Efficient microplastics extraction from sand. A cost effective methodology based on sodium iodide recycling Mikaël Kedzierski a , Véronique Le Tilly a , Guy César b , Olivier Sire a , Stéphane Bruzaud a, ⁎ a Université Bretagne Sud, IRDL FRE CNRS 3744, 56100 Lorient, France b SERPBIO, Université Bretagne Sud, 56321 Lorient, France abstract article info Article history: Received 15 September 2016 Received in revised form 28 November 2016 Accepted 2 December 2016 Available online xxxx Evaluating the microplastics pollution on the shores requires overcoming the technological and economical chal- lenge of efficient plastic extraction from sand. The recovery of dense microplastics requires the use of NaI solu- tions, a costly process. The aim of this study is to decrease this cost by recycling the NaI solutions and to determine the impact of NaI storage. For studying the NaI recyclability, the solution density and the salt mass have been monitored during ten life cycles. Density, pH and salt mass have been measured for 40 days to assess the storage effect. The results show that NaI solutions are recyclable without any density alterations with a total loss of 35.9% after the 10 cycles of use. During storage, chemical reactions may appear but are reversible. Conse- quently, the use of recycling methods allows for a significant cost reduction. How far the plastic extraction by dense solutions is representative is discussed. © 2016 Elsevier Ltd. All rights reserved. Keywords: Microplastic pollution Extraction technics Sand Sodium iodide Recycling Storage 1. Introduction The plastic production has increased exponentially during the second half of the 20th century (PlasticsEurope, 2013). In the same time, due to the lack of waste management plants, the environmen- tal pollution by plastics is rising inexorably (Jambeck et al., 2015). A lot of studies have shown that plastic particles, and more particularly microplastics, could be ingested directly by a large range of organ- isms, living in aquatic environment, from plankton (Cole et al., 2013; Frias et al., 2014; Setälä et al., 2014) to mammals (Bravo Rebolledo et al., 2013; Denuncio et al., 2011; Secchi and Zarzur, 1999) passing by crustaceans (Murray and Cowie, 2011), molluscs (Van Cauwenberghe et al., 2015), fishes (Lusher et al., 2013) and birds (Ryan, 2008). Organisms which live in sediments, such as lug- worms Arenicola marina (Green et al., 2016; Van Cauwenberghe et al., 2015) or sandhoppers Talitrus saltator (Ugolini et al., 2013), are particularly exposed to microplastics mixed with sand. Microplastics can also be ingested indirectly by feeding on contaminated preys (Farrell and Nelson, 2013). Hence, all the food chain could be involved (Andrady, 2011; Fendall and Sewell, 2009; Lima et al., 2014). Different effects of the plastic ingestion have been highlight- ed on feeding activity (Azzarello and Vleet, 1987; Sussarellu et al., 2016; Wright et al., 2013), mobility (Rehse et al., 2016) or reproduc- tion (Sussarellu et al., 2016). From this ingestion of plastics arises a major threat for marine life and implies to survey the plastic pollution. Microplastics pollutions have been observed in various natural envi- ronments. They are well documented on the water surface of rivers (Gasperi et al., 2014), lakes (Biginagwa et al., 2016; Eriksen et al., 2013; Free et al., 2014; Imhof et al., 2016), sea (Lusher et al., 2014; Pedrotti et al., 2016) and oceans (Desforges et al., 2014; Shim and Thompson, 2015). They are also present in benthic environments (Koutsodendris et al., 2008; Van Cauwenberghe et al., 2013b) and in shore environments (Hidalgo-Ruz and Thiel, 2013; Imhof et al., 2013; Ng and Obbard, 2006), where they are generally mixed with sand. To re- cover them, different extraction methods are required. Dense salt solu- tions are generally used like sodium chloride (density: 1–1.18 g/mL) (Frias et al., 2016; Thompson et al., 2004). However, this method has a low capacity to extract denser microplastics than 1.20 g/mL (Claessens et al., 2013; Imhof et al., 2012; Nuelle et al., 2014). As a consequence, denser solutions have been proposed such as zinc chloride (density: 1–1.81 g/mL) (Imhof et al., 2012; Liebezeit and Dubaish, 2012), sodium polytungstate (density: 1–3.2 g/mL) (Corcoran et al., 2009) or sodium iodide (NaI; density: 1–1.84 g/mL) (Dekiff et al., 2014; Van Marine Pollution Bulletin xxx (2016) xxx–xxx ⁎ Corresponding author. E-mail address: stephane.bruzaud@univ-ubs.fr (S. Bruzaud). MPB-08221; No of Pages 10 http://dx.doi.org/10.1016/j.marpolbul.2016.12.002 0025-326X/© 2016 Elsevier Ltd. All rights reserved. Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul Please cite this article as: Kedzierski, M., et al., Efficient microplastics extraction from sand. A cost effective methodology based on sodium iodide recycling, Marine Pollution Bulletin (2016), http://dx.doi.org/10.1016/j.marpolbul.2016.12.002