REMOVAL OF OXYANIONS FROM METALS' EXTRACTION WASTEWATER BY
MODIFIED ZEOLITE
Marinela Panayotova - Dept. of Chemistry, Vladko Panayotov - Dept. of Mineral Processing
University of Mining and Geology, Sofia - 1700, Bulgaria, e-mail: marichim@mgu.bg
ABSTRACT
Wastewater from mining and mineral processing activities is often polluted by hazardous heavy metals and sulfates. Natural low cost materials, including zeolites, are successfully applied to remove heavy metals from wastewater. However, it is widely accepted that natural zeolites are not effective in removing heavy metals in anionic form, as well as other anions-pollutants. The paper presents study on use of metal modified natural zeolite clinoptilolite to remove Cr (VI) ions, molybdates and sulfates from model wastewater. Best working metals-modifiers for each of the pollutants, as well for their mixture are pointed out. The impact of solid to liquid ratio, zeolite particles' size, initial pollutant concentration, initial pH value of the wastewater, and the water hardness on the pollutants' removal is presented and discussed.
Kinetics and thermodynamics of the uptake process are commented. Finding a satisfactory way to remove anions-pollutants from the mineral processing wastewater will render this industry more environmentally friendly and socially acceptable.
KEYWORDS
Wastewater, Oxyanions, Modified zeolite clinoptilolite, Kinetics