The production of nano-porous activated carbon from some vegatable pulps and investigation of availability in some adsorption practices

In order to contribute to the studies related to the preparation of activated carbon that never losts its importance due to its high surface area and porosity, the preparation of new kinds of low cost activated carbons constitutes the basis of this doctoral study. The production of activated carbons from abundant and easily available wastes that release to the environment as a result of industrial activities is located in the centre of the works performed in this area in recent years. For this, the preparation of new kinds of nano-porous activated carbons under optimum preparation conditions from the highly abundant, easily available and economic vegetable pulp and characterization of these activated carbons by some physical and chemical methods have been aimed. For this purpose, in the production of the activated carbons, the wastes that produce in large amounts after the processing stage in the food industry such as grape, tomato and carob pulps were selected as precursor. In order to test the suitability of the selected pulps to the preparation the activated carbons, the component, proximate, ultimate and thermogravitmetric analyses of the pulps were carried out. ZnCl2 was used as chemical activator in the preparation of the activated carbons from the suitable pulps. In order to optimize the preparation conditions of the activated carbons, in the nitrogen gas atmosphere the effects of the activator impregnation ratio, carbonization/activation temperature and carbonization/activation time were examined, respectively. The optimum preparation conditions were determined as 6:1 gZnCl2/gpulp, 600oC and 1 hour impregnation ratio, carbonization/activation temperature and time, respectively. The physicochemical properties of the optimal activated carbons were characterized with surface area and pore size distributions, FT-IR, XRD, SEM, proximate, ultimate analyses and Boehm titration and point of zero charge measurements. Besides, in order to examine the effect of the chemical activator, biocarbons were obtained at predetermined optimum conditions (600 oC and 1 hour) without using ZnCl2.under the nitrogen atmosphere and again at predetermined optimum conditions (600 oC and 1 hour), these biocarbons were activated with CO2 physical activation at 800 oC without using ZnCl2, thus physical activated carbons were prepared. The surface area and pore size distributions of the prepared biocarbons and physical activated carbons were analyzed. In order to test the adsorption capabilities of the prepared optimal activated carbons, two very common dyestuffs with different ionic character used in textile industry, Malachite green and Congo red, and a very common antibiotic used in the pharmaceutical industry, tetracycline were used as adsorbate. In order to optimize the removal of efficiency, the effects of various parameters such as solution pH, adsorbent dosage, initial adsorbate concentration and contact time, ionic strength (salt effect) and temperature were examined. Kinetics and isotherm studies were carried out at the determined optimum adsorption conditions. After the kinetics and isotherm studies it was observed that, the adsorptions occurred in a short time, at higher concentrations and temperatures. Hence, in order to compare the performance of the optimal activated carbons with the prepared biocarbons and physical activated carbons, adsorption studies were carried out at the maximum studied temperature of the optimal activated carbons. Furthermore, in order to test the reusability of the prepared optimal activated carbons, adsorption-desorption cycle studies were carried out with various eluents. The results obtained in this study indicated that these abundantly available wastes selected in the scope of this thesis for the first time by us such as grape, tomato and carob wastes could be used as raw material in the production of activated carbon and the produced optimal activated carbons' pore characteristics indicated the feasibility of usage of them as adsorbent in the removal of different types of contaminants from aqueous solutions. Also, the production cost analyses showed that these raw materials could be used in the production of low cost and high capacity commercial activated carbons. Note: The part of characterization related to the grape pulp and it's optimal activated carbon was accepted as titled "Conversion of grape industrial processing waste to activated carbon sorbent and its performance in cationic and anionic dyes adsorption" for publication in "Journal of Cleaner Production". Keywords: Industrial agricultural wastes, activated carbon, Malachite green, Congo red, Tetracycline, kinetics, isotherm, thermodynamics, desorption.