دراسة امتزاز وامتصاص بعض الملوثات العضوية على ثنائي اوكسيد التتانيوم == Sorption study of Some Organic Pollutants on Titanium Dioxide
Author name:
قيس محمد عبد الحسين
Supervisor name:
خلود عبد صالح السعدي
General topic:
Chemistry
Specific topic:
Physical Chemistry
Degree:
Master
University:
Al-Nahrain University - College Of Science - Chemistry Department
Language:
English
University location:
Baghdad
First pages:
25T1654 - p.pdf
Abstract:
The subject of this thesis involves studying the possibility removed of four organic compound by TiO2. These organic compounds (considered as pollutants) which are; Birlliant blue (dye), polyvinyl alcohol (PVA), Linear alkyl benzene sulfonate (LAS) and Lambdacyholothrin as (pesticides). The thermal and photo - stability were studied and the results showed that all pollutants are stable in temperature range about (288 - 318) K, and stable against UV - linght in the wave length range (290 - 320) nm.Titanium dioxide successed in removing; 95 - 54% of dye, 6.2% of PVA, 13.19% of LAS and failed in removeing pesticides.UV - Vis absorption spectrophotometric technique was used to follow the pollutants concentration before and after adsorption process and after different periods of time, since the sorption isotherms were obtained by obeying Langmiur and Freundlich adsorption isotherms, with R2 (1 - 0.9993) for dye, R2 (0.9992 - 0.9574) for PVA, R2 (0.9503 - 0.9813) for LAS.The dye adsorption isotherms take S - shapes which related to a strong interaction between dye and TiO2 with thermodynamic values DH = +(5.962 - 26.57)J, DG = - (966 - 999)J, DS = +(3.45 - 9.1906)J.The thermodynamic parameters were studied by using the sorption process of the three pollutants on TiO2 of different temperatures ranging (293 - 318)K, and from the sorption isotherms the values of DH, DG, and DS for PVA DH = - (133.4 - 212.83)J, DG = +(78 - 157.4)J, DS = - (500)J, LAS DH = +(53.14 - 66.14)J, DG = - (1.21 - 1.38)kJ, DS = +(4 - 14)J. The sorption process of dye and LAS a positive DH values, negative DG values and positive DS values, which indicates the spontaneous absorption process, which for the negative DH values, positive DG values and negative DS values are due to the non spontaneous adsorption process for PVA. The kinetic study of pollutants sorption on TiO2 was studied depending on three kinetic equations : 1 - Lagergren equation : it was used to obtain the order of the sorption process, and the results showed a good obey with R2 = (0.9477 - 0.9995) for dye, R2 = (0.956 - 0.9942) for PVA, R2=(0.9948) for LAS, to this equation, which indicates that the sorption processfollowed a pseudo - 1st order kinetics, and from the linear Lagergren equation for the pollutants sorption the rate constants of sorption were calculated at different temperatures, and the activation energy for the sorption process was also calculated which reached 39.011 kJ.mol - 1 for sorption of dye.2 - Morris - Weber model : was employed and it gave a good match with the straight linear equation with R2 = (0.98 - 0.994) for dye, R2=(0.9892) for PVA, R2 = (0.9989) for LAS. This relation indicates that the diffusion process was so obvious, and it involvesthe transport of pollutant from the bulk solution into the TiO2 surface, which is considered the rate - limiting step. 3 - Reichenberg model : was employed and it gave a good linear relationship between Bt and time with acceptable correlation coefficient R2 = (0.9891) for dye, R2 = (0.9306) for PVA, R2 = (0.9776) for LAS.This relation indicates that the rate limiting mechanism is the absorption and the sorption process involving three steps : absorption, adsorption and desorption).
