IOSR Journal of Applied Chemistry (IOSR-JAC) e-ISSN: 2278-5736.Volume 9, Issue 9 Ver. I (Sep. 2016), PP 55-62 www.iosrjournals.org DOI: 10.9790/5736-0909015562 www.iosrjournals.org 55 |Page Effect of Time on the Adsorption of Methylene Blue, Methyl Orange and Indigo Carmine onto Activated Carbon Ocholi O.J 1 *, Gimba C.E 1 ., Ndukwe G.I 1 ., Turoti M 2 ., Abechi S.E 1 and Edogbanya P.R.O 3 1 Department of Chemistry, Ahmadu Bello University, Zaria- Nigeria. 2 Department of Chemistry, Obafemi Awolowo University, Ile Ife- Nigeria. 3 Department of Biological Sciences, Ahmadu Bello University, Zaria- Nigeria. Abstract: The effect of time on the adsorption of methylene blue (MB), methyl orange (MO) and indigo carmine(IG) from aqueous media onto activated carbon (AC) was monitored using two(2)similar experimental procedures. In the first procedure, 20mg of AC was interacted separately with 10cm 3 of 20ppm of each dye at residence time of 5, 10, 15, 20, 30, 45 and 60 minutes, while in the second procedure, 10mg of AC was interacted separately with 10cm 3 of 10ppm at residence time of 15, 30, 45 and 60 minutes respectively. From the results, MO was adsorbed more than the others while MB was the most time dependent of the three dyes. Results also showed that chemisorption was the predominant adsorption type, while the adsorption process was particle-diffusion controlled. Keywords: Adsorption, Methylene blue, Methyl orange, Indigocarmine. I. Introduction Time is crucial to the success of most chemical processes. For Adsorption processes, the rates of adsorption or the time taken to reach equilibrium is usually monitored; where fast rates are usually desired. Fast adsorption rates are related to high degree of affinity between the adsorbate and adsorbent via chemisorption. (Hameed et al. in Kathiresan et al., 2010.) The rate or kinetics of adsorption processes can give valuable information regarding the “order” of the process. It can help to predict if the process is Physisorption or Chemisorption, and it can also give insight to the sorption process( i.e whether film diffusion or particle diffusion is occuring)(Horsfall Jnr and Spiff, 2005). For this work, The effect of time on the adsorption of individual dyes(MB, MO and IG) was monitored as part of a preliminary work which was to study the adsorption of multi-component adsorbate systems onto activated carbon surfaces. II. Materials And Methods Activated Carbon Sample The activated carbon sample used for the work was extra pure food grade granular activated carbon from Merck Darmstadt Germany. Below is the summary of its factory specifications. The sample was pulverized and sieved. Particle size of between 425 μm - 850μm was used for the work. Table 1: Factory Specifications of AC sample Identity Conforms Particle Size 1.5mm Substances soluble in Nitric acid ≤ 5% Chlorides ≤500ppm Cyano compounds Passes test Arsenic ≤ 5ppm Iron ≤ 500ppm Lead ≤ 20 ppm Zinc ≤ 100ppm n-hexane adsorption ≥ 30% Residue on ignition ≤ 6% Loss on drying ≤ 10% Preparation of methylene blue, methyl orange and indigocarmine stock solutions 1000ppm solutions of each dye was prepared by separately weighing 0.5g of MO and MB dye and were partially dissolved in a beaker using distilled water . It was then transferred into a 500cm 3 volumetric flask and was made up to the mark using distilled water. They were then stored in amber coloured bottles and kept in a locker. For IG, smaller volumes of stock solution were prepared (i.e. 100cm 3 capacity) when needed. This was