Adsorption Kinetics of Matter Contained in a Leachate Using Eggshell and Activated Carbon

Abstract

The generation of highly polluting leachate from Sanitary Landfills has prompted the development of technologies applicable to treatment of these liquids. The aim of this study was to determine the kinetics of adsorption of organic and inorganic matter contained in pre-treated leachate (by advanced oxidation by the Fenton reaction); after two adsorbents were used, first eggshell and then activated carbon. To determine the content of organic and inorganic matter COD was measured; this was the parameter for monitoring the kinetics. The leachate was subjected to advanced oxidation treatment by the Fenton reaction, then the adsorption process was conducted by batch, in two consecutive steps, the first step was the use of eggshell and the second step activated carbon. Due to the oxidation treatment the pH value decreased to 2, after the adsorption eggshell the pH increased to 6.9 and this was maintained in the treatment with activated carbon. The kinetics of adsorption of organic and inorganic matter on eggshell was evaluated by models pseudo-first-order and pseudo-second-order, the better fitting was the latter. The adsorption process was adjusted to the model of Langmuir. The negative value of ΔHads indicated that the adsorption process was exothermic, spontaneous and favorable. The separation factor RL of Langmuir Isotherm values indicated that the adsorption of the matter on the eggshell was favorable at different temperatures. Finally, the activated carbon adsorption of liquid obtained from treatment with eggshell was favored with the kinetic model of pseudo second order. With the oxidation process, eggshell adsorption and activated carbon adsorption, the removal COD was 98.6%. The final COD value was fulfilled with the Mexican standard NOM-001-SEMARNAT-1996.