scholarly journals Kinetics and equilibrium studies for removal of fluoride from underground water using cryptocrystalline magnesite

2015 ◽  
Vol 5 (3) ◽  
pp. 282-292 ◽  
Author(s):  
Vhahangwele Masindi ◽  
Wilson Mugera Gitari ◽  
Tholiso Ngulube
Keyword(s):  
Rural Areas ◽  
Fluoride Concentration ◽  
Underground Water ◽  
Fluoride Removal ◽  
Equilibrium Studies ◽  
Adsorption Mechanisms ◽  
Quality Guidelines ◽  
Monolayer Adsorption ◽  
Freundlich Adsorption Isotherm ◽  
Pseudo Second Order

In the present study, the defluoridation capabilities and adsorption mechanisms of cryptocrystalline magnesite were evaluated. All experiments were done by batch procedure. Conditions assessed include time, dosage, concentration, pH and the effects of competing ions. Optimum defluoridation conditions were observed to be 20 g/L magnesite, 2:100 solid:liquid ratio, 20 min of agitation and 60 mg/L fluoride concentration. Adsorption of fluoride by magnesite was observed to be independent of pH. Cryptocrystalline magnesite showed >99% efficiency for fluoride removal. Adsorption kinetics fitted better to a pseudo-second order than a pseudo-first order thus confirming chemisorption. Adsorption data fitted better to a Langmuir than a Freundlich adsorption isotherm thus confirming monolayer adsorption. Cryptocrystalline magnesite successfully removed excess fluoride from aqueous solution to below Department of Water Affairs and Forestry water quality guidelines. As such, this material can be used for a point source defluoridation technique in rural areas and households in South Africa and other developing countries. Based on comparison studies, cryptocrystalline magnesite proved to have high adsorption capacity for fluoride removal and can be used as a substitute for conventional treatment methods.

scholarly journals REMOVAL OF FLUORIDE USING NEEM LEAVES BATCH REACTOR: KINETICS AND EQUILIBRIUM STUDIES

2018 ◽  
Vol 11 (3) ◽  
pp. 237
Author(s):  
Tej Pratap Singh ◽  
Majumder Cb
Keyword(s):  
Removal Efficiency ◽  
Batch Reactor ◽  
Low Cost ◽  
Fluoride Concentration ◽  
Second Order ◽  
Fluoride Removal ◽  
Equilibrium Studies ◽  
Neem Leaves ◽  
Pseudo Second Order ◽  
Adsorbent Dose

 Objective: The aim of this paper is to study the fluoride removal efficiency of the neem leaves low-cost biosorbent for defluoridation of sewage wastewater.Methods: For finding the best operating condition for maximum removal of fluoride, batchwise experiments were performed at different contact times and keeping other parameters to be constant such as pH, initial fluoride concentration, and adsorbent dose. Various kinetic models such as intraparticle diffusion model, Bangham’s model, and Elovich model had been investigated for determining the suitable adsorption mechanism. The rate of adsorption of fluoride on neem leaves has been determined by pseudo-first-order and pseudo-second-order rate models.Results: The adsorption kinetics rate and mechanism was best described by the pseudo-second-order model and Bangham’s model, respectively. The optimum pH, initial concentration, adsorbent dose, and contact time were found to be 7, 20 mg/L, 10 g/L, and 40 min, respectively, for which there was maximum fluoride removal.Conclusion: The result obtained from the experiments show that the neem leaves have been proved to be a low-cost biosorbent for the defluoridation of the sewage wastewater and have high fluoride removal efficiency.

scholarly journals Characterisation of smectite-rich clay soil: Implication for groundwater defluoridation

2016 ◽  
Vol Volume 112 (Number 11/12) ◽  
Author(s):  
Rabelani Mudzielwana ◽  
Mugera W. Gitari ◽  
Titus A.M. Msagati ◽  
◽  
◽  
...  
Keyword(s):  
South Africa ◽  
Rural Areas ◽  
Contact Time ◽  
Clay Soil ◽  
Dental Fluorosis ◽  
Fluoride Concentration ◽  
Limpopo Province ◽  
World Health ◽  
Fluoride Removal ◽  
X Ray

