New generation adsorbents for the removal of fluoride from water and wastewater: A review

Water is essential for life and is threatened by the pollution and contamination generated by human activity and industries. Fluoride contamination of water is a serious problem in the world. The review article highlights on new generation adsorbents including carbon-based adsorbents, nano-adsorbents, bio-sorbents, inorganic materials, modified and composite adsorbents for purification of fluoride from water. It was indicated from the review that a Zinc oxide nanoparticles is the best adsorbents for the removal of fluoride from aqueous media, with a capacity adsorption (qmax) of 100 mg/g. The fluoride uptake best-fit both the Langmuir and Freundlich isotherm models as well as a pseudo second order kinetic model. A wide range of values for the thermodynamic parameters (both negative and positive) were reported for fluoride across different studies. Kinetic and thermodynamic, molecular modelling and simulations, knowledge gaps and future prospects are also presented.