Adsorption Properties of Dextrin onto Modified Coal Surface

Abstract

In this adsorption studies, adsorption properties of dextrin on modified coal surfaces were investigated. Measured quantities such as: pH, initial concentration and temperature were investigated. There was a rapid increase in adsorption of dextrin from a low pH of 2 to a pH of 4. A plateau region was observed from pH 4 to pH 6 for dextrin and the maximum adsorption capacities occurred at pH 6. Adsorption capacity of 61.25 mg/g and 55.00 mg/g was achieved at initial concentration of 200 mg/L for Aluminium coated bituminous coal (ACB) and Aluminium coated lignite coal (ACL) respectively. The equilibrium data have been modelled using Langmuir, Freundlich and Temkin isotherms. The result indicated that the Freundlich isotherm provides the best correlation of the equilibrium data and its equation is found to best represent the equilibrium separation data in the temperature range of 303 -343 K. The maximum adsorption capacity of dextrin onto coal surface was obtained to be 6.71 and 4.42 mg/g for both ACB and ACL respectively. Dextrin from cassava appeared to be more stable adsorbate in solution when the coal surface is modified with Al3+ from AI2(SO4)3.