SHORT RESEARCH AND DISCUSSION ARTICLE F sorption/desorption on two soils and on different by-products and waste materials Ana Quintáns-Fondo 1 & Gustavo Ferreira-Coelho 2 & Remigio Paradelo-Núñez 3 & Juan Carlos Nóvoa-Muñoz 3 & Manuel Arias-Estévez 3 & María J. Fernández-Sanjurjo 1 & Esperanza Álvarez-Rodríguez 1 & Avelino Núñez-Delgado 1 Received: 11 February 2016 /Accepted: 23 May 2016 /Published online: 1 June 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract We used batch-type experiments to study F sorption/ desorption on a forest soil, a vineyard soil, pyritic material, gra- nitic material, finely and coarsely ground mussel shell, mussel shell calcination ash, oak wood ash, pine-sawdust, slate process- ing fines, and three different mixtures that included three com- ponents: sewage sludge, mussel shell ash, and calcined mussel shell or pine wood ash. The three waste mixtures, forest soil, pyritic material, and shell ash showed high sorption capacity (73–91 % of added F) and low desorption, even when 100 mg F L -1 was added. All these materials (and to a lower extent wood ash) could be useful to remove F from polluted media (as certain soils, dumping sites, and contaminated waters). The vineyard soil, the granitic material, mussel shell, slate fines, and pine-sawdust were less effective in F removal. In most cases, sorption data fitted better to the Freundlich than to the Langmuir equation. These results can be useful to program the correct management of the soils, by-products, and waste mate- rials assayed, mostly in situations where F concentrations are excessive and F removal should be promoted. Keywords Adsorption . By-products . Desorption . Fluoride . Soils . Wastes Introduction Fluoride can cause public health problems when its con- centration in soil, water, and/or food is excessive. In par- ticular, fluorosis is a disease that in most cases is closely associated with the consumption of fluoride-rich waters (Shitumbanuma et al. 2006; Oruc 2008; Yadav et al. 2009; Yesilnacar et al. 2016). In fact, F concentrations higher than 1.0–1.5 mg L -1 can be considered problem- atic (WHO 2004) and F concentrations are generally less- er than 0.3 mg L -1 in unpolluted waters (Msonda et al. 2007). Mottling of teeth and dental fluorosis may occur at concentrations >1.5 mg L -1 , whereas F concentrations >3 mg L -1 can cause skeletal fluorosis (WHO 1996; Shyam and Kalwania 2012). In many cases, F precipi- tates with Ca forming insoluble fluorite (CaF 2 ), which would be the main mineral controlling the concentrations of F dissolved in groundwater (Saxena and Ahmed 2003). Given the large number of variables that influence F concentration in groundwater (geology, porosity, soil acidity, chemical characteristics of the aquifer, and temperature), the concentration of fluoride in these waters can range from less than 1 to more than 35 mg L -1 . High levels of soluble F in rocks and soil can increase F leaching towards fresh and groundwater (Chaudhary et al. 2008). F may be accumulated in soils mainly due to erosion of minerals with high F content (Tosche et al. 2000; Cronin et al. 2003). The dissolution of fluorite, apatite, and topaz from local bedrocks leads to high F concentration in groundwater (Suthar et al. 2008). The presence of F in soils is mainly related to the geological substrate, but some industrial sources are also important, the most common being aluminum and phosphate-fertilizer factories (Weinstein and Davison 2004; Gago et al. 2002, 2014). In addition, agriculture and forestry Responsible editor: Zhihong Xu * Avelino Núñez-Delgado avelino.nunez@usc.es 1 Department of Soil Science and Agricultural Chemistry, Engineering Polytechnic School, Universidade de Santiago de Compostela, Lugo 27002, Spain 2 Center for Agricultural Sciences, State University of West Paraná, Marechal Cândido Rondon, Paraná, Brazil 3 Department of Plant Biology and Soil Science, Faculty of Sciences, Campus Ourense, University of Vigo, Ourense 32004, Spain Environ Sci Pollut Res (2016) 23:14676–14685 DOI 10.1007/s11356-016-6959-8