Treatability of textile industry polyester cloth dyeing wastewater by adsorption and photocatalytic method using nTiO(2)

Abstract

Textile industry wastewater includes organic dyes and decomposition products which could have toxic and mutagenic effects on life. The majority of industries in this sector use nonbiodegradable, heat-resistant, light, oxidizing agents and therefore synthetic dyes that are difficult to remove color. In this study, Dianix Yellow Brown CC (0.22%), Dianix Rubine CC (0.79%) and Setapers Blue CE3R (0.015%) containing disperse dye have been used in the production of wastewater from the dyehouse. In this study, textile wastewater has been treated which has applied adsorption and photocatalytic methods by using nano-titanium dioxide (nTiO(2)). Optimum chemical oxygen demand (COD) and color removal efficiencies have been determined for these two methods. Moreover, under the optimum conditions in the adsorption method, the COD removal efficiency has been obtained as 58.07% and also color removal efficiencies have been obtained as 95.24%, 95.15%, 96.83% for 436, 525 and 620 nm, respectively (pH 2, nTiO(2) dose 2.5 g L-1 and 30 min reaction time). Therefore, under the optimum conditions in the photocatalytic method the COD removal efficiency has been obtained as 57.59% and also color removal efficiencies have been obtained as 95.24%, 96.31%, 94.71% for 436, 525 and 620 nm, respectively (pH 2, nTiO(2) dose 1.5 g L-1 and 60 min reaction time). Four different kinetic, that is, first-order kinetic, second-order kinetic, pseudo-first-order, pseudo-second-order, models have been used for the processes adsorption and photocatalytic. The pseudo-second-order kinetic model has been found to be the most suitable model for both processes. As a result, regression coefficients (R-2) has been obtained for adsorption as 1 and for photocatalytic as 0.9999 and reaction rate constants (k) have been obtained for adsorption as 6.9 x 10(-4) L mg(-1) min(-1) and for photocatalytic as 2.2 x 10(-3) L mg(-1) min(-1).