The adsorption of reactive blue 19 and reactive yellow 145 dyes by wheat bran

ABSTRACTMSc ThesisTHE ADSORPTION OF REACTIVE BLUE 19 AND REACTIVE YELLOW 145 DYESBY WHEAT BRANFatma ÇİÇEKFırat UniversityGraduate School of Natural and Applied SciencesDepartment of Chemical Engineering2007, Page: 70In this study, adsorption of Reactive Blue 19 (RB19) and Reactive Yellow 145 (RY145)dyes from aqueous solutions have been investigated by using wheat bran. The effects ofadsorption parameters such as pH and temperature of solutions, initial dye concentration,adsorbent dose and particle size on the adsorption yield of RB19 and RY145 dyes have beenstudied.The equilibrium time for the adsorption process of RB19 and RY145 dyes weredetermined as 1830 and 1710 min., respectively. Although the adsorption yields of RB19 andRY145 dyes are, to a large extent, dependent on pH of the solution, the maximumdecolourisation of both dyes were observed at acidic pHs and the optimum pH for theadsorption of both dyes onto the wheat bran were determined as 1.5. The removal percentage ofboth dyes were increased with decreasing initial dye concentration and adsorbent size, withincreasing adsorbent dose. When 500 ml RB19 solution of 100 mg/L was contacted with 0.5 gwheat bran at 20 oC, pH 1.5 and optimum contact time, 87.38 % of RB19 dye present in thesolution was removed. The adsorption yield of RY145 dye was 90.31 % at the same conditions.On the other hand, the results of the experiments carried out at various temperatures(20, 40 and 60 oC) were applied to the Langmuir and Freundlich isoterms equations. It wasfound that the experimental results fitted the Langmuir equation better than the Freundlichequation with a good correlation (R2≥0.99). The constants calculated from isotherm equationswere showed that the adsorption yield of RB19 and RY145 dyes increased with a rise in thetemperature of the solutions. The maximum adsorption capacities (qmax) of wheat bran at 20, 40and 60 oC for the RB19 dye adsorption were calculated from Langmuir equation as 97.09,104.17 and 117.65 mg/g, respectively. The values of maximum adsorption capacities for RY145PDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.comdye at temperatures mentioned above were 125, 147.06 and 196.08 mg/g, respectively. Enthalpychanges (∆Ho) for adsorption processes of RB19 and RY145 dyes were calculated as 17.98 and1.37 kJ/mol, respectively, at temperature range studied. That the enthalpy changes of process forboth dye are positive and the values of qmax increase with a rise in the temperature shows thatthe adsorption process of RB19 and RY145 dyes by wheat bran is endothermic.The free energy changes related to the RB19 and RY145 dyes adsorption by wheat branhave negative sign and the absolute values of them increased with increasing the temperature ofthe solutions. The results related to the adsorption process of RB19 and RY145 dyes by wheatbran were applied to the pseudo first and second order kinetic models to calculate adsorptionrate constants. It was observed that these results fitted the second order kinetic model better thanthe first order kinetic model with a good correlation (R2≥0.999).Keywords: Reactive Blue 19, Reactive Yellow 145, Dye, Adsorption, Wheat Bran.PDF Created with deskPDF PDF Writer - Trial :: http://www.docudesk.com