Effect of Temperature for the Adsorption of Methylene Blue onto Activated Carbon Produced from Waste Dogrose Seeds Ahmet Gürses 1 , Çetin Doğar 2 , Metin Açıkyıldız 1 , Esra Özkan 3 and Ramis Bayrak 1 1 Department of Chemistry, Kazim Karabekir Faculty of Education, Atatürk University, 25240 Erzurum, Turkey 2 Department of Primary Education, Erzincan Faculty of Education, Atatürk University, 24100 Erzincan, Turkey 3 Department of Primary Education, Bayburt Faculty of Education, Atatürk University, 69100 Bayburt, Turkey Keywords: adsorption isotherm, BET isotherm, Rosa sect. Caninae, rose-hip Abstract Activated carbon, produced from dogrose (Rosa section Caninae) seeds, was used for the removal of methylene blue (basic dye). Adsorption studies were carried out at 20°C and 40°C at various initial dye concentrations (20, 40, 60, 80, and 100 mg/L) and at different lengths of time (15, 30, 60, and 120 min). Adsorption isotherms of the basic dye on the prepared adsorbent were determined and correlated with common isotherm equations. Fitting of the isotherm data to the BET adsorption isotherm model was better in high concentration ranges than in the other models. Thermodynamic parameters such as change in isosteric adsorption enthalpy (∆H) y and isosteric adsorption entropy (∆S) y were also determined to 40.8 kJ and 0.141 kJ, respectively. It was concluded that the adsorption of methylene blue increases with increasing temperature. BET model fitting indicates that the hydrophobic interactions between the dye and the produced active carbon at the first layer and the dipole-dipole interactions between methylene blue molecules and the adsorbed molecules at the secondary layer predominate. To investigate the adsorptive characteristics of the produced active carbon, porosity and BET surface area measurements were made. INTRODUCTION Industrial effluents are one of the major causes of environmental pollution. Effluents discharged from dyeing industries are highly colored and have low BOD (biochemical oxygen demand) and high COD (chemical oxygen demand). Disposal of this colored water into receiving waters can be toxic to aquatic life. The dye itself can upset the biological activity in water bodies, and cause problem due to mutagenic and carcinogenic activity with potential damages to human beings, such as dysfunction of kidneys, reproductive system, liver, brain and the central nervous system (Gürses et al., 2003; Kadirvelu et al., 2003). The traditional approach for dealing with waste water consists of biological, physical and chemical methods as well as various combinations of these methods (Bayramoğlu et al., 2004; Gürses et al., 2002). Adsorption is now widely accepted as an effective purification method for the treatment of waste water. The removal of color by various adsorbents has been the subject of several recent research papers. Activated carbon is an adsorbent that is widely used in adsorption processes because of its extended surface area, microporous structure, high adsorption capacity and high degree of surface reactivity. Variation in pore structure and size distribution results in different adsorption properties (Gürses et al., 2003). However, commercially available activated carbons are expensive. They are usually manufactured from substrates ranging from industrial waste to agricultural products (Kadirvelu et al., 2003). A wide variety of carbons have been prepared from agricultural wastes such as peanut hull (Periasamy and Namasivayam, 1996), baggage pith (McKay et al., 1987), paddy straw (Namila and Mungoor, 1993), wood products (Fung and Miller, 1993), and coir pith (Kadirvelu et al., 2001). Each has its drawbacks and advantages. Among many new technologies, the utilization of plant residues as adsorbents for the removal of dyes 277 Proc. 1 st Intl. Rose Hip Conf. Eds. H. Nybom and K. Rumpunen Acta Hort. 690, ISHS 2005