A SIMPLIFIED SOLUTION TECHNIQUE FOR CARBON ADSORPTION MODEL

A new method of solving the homogeneous surface diffusion model for ac tivated carbon absorption makes use of Laplace transforms on the equat ions developed by applying orthogonal collocation. The simultaneous eq uations which are developed are non-linear so an iterative method is i ntroduced to make them solvable when one wishes to calculate the surfa ce diffusion coefficient, D(s), and the film transfer coefficient, K(f ), from batch adsorption data. The proposed model has the advantage of being continuous in time in contrast to earlier models which relied o n finite difference numerical methods to solve the system of equations comprising the homogeneous surface diffusion model. The model is appl ied to one data set from the literature. The proposed method gave valu es of K(f) and D(s) nearly identical to values found by other investig ators. The model was applied to three new data sets obtained in our la boratories: an agricultural waste, a dye waste and an aqueous waste st ream containing a herbicide. The industrial wastes were composed of a mixture of species, whereas the herbicide waste contained a single org anic compound. The model produced a good match between experiment and prediction for all waste streams. The final form of the equations is p resented in a form readily useable by the person interested in applica tions to carbon adsorption bed practice.