ARTICLE IN PRESS JID: JTICE [m5G;November 30, 2017;21:32] Journal of the Taiwan Institute of Chemical Engineers 000 (2017) 1–12 Contents lists available at ScienceDirect Journal of the Taiwan Institute of Chemical Engineers journal homepage: www.elsevier.com/locate/jtice Efficient removal of anionic and cationic dyes from aqueous systems using spent Yerba Mate “Ilex paraguariensis” Ahmad B. Albadarin ∗ , Samuel Solomon , Mohamad Abou Daher , Gavin Walker Department of Chemical Sciences, Bernal Institute, University of Limerick, Limerick, Ireland a r t i c l e i n f o Article history: Received 12 September 2017 Revised 24 October 2017 Accepted 10 November 2017 Available online xxx Keywords: Biosorption mechanisms Dyes removal Yerba Mate Analytical techniques Wastewater treatment a b s t r a c t The overarching aim of this work was to assess the performance of low cost and readily available biomass, Yerba Mate (Y-Mate), for the removal of Orange II dye (OII) and Methylene Blue (MB) as a function of so- lution pH, dosage and particle size at different initial dye concentrations and contact time. The data was quantitatively described through appropriate isotherms and kinetic equations. OII biosorption on Y-Mate significantly decreased with increasing pH from 2 to 6, whereas, MB biosorption increased steadily with increasing pH. The Sips isotherm model best represented biosorption isotherms for both contaminants. Under the experimental conditions explored, the Langmuir maximum biosorption capacities reached 47 and 52 mg/g for OII and MB, respectively. The biosorption kinetics were well represented with the pseudo second-order equation. Surface area and point of zero charge (PZC), thermo-gravimetric analysis (TGA), scanning electron microscope (SEM), fourier transform infrared (FTIR) spectroscopy and X-ray photoelec- tron spectroscopy (XPS) analytical techniques were considered to characterise the surface chemistry of Y-Mate. The analysis indicated that the mechanisms of Y-Mate towards both anionic and cationic dyes are mainly through the co-action of π –π interaction and hydrogen bonding, while electrostatic attrac- tion had an additional effect on the biosorption. © 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. 1. Introduction Large amounts of water are being consumed yearly by the tex- tile industry. In turn, water generated from dye rinse processes and exhausted dye-baths contains unfixed dyes and are gener- ally extremely coloured. Dyes discharged from other sources such as; pulp industries, cosmetics and pharmaceuticals are considered as potent contaminants released into the natural water resources. When discharged, these coloured dye-contaminated effluents af- fect light penetration in the water and their degraded by-products are toxic to aquatic organisms and animals [1]. There is no single technique effective for satisfactory treatment of these effluents, but combinations of different biological and physical–chemical tech- niques can remove the majority of the organic content of the textile wastewaters. As a result, a final refining treatment is ad- ditionally essential to eliminate the remaining colour. This final step is crucial for potential water recycle [2]. Biosorption and ad- sorption provide successful and resourceful processes for the re- moval of dyes from wastewater, especially when readily available and inexpensive materials are used [3–6]. Adsorbents essentially add towards the ultimate performance throughout a biosorption/ ∗ Corresponding author. E-mail address: Ahmad.B.Albadarin@ul.ie (A.B. Albadarin). adsorption process, so in recent years, engineers and scientists have put considerable effort into the discovery and advancement of novel and highly effective adsorbents [7]. Table 1 provides a com- parison of the Biosorption/adsorption capacities of various materi- als for the removal of dyes from aqueous solutions [8–13]. Yerba Mate (Y-Mate) is one of the most common tea-like hot drinks in South America and areas of the Mediterranean. There is a huge amount of exhausted yerba mate; approx. 280,000 tons of Yerba Mate are produced yearly in Argentina alone. It is consid- ered a good source of natural polyphenols (an extracted adsorbent) [14] and has been used as a precursor to the manufacture of ac- tivated carbon [15] because it has abundant free amino, hydroxyl and carbonyl groups on its carbon structure. However, the capac- ity of Yerba Mate as a biomaterial for the elimination of pollutants from aqueous solutions has been underestimated. Methylene blue (MB), a heterocyclic basic dye, is frequently used in textile indus- tries for dyeing purposes and also has medical applications such as; staining tissues, an antidote for cyanide poisoning and for the treatment of methemoglobinemia at therapeutic dosages [16]. Even though MB is not extremely hazardous, its presence in water can cause some negative consequences on human health [17–21] and so, it is essential to remove MB from wastewater. Acid orange or Orange II (OII), like most other azo dyes, is discarded in industrial wastewater and presents serious health threats. It is a toxic dye https://doi.org/10.1016/j.jtice.2017.11.012 1876-1070/© 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Please cite this article as: A.B. Albadarin et al., Efficient removal of anionic and cationic dyes from aqueous systems using spent Yerba Mate “Ilex paraguariensis”, Journal of the Taiwan Institute of Chemical Engineers (2017), https://doi.org/10.1016/j.jtice.2017.11.012