Characterization of Activated Carbon sample: Cu+2 Adsorption Isotherm A Major Qualifying Project Submitted to the faculty of the Chemical Engineering Department at Worcester Polytechnic Institute In partial fulfillment of the requirements for the Degree of Bachelor of Science Submitted by: _____________________ Shannon DaCosta 27th, 2017 Approved by: _________________
requiring constant equilibrium adsorption. In practice, keeping an adsorbent-adsorbate system at constant temperature is simplest and so the adsorption isotherm is the most widely used method to represent the equilibrium state of an adsorbent-adsorbate system. 5.1.2.1 Adsorption Isotherm The adsorption isotherm can be used to derive many different properties of the adsorbent and adsorbate such as the surface area, pore volume and size distribution, relative adsorbability and the enthalpy of adsorption. Many adsorption isotherm equations have been derived including the Langmuir, the Freundlich, the Brunauer-Emmett-Teller (BET) and the Dubinin equations. These are some of the most widely used isotherms but for the purposes of this project we will be using the Langmuir isotherm equations to represent the equilibrium state of our systems. According to Bansal and Goyal, there are three theoretical approaches for the derivation of an adsorption isotherm: The kinetic approach The statistical approach The thermodynamic approach Of these we will be using the kinetic approach to derive the Langmuir isotherm considering the kinetic approach uses the condition of equilibrium which states that the rate of adsorption must be equal to the rate of desorption. 5.1.2.2 Langmuir Isotherm Derivation If it is assumed that the number of filled at equilibrium is θ and the number of sites not filled is θo such that θ + θo = 1, then rate of adsorption, denoted as rabs can be written as, equ. 5.1 where a is the adsorption coefficient, the fraction of molecules adsorbed onto the surface of the
8. Conclusions and Recommendations In conclusion, the specific surface area, the maximum monolayer capacity, nm, and the Langmuir constant, b, were calculated for this particular activated carbon sample, 16hr glucose char. The specific surface area was calculated to be 8.737E15m2g-1. The maximum capacity was calculated to be, 2.455E-4mol/g. And the Langmuir constant, b, was calculated to be 40.34. For future teams it is suggested that they construct their own isotherm and merge it with these data to create a more accurate isotherm. It is also recommended that they calculate the adsorption coefficient of the char using data obtained from the isotherm. 9. References Yang, R. T. Adsorbents: fundamentals and applications. (Wiley, 2003). Henley, E.J., Seader, J.D. Separation Process Principles. (Wiley, 1998). Bhatt, A. S., Sakaria P. L., Vasudevan, M., Pawar, R. R., Sudheesh, N., Bajaj H. C., Mody, H. M. Adsorption of an anionic dye from aqueous medium by organoclays: equilibrium modeling, kinetic and thermodynamic exploration. (RSC Advances, 2012) Marsh, H., Rodriguez-Reinoso, F. Activated Carbon. (Elsevier Science and Technology books, 2006) Bansal, R. C., M. Activated Carbon Adsorption. (Taylor & Francis, 2005) Escapa, S. Copper Adsorption on Carbon Surfaces. (WPI, 2016) Seidel, A., Kroschwitz, J. I. Kirk-Othmer Encyclopedia of Chemical Technology. (Wiley, 2004-2007)