Self-cleaning and mechanical properties of modified white cement with nanostructured TiO2.

In the present study, self-cleaning and mechanical properties of white Portland cement by addition of commercial available TiO2 nanoparticles with the average particle size of 80 nm were investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET were used to characterize TiO2 nanoparticles. For determination of self-cleaning properties of TiO2-modified white cement, colorimetric tests in decolorization of C.I. Basic Red 46 (BR46) in comparison to unmodified cement samples was applied. The results indicated that with increasing the amount of TiO2 nanoparticles in modified cement, self-cleaning property of the samples increased. The mechanical properties of TiO2-modified and unmodified cement samples, such as time of setting of hydraulic cement, compressive strength of hydraulic cement mortar and flexural strength of hydraulic cement mortar were examined. The results indicated that addition of TiO2 nanoparticles up to maximum replacement level of 1.0% improved compressive and flexural strength and decreased its setting time.

Chemometrics approach for determination and optimization of simultaneous photooxidative decolourization of a mixture of three textile dyes.

In this paper simultaneous photooxidation of three textile dyes (CI Basic Red 46 (BR46), Malachite Green (MG) and CI Basic Blue 3 (BB3)) by UV/H2O2 process is reported. A rapid analytical methodology based on recording UV-Vis spectra during the photooxidative decolourization process and the data treatment using multivariate curve resolution with alternating least squares (MCR-ALS) was developed. The three textile dyes were quantified simultaneously despite the overlap of their spectra. Also, the central composite design was applied for optimization of the photooxidative decolourization of the solution containing three dyes using the UV/H2O2 process. The investigated factors (variables) were the reaction time, initial concentration of the three dyes and initial concentration of H2O2. The optimum initial concentration of the three dyes, H2O2 initial concentration and reaction time were found to be 4 mg/L, 48 mg/L and 30 min, respectively. The photodegradation products of three dyes were identified by the GC-MS technique.