Study On Flotation Separation Determination Of Lead, Cadmium, Mercury In Soil

Soil is a thin covering over the land consisting of a mixture of minerals,organic material,living organisms,air and water that together support the growth of plant life.Soil is polluted by some contaminations as aresult of both natural environment and human activities. Then the contaminated soil is come to be a pollution source again to water resources and atmosphere. Among those contaminations, more attentions are paid to the heavy metals.It is potentially harmful to the environment and human health. In this dissertation, based on the determination of the concentrations of lead, cadmium, mercury in the soils of citrus grandis var.shatimyuHout of Meixuan.There are three main parts of this dissertation. The first is the analyses of collecting, physio-chemical properties and mineral of tested soil. Soil samples were collected in the citrus grandis var.shatimyuHout of Meixuan.Sampling vertical distance is about 0~20cm layer. 10 soil samples were collected. Based on physio-chemical properties were analyzed. The results were as follows: moist basis water content 16.6-22.5%, pH4.25~8.05, organic matter 6.90~22.60(g/kg), amino nitrogen 1.41-9.4 l(mg/kg), nitric nitrogen0.98~5.52(mg/kg), available P 3.36-115(mg/kg), available K 94~105(mg/kg), available Cu 0.77~7.63(mg/kg), available Zn 0.33~4.87(mg/kg), available Fe 4.03-133(mg/kg), available Mn 0.033-4.3 l(mg/kg), available Mo 0.56~4.97(mg/kg). Based on mineral element were analyzed. The results were as follows: total Cu 12.8~39.5(mg/kg), total Zn 48.3-105(mg/kg), total Fe 3.56~9.92(g/kg), total Mn 399~67.7(mg/kg), total Cd 0.10~0.69(mg/kg), total Pb 21.8~61.1(mg/kg), total Hg 0.12~0.98(mg/kg), total Ni 18.6~30.5(mg/kg), total Cr 20.6~45.3(mg/kg), total Ca 86~503(mg/kg), total Mg 0.98~2.89(mg/kg).In part two,the flotation behaviour of lead, cadmium,mercury were studied. Theresults showed that when KI and methyl violet (MV) were present together, the Pbl42 formed from Pb2+ and I" was precipitated with the cation of methyl violet (MV+), and formed the precipitation (MV)2(PbI4). When KI and rhodamin B(RhB) were present together, the CdLf formed from Cd"+ and I" was precipitated with the cation of rhodamin B(RhB+), and formed the precipitation (RhB)2(CdI4).When NH4SCN and cetylpyrinium bromide(CPB) were present together, the precipitation (CPB)2[Hg(SCN)4] could be formed by Hg(II) reacted on I" and the cation of cetylpyrinium bromide (CPB+ ).The precipitation (MV)2(PbL,), (RhB)2(CdI4) and (CPB)2[Hg(SCN)4] stayed above the water phase and formed the interface-clear liquid-solid biphase.In the course of two phase forming, Pb2+,Cd2+,Hg2+ could be floated quantitatively, and Cu( II), Zn(II), Mn(II), Ni(II), Co (II), Fe(II), Al(III) could not be floated, So Pb2+,Cd2+,Hg2+ could be separated successfully from those metal ions without any masking agent by flotation.In part three, the flotation separation determination of lead, cadmium,mercury in soil sample were studied. On the flotation behaviour of lead, cadmium,mercury, Based on the flotation separation determination of lead, cadmium,mercury were analyzed. The results were as follows: Pb 22.1~62.0mg/kg , RSD2.99~7.65%,Cd 0.13~0.69mg/kg, RSD3.28~23.1%, HgO.13~0.96mg/kg, RSD4.50~19.6%.