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 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 Development of Kaolin Clay as a Cost-Effective Technology for Defluoridation of Groundwater

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Adane Adugna Ayalew
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Rural Areas ◽  
Contact Time ◽  
Cost Effective ◽  
Isotherm Models ◽  
Kaolin Clay ◽  
Fluoride Removal ◽  
Batch Adsorption ◽  
Bet Analysis

Excessive fluoride in potable groundwater is a serious health problem in rural areas of many developing countries. The presence of a small amount of fluoride in potable water is beneficial to human health, but a high amount (>1.5 mg/L) has adverse effects. The present study is aimed to prepare a new cost-effective adsorbent of kaolin clay that can be used as a valuable defluoridating agent. Characterization of the prepared adsorbent was carried out using DSC, FTIR, TGA, and XRD. Also, the surface area of the adsorbent was measured by BET analysis. The clay was activated with concentrated H2SO4, and the effects of various experimental parameters such as temperature (25, 40, 50, and 60°C), pH (2, 4, 6, and 8), particle size (<0.075, 0.075–0.15, and 0.15–0.30 mm), contact time (30, 60, 90, 120, and 150 min), and dose of the adsorbents (0.5, 1, 1.5, 2.0, and 2.5 g) were investigated using a batch adsorption method. The specific surface area of raw and activated clay was found to be 10.598 m2/g and 5.258 m2/g, respectively. The optimum fluoride removal by both adsorbents was obtained at pH 4, temperature 50°C, particle size 0.075 mm, and 60 min. In both adsorbents, the degree of fluoride removal was increased with a decrease in the particle size of the adsorbent and increased contact time and dosage of the adsorbent. In all parameters, adsorption by activated clay was better than raw kaolin clay for retaining fluoride. The obtained data were well fitted with Freundlich and Langmuir isotherm models.

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.

Iron-oxide nanoparticles by the green synthesis method using Moringa oleifera leaf extract for fluoride removal

2017 ◽  
Vol 39 (22) ◽  
pp. 2926-2936 ◽  
Author(s):  
Carole Silveira ◽  
Quelen Letícia Shimabuku ◽  
Marcela Fernandes Silva ◽  
Rosângela Bergamasco
Keyword(s):  
Iron Oxide ◽  
Green Synthesis ◽  
Iron Oxide Nanoparticles ◽  
Leaf Extract ◽  
Moringa Oleifera ◽  
Synthesis Method ◽  
Fluoride Removal ◽  
Oxide Nanoparticles

scholarly journals Green Activated Magnetic Graphitic Carbon Oxide and Its Application for Hazardous Water Pollutants Removal

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 935 ◽  
Author(s):  
Lakshmi Prasanna Lingamdinne ◽  
Jong-Soo Choi ◽  
Yu-Lim Choi ◽  
Jae-Kyu Yang ◽  
Janardhan Reddy Koduru ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Low Cost ◽  
Reaction Medium ◽  
Carbon Oxide ◽  
Graphitic Carbon ◽  
Batch Adsorption ◽  
Ozone Oxidation ◽  
Fundamental Information ◽  
Pollutants Removal ◽  
Kinetics And Isotherms

Graphitic carbon oxide (GCO) and magnetic graphitic carbon oxide (MGCO) were prepared from sugar via optimized green activation by employing ozone oxidation, and applied to wastewater treatment. The maximal oxidation and adsorption yield of pollutants were achieved at pH 2.0−4.0, which is the optimized pH for ozone oxidation of GC to generate GCO. As-prepared GCO and MGCO were characterized using X-ray, infrared, and microscopic techniques. The MGCO has enough saturation magnetization (MS) of 41.38 emu g−1 for separation of the sorbent from the reaction medium by applying an external magnetic field. Batch adsorption of radioactive and heavy metals (Th(IV), Pb(II)), and a dye (methylene blue (MB)) using GCO and MGCO was evaluated by varying the adsorbent dose, equilibrium pH, contact time, initial metal and dye concentrations, and kinetics and isotherms. Adsorption kinetics and isotherm studies indicated that Th(IV), Pb(II), and MB adsorption were best described by pseudo-second-order kinetics and Langmuir isotherm with R2 (correlation coefficient) > 0.99, respectively. The maximum adsorption capacities for Th(IV), Pb(II), and MB were 52.63, 47.39, and 111.12 mg g−1 on GCO and 76.02, 71.94, and 76.92 mg g−1 on MGCO. GCO and MGCO are prospectively effective and low-cost adsorbents for ion removal in wastewater treatment. As prepared MGCO can be reused up to three cycles for Th(IV), Pb(II), and MB. This work provides fundamental information about the equilibrium adsorption isotherms and mechanisms for Th(IV), Pb(II), and MB on GCO and MGCO.

