-The substrate heating method was used to grow zeolite 4A coatings on copper plates. The reaction mixture was kept at 25°C, while the plate was heated to a higher temperature. In some of the synthesis experiments performed, the reaction mixture was circulated in the system. The coatings prepared were characterized by X-ray diffraction and scanning electron microscopy. It was demonstrated that crystalline and pure zeolite 4A coatings could be formed on copper by using the substrate heating method from a highly alkaline solution, in which dissolution and oxidation of the copper plates took place. A coating with about 310 μm mass equivalent thickness could be grown on copper after 72 h of synthesis. The thickness decreased when circulation was applied. Compared to coatings previously prepared on stainless steel plates under similar experimental conditions, thicker coatings were grown on copper. It is possible that the roughened surface of copper in the highly alkaline reaction mixture provided a higher number of nucleation sites.

SUMMARYThe olive oil mill wastewater presents serious environmental threats. In this study, adsorption heat pumps utilizing zeolite coatings were proposed for olive oil mills as a helping tool for the treatment of wastewater, as well as for providing a cooling effect, which may especially be useful to prevent thermal deterioration of the olive oil. The performance of a heat pump using two adsorbers operating with waste heat was determined for different operating conditions. It was established that a sufficiently high amount of olive oil wastewater might be treated in such a system when a suitable source of waste heat is used for heating the adsorbers of the heat pump.

No abstract

No abstract

Sodium clinoptilolite-rich tuff from the Western Anatolia, Bigadic region was modified with octadecyltrimethylammonium bromide(ODTMA-Br) and hexadecyltrimethylammonium bromide (HDTMA-Br), and used for the first time to remove chromium(VI) from aqueous solution in a series of batch adsorption experiments. Various physico-chemical parameters affecting the adsorption process such as the contact time, pH, the optimum sorbent dosage and the initial concentration of chromium were studied. The Cr(VI) adsorption capacity of ODTMA-and HDTMA-treated clinoptilolite (Cp) was highly pH-dependent, and was found to be 3.65 mg/g and 2.85 mg/g at pH 2.0 and 3.0, and 0.25 g/50 mL sorbent dosage, 3 h equilibrium time and 25ºC, respectively. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the adsorption isotherms. Langmuir's model fitted the equilibrium data better than the Freundlich isotherm. From the D-R isotherm model, the mean adsorption energy (E) calculated as 15.075 and 14.744 kJ/mol for ODTMA-Cp and HDTMA-Cp sorbents showed that the adsorption of chromium occurred by chemisorption. The kinetic data indicated that the sorption of hexavalent chromium onto modified Cp followed well the pseudo-first-order kinetics. The current study considers that further developments in this line of research should continue