278 ISSN 1229-9197 (print version) ISSN 1875-0052 (electronic version) Fibers and Polymers 2017, Vol.18, No.2, 278-284 Exploration of Biosorption Potential of Forest Industry By-product for Removal of Reactive Dye from Aqueous Solution Fatih Deniz* and Remziye Aysun Kepekci 1 Department of Environmental Engineering, Faculty of Engineering and Architecture, Sinop University, Sinop 57000, Turkey 1 Department of Food Processing, Vocational High School of Technical Sciences, Gaziantep University, Gaziantep 27310, Turkey (Received May 20, 2016; Revised October 4, 2016; Accepted December 19, 2016) Abstract: Natural sawdust of Calabrian pine was explored as low-cost industrial by-product for a hetero-bireactive dye removal from aqueous solution in this study. Batch experiments were carried out to investigate the effects of contact time and dye concentration on biosorption efficiency. Maximum biosorption amounts were achieved almost in the 20-30 min of contact for the studied dye range (50-200 mg l ). An increase in the dye concentration resulted in decrease in the percent dye removal and increase in the biosorption capacity of biosorbent. Different kinetic and isotherm models were used to examine the biosorption experimental data for elucidating the dye removal mechanism. The equilibrium data were best represented by Freundlich isotherm model confirming multilayer coverage. The kinetics of dye biosorption best obeyed the pseudo-second- order equation. The negative value of standard Gibbs free energy change (-3.61 kJ mol ) indicated that physical forces were involved in the spontaneous dye biosorption. Thus, the sawdust as a possible non-conventional biosorbent presented an interesting option for bioremediation of contaminated environments by such unsafe dyes. Keywords: Calabrian pine, Sawdust, Hetero-bireactive dye, Biosorption Introduction With the rapid development of modern industry, discharges of dye wastewaters from several industrial processes such as textile, leather, paper and cosmetic have become a major environmental concern due to their adverse effects on biota and environment [1]. Color is one of the most easily detected properties of an effluent and the most obvious indicator of water pollution [2]. Since the great majority of dyes are of synthetic origin, they mainly contain aromatic rings and azo groups. Such molecules having non-biodegradable nature are not effectively purified by the conventional treatment processes. Thus, a powerful method for the removal of these components of industrial effluents is required. From a practical standpoint, biosorption is one of the most promising techniques for dye removal from the effluents since this biotechnological process has significant advantages, especially from economic and environmental viewpoints [3]. The most widely used biosorbent for pollutants removal is the activated carbon. However, its operation and maintenance cost is relatively high [1,4]. The prominent and emerging trend of subjecting biosorbents in the biosorption technology is mainly because of their natural existence, abundance, renewable, biodegradable and economic properties [5]. The usage of lignocellulosic waste materials as alternative effective biosorbent to the activated carbon has therefore received considerable attention [4,6]. Pines are coniferous trees in the Pinaceae family. The pine tree exists in large amounts and in various species across the world [7]. Calabrian pine is a characteristic species of the eastern Mediterranean. It is widely extended in Turkey and far Eastern Greece, secondarily in the Crimea, Caucasus coast, Azerbaijan, Iraq, Syria, Lebanon, Crete and Cyprus [8]. Its forests represent about 27 % of Turkey’s forest area, which totals at 5,854,673 ha in 2012 [9]. It is an economically important forest tree providing both timber resources and amenity. Also, this pine is used widely in afforestation and reforestation programs [10]. On the other hand, the wood processing industries of Calabrian pine often generate a massive amount of sawdust. The waste sawdust produced is generally used as a solid fuel. Any possible alternative usage of this forest by-product will yield economic and environmental dividends. Other main advantages of this residue are its low-cost and minimal processing demand. However, no known effort has been made to utilize the sawdust of Calabrian pine as potential biosorbent for the biosorption of any dye so far. As the brightest class of soluble dyes, the reactive dyes pose serious health and environmental risks [11]. The removal of such dyes is a very important aspect of water treatment before discharge. Thus, C.I. Reactive Red 238 was selected as a model hetero- bireactive dye in this research. It is a water soluble reactive dye used extensively in the textile industry as a staining agent. Any study dealing with the removal of this dye by biosorption using biological by-product is not available in the literature. Thus, the main aim of this study was to investigate the potentiality of Calabrian pine sawdust as an effective biosorbent for the biosorption of C.I. Reactive Red 238. The effects of dye concentration and contact time on the dye removal were studied. The biosorption isotherms and kinetics parameters were computed and discussed. The studies of SEM and FTIR were also performed to elucidate the dye biosorption mechanism. *Corresponding author: f_deniz@outlook.com DOI 10.1007/s12221-017-6550-z