Abstract Groundwater is a widely used and affordable source of drinking water in most of the rural areas of South Africa. Several studies have indicated that groundwater in some boreholes in South Africa has a fluoride concentration above the level recommended by the World Health Organization (1.5 mg/L). Fluoride concentrations above the permissible limit (>1.5 mg/L) lead to dental fluorosis, with even higher concentrations leading to skeletal fluorosis. In the present work, we evaluate the application of smectite-rich clay soil from Mukondeni (Limpopo Province, South Africa) in defluoridation of groundwater. The clay soil was characterised by mineralogy using X-ray diffraction, by elemental composition using X-ray fluorescence and by morphology using scanning electron microscopy. Surface area and pore volume was determined by the Brunauer–Emmett–Teller surface analysis method. Cation exchange capacity and pHpzc of the soil were also evaluated using standard laboratory methods. Batch experiments were conducted to evaluate and optimise various operational parameters such as contact time, adsorbent dose, pH and initial adsorbate concentration. It was observed that 0.8 g/100 mL of smectite-rich clay soil removed up to 92% of fluoride from the initial concentration of 3 mg/L at a pH of 2 with a contact time of 30 min. The experimental data fitted well to a Langmuir adsorption isotherm and followed pseudo second order reaction kinetics. Smectite-rich clay soil showed 52% fluoride removal from field groundwater with an initial fluoride concentration of 5.4 mg/L at an initial pH of 2 and 44% removal at a natural pH of 7.8. Therefore smectite-rich clay soil from Mukondeni has potential for application in defluoridation of groundwater. Chemical modification is recommended to improve the defluoridation capacity.

Methylene Blue Adsorption onto Neem Leave/Chitosan Aggregates: Isotherm, Kinetics and Thermodynamics Studies

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Francis Oluwadayo Asokogene ◽  
Muhammad Abbas Ahmad Zaini ◽  
Muhammad Misau Idris ◽  
Surajudeen Abdulsalam ◽  
El-Nafaty Aliyu Usman
Keyword(s):  
Methylene Blue ◽  
Binding Capacity ◽  
Textural Properties ◽  
Intraparticle Diffusion ◽  
Water Binding ◽  
Adsorption Mechanisms ◽  
Solution Interface ◽  
Monolayer Adsorption ◽  
Equilibrium Data ◽  
Pseudo Second Order

Abstract The work was aimed at evaluating the adsorptive properties of neem leave/chitosan aggregates for methylene blue removal. The adsorbent was screened to form coarse (CCANL, 600 µm), medium (MCANL, 300 µm) and fine (FCANL, 150 µm) neem leave/chitosan particles. The samples were characterized for pH, water binding capacity (WBC), surface chemistry by Fourier transform infrared spectroscopy, surface morphology by scanning electron microscope and textural properties by Brunauer-Emmett-Teller method. CCANL, MCANL and FCANL possessed specific surface area of 255, 258 and 242 m2/g, respectively. The effects of initial concentration, adsorbent dosage, contact time, pH and temperature were studied. CCANL, MCANL and FCANL demonstrated adsorption capacity of 102, 92.5 and 105 mg/g, respectively, in which ionic interaction and mesopore filling were the possible adsorption mechanisms. The equilibrium data were well fitted by Redlich-Peterson model, suggesting a monolayer adsorption onto a heterogeneous surface of adsorbent. The kinetics data were best described by pseudo-second-order and intraparticle diffusion models, for which the film diffusion, intraparticle diffusion and surface adsorption could co-exist as the controlling steps in adsorption. Adsorption of methylene blue onto chitosan composites was spontaneous, endothermic and demonstrated increased randomness at solid-solution interface.

scholarly journals A Facilely Synthesized Tourmaline-Biochar Composite For Enhanced Removal of Cr (VI) From Aqueous Solution

2021 ◽  
Author(s):  
Qi Lu ◽  
Siyi Huang ◽  
Xiaorui Ma
Keyword(s):  
Aqueous Solution ◽  
Pyrolysis Temperature ◽  
Adsorption Property ◽  
Energy Dispersive Spectrometer ◽  
Maximum Adsorption Capacity ◽  
X Ray Diffraction ◽  
Adsorption Mechanisms ◽  
Monolayer Adsorption ◽  
Initial Ph ◽  
Pseudo Second Order

