Defluoridation of groundwater using Fe<sup>3+</sup>-modified bentonite clay: optimization of adsorption conditions

Gitari, Wilson M.; Ngulube, Tholiso; Masindi, Vhahangwele; Gumbo, Jabulani R.

doi:10.1080/19443994.2013.855669

Cited by 72 publications

(29 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…CEC, surface area, pore volume and diameter and pH pzc CEC refers to the total quantity of exchangeable cations that the soil can retain on their surfaces by electrostatic force at given pH. The CEC for smectite-rich clay was identified by measuring the concentrations of Na + , K + , Mg 2+ and Ca 2+ in ppm released in solution and the concentrations were then converted to milliequivalent per 100 g 12 who also concluded that CEC is independent of pH. It can also be concluded that the smectite-rich clay soil has moderate CEC.…”

Section: Scanning Electron Microscope Analysismentioning

confidence: 99%

“…5 Recently, more studies have focused on the use of clay soils for defluoridation because of their good adsorptive properties such as a large specific surface area, chemical and mechanical stability, layered structure and high cation exchange capacity. Several studies that have reported the use of clay soils for defluoridation have been published, including a study on illite-goethite soil in China 9 , a study on selected South African clays 6 , the use of chemically modified bentonite clay 10 , magnesium incorporated bentonite clay 11 , Fe 3+ -modified bentonite in South Africa 12 and Al 3+modified bentonite in South Africa 13 . Smectite-rich clay from Mukondeni (a village in the Limpopo Province of South Africa) has been used for a very long time to make ceramic water filters and has been found to be effective in improving water quality.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Mudzielwana¹,

Gitari²,

Msagati³

2016

S. Afr. J. Sci.

View full text Add to dashboard Cite

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.

show abstract

Section: Scanning Electron Microscope Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Mudzielwana¹,

Gitari²,

Msagati³

2016

S. Afr. J. Sci.

View full text Add to dashboard Cite

show abstract

“…Defluoridation based on adsorption technology is considered to be the most appropriate for rural communities because of its low cost, ease of operation, needless of operational skill and electric power to run. In the light of these factors, some of the materials that have been tested include activated charcoal, [8] activated alumina, [9] clay soils and their modified species [10,11] and aluminium hydroxide impregnated macroreticular aromatic polymeric resin [12] among others.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and performance evaluation of Al/Fe oxide coated diatomaceous earth in groundwater defluoridation: Towards fluorosis mitigation

Izuagie

Gitari

Gumbo

2016

Journal of Environmental Science and Health, Part A

View full text Add to dashboard Cite

The quest to reduce fluoride in groundwater to WHO acceptable limit of 1.5 mg/L to prevent diseases such as teeth mottling and skeletal fluorosis was the motivation for this study. Al/Fe oxide-modified diatomaceous earth was prepared and its defluoridation potential evaluated by batch method. The sorbent with pHpzc 6.0 ± 0.2 is very reactive. The maximum 82.3% fluoride removal attained in 50 min using a dosage of 0.3 g/100 mL in 10 mg/L fluoride was almost attained within 5 min contact time; 81.3% being the percent fluoride removal at 5 min contact time. The sorbent has a usage advantage of not requiring solution pH adjustment before it can exhibit its fluoride removal potential. A substantial amount of fluoride (93.1%) was removed from solution when a sorbent dosage of 0.6 g/100 mL was contacted with 10 mg/L fluoride solution for 50 min at a mixing rate of 200 rpm. The optimum adsorption capacity of the adsorbent was 7.633 mg/g using a solution containing initially 100 mg/L fluoride. The equilibrium pH of the suspensions ranged between 6.77 and 8.26 for 10 and 100 mg/L fluoride solutions respectively. Contacting the sorbent at a dosage of 0.6 g/100 mL with field water containing 5.53 mg/L at 200 rpm for 50 min reduced the fluoride content to 0.928 mg/L-a value below the upper limit of WHO guideline of 1.5 mg/L fluoride in drinking water. The sorption data fitted to both Langmuir and Freundlich isotherms but better with the former. The sorption data obeyed only the pseudo-second-order kinetic, which implies that fluoride was chemisorbed.

show abstract

“…Nitrogen adsorption-desorption isotherms were used to determine specific surface area of the adsorbent according to Brunauer Emmett Teller (BET) model. Cation exchange capacity was determined using ammonium acetate buffer at pH 5.4 and 7.4 as described by Gitari et al 17 The surface charge and point of zero charge was determined using solid addition method as described by Kumar et al 19 …”

Section: Physicochemical and Mineralogical Characterization Of Mnmentioning

confidence: 99%

“…Bentonite clay modified with Mg 2+ , Fe 3+ and Al 3+ have been observed to provide improved fluoride adsorption capacity. [16][17][18] Mn 2+ is a high charge density polycation that is stable at extreme pH levels and its use in defluoridation has not been exploited. This study aimed at evaluating the applicability of Mn 2+ -modified bentonite clay in defluoridation of groundwater.…”

Section: Introductionmentioning

confidence: 99%

Performance of Mn2+ modified Bentonite Clay for the Removal of Fluoride from Aqueous Solution

Mudzielwana¹,

Gitari²,

Akinyemi³

et al. 2018

S.Afr.j.chem.

View full text Add to dashboard Cite

show abstract

Defluoridation of groundwater using Fe³⁺-modified bentonite clay: optimization of adsorption conditions

Cited by 72 publications

References 14 publications

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

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

Synthesis and performance evaluation of Al/Fe oxide coated diatomaceous earth in groundwater defluoridation: Towards fluorosis mitigation

Performance of Mn2+ modified Bentonite Clay for the Removal of Fluoride from Aqueous Solution

Contact Info

Product

Resources

About

Defluoridation of groundwater using Fe3+-modified bentonite clay: optimization of adsorption conditions

Cited by 72 publications

References 14 publications

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

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

Synthesis and performance evaluation of Al/Fe oxide coated diatomaceous earth in groundwater defluoridation: Towards fluorosis mitigation

Performance of Mn2+ modified Bentonite Clay for the Removal of Fluoride from Aqueous Solution

Contact Info

Product

Resources

About

Defluoridation of groundwater using Fe³⁺-modified bentonite clay: optimization of adsorption conditions