Title: Ενεργοποίηση του υπερθειικού άλατος με χρήση ερυθράς ιλύος για την επεξεργασία μικρορύπων στο νερό
Abstract: Red mud is produced during the production process of alumina from bauxite through the Bayer process. It is the by-product of the process and is discarded. In Greece are pro-duced annually 700,000 t. Because of the large produced volume and the high pH of red mud, there are environmental impacts when it is deposited, which is why there are re-searches about ways to exploit it. The only alumina production industry in Greece is ‘Alu-minum of Greece’ where part of the quantity of red mud produced is deposited in the sea and more specifically in the gulf of Antikyra in Corinthian Gulf.
In addition, the constantly increasing consumption of pharmaceuticals over the last decades and their irresponsible rejection in the environment as well as the inefficiency of the already known biological methods for the complete degradation of pharmaceuticals have led to the need to search for a new generation of technologies that are more effi-cient and environmentally friendly. Advanced Oxidation Processes (AOPs) have been ap-plied over the past decade in the field of water and wastewater treatment and in particu-lar for the removal of pharmaceuticals with successful results. Among these processes is the Fenton process, which refers to the mixture of hydrogen peroxide and iron salts as catalysts. Due to the rich composition of red mud on iron, aluminum and titanium oxides, it is an ideal candidate a) as a source of iron for Fenton type reactions in dark or under solar radiation, b) as a flocculant, and c) as a source of titania for heterogeneous photoca-talysis .
Sodium persulfate (SPS) is a promising source of reactive sulfate radicals because of its moderate cost and high sulfate radicals’ potential (2.6 V which is comparable to that of hydroxyl radicals). The conversion of SPS into sulfate radicals does not occur spontaneous-ly but can be catalyzed by high temperatures, alkaline environment and transition metals.
In this paper we study the potential utilization of red mud as a catalyst for the activa-tion of persulfate to sulfate radicals due to its high content of iron and other metals for the degradation of propylparaben in water. Propylparaben selected as a standard mi-cropollutant appears as a natural substance in many plants and insects, although it is also synthesized in order to be used in cosmetics, pharmaceuticals and food. The red mud, used in the present thesis, was obtained from Aluminum Hellas S.A. and dried at 100° C. In particular, different ways of pre-treatment of red sludge (hydrothermal, acid addition and calcination at different temperatures) are investigated. At the same time, the parameters influencing the paraben oxidation are being studied, such as red mud concentration, paraben concentration, pH, persulfate concentration, while experiments are carried out on different aqueous matrices (ultrapure water, drinking water and secondary effluent). The reuse of the catalyst is also studied.
Finally, the use of five other catalysts synthesized from the mining and metallurgical waste processing by the Department of Chemical and Environmental Engineering, Univer-sity of Oviedo (Dr. Paula Oulego Blanco) is studied. Experiments were carried out to select the most efficient oxidant and catalyst concentration for degradation of the same mi-cropollutant (propylparaben). In addition, other factors such as the effect of pH, water matrix, the use of scavengers and the use of salts are investigated.
Publication Year: 2018
Publication Date: 2018-02-15
Language: en
Type: dissertation
Access and Citation
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot