Removal of toxic metals using endocarp of açaí berry as biosorbent Affonso Celso Gonçalves Jr, Daniel Schwantes, Marcelo Angelo Campagnolo, Douglas Cardoso Dragunski, César Ricardo Teixeira Tarley and Arthur Kinkas dos Santos Silva ABSTRACT The effectiveness of açaí endocarp as biosorbent for removal of Cd 2þ , Pb 2þ and Cr 3þ from single solute solutions was analyzed. The biomass of açaí endocarp was characterized by scanning electron microscopy, infrared spectroscopy and determining the point of zero charge. The optimum conditions for adsorption process were obtained at solution pH 6.0 for Cd(II) removal, pH 5.0 for Pb(II) removal, and, pH 4.0 for Cr(III). Furthermore, the average optimum efficiency of biosorbent in the optimum conditions was 8, 20 and 12 g of biosorbent per litre of contaminant solution, respectively, for Cd(II), Pb(II) and Cr(III). The best dynamic equilibrium time was reached at 60 min and Langmuir’s model had the best fit for Cd(II) and Cr(III) biosorption, indicating a monolayer adsorption. Freundlich’s model exhibited the best fit for Pb(II) ion. Elution rates were low, indicating a strong metal interaction with the adsorbent’s surface. Thermodynamic parameters showed a spontaneous and endothermal process in the case of Cd(II) and Pb(II) ions, but not for Cr(III) ion, which appears to be an exothermic process. Results show that the use of the açaí biosorbent may be a promising alternative for the remediation of polluted water, due to its low cost and highly availability. Affonso Celso Gonçalves Jr (corresponding author) Arthur Kinkas dos Santos Silva Center for Agricultural Sciences, State University of Western Paraná, Pernambuco street, 1777, CEP 85960-000, Marechal Cândido Rondon – Paraná, Brazil E-mail: affonso133@hotmail.com Daniel Schwantes Department of Engineering and Exact Sciences, Federal University of Paraná, Palotina Sector – Pioneiro Street, 2153, CEP: 85950-000 Palotina – Paraná, Brazil Marcelo Angelo Campagnolo Environmental Engineering, Polytechnic School – Toledo, Pontifical Catholic University of Paraná, União Avenue, 500, CEP: 85902-532, Toledo – Paraná, Brazil Douglas Cardoso Dragunski Department of Chemistry, State University of Western Paraná, College street, 645, CEP 85903-000, Toledo - Paraná, Brazil César Ricardo Teixeira Tarley Department of Chemistry, Londrina State University, Celso Garcia Cid Highway, CEP 86050-482, Londrina – Paraná Brazil Key words | adsorption, Euterpe oleracea Mart., metal remediation, natural adsorbent, water treatment INTRODUCTION Among the several contaminating elements of water resources, heavy metals are dangerous compounds derived from the inadequate storage of non-treated industrial waste. They are priority contaminants due to their toxicity and to their mobility in surface or underground waters, con- stituting a serious environmental and public health issue. Cadmium (Cd), lead (Pb), chromium (Cr) and other metals are highly toxic in human physiology, causing several dis- eases and disorders (Bulgariu & Bulgariu ). There are several methods for the removal of these con- taminants, such as chemical and physical precipitation, ionic exchange, extraction by solvents, bio-accumulation by aquatic plants or micro-organisms, and filtration by mem- branes. The adsorption process is one of the most promising for metal remediation (Witek-Krowiak ). Activated carbon is one of the most frequently used adsor- bents, although at high costs of production (Santhi et al. ). The main characteristics of this material are high surface area, 1547 © IWA Publishing 2018 Water Science & Technology | 77.6 | 2018 doi: 10.2166/wst.2018.032 Downloaded from https://iwaponline.com/wst/article-pdf/77/6/1547/242436/wst077061547.pdf by guest on 05 November 2018