Removal of doxycycline hyclate by adsorption onto cobalt oxide at three different temperatures: isotherm, thermodynamic and error analysis

Abstract

The adsorption of doxycycline hyclate on the low-cost adsorbent cobalt oxide was carried out, in a thermostated shaker at three different temperatures (40 °C, 50 °C and 60 °C), and studied other parameters were effected on the adsorption process including initial concentration, a weight of cobalt oxide and effect of pH. The high value of coefficient of determination of 0.985 and low value for Chi-square test of 0.346 for Langmuir linear equation at the temperature of 40 °C are referred to a good accuracy and agreement for the method. Also it was observed that the Freundlich linear equation showed the high value of coefficient of determination of 0.914 and low value of Chi-square test of 0.679 at the same temperature, and it can be realized that the Freundlich linear isotherm provided better agreement with the Langmuir linear isotherm at the temperature of 40 °C. Moreover, the negative values of the Gibbs free energy and the positive value of the enthalpy indicated spontaneity and exothermic nature of the adsorption process.