KAOLIN BASED ADSORBENT FOR ENVIRONMENTAL APPLICATIONS

Abstract

Kaolin is an abundant clay material that can be used for the adsorption of methylene blue dye, the water pollutant generated by the textile industry. Current research in this area is performed by studying different kaolin materials in a powder form, while the shaped adsorbents are not widely considered. The deficiency in the studies about the shaped adsorbents could be the convenience of utilizing the powder materials for experiments and the absence of a detailed recipe for the preparation of shaped adsorbents and catalysts. In this work, the preparation of the shaped kaolin adsorbent by extrusion is explored, and its adsorption ability of methylene blue is studied. The parent kaolin powder was exposed to thermal, acid, and base treatment. The adsorption capacity of the kaolin powder increased from 9.25 mg/g to 26.47 mg/g after the treatment. The first part of the thesis was dedicated to finding the best combination of the treatment parameters and pellet preparation parameters, and the second part was dedicated to adsorption studies. The pellets prepared from the activated kaolin and extrusion with 1.5% PVA solution binder demonstrated the best mechanical and adsorption properties among all tested alternatives. The kaolin was characterized after each treatment and pellet formation by SEM, XRD, FTIR, TGA, and BET analyses. The composition of the parent kaolin was identified by the XRF method. The adsorption experiments performed by activated kaolin pellets lasted for 2 days, and the maximum adsorption capacity was equal to 20.09 mg/g. The experimental data were fit to Langmuir equilibrium isotherm, with an R2 value of 0.9991 and a predicted maximum adsorption capacity of 21.58 mg/g. The kinetic experiments were done for 10 hours and samples were taken each 30 minutes. Obtained experimental results demonstrated pseudo-first-order kinetic behavior, with the R2 equal to 0.9722.