scholarly journals Optimization of Fluoride Adsorption on Acid Modified Bentonite Clay Using Fixed-Bed Column by Response Surface Method

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7112
Author(s):  
Adane Woldemedhin Kalsido ◽  
Beteley Tekola Meshesha ◽  
Beshah M. Behailu ◽  
Esayas Alemayehu
Keyword(s):  
Fluoride Concentration ◽  
Fixed Bed ◽  
Volumetric Flow Rate ◽  
Packed Bed ◽  
Field Application ◽  
Adsorptive Capacity ◽  
Small Scale ◽  
Fluoride Removal ◽  
Acid Activation ◽  
Column Adsorption

Using small-scale batch tests, various researchers investigated the adsorptive removal of fluoride using low-cost clay minerals, such as Bentonite. In this study, Column adsorption studies were used to investigate the removal of fluoride from aqueous solution using acid-treated Bentonite (ATB). The effects of initial fluoride concentration, flow rates, and bed depth on fluoride removal efficiency (R) and adsorption capability (qe) in continuous settings were investigated, and the optimal operating condition was determined using central composite design (CCD). The model’s suitability was determined by examining the relationship between experimental and expected response values. The analysis of variance was used to determine the importance of independent variables and their interactions. The optimal values were determined as the initial concentration of 5.51 mg/L, volumetric flow rate of 17.2 mL/min and adsorbent packed-bed depth of 8.88 cm, with % removal of 100, adsorptive capacity of 2.46 mg/g and desirability of 1.0. This output reveals that an acid activation of Bentonite has made the adsorbent successful for field application.

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.

scholarly journals Column Efficiency of Fluoride Removal Using Quaternized Palm Kernel Shell (QPKS)

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Ayu Haslija Abu Bakar ◽  
Luqman Chuah Abdullah ◽  
Nur Amirah Mohd Zahri ◽  
Ma’an Alkhatib
Keyword(s):  
Fluoride Concentration ◽  
Fixed Bed ◽  
Palm Kernel ◽  
Fluoride Removal ◽  
Trimethylammonium Chloride ◽  
Transfer Resistance ◽  
Adsorption Models ◽  
Palm Kernel Shell ◽  
Bed Height ◽  
Fixed Bed Adsorption

In this research, the adsorption potential of quaternized palm kernel shell (QPKS) to remove F− from aqueous solution was investigated using fixed-bed adsorption column. Raw palm kernel shell waste was reacted with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHMAC) in order to modify the surface charge. The effects of inlet F− concentrations (2–12 mg/l) and QPKS bed height (2–10 cm) with optimum pH (pH = 3) on the breakthrough characteristics of the adsorption system were determined. In the fixed-bed column, breakthrough time increases with increasing bed height due to increasing amount of active site on adsorbents to adsorb the fluoride ion. Decreasing trend of breakthrough values was obtained with increasing initial fluoride concentration due to greater driving force for the transfer process to overcome the mass transfer resistance in the column. The adsorptions were fitted to three well-established fixed-bed adsorption models, namely, Thomas, Yoon–Nelson, and Adams–Bohart models. The results fitted well to the Thomas and Yoon–Nelson models with correlation coefficient, R2 ≥ 0.96.

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.

Modeling and Simulation of a Packed-bed Reactor for Carrying out the Water-Gas Shift Reaction

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Yaidelin A. Manrique ◽  
Carlos V. Miguel ◽  
Diogo Mendes ◽  
Adelio Mendes ◽  
Luis M. Madeira
Keyword(s):  
Fixed Bed ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Fixed Bed Reactor ◽  
Water Gas Shift ◽  
Small Scale ◽  
Heterogeneous Model ◽  
Co Conversion ◽  
Reactor Operating ◽  
Water Gas

Abstract In this work the water-gas shift (WGS) process was addressed, with particular emphasis in the development of phenomenological models that can reproduce experimental results in a WGS reactor operating at low temperatures. It was simulated the conversion obtained in a fixed-bed reactor (PBR) packed with a Cu-based catalyst making use of a composed kinetic equation in which the Langmuir-Hinshelwood rate model was used for the lowest temperature range (up to 215 ºC), while for temperatures in the range 215 – 300 ºC a redox model was employed. Several packed-bed reactor models were then proposed, all of them without any fitting parameters. After comparing the simulations against experimental CO conversion data for different temperatures and space time values, it was concluded that the heterogeneous model comprising axial dispersion and mass transfer resistances shows the best fitting. This model revealed also good adherence to other experiments employing different feed compositions (CO and H2O contents); it predicts also the overall trend of increasing CO conversion with the total pressure. This modeling work is particularly important for small scale applications related with hydrogen production/purification for fuel cells.

scholarly journals Volcanic Rock Materials for Defluoridation of Water in Fixed-Bed Column Systems