Abstract A tourmaline-biochar composite (TMBC) was facilely synthesized to effectively remove Cr (Ⅵ) from aqueous solution. The effects of different ratio (TM: BC) and pyrolysis temperature on TMBC adsorption performance were compared for optimal condition of TMBC preparation. The TMBC samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). The kinetics and thermodynamics were analyzed to investigate the sorption mechanism for removal of Cr (VI). The results showed that the proper pyrolysis temperature was 650℃, and the ratio of TM and BC was 1:3. SEM results showed that there are many pores in the biochar structure, which is helpful for tourmaline dispersion. The adsorption kinetics was fitted well by the pseudo-second-order model, indicating the sorption is related to chemical absorption. Freundlich adsorption isotherms suggested monolayer adsorption between Cr (Ⅵ) and TMBC, and the maximum adsorption capacity of TMBC for Cr (Ⅵ) was 53.10 mg/g at initial pH 4.0, which is more than twice higher than pristine TM (17.85 mg/g). Such adsorption mechanisms included water automatically polarized, ion exchange and electrode adsorption, among which the automatic polarization of water caused by tourmaline was the unique adsorption property of TMBC. So TMBC composite can be used as an economic adsorbent in the remediation of heavy metal pollution in water.

scholarly journals Eggshell-Derived Nanohydroxyapatite Adsorbent for Defluoridation of Drinking Water from Bofo of Ethiopia

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Kifle Workeneh ◽  
Enyew Amare Zereffa ◽  
Toshome Abdo Segne ◽  
Rajalakshmanan Eswaramoorthy
Keyword(s):  
Removal Efficiency ◽  
Fluoride Concentration ◽  
Fluoride Removal ◽  
Batch Adsorption ◽  
Alternative Source ◽  
Fluoride Adsorption ◽  
Initial Ph ◽  
Pseudo Second Order ◽  
Ft Ir ◽  
Eggshell Waste

Fluoride has become a notable toxicological environmental hazard worldwide because it is often found in groundwater. In the present study, hydroxyapatite adsorbent was synthesized from eggshell waste to remove fluoride from aqueous solution. XRD, FT-IR, and TGA techniques were used to characterize the prepared adsorbent. Batch adsorption studies were performed to examine the adsorption capacity of hydroxyapatite such as the effect of the initial pH of the solution, contact time, adsorbent dose, and initial fluoride concentration. The fluoride ion-selective electrode was used to determine the fluoride removal efficiency. 98.8% of fluoride was removed at pH 3.0, but at pH ~7.0, 85% of fluoride was removed; it shows that the fluoride adsorption is pH dependent. The adsorption isotherm studies (Langmuir and Freundlich models) and the experimental results for the removal of fluoride showed that the Langmuir model was more favorable and the reaction followed pseudo-second-order kinetics. In real water samples, the prepared hydroxyapatite derived from eggshell exhibited 81% removal efficiency. Our results indicate that eggshell waste-derived hydroxyapatite may be an alternative source for defluoridation in developing countries.

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.

scholarly journals Application of cryptocrystalline magnesite-bentonite clay hybrid for defluoridation of underground water resources: implication for point of use treatment

2016 ◽  
Vol 7 (3) ◽  
pp. 338-352 ◽  
Author(s):  
V. Masindi
Keyword(s):  
Rural Areas ◽  
Synthesis Method ◽  
Bentonite Clay ◽  
Underground Water ◽  
Fluoride Removal ◽  
Batch Adsorption ◽  
Optimum Conditions ◽  
Treatment Technology ◽  
Kinetics And Isotherms ◽  
G Ratio

A new synthesis method was established to fabricate a nanocomposite material comprising of cryptocrystalline magnesite and bentonite clay that has high adsorption capacity for ionic pollutants. To synthesize the composite at 1:1 weight (g): weight (g) ratio, a vibratory ball mill was used. Batch adsorption experiments were carried out to determine optimum conditions for fluoride adsorption. Parameters optimized included: time, dosage, concentration and pH. Optimum conditions for defluoridation were found to be 30 min of agitation, 0.5 g of dosage, 0.5:100 solid to liquid (S/L) ratios and 25 mg L−1 of initial fluoride ions. Fluoride removal was independent of pH. The adsorption kinetics and isotherms were well fitted by pseudo-second-order and Langmuir models, respectively, indicating chemical and monolayer adsorption. Findings illustrated that the newly synthesized adsorbent was a promising adsorbent for the environmental pollution clean-up of excess fluoride in underground water and it can be used as a point source treatment technology in rural areas of South Africa and other developing countries.

scholarly journals Adsorption Efficiency of Cement Impregnated Magnesium Oxide on the Removal of Fluoride

