Abstract
Fruit consumption and processing result in considerable volumes of residual biomass. Transformation of this biomass into biosorbents offers an alternative for its reuse and disposal. As the green coconut shell is a waste often discarded in landfills and dumps, generating gases and leachate, two biosorbents were developed from the epicarp and mesocarp of green coconut to adsorb fluoride ions in aqueous solution. The kinetic experiments showed that sorption of fluoride ions reached equilibrium at 300 min for both epicarp and mesocarp at temperatures of 25°C, 35°C, and 45°C. The removal efficiency of fluoride ions varied from 66.25% (at 25°C) to 77.50% (at 45°C) for the epicarp and from 90% (at 25°C) to 97.50% (at 45°C) for the mesocarp. The thermodynamic parameters of the adsorption process showed that adsorption is a spontaneous, endothermic process for both biosorbents. The adsorption was classified as chemical, with the Langmuir isotherm model best suited to the adsorption isotherms data.
Highlights
IntroductionE concentration of fluoride ions can vary from 0.5 to 50 mg·L− 1, depending on geological factors [1,2,3,4,5,6]
Groundwater from countries such as Algeria, Argentina, Australia, Bangladesh, China, South Korea, Egypt, Spain, United States, Ghana, India, Iran, Iraq, Israel, Italy, Japan, Jordan, Libya, Mexico, Morocco, New Zealand, Kenya, Senegal, South Africa, Sri Lanka, Tanzania, and Turkey, as well as countries in South America, is contaminated with fluoride ions. e concentration of fluoride ions can vary from 0.5 to 50 mg·L− 1, depending on geological factors [1,2,3,4,5,6]. the maximum acceptable concentration of fluoride ions in drinking water established by the World Health Organization is 1.5 mg·L− 1, some countries have adopted other limits
Removal of fluoride ions by the epicarp and mesocarp of green coconut was investigated. e epicarp showed removal efficiency ranging from 66.25% to 77.50%, while the mesocarp showed removal efficiency ranging from 90% to 97.50%
Summary
E concentration of fluoride ions can vary from 0.5 to 50 mg·L− 1, depending on geological factors [1,2,3,4,5,6]. The maximum acceptable concentration of fluoride ions in drinking water established by the World Health Organization is 1.5 mg·L− 1, some countries have adopted other limits. Concentrations of fluoride ions greater than 1.5 mg·L− 1 can lead to dental fluorosis, while concentrations above 3 mg·L− 1 can cause skeletal fluorosis. It is estimated that 26 million people in China suffer from dental fluorosis and 1 million from skeletal fluorosis, due to the consumption of water contaminated with high levels of fluoride ions [11,12,13,14]
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