Kinetics Adsorption of Strontium(II) by Silica Xerogel from Fly Ash

Abstract

A study of liquid waste adsorption containing strontium was carried out using the adsorption method using silica xerogel adsorbent. Silica xerogel synthesized from coal fly ash using the sol-gel method, produces a specific surface area of 84.8884 m2/g. This study was intended to determine the appropriate kinetics law. Data were obtained by following changes in Sr concentration to the time of adsorption at temperature of 25 °C and 35 °C. The data obtained was matched with 5 kinetic models, namely zeroth order kinetics, first order, second order, pseudo first order, and pseudo second order. Based on data analysis by means of linear regression and the number of minimum sum squared of errors, the adsorption kinetics model that is suitable for the adsorption of strontium by silica xerogel is a pseudo second order. The reaction rate constant at 298 K and 308 K were 0.1023 g/mg/min and 0.0716 g/mg/min respectively. The value of the activation energy is negative so the higher the temperature, the lower the adsorption rate. It is indicate that the adsorption is reversible.