scholarly journals MULTIVARIATE ANALYSIS APPLIED AT THE SCHOOL OF THE UBERLAND-AMERICAN FIELD OF CONSUMER UNDERGROUND WATER QUALITY

2019 ◽  
Vol 16 (32) ◽  
pp. 833-847
Author(s):  
M. S. MEDEIROS ◽  
A. C. GOULART ◽  
I. S. PACHECO ◽  
F. A. AMARAL ◽  
S. C. CANOBRE
Keyword(s):  
Multivariate Analysis ◽  
Rural Areas ◽  
Pearson Correlation ◽  
Microbiological Quality ◽  
Well Being ◽  
Underground Water ◽  
Septic Tank ◽  
Human Consumption ◽  
Sources Of Pollution ◽  
Artesian Wells

The decrease of the water available for human consumption is directly related to the unregulated and unconscious action from the man himself. In rural areas, this depreciation is related to inappropriate conditions of artesian wells that capture the water (old wells and poorly sealed) and which are usually close to sources of pollution, such as septic tanks and animal grazing. In this context, the objective of the present work was to evaluate the physico-chemical and microbiological quality of underground water samples made available for consumption in three schools in the field next to the municipality of Uberlândia-MG. Methodologically, the data were statistically processed by means of descriptive and multivariate analysis (Pearson correlation coefficient). All schools are supplied by an artesian well, being carried out simplified treatment (chlorination mechanism of chemical treatment). In only one of the schools was identified the presence of a septic tank sewage collection system. Of samples evaluated, all were at odds with the standards laid down in annex XX of the Consolidation Ordinance No. 5 of the Ministry of health (old law 2,914/2011) in at least one of the parameters evaluated. Therefore, the results reflect the possibility of biological contamination of the water by grazing areas located in the region close to the wells, as well as the need for emerging measures, such as regular cleaning and maintenance of storage systems and distribution of the water consumed in the institutions.

scholarly journals Removal of Fluoride from Drinking Water by Sorption Using Diatomite Modified with Aluminum Hydroxide

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Tesfaye Akafu ◽  
Achalu Chimdi ◽  
Kefyalew Gomoro
Keyword(s):  
Aluminum Hydroxide ◽  
Contact Time ◽  
Fluoride Concentration ◽  
Freundlich Isotherm ◽  
Intraparticle Diffusion ◽  
Fluoride Removal ◽  
Contaminated Water ◽  
Optimum Conditions ◽  
Intraparticle Diffusion Model ◽  
Adsorbent Dose

Exposure to fluoride beyond the recommended level for longer duration causes both dental and skeletal fluorosis. Thus, the development of cost-effective, locally available, and environmentally benign adsorbents for fluoride removal from contaminated water sources is absolutely required. In the present study, diatomaceous earth (diatomite) locally available in Ethiopia, modified by treating it with an aluminum hydroxide solution, was used as an adsorbent for fluoride removal from aqueous solutions. Adsorption experiments were carried out by using batch contact method. The adsorbent was characterized using FT-IR spectroscopy. Effects of different parameters affecting efficiency of fluoride removal such as adsorbent dose, contact time, initial fluoride concentration, and pH were investigated and optimized. The optimum adsorbent dose, contact time, initial fluoride concentration, and pH values were 25 g/L, 180 min, 10 mg/L, and 6.7, respectively. The performance of the adsorbent was also tested under optimum conditions using groundwater samples taken from Hawassa and Ziway. Langmuir and Freundlich isotherm models were applied to describe the equilibrium data. Compared to Langmuir isotherm (R2 = 0.888), the Freundlich isotherm (R2 = 0.985) model was better fitted to describe the adsorption characteristics of fluoride on Al-diatomite. The Langmuir maximum adsorption capacity was 1.67 mg/g. The pseudosecond-order model was found to be more suitable than the pseudofirst-order to describe the adsorption kinetics. The low correlation coefficient value of R2 = 0.596 for the intraparticle diffusion model indicates that the intraparticle diffusion model does not apply to the present studied adsorption system. The maximum fluoride removal was observed to be 89.4% under the optimum conditions which indicated that aluminum hydroxide-modified diatomite can be used as efficient, cheap, and ecofriendly adsorbents for the removal of fluoride from contaminated water.

