrowband High-Temperature Superconducting Filter With High Selectivity and Flat Group Delay

2009 ◽  
Vol 57 (7) ◽  
pp. 1767-1773 ◽  
Author(s):  
Lu Gao ◽  
Liang Sun ◽  
Fei Li ◽  
Qiang Zhang ◽  
Yuehui Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Group Delay ◽  
High Selectivity ◽  
High Temperature Superconducting

scholarly journals Eggshell Powder as an Adsorbent for Removal of Fluoride from Aqueous Solution: Equilibrium, Kinetic and Thermodynamic Studies

2012 ◽  
Vol 9 (3) ◽  
pp. 1457-1480 ◽  
Author(s):  
R. Bhaumik ◽  
N. K. Mondal ◽  
B. Das ◽  
P. Roy ◽  
K. C. Pal ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Adsorption Process ◽  
Low Cost ◽  
Fluoride Removal ◽  
Contaminated Water ◽  
Fluoride Adsorption ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
Kinetic And Thermodynamic Studies ◽  
Maximum Removal

A new medium, eggshell powder has been developed for fluoride removal from aqueous solution. Fluoride adsorption was studied in a batch system where adsorption was found to be pH dependent with maximum removal efficiency at 6.0. The experimental data was more satisfactorily fitted with Langmuir isotherm model. The kinetics and the factor controlling adsorption process fully accepted by pseudo-second-order model were also discussed. Eawas found to be 45.98 kJmol-1by using Arrhenius equation, indicating chemisorption nature of fluoride onto eggshell powder. Thermodynamic study showed spontaneous nature and feasibility of the adsorption process with negative enthalpy (∆H0) value also supported the exothermic nature. Batch experiments were performed to study the applicability of the adsorbent by using fluoride contaminated water collected from affected areas. These results indicate that eggshell powder can be used as an effective, low-cost adsorbent to remove fluoride from aqueous solution as well as groundwater.

Purification of Eucalyptus globulus water prehydrolyzates using the HiTAC process (high-temperature adsorption on activated charcoal)

Holzforschung ◽  
2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Jenny Sabrina Gütsch ◽  
Herbert Sixta
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Adsorption Process ◽  
Value Added ◽  
Sustainable Utilization ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Charcoal Adsorption ◽  
Increasing Temperature ◽  
Value Added Products

Abstract The implementation of biorefinery concepts into existing pulp and paper mills is a key step for a sustainable utilization of the natural resource wood. Water prehydrolysis of wood is an interesting process for the recovery of xylo-oligosaccharides and derivatives thereof, while at the same time cellulose is preserved to a large extent for subsequent dissolving pulp production. The recovery of value-added products out of autohydrolyzates is frequently hindered by extensive lignin precipitation, especially at high temperatures. In this study, a new high-temperature adsorption process (HiTAC process) was developed, where lignin is removed directly after the autohydrolysis, which enables further processing of the autohydrolyzates. The suitability of activated charcoals as a selective adsorbent for lignin under process-relevant conditions (150 and 170°C) has not been considered up to now, because former experiments showed decreasing efficiency of charcoal adsorption of lignin with increasing temperature in the range 20–80°C. In contrast to these results, we demonstrated that the adsorption of lignin at 170°C directly after autohydrolysis is even more efficient than after cooling the hydrolyzate to room temperature. The formation of lignin precipitation and incrustations can thus be efficiently prevented by the HiTAC process. The carbohydrates in the autohydrolysis liquor remain unaffected over a wide charcoal concentration range and can be further processed to yield valuable products.

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−.

scholarly journals Rare Earth Elements Enhanced the Oxidation Resistance of Mo-Si-Based Alloys for High Temperature Application: A Review

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1144
Author(s):  
Laihao Yu ◽  
Yingyi Zhang ◽  
Tao Fu ◽  
Jie Wang ◽  
Kunkun Cui ◽  
...  
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Rare Earth Elements ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Strengthening Mechanism ◽  
Advanced Materials ◽  
Performance Requirements ◽  
Large Numbers ◽  
The One