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 977 ◽  
Author(s):  
Wondwosen Sime Geleta ◽  
Esayas Alemayehu ◽  
Bernd Lennartz
Keyword(s):  
Flow Rate ◽  
Volcanic Rocks ◽  
Fixed Bed ◽  
Water Volume ◽  
Fluoride Removal ◽  
High Concentration ◽  
Solution Ph ◽  
Fixed Bed Column ◽  
Column Adsorption ◽  
Defluoridation Of Water

Consumption of drinking water with a high concentration of fluoride (>1.5 mg/L) causes detrimental health problems and is a challenging issue in various regions around the globe. In this study, a continuous fixed-bed column adsorption system was employed for defluoridation of water using volcanic rocks, virgin pumice (VPum) and virgin scoria (VSco), as adsorbents. The XRD, SEM, FTIR, BET, XRF, ICP-OES, and pH Point of Zero Charges (pHPZC) analysis were performed for both adsorbents to elucidate the adsorption mechanisms and the suitability for fluoride removal. The effects of particle size of adsorbents, solution pH, and flow rate on the adsorption performance of the column were assessed at room temperature, constant initial concentration, and bed depth. The maximum removal capacity of 110 mg/kg for VPum and 22 mg/kg for VSco were achieved at particle sizes of 0.075–0.425 mm and <0.075 mm, respectively, at a low solution pH (2.00) and flow rate (1.25 mL/min). The fluoride breakthrough occurred late and the treated water volume was higher at a low pH and flow rate for both adsorbents. The Thomas and Adams–Bohart models were utilized and fitted well with the experimental kinetic data and the entire breakthrough curves for both adsorbents. Overall, the results revealed that the developed column is effective in handling water containing excess fluoride. Additional testing of the adsorbents including regeneration options is, however, required to confirm that the defluoridation of groundwater employing volcanic rocks is a safe and sustainable method.

Design of a continuous flow immobilized-cell reactor for biosynthetical production of L-aspartic acid

1985 ◽  
Vol 50 (10) ◽  
pp. 2122-2133 ◽  
Author(s):  
Jindřich Zahradník ◽  
Marie Fialová ◽  
Jan Škoda ◽  
Helena Škodová
Keyword(s):  
Aspartic Acid ◽  
Continuous Flow ◽  
Immobilized Cells ◽  
Scale Up ◽  
Fixed Bed ◽  
Packed Bed ◽  
Fixed Bed Reactor ◽  
Experimental Program ◽  
Design Parameters ◽  
Immobilized Cell

An experimental study was carried out aimed at establishing a data base for an optimum design of a continuous flow fixed-bed reactor for biotransformation of ammonium fumarate to L-aspartic acid catalyzed by immobilized cells of the strain Escherichia alcalescens dispar group. The experimental program included studies of the effect of reactor geometry, catalytic particle size, and packed bed arrangement on reactor hydrodynamics and on the rate of substrate conversion. An expression for the effective reaction rate was derived including the effect of mass transfer and conditions of the safe conversion-data scale-up were defined. Suggestions for the design of a pilot plant reactor (100 t/year) were formulated and decisive design parameters of such reactor were estimated for several variants of problem formulation.

scholarly journals Development of a simplified gas ultracleaning process: experiments in biomass residue-based fixed-bed gasification syngas

2021 ◽  
Author(s):  
Christian Frilund ◽  
Esa Kurkela ◽  
Ilkka Hiltunen
Keyword(s):  
Activated Carbons ◽  
Low Cost ◽  
Fixed Bed ◽  
Carbonyl Sulfide ◽  
Gas Analysis ◽  
Small Scale ◽  
Cleaning Process ◽  
Medium Temperature ◽  
Gas Cleaning ◽  
Adsorption Affinity

AbstractFor the realization of small-scale biomass-to-liquid (BTL) processes, low-cost syngas cleaning remains a major obstacle, and for this reason a simplified gas ultracleaning process is being developed. In this study, a low- to medium-temperature final gas cleaning process based on adsorption and organic solvent-free scrubbing methods was coupled to a pilot-scale staged fixed-bed gasification facility including hot filtration and catalytic reforming steps for extended duration gas cleaning tests for the generation of ultraclean syngas. The final gas cleaning process purified syngas from woody and agricultural biomass origin to a degree suitable for catalytic synthesis. The gas contained up to 3000 ppm of ammonia, 1300 ppm of benzene, 200 ppm of hydrogen sulfide, 10 ppm of carbonyl sulfide, and 5 ppm of hydrogen cyanide. Post-run characterization displayed that the accumulation of impurities on the Cu-based deoxygenation catalyst (TOS 105 h) did not occur, demonstrating that effective main impurity removal was achieved in the first two steps: acidic water scrubbing (AWC) and adsorption by activated carbons (AR). In the final test campaign, a comprehensive multipoint gas analysis confirmed that ammonia was fully removed by the scrubbing step, and benzene and H2S were fully removed by the subsequent activated carbon beds. The activated carbons achieved > 90% removal of up to 100 ppm of COS and 5 ppm of HCN in the syngas. These results provide insights into the adsorption affinity of activated carbons in a complex impurity matrix, which would be arduous to replicate in laboratory conditions.

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