Metal alkoxide based composite materials synthesis and use in dye adsorption

In this thesis, composite adsorbent materials and an activated carbon have been prepared to be used in removal of Methylene Blue, Orange II and Reactive Remazol Brillant Blue dyes, which are important industrial pollutants, from waste water. Composite adsorbents have been prepared by combining raw pine sawdust, an agricultural waste, with hydrolysis products of Ti(OPrn )4, Ti(OBun )4 ve Al(OBus )3 prepared by sol-gel method. Activated carbon samples have been prepared from the same pine sawdust, using a chemical activation method. The structural and surface properties of prepared adsorbents have been investigated by FTIR, XRD, BET, TGA/DTA, SEM, Boehm techniques and Zeta potential measurements. In this study, adsorption properties of the prepared composite materials and activated carbon samples have been studied for three dyes. Effects of adsorbent amount, adsorbate concentration, pH, temperature, mixing time and speed have been investigated and optimum levels for the adsorption parameters have been determined. Equilibrium investigation of adsorption systems has been carried out for varying concentration of dyes and temperature. Agreement of adsorption equilibrium data with Langmuir, Freundlich, Dubinin-Raduskevich, Redlich-Peterson and Temkin isotherm equations has been investigated. The adsorption equilibrium constant, mono layer 7 capacity, adsorption energy, adsorption heat, adsorption power and binding energy values and their temperature dependence have been investigated. It was found that dye adsorption on composite adsorbents and activated carbon takes place on a mono layer and Langmuir isotherm can be applied for any temperature and concentration. Adsorption kinetics has also been investigated at several temperatures for adsorption systems. Parameters such as adsorption rate constant, surface coverage fraction and theoretical adsorption capacity and their temperature dependance have been determined by employing Pseudo first and second order, Elovich and Bangham's, Intraparticle Diffusion and Modified Freundlich kinetic models. It was determined that all adsorbent/adsorbate systems obey the Pseudo second order kinetic model. Overall and activation thermodynamics of the adsorption systems have been investigated as a function of temperature and thermal nature of adsorption process has been studied. Zeta potential changes of adsorbent materials used in this thesis have been examined before and after adsorption as a function of pH.