scholarly journals Application of ZnO Nano Rods for the Batch Adsorption of Cr(VI): A Study of Kinetics and Isotherms

2019 ◽  
Vol 16 (3) ◽  
pp. 101-112 ◽  
Author(s):  
Sushma Kamath ◽  
Venu Gopal Vishwakarma Ramanjaneyalu ◽  
Susmita Kamila
Keyword(s):  
Batch Adsorption ◽  
Nano Rods ◽  
Kinetics And Isotherms

Microbial Community Analysis of Underground Drinking Water Using Denaturing Gradient Gel Electrophoresis and Flow Cytometry Technologies

2014 ◽  
Vol 700 ◽  
pp. 519-524 ◽  
Author(s):  
Jie Liu ◽  
Yan Li Ding ◽  
Mark Bartlam ◽  
Ying Ying Wang
Keyword(s):  
Drinking Water ◽  
Microbial Community ◽  
Rural Areas ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Poyang Lake ◽  
Removal Rate ◽  
Underground Water ◽  
Water Sources ◽  
Gradient Gel Electrophoresis ◽  
Bacteria And Fungi

Underground water is directly used as drinking water in most rural areas of developing countries due to limitations in infrastructure. As an important indicator of drinking water quality, however, microbial quality has been largely ignored for a long time. Microbial quality poses a great threat to the safety of underground drinking water, especially in rural areas. The current study compared microbial abundance and community structure of three different water sources, i.e. underground water, Poyang Lake and Hai River, combined with flow cytometry (FCM) and denaturing gradient gel electrophoresis (DGGE). FCM results showed that the bacterial concentration of underground water is the lowest (1.037×106cell/ml) of the three water sources, but still approximates that of the Poyang Lake. The removal rate of bacteria after filtration through a 0.45μm-pore-size filter is 98.16% in underground water. The removal rate for Poyang Lake and Hai River is much lower (i.e. 66.57% and 74.17% respectively). DGGE profiles demonstrated that the microbial community structure in underground water shares higher similarity to Poyang Lake (51.0% and 53.1% similarity for bacteria and fungi respectively) than Hai River. The microbial diversity index (i.e. Shannon-Weaver index) for bacteria and fungi are 2.906 and 2.847 respectively in underground water, which is lower than in Poyang Lake. The evenness (i.e. Simpson index) of groundwater was lowest among the three water sources tested. The results suggested that groundwater has a complex microbial community and hence it is critical to apply necessary hygienic barriers to remove microbes for the safety of underground drinking water.

Adsorption of Ni(II) by a thermo-sensitive colloid: methylcellulose/calcium alginate beads

2019 ◽  
Vol 68 (7) ◽  
pp. 495-508
Author(s):  
Zhongmin Li ◽  
Wanwan Wu ◽  
Wenyan Jiang ◽  
Guangtao Wei ◽  
Yunshang Li ◽  
...  
Keyword(s):  
Calcium Alginate ◽  
Adsorption Process ◽  
Alginate Beads ◽  
Batch Adsorption ◽  
Order Kinetic ◽  
Adsorption Model ◽  
Isothermal Adsorption ◽  
Calcium Alginate Beads ◽  
Lower Temperature ◽  
Kinetics And Isotherms

Abstract The adsorption of Ni(II) by a thermo-sensitive adsorbent of methylcellulose/calcium alginate beads (CAMCBs) was studied using batch adsorption tests to determine the adsorption process and properties, the effects of adsorbent dosage, initial concentration, adsorption time and temperature. The adsorption process was further investigated using kinetics, isotherms and thermodynamic methods. The kinetics and isotherms studies showed the adsorption of Ni(II) on CAMCBs was fitted by the pseudo-second-order kinetic model and Langmuir isothermal adsorption model, respectively. The thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic at lower temperature, and the entropy of the adsorption process was negative. In the study of regeneration, it was confirmed that under the temperature of 60 °C, the desorption agent of CaCl2 with concentration of 3 g·L−1 was more conducive to the desorption of Ni(II) from CAMCBs. Both adsorption capacity and mechanical strength of the used CAMCBs could be basically recovered to the level of fresh CAMCBs after desorption. The prepared CAMCBs had a good property of adsorption of Ni(II) and an excellent regeneration performance.

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