Experimental Treatment Of Hg(Ⅱ) And Cd(Ⅱ) And Cr(Ⅵ) Bearing In Waste Water By Natural Magnetite And Limonite

The contaminants of heavy metals harm greatly environmental quality and human health. Then people pay more attention to disposal heavy metals in wastewater. Some research works on method of treatment for heavy metals have been done. However using natural minerals to disposal heavy metals in wastewater is beginning. This paper deals with experimental treatment of Hg( II ),Cd( II) and Cr(VI) -bearing wastewater by natural magnetite and limonite. The research works include their ability of adsorption and their behavior of the adsorption in order to provide some basic data and theoretics to be used in the field of harnessing contamination of heavy metals in the future.The research conclusions are as followings:1 Natural magnetite and limonite is analysed on chemical composition and X-ray diffraction. The results of DTA and IR analyses show that natural magnetite and limonite surfaces contain hydrated hydroxide; Natural magnetite and limonite surfaces' acreage are 4.29m2/g and 42.27m2/g separately, and their surfaces' site- concentration are 4.10x 10-5mol/g and 4.78 x 10-6mol/g separately by N2-BET and acid-caustic titration.2 The adsorption of Hg( II ),Cd( II) and Cr(VI) ions can be effected by time, solution pH value,dosage, original concentration and ionic strength, which mechanism is also discussed in the paper by studying experiment of isotherm adsorption. The outcome indicate that solution pH value is the most important factor to disposal; the adsorption behavior of Hg( II ),Cd( II) and Cr(VI) ions on natural magnetite and limonite can be described by Langmuir and Freundlich equations.3 Under conditions of varied NaNO3 concentration and same solution pH value, disposal hardly be effected by NaNO3 concentration when natural magnetite adsorb Hg(II) and Cr(VI) ions; but disposal be effected by NaNO3 concentration when natural limonite adsorb Hg( II) and Cr(VI) ions.4 The IR analyses results show that hydrated hydroxide absorbance don't occur change on magnetite adsorbed Hg( II ),Cd( II) and Cr(VI) ions .Whereas hydrated hydroxide absorbance take place frequency excursion on limonite adsorbed Hg( II) and Cd( II) ions.5 The results of XPS analyses show that samples have adsorbed ions except magnetite and limonite adsorbed Hg( II) ion after washings.