2020 ◽  
Vol 5 (2) ◽  
pp. 109-117
Author(s):  
Iohborlang M. Umlong ◽  
Bodhaditya Das ◽  
Rashmi Rekha Devi
Keyword(s):  
Drinking Water ◽  
Magnesium Oxide ◽  
Fluoride Concentration ◽  
Sorption Process ◽  
Fluoride Removal ◽  
Cement Slurry ◽  
Freundlich Isotherms ◽  
Removal Capacity ◽  
Complex Process ◽  
Pseudo Second Order

Presence of fluoride in drinking water above the prescribed limit may lead to a severe health complication. We present in this paper the fluoride removal capacity of cement impregnated MgO (MgO-cement) from drinking water. MgO-cement was prepared by adding magnesium oxide (MgO) into the cement slurry solution in the ratio of 1:10. Batch experiments were performed as a function of adsorbent dose, contact time, effect of pH and effect of co-ions. The percentage removal decreases with increasing initial fluoride concentration. Co-ions effect revealed that hydroxide ion was found to interfere more with fluoride removal followed by bicarbonate and least effect with sulphate. Reaction mechanism follows Freundlich isotherms. From the kinetic study we observed that uptake of fluoride ion is fast in the first sixty minutes and equilibrium time found to be independent of the initial fluoride concentration. Adsorption kinetics followed the pseudo second order model showing that the sorption of fluoride is a complex process. Surface as well as intraparticle diffusion contribute in the sorption process. No leaching of magnesium in the treated water was detected.

scholarly journals Removal of Fluoride from Water by Adsorption onto Fired Clay Pots: Kinetics and Equilibrium Studies

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
G. P. Kofa ◽  
V. H. Gomdje ◽  
C. Telegang ◽  
S. Ndi Koungou
Keyword(s):  
Ionic Strength ◽  
Rural Areas ◽  
Cost Effective ◽  
Equilibrium Studies ◽  
Fluoride Adsorption ◽  
Jar Test ◽  
Cost Effective Method ◽  
Pseudo Second Order ◽  
Fire Wood ◽  
Clay Pots

Excessive fluoride in potable water is a serious health problem in rural areas of many developing countries. Hence, there is a need to find a simple and cost-effective method for water defluoridation in such areas. In the northern part of Cameroon, clay pots are used for cooking food and water storage. The firing of these pots consists of intensive burning using fire wood. They were tested as a potential adsorbent for removing excess fluoride from water. Experiments were carried out in a jar test at room temperature (25 ± 2°C). Effects of contact time (0–90 min), pH (4, 5, 7, 8, and 9), stirring speed (60, 90, 120, and 200 rpm), and ionic strength (0–1000 mg/L) were investigated. Results showed that equilibrium was attained in 10 min whatever the pH. Pseudo-second-order and pore diffusion models described well the adsorption process. The highest amount of fluoride adsorbed (1.6 mg/g) was obtained at pH 4-5 and the optimum stirring speed is 120 rpm. Ionic strength has a significant effect on fluoride adsorption.

scholarly journals SYNTHESIS OF STARCH MODIFIED MONTMORILLONITE AS AN EFFECTIVE ADSORBENT FOR Pb (II) REMOVAL FROM WATER

2019 ◽  
Vol 57 (3A) ◽  
pp. 94
Author(s):  
Tam Hoang Luu ◽  
Hung Van Nguyen ◽  
Nhan Thuc Chi Ha ◽  
Khoa Nguyen Dang Vo
Keyword(s):  
Experimental Data ◽  
Kinetic Studies ◽  
Batch Process ◽  
Second Order ◽  
X Ray Diffraction ◽  
Equilibrium Studies ◽  
Factors Affecting ◽  
Order Rate ◽  
Monolayer Adsorption ◽  
Pseudo Second Order

The adsorbent is prepared by the montmorillonite co-modification with starch for the removal of Pb (II) ions from aqueous solution. The Fourier-transformed infrared (FTIR), X-ray diffraction (XRD) spectroscopies were used to determine the structure and characteristics of the adsorbent. The main factors affecting the removal of Pb (II) ions were investigated, including the effect of pH, contact time, adsorbent dosage and the initial concentration of Pb (II). Batch process can be used for adsorption and equilibrium studies. The experimental data were fitted using Freundlich and Langmuir adsorption models. The Langmuir isotherm best fitted the experimental data with R2> 0.99 and maximum Pb (II) adsorption capacity of 21.5 mg/g indicated monolayer adsorption. Kinetic studies using pseudo-first-order and pseudo-second-order rate models showed that the process complied well with the pseudo second-order rate model.

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