Traditional refractory materials such as nickel-based superalloys have been gradually unable to meet the performance requirements of advanced materials. The Mo-Si-based alloy, as a new type of high temperature structural material, has entered the vision of researchers due to its charming high temperature performance characteristics. However, its easy oxidation and even “pesting oxidation” at medium temperatures limit its further applications. In order to solve this problem, researchers have conducted large numbers of experiments and made breakthrough achievements. Based on these research results, the effects of rare earth elements like La, Hf, Ce and Y on the microstructure and oxidation behavior of Mo-Si-based alloys were systematically reviewed in the current work. Meanwhile, this paper also provided an analysis about the strengthening mechanism of rare earth elements on the oxidation behavior for Mo-Si-based alloys after discussing the oxidation process. It is shown that adding rare earth elements, on the one hand, can optimize the microstructure of the alloy, thus promoting the rapid formation of protective SiO2 scale. On the other hand, it can act as a diffusion barrier by producing stable rare earth oxides or additional protective films, which significantly enhances the oxidation resistance of the alloy. Furthermore, the research focus about the oxidation protection of Mo-Si-based alloys in the future was prospected to expand the application field.

scholarly journals Novel Lanthanum Doped Magnetic Teff Straw Biochar Nanocomposite and Optimization Its Efficacy of Defluoridation of Groundwater Using RSM: A Case Study of Hawassa City, Ethiopia

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Temesgen Abeto Amibo ◽  
Surafel Mustafa Beyan ◽  
Tsegaye Markos Damite
Keyword(s):  
Rotational Speed ◽  
Ligand Exchange ◽  
Contact Time ◽  
Adsorption Process ◽  
Quadratic Model ◽  
Fluoride Removal ◽  
Fluoride Ions ◽  
Removal Capacity ◽  
Mathematical Process

The problem extent of the large concentration of fluoride ions in drinking water is still a central health issue. In the present study, lanthanum doped magnetic Teff straw biochar (LDMTSB) was developed as a novel adsorbent for removing fluoride ions in the groundwater in Rift-Valley regions, especially Hawassa city, Ethiopia. The synthesized LDMTBC was characterized via FTIR, XRD, SEM, and BET. And, this analysis proposed that multiadsorption techniques such as ligand exchange, precipitations, and electrostatic interaction could be evinced throughout the fluoride ions adsorption process by LDMTSB. The constraints that influence the adsorption efficacy, namely, a dosage of LDMTSB, contact time, pH of the solution, and rotational speed, were analyzed and optimized using the response surface methodology approach. Under the optimum situations, LDMTSB dosage: 3.97 g, contact time: 56.36 min, rotational speed: 591.19 rpm, and pH: 3.968 demonstrate high efficacy of LDMTSB with 98.89% fluoride removal capacity. Further, the quadratic model (R2 = 0.9841) was designated for governing the mathematical process. The LDMTSB was successful in the removal of fluoride ions in the groundwater. This study provides a valuable economical solution for the application of Teff straw.

scholarly journals Results from field tests of the one-dimensional Time-Encoded Imaging System.

2014 ◽  
Author(s):  
Peter Marleau ◽  
James S. Brennan ◽  
Erik Brubaker
Keyword(s):  
Imaging System ◽  
Field Tests ◽  
One Dimensional ◽  
The One

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.

Identification of the Triplet State N-V Defect in Neutron Irradiated Silicon Carbide by Electron Paramagnetic Resonance

2006 ◽  
Vol 527-529 ◽  
pp. 555-558 ◽  
Author(s):  
Marina V. Muzafarova ◽  
Ivan V. Ilyin ◽  
E.N. Mokhov ◽  
Vladimir Ilich Sankin ◽  
P.G. Baranov
Keyword(s):  
High Temperature ◽  
Triplet State ◽  
Hyperfine Splitting ◽  
Vacancy Defect ◽  
Strong Temperature Dependence ◽  
High Temperature Annealing ◽  
Paramagnetic Resonance ◽  
Anisotropic Hyperfine ◽  
The One ◽  
Electron Paramagnetic

Two types of a new triplet centers labeled as N-V have been observed in heavily neutron irradiated (dose of 1021 cm-2) and high-temperature annealed (2000°C) 6H-SiC crystals. The centers have an axial symmetry along c-axis. Anisotropic hyperfine splitting due to the one 14N nucleus has been observed. The EPR spectra of N-V defects in the triplet state in 6H-SiC reveal strong temperature dependence. The parameters of these centers are similar to that for well-known N-V center in diamond. It seems to consist of silicon vacancy and carbon substitutional nitrogen in the adjacent lattice cites oriented along c-axis. Similar to the diamond N-V centers in SiC have been produced by neutron irradiation and high-temperature annealing of the crystals containing nitrogen. For the first shell the structure of the N-V defect in 6H-SiC is practically identical with that in diamond. The charge state of this defect seems to be +1 compare with neutral state for nitrogensilicon vacancy defect in 6H-SiC with S=1/2.

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