Contribution to the sustainable management of resources by novel combination of industrial solid residues into red ceramics.

Limited amounts of industrial residues are recycled while the remaining huge quantities are stockpiled or disposed of, thus frequently leading to soil contamination. The utilization of industrial residues as valuable secondary resources into ceramics can contribute to efficient waste management and substitution for massive amounts of natural resources (clayey minerals) demanded for ceramic production. The low cost of these residues and even possible energy savings during mixture firing may also be beneficial. In the present study, the innovative combination of lignite fly ash with steel-making dust into clay-based red ceramics is undertaken, to contribute both to sustainable use of resources and prevention of soil contamination. Brick specimens were shaped by extrusion and fired, their microstructure was examined and the effect of the mixture composition and firing temperature on physico-mechanical properties was determined. Ceramic microstructures were successfully obtained by a suitable combination of fly ash with steel dust (5 + 5 wt%) into clays. Properties can be predicted and tailored to meet the needs for specific applications by appropriately adjusting the mixture composition and sintering temperature.

Decolorization kinetics of Procion H-exl dyes from textile dyeing using Fenton-like reactions.

The decolorization kinetics of three commercially used Procion H-exl dyes was studied using a Fenton-like reagent. The effect of the major system parameters (pH, concentration of H(2)O(2) and Fe(3+) and initial dye concentration) on the kinetics was determined. For comparison, the effect of the use of UV irradiated Fenton-like reagent and of Fenton reagent on the kinetics was also examined. In addition, mineralization rates and the biodegradability improvement as well as the effect of the addition of Cl(-), CO(3)(2-) or HCO(3)(-) on the decolorization rates was studied. The reactions were carried out in a 300 ml stirred cylindrical reactor with the capability of UV irradiation. The dye half-life time goes through a minimum with respect to the solution pH between 3 and 4. It also exhibits a broad minimum with respect to Fe(3+) and H(2)O(2) at molar ratios of H(2)O(2)/Fe(3+) from about 100 to 10. The addition of CO(3)(2-) and HCO(3)(-) substantially reduces the decolorization rates, while this effect is significantly less pronounced with Cl(-). At an optimum range of parameters, the mineralization rate (TOC reduction) is very slow for the Fenton-like process (TOC decrease from an initial 49.5 to 41.1 mg/l after 30 min and to only 35.2 mg/l after 600 min), but it increases significantly for the photo-Fenton-like process (to TOC values of 39.7 and 11.4 mg/l, respectively). The biodegradability, as expressed by the BOD/COD ratio, increases significantly from an initial value of 0.11-0.55 for the Fenton-like and to 0.72 for the photo-Fenton-like processes.