y2016m11b16
20161124081000
assa
nadine@assaf.org.za
assa
South African Journal of Science
S. Afr. J. Sci
0038-2353
1996-7489
11242016
Volume 112
Number 11/12
Characterisation of smectite-rich clay soil: Implication for groundwater defluoridation
Characterisation of smectite-rich clay soil: Implication for groundwater defluoridation
Rabelani
Mudzielwana
Environmental Remediation and Pollution Chemistry Research Group, Department of Ecology and Resource Management, University of Venda, Thohoyandou, South Africa
Mugera W.
Gitari
http://orcid.org/0000-0002-6387-0682
Environmental Remediation and Pollution Chemistry Research Group, Department of Ecology and Resource Management, University of Venda, Thohoyandou, South Africa
Titus A.M.
Msagati
College of Science Engineering and Technology, University of South Africa, Johannesburg, South Africa
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.
11242016
http://creativecommons.org/licenses/by/2.5/za/
http://creativecommons.org/licenses/by/2.5/za/
10.17159/sajs.2016/20150442
20161124081000
http://sajs.co.za/characterisation-smectite-rich-clay-soil-implication-groundwater-defluoridation/rabelani-mudzielwana-mugera-w-gitari-titus-m-msagati
-
http://sajs.co.za/sites/default/files/publications/pdf/SAJS-112-11-12-Mudzielwana_ResearchArticle.pdf
-
http://sajs.co.za/sites/default/files/publications/pdf/SAJS-112-11-12-Mudzielwana_ResearchArticle.pdf
-
http://sajs.co.za/sites/default/files/publications/pdf/SAJS-112-11-12-Mudzielwana_ResearchArticle.pdf
-
http://sajs.co.za/sites/default/files/publications/pdf/SAJS-112-11-12-Mudzielwana_ResearchArticle.pdf
-
http://sajs.co.za/sites/default/files/publications/pdf/SAJS-112-11-12-Mudzielwana_ResearchArticle.pdf
-
http://sajs.co.za/sites/default/files/publications/pdf/SAJS-112-11-12-Mudzielwana_ResearchArticle.pdf
-
http://sajs.co.za/sites/default/files/publications/pdf/SAJS-112-11-12-Mudzielwana_ResearchArticle.pdf