A Comparative Study of the Adsorption of Acid Brown 75 and Direct Yellow 162 onto Unmodified and Surfactant Modified Granule Developed from Coal Fly Ash Chayada Pansuk The Joint Graduate School of Energy and Environment King Mongkut’s University of Technology Thonburi Bangkok, Thailand e-mail: chayada_ps@hotmail.com Soydoa Vinitnantharat School of Energy, Environment and Materials King Mongkut’s University of Technology Thonburi Bangkok, Thailand e-mail: soydoa.vin@kmutt.ac.th Abstract—This study aims to use unmodified fly ash (Un-G) and surfactant modified granule (Mo-G) for adsorption of two anionic dyes; acid brown 75 (AB 75) and direct yellow 162 (DY 162) from aqueous solution. The granule was prepared by wet granulation of fly ash powder. The formation of fly ash pellet occurred between 18-20 % water content and heat more than 800 °C. Coal fly ash in powder form was agglomerated into porous granule and modified with Hexadecyltrimetylammonium Bromide (HDTMA-Br), which optimal condition was 3.6 mmolL -1 . The adsorption capacities and the effect of temperature for anionic dyes adsorption at various contact times and adsorbate concentration were investigated. The equilibrium data were found to be well represented by the Langmuir isotherm equation. The sorptions of the aqueous anionic dyes onto the unmodified granule (Un-G) were small while the Mo-G’s sorption was significantly increased. The adsorption process of AB 75 and DY 162 were endothermic. Keywords-component; Adsorption; Anionic dye; Granulation; Fly ash I. INTRODUCTION Fly ash is a predominantly inorganic residue obtained from the flue gases of furnace at pulverized coal power plants. Fly ash contains trace concentrations of many heavy metals that are known to be detrimental to health in sufficient quantities [1]. Thus, storage and disposal of coal fly ash can resulted in releases of leached metals into soils, surface and ground water. Throughout the world, much research is being conducted on the use of waste materials in order to either avert an increasing toxic threat to the environment or to streamline present waste disposal techniques by making them more affordable. Therefore, follows logically that an economically viable solution to this problem should include utilization of fly ash rather than disposal in a landfill. Coal fly ash has been used as an efficient adsorbent to replace activated carbon for adsorption of pollutants in wastewater [2-5]. However, the adsorption efficiency of fly ash for anion species is low because fly ash surface has anionic charge. Silicon oxide, lime, and metal oxide, the component of fly ash, could react with water (H 2 O) give fly ash a pH somewhere between 10 and 12. Because of this, its surface is negatively charged that can be balanced by exchangeable cations. It has been demonstrated that the cationic surfactants have a great affinity to the negative charge. This property could be applied to modify the external surface of the fly ash for improvement anion exchange capacity. The surfactant that is commonly employed to be attached on the adsorbent surface is the quaternary ammonium cations such as hexadecyltrimetylammoniumdodecyltrimetylammonium; benzyltrimetylammonium, cetylpyridinium chloride [6-8]. One major drawback in the use of fly ash is that it results in a fine particle size which makes difficulty during filtration or settling. Recently, Vinitnantharat et al. (2010) proposed the use of a pellet of adsorbent made from water treatment sludge for removal of fluoride [9]. However, less studies on a development of adsorbent granule form fly ash for adsorption of anionic and cationic surfactant. The objective of this study is to investigate the adsorption potential of surfactant modified granule made from coal fly ash for removal of anionic dyes and from single solute system. The capacity of the modified fly ash granule for adsorbing anionic dyes was compared with that of an unmodified fly ash granule. Moreover, the adsorption thermodynamics and removal mechanisms of modified fly ash were investigated. II. MATERIAL AND METHODS A. Preparation of surfactant modified granule and adsorbates Fly ash from Mae Moe power plant, Thailand was used as the adsorbent in this study. The chemical compositions of fly ash are: SiO 2 (52.5%), Al 2 O 3 (27.9), CaO (6.27%), MgO (1.6%), Fe 2 O 3 (6.3%), SO 3 (0.79%), and LOI (‘‘loss on ignition”– the unburned carbon portion in the sample; 5.01%); according to ASTM C618, this material can be classified as class F because it contained less than 10% CaO, 5% SO 3 , and 12% LOI and greater than 70% of the three main components (SiO 2 , Al 2 O 3 , and Fe 2 O 3 ) combined. Fly ash powder was mixed with distilled water to yield the moisture content of 18 ± 2%. The moisten fly ash was then pressed through an extruder which has a barrel into which the fly ash is forced by a screw. In the next step, It was heated in the oven at 800 ± 10 ºC for 90 mins. After be heated, the granules were left at room temperature (30 ± 2 °C) to let them cool. The tabular granules were cut to a uniform size of 2.0 - 2.5 mm and then stored in the desiccators until use. The modified granules were prepared by exchanging the V1-49 2011 2nd International Conference on Environmental Science and Technology IPCBEE vol.6 (2011) © (2011) IACSIT Press, Singapore