Valorization of Tunisian Pottery Clay onto Basic Dyes Adsorption

This study examined the adsorption behavior of two cationic dyes used in textile industries (CI Basic Red 46 and CI Basic Blue 3) on Tunisian clay used in pottery. The ability of pottery clay to remove the basic dyes from aqueous solution was compared to that of the commercial powdered activated carbon (PAC) and raw clay. Physicochemical characteristics of these adsorbents were performed by Boehm dosage, pHPZC and CEC determination, particle size distribution and spectroscopic analysis (FTIR and UV Vis). The pHPZC of the pottery clay was about 9.86 and the CEC was about 15.6 meq/g. The empirical kinetic data fitted very well the pseudo second order model for the adsorbent studied. The isotherm data fitted rightly to the Langmuir isotherm model. The maximum adsorption capacities of the raw clay, pottery clay and PAC onto CI Basic Red 46 (CI Basic Blue 3) were respectively2806 mmol/g(785 mmol/g), 2114mmol/g (116. mmol/g) and 2123mmol/ g (343.9 mmol/g). These results showed the large adsorption capacities of the studied samples onto the basic dyes. Based on thermodynamic study, the adsorption of the cationic dye on raw clay, pottery clay and PAC appears to be physical adsorption process. The effect of the ionic strength study showed that the presence of electrolyte had an important effect on the basic dyes removal.