ASIAN JOURNAL OF CHEMISTRY ASIAN JOURNAL OF CHEMISTRY https://doi.org/10.14233/ajchem.2017.20616 INTRODUCTION Ever since the beginning of mankind, they have been trying to add colours to the world around them in various ways such as in textile, paper, leather tanning, plastics and food. During these processes the dye effluents are being dumped directly into the environment which constitutes a serious concern to the eco-system [1]. Hence it is important to remove the dyes from the effluents. The techniques generally employed for the removal of pollutants include adsorption, filtration, membrane separation [2-4], electrochemical destruction [5], ion-exchange and advanced oxidation technology [6]. Among these methods adsorption process is a highly efficient and low cost method with a simple operation process for waste water treatment [7-12]. Methylene blue (MB) is a cationic basic dye which is used in textile industries is hazardous and toxic on exposure to humans. The symptoms on exposure are increasing heart rate, vomiting, shock, Heinz body formation, cyanosis, jaundice, quadriplegia and tissue necrosis [13]. Further in aqueous solutions it is stable towards heat, oxidizing agents and non- degradable [14]. Due to these reasons methylene blue was chosen as a model compound for the adsorption studies. Recently, numerous metal oxide nanoparticles have been used as adsorbents to remove methylene blue [15-22], but their Mesoporous COK-12 Supported Co 3 O 4 Composites for Adsorption of Methylene Blue from Aqueous Solution YADAGIRI JYOTHI 1,2 , RESHMA 1 , KONDEBOINA MURALI 2 , B. SHANKAR 1 , KAMARAJU SEETHA RAM RAO 2 , BURRI DAVID RAJU 2 and PUPPALA VEERA SOMAIAH 1,* 1 Department of Chemistry, University College of Science, Osmania University, Hyderabad-500 007, India 2 Catalysis Laboratory, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500 007, India *Corresponding author: Tel: +91 40 27682337; E-mail: vs_puppala@rediffmail.com; profvspuppala@gmail.com Received: 1 March 2017; Accepted: 24 April 2017; Published online: 13 May 2017; AJC-18404 A simple batch adsorption experiment has been accomplished for the removal of methylene blue using Co3O4/COK-12 catalysts prepared by impregnation method with varying Co loadings (5-20 wt %). The as prepared catalysts were characterized by X-ray diffraction analysis, Fourier transform-infrared spectroscopy and nitrogen adsorption-desorption techniques to examine the morphology and the meso structure of the obtained composites. The effects of various experimental parameters, such as contact time, adsorbate dose, metal loading were investigated. Among the series 10 wt % Co3O4/COK-12 exhibited maximum adsorption capacity of about 27 mg/g. It was observed that the methylene blue adsorption represents pseudo-second order kinetics model as an appropriate model to represent the present data. Keywords: Methylene blue, Co3O4/COK-12, Mesoporous structure, Amount adsorbed, Adsorption. Asian Journal of Chemistry; Vol. 29, No. 7 (2017), 1612-1616 main disadvantage is that they mainly exist in the colloidal form and very difficult to obtain spherical beads of the desired size for practical applications. Moreover, it is also very difficult to recover or separate MO x nanoparticles from the solution after adsorption [23,24]. Suitable ways to circumvent this problem is to disperse the metal oxide particles onto supports with high surface area and loading MO x nanoparticles in a polymer or resin [25,26]. The nanoparticles thus enhance the surface to volume ratio of the polymers and increase the avail- able adsorption sites. These methods enhance the mechanical and chemical stability of the catalysts, which increase the prac- tical utility and thermal reusability of the adsorbent. Mesoporous material is one of the materials which offers possibility of preparing adsorbents that are applicable in many industrial processes by possessing high surface area, large adsorption capacity and porous structure making mesoporous materials as very promising candidates in oil refining, petro chemistry, organic synthesis and waste treatment [27-30]. Suraja et al. [31] reported the influence of SBA-15 support on Co 3 O 4 catalyst for the adsorption of methylene blue. Hany et al. [32] reported the adsorption of methylene blue over Co 3 O 4 /SiO 2 catalysts. Warang et al. [33] reported for the photo degradation of methylene blue over Co 3 O 4 catalysts synthe- sized by different techniques. Their disadvantage is that either the synthesis method or amount adsorbed is less. Recently,