Journal of the University of Chemical Technology and Metallurgy, XXXVI, Book1, 2001

CHEMICAL TECHNOLOGIES

HEAVY METALS REMOVAL FROM WASTEWATER TROUGH ELECTROCHEMICAL TREATMENT
V.Panayotov, M.Panayotova, Ts.Mitrov, E.Gock, P.Zommer

COMPOSITIONAL TRENDS OF THE PROPERTIES IN Ge-Se-Ga CHALCOGENIDE GLASSES
T.Petkova, Y.Nedeva, P.Petkov

 

HEAVY METALS REMOVAL FROM WASTEWATER TROUGH ELECTROCHEMICAL TREATMENT
V. Panayotov, M. Panayotova, Ts. Mitrov, E. Gock, P. Zommer

 

University of Mining and Geology 1700 Sofia, Bulgaria, Clausthal Technical University, Clausthal -Zelerfeld, Germany E-mail marichim@mgu.bg

Received 20 March2001 Accepted 02 April 2001

ABSTRACT
A method is proposed for the treatment of wastewater from the non-ferrous metallurgy. The method is based on electrolysis, electrocoagulation, electroflotation, precipitation, and co-precipitation processes. As a result of proper design of the electrochemical cell, concentrations of lead, cadmium, copper, zinc and arsenic ions in treated wastewater as well as its pH value meet the requirements of Regulation No 6 / 09.11.2000 for industrial wastewater discharge. Additional ions' introduction into treated water is avoided. The method allows posterior recovery of valuable components born by the wastewater and isolated in by-products resulting from the treatment.
Keywords: non-ferrous metallurgy wastewater, heavy metals, electrochemical treatment

 

IR SPECTROSCOPY STUDY OF NANOPARTICLES AND COMPOSITES
I. Markova - Deneva, K. Alexandrova, G. Ivanova, M. Pankova, I. Dragieva

 

University of Chemical Technology and Metallurgy, 8 Kl. Ohridski, 1756 Sofia, Bulgaria e-mail: vania@uctm.edu

Received 27 April 2001 Accepted 06 June 2001

ABSTRACT
Investigations by means of infrared spectroscopy (IR-spectroscopy) of amorphous and crystalline CoxByHz nanoparticles and their composites with AlN in the 4000 - 400 cm-1 range are carried out. Proofs for creation of chemical bonds between boron and oxygen atoms and a formation of BO3 and BO4 type of groups incorporated in boroxol rings (B3O4,5) x and structured as diborate, triborate and tetraborate units are given. Three modes of vibration in the frequency region typical for the B-O-B bonds in the BO3 and BO4 groups forming diferent structural units have revealed: symmertic stretching n1 (BO4) at 750 cm-1 , asymmetric stretching n3 (BO3) at 1020 cm-1 and deformation mode n4 (BO4) at 520 cm-1. The bands of absorption grow in intensity and shift to lower frequencies with increasing of the heat-treatment temperatures from 200 to 850oC At lower temperatures (200-500oC) the bands are broad while at higher temperatures (550-850oC) they are intensive and sharp. Composites with AlN which are heat-treated at high temperatures show the existence of chemical bonds between aluminum and oxygen atoms forming coordination groups of the types AlO4 and AlO6. The IR studies of the composites with AlN have characteristic stretching vibrations typical for the Al-O bonds in the AlO4 tetrahedra (900-650 cm-1) and AlO6 octahedra (650-500 cm-1).The increasing of the quantity of the AlN in the prepared isotropic composites has a opposite effect to the heat-treatment temperature effect.
Keywords: infrared spectra, CoxByHz nanoparticles,composites , AlN additive