Fluoride Adsorption onto Soil Adsorbents: The Role of pH and Other Solution Parameters

Soil adsorbents continue to attract increasingly high numbers of researchers in water defluoridation studies. An aspect of solution parameters, that is the aqueous adsorption of fluoride onto soil adsorbents in defluoridation studies, has been reviewed and reported. The pH was found to be the main factor controlling fluoride adsorption on the popular soil adsorbents including: aluminosilicates, iron (hydr)oxides, aluminum (hydr)oxides, apatites, carbonaceous minerals, calcareous soils and zeolites and the other key parameters being temperature, time of contact, and co-existent ions. Fluoride adsorption onto metal-exchanged zeolites and hydroxyapatites (optimum pH = 4–10), iron (hydro)oxide minerals (pH = 2–7), and carbonaceous minerals (pH = 4–12) is relatively pH-independent, and high amounts of fluoride are able to sorb upon the surfaces of these minerals in a wide range of pH values. However, montmorillonites (optimum pH = 5–6), aluminum (hydro)oxide minerals (pH = 5–7), and calcareous minerals (pH = 5–6) only sorb significant amount of fluoride in a narrow range of pH values. The fluoride adsorption onto the latter class of minerals, also generally occurring at slightly above room temperatures, appears to be highly specific and not strongly affected by the presence of coexistent anions including: PO43−,SO42−,Cl−,andNO3−

Excessive Copper(II) and Zinc(II) Levels in Drinkable Water Sources in Areas Along the Lake Victoria Shorelines in Siaya County, Kenya

International audienc

Characteristics and trends in global tea research: a Science Citation Index Expanded-based analysis

International audienc

Fluoride Adsorption onto Acid-Treated Diatomaceous Mineral from Kenya

International audienc

Regeneration of spent bleaching earth and its adsorption of copper (II) ions from aqueous solutions

International audienc

Characteristics and trends in global tea research: a Science Citation Index Expanded-based analysis

Wambu, E.W., Fu, H.Z. and Ho, Y.S. ；2017, Characteristics and trends in global tea research: a Science Citation Index Expanded-based analysis. International Journal of Food Science and Technology, 52 ；3, 644-651

High fluoride water in Bondo-Rarieda area of Siaya County, Kenya: a hydro-geological implication on public health in the Lake Victoria Basin

International audienc

Socio-economic factors influencing the spread of drinking water diseases in rural Africa: case study of Bondo sub-county, Kenya

International audienceSocio-economic and medical information on Bondo sub-county community was studied to help establish the relationship between the water quality challenges, community health and water rights conditions. Health challenges have been linked to water quality and household income. A total of 1,510 households/respondents were studied by means of a questionnaire. About 69% of the households have no access to treated water. Although 92% of the respondents appear to be aware that treatment of water prevents waterborne diseases, the lowest income group and children share a high burden of waterborne diseases requiring hospitalization and causing mortality. Open defecation (12.3%) in these study areas contributes to a high incidence of waterborne diseases. The community's constitutional rights to quality water in adequate quantities are greatly infringed. The source of low-quality water is not a significant determinant of waterborne disease. The differences in poverty level in the sub-county are statistically insignificant and contribute less than other factors. Increased investment in water provision across regions, improved sanitation and availability of affordable point-of-use water purification systems will have major positive impacts on the health and economic well-being of the community

Removal of Cadmium(II) Ions from Water by Adsorption using Water Hyacinth (Eichhornia crassipes) Biomass

The kinetics and equilibrium binding of Cd(II) ions onto raw water hyacinth (Eichhornia crassipes) biomass (RBH) were investigated with the view to utilize it as a low-cost biosorbent for removal of toxic metal ions from water. The biosorption was analyzed through batch experiments with respect to the effect of contact time, agitation speed, biosorbent dosage, solution pH, Cd(II) concentration, and the presence of other metal ions. Cadmium adsorption onto Eichhornia crassipes biomass was pH- and temperature-dependent, and complete Cd(II) removal from solution was achieved at all Cd(II) concentrations up to 10 mg/L. The biosorption equilibrium was described by Langmuir and Freundlich isotherms, and the RBH Cd(II) uptake capacity was 104 mg/g. The biosorption process followed the pseudo-second-order model (R2 0.99). The root biomass of water hyacinth had one of the highest Cd(II) sequestration efficiencies when compared to other biosorbents that have been used to remove Cd(II) from water