Activated carbon production from apricot stone and almond shell mixture and removal of dyes from aqueous solutions

In this thesis study, the adsorption of single and binary combinations of Basic Yellow 51 (BY51) and Basic Blue 3 (BB3) cationic dyes onto activated carbon, which chemically activated with K2CO3, prepared from a mixture of apricot stone and almond shells was investigated in a batch system. The BET surface area of the prepared activated carbon was found to be 1329.31 m2/g. The effects of solution pH, temperature and initial dye concentration on the adsorption yield of BY51 and BB3 dyes were investigated in experimental studies in a batch system. The equilibrium time for the adsorption onto activated carbon of BY51 and BB3 dyes were determined as 780 and 840 min., respectively. The optimum pH value was determined as 9.0. It has been determined that the adsorbed dyes percentage decreased and the adsorption capacity increased with increasing initial Basic Yellow 51 and Basic Blue 3 dyes concentrations. Removal yield of 98.57 % and 98.15 % for BY51 and BB3 dyes in the initial dye concentration of 25 ppm were obtained, respectively. Maximum adsorption capacity was obtained at 45oC. The results of the experiments carried out at 25, 35 and 45C for each dye were applied to Langmuir, Freundlich and Dubinin-Radushkevich isotherms. The Langmuir model for both dyes has been observed to better define adsorption equilibrium data. The maximum adsorption capacities (qmax) of activated carbon at 25, 35 and 45C for the BY51 dye adsorption were calculated from Langmuir equation as 657.89, 666.67 ve 704.23 mg/g, respectively. The values of maximum adsorption capacities for BB3 dye at same temperatures were found as 588.24, 625.00 ve 666.67 mg/g, respectively. The values of ΔH0 for both dyes are positive and the increase the values of qmax with increasing temperature indicates that the adsorption process is endothermic. Also, the values of ΔG0 are negative and shows that the adsorption process is occur spontaneously at temperature range studied. The results related to the adsorption process of BY51 and BB3 dyes by activated carbon were applied to the pseudo first and second order kinetics and intraparticle diffusion kinetic models to calculate the kinetic constants. It was observed that the results obtained fitted the second order kinetic model. The adsorption of binary mixtures of Basic Yellow 51- Basic Blue 3 dyes onto activated carbon was studied at 25oC, how the first component affected the adsorption rate and the amount adsorbed at equilibrium per unit weight of the adsorbent of second component was investigated by changing the concentration of the first dye while the concentration of the second dye was kept constant. It was observed that the presence of Basic Yellow 51 in the medium decreased the adsorption of Basic Blue 3, and also the presence of Basic Blue 3 decreased the adsorption of Basic Yellow 51 (antagonistic effect). An extended Langmuir model and Jain and Snoeyink Model have been used to predict the isotherm data for the binary systems using the single component data. It was concluded that in spite of the Extended Langmuir model fails to identify the data in the binary mixture, it is better than the Jain and Snoeyink model in describing the adsorption behavior of dyes in binary mixtures onto activated carbon.