Study On The Technology Of Removing Heavy Metals From Oil Crops And Their Products

With the increase of human acticitives such as industry and agriculture production,soil heavy metal pollution was become more and more serious. Phytoremediation, as an environmentally-friendly technology, has been more concerned due to the serious soil heavy metal pollution. Heavy metal was accumulated in the fruit and its products through plant absorption due to its non-biodegradablel, which is harmful to people's health.So it is necessary to remove the heavy metals. The research focused on the heavy metals'content distribution in different oil fruits, by choosing the above three crops which were planted in seriously heavy metal polluted soils, and analyzed the heavy metal residues in oil extracts by using five kinds of organic solvents (N-hexane,Petroleum,Acetone,Isopropyl alcohol and Chlorofrom) to do soxhlet extraction to their fruits. Finally it removes the heavy metal in each oilseed meal by using three different kinds of extracting agent (potassium Citrate, Tartrate and Ammonium salt of EDTA, containing 70%ethanol) to investigate the removal efficiency of three different kinds of extractant and to compare the change of nutrient elements and protein before and after extraction.The main conclusions were as follows:(1) The Analysis of the heavy metal residues in oil extracts by using five kinds of organic solvents shows that N-hexane is the best extraction for rapeseed and sesame, Petroleum ether is the best extraction for peanut. The heavy metals of Pb,As in oil were accord with the national edible health standards GB2716-2005, and the heavy metals content of Cd and Hg in oil also accord with Hygienic standard for grains (GB2715-2005).(2) The heavy metals removal efficiency of rapeseed meal by using potassium Citrate, potassium Tartrate and Ammonium salt of EDTA shows that the removal effect of heavy metal Pb, Zn, Cu, Cd, As and Hg change with time, temperature, concentration and extraction times. The optimum condition for extraction of potassium Citrate, potassium Tartrate and Ammonium salt of EDTA is 12h for extraction process and room temperature, concentration being 30mmol/L,3 times extraction.(3) The removal of the heavy metals in the meals of rapeseed, peanut and sesame by using three kinds of extraction shows that potassium Citrate, potassium Tartrate and Ammonium salt of EDTA have a good removal efficiency of Pb, Zn, Cu, Cd, As and Hg in them. In addition, after the removal of heavy metals to meal, the content of nutrient elements and crude protein in each meal are reduced a little by potassium Citrate and potassium Tartrate, but parts of nutrient elements were decreased more by Ammonium salt of EDTA. Comparatively speaking, potassium Citrate and potassium Tartrate are more appropriate than Ammonium salt of EDTA to remove the heavy metals in the meals of rapeseed, peanut and sesame.