Research article Biosorption removal of benzene and toluene by three dried macroalgae at different ionic strength and temperatures: Algae biochemical composition and kinetics Carlos E. Flores-Chaparro a , Luis Felipe Chazaro Ruiz a , Ma. Catalina Alfaro de la Torre b , Miguel Angel Huerta-Diaz c , Jose Rene Rangel-Mendez a, * a Divisi on de Ciencias Ambientales, Instituto Potosino de Investigaci on Científica y Tecnol ogica A.C., Camino a la Presa San Jos e 2055, Col. Lomas 4a secci on, C.P. 78216, San Luis Potosí, SLP, Mexico b Universidad Aut onoma de San Luis Potosí,  Alvaro Obreg on 64, Centro Hist orico, C.P. 78000, San Luis Potosí, SLP, Mexico c Universidad Aut onoma de Baja California, Campus Ensenada, Km. 103, Carretera TijuanaeEnsenada, Ensenada, Baja California, Mexico article info Article history: Received 24 November 2016 Received in revised form 31 January 2017 Accepted 3 February 2017 Keywords: Biosorption Macroalgae Soluble-hydrocarbons Ionic strength abstract Release of lowmolecular aromatic hydrocarbons (HC) into natural waters brings severe consequences to our environment. Unfortunately very limited information is available regarding the treatment of these pollutants. This work evaluated the use of brown, green and red macroalgae biomass as biosorbents of benzene and toluene, two of the most soluble HC. Raw seaweed biomasses were completely charac- terized, then evaluated under different temperatures and ionic strengths to assess their potential as biosorbents and to elucidate the biosorption mechanisms involved. Brown macroalgae registered the highest removal capacities for benzene and toluene (112 and 28 mg$g 1 , respectively), and these were not affected at ionic strength < 0.6 M. Langmuir and Sips isotherm equations well described biosorption data, and the pseudo-second order model provided the best fit to the kinetics rate. Hydrocarbons are adsorbed onto the diverse chemical components of the cell wall by London forces and hydrophobic interactions. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction Water pollution by oil spills is a serious problem in petro- chemical activities, with a total volume of oil lost to the environ- ment in 2015 of approximately 7000 tonnes (ITOPF, 2016). It has been calculated that around 1e3% (sometimes up to 15%) of crude oil can pass into the dissolved state (Njobuenwu et al., 2005), although low molecular aromatic compounds like benzene and toluene, present higher water solubilities and bioavailabilities than other petroleum hydrocarbon components and, as a consequence, have been classified as a risk to the environment (US EPA, 2013). Insitu removal of these pollutants by adsorption onto activated carbon has been considered a more suitable technology than aeration or photocatalysis, mainly due to the hydrophobic nature of the adsorbent, its high surface area and high affinity to a broad type of pollutants (Cooney, 1999). However, the advantages of activated carbon could be restricted for remediation purposes because it has been associated to secondary ecotoxicological effects in sediments (Lillicrap et al., 2015). Another viable option is the usage of mac- roalgae utilized as biosorption matrix, a process that constitutes a low cost and environmental friendly alternative for the removal of the dissolved fractions of petroleum (Hubbe et al., 2014). Bio- sorption involves the passive binding to metabolic inactive mate- rials derived from i.e. industrial or agricultural by-products, forestry, marine or terrestrial biological materials and microbe biomass (Caz on et al., 2014; Holkaret al., 2016; Valili et al., 2013). For the special case of macroalgae biomass, it is widely available (15.8 million tons harvested in 2010), occurs in a wide variety of habitats (ranging from marine to freshwater), and contains different active sites in its cell structures that are accessible for organic biosorption, i.e. hydroxyl, carboxyl and amine (Ghadiryanfar et al., 2016; Henriques et al., 2017). There are three types of macroalgae: red, green and brown (Davis et al., 2003), but all have cell walls that are complex net- works of biopolymers consisting in a skeleton of crystalline and fibrous parts (cellulose, hemicellulose, etc.) and an embedding * Corresponding author. E-mail address: rene@ipicyt.edu.mx (J.R. Rangel-Mendez). Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman http://dx.doi.org/10.1016/j.jenvman.2017.02.005 0301-4797/© 2017 Elsevier Ltd. All rights reserved. Journal of Environmental Management 193 (2017) 126e135