Research On Heavy Metal Removal Technology From Porphyra Haitanensis

In this study, a method of microwave digestion coupled plasma atomic emission spectroscopy(ICP-AES) was developed for the determination of heavy metals in porphyra haitanensis. Basedon the contents of metallic elements limited in GB2762-2012and GB19643-2005, the method ofultrasonic treatment assisted citric acid was developed for removing the heavy metals, such asCd,As, Cr, Pb, In addition, a comparative study was conducted to evaluate the quality of porphyrahaitanensis during this process. The main results were as follows:1、The process of microwave digestion of porphyra haitanensis was optimized by the methodof response surfacemethodology. And a comparative study between microwave digestion and wetdigestion was conducted, which were both used in the pretreatment process of ICP-AES todetermine the contents of heavy metals. According to the results, the optimum coditions ofmicrowave digestion were as follows: temperature of164℃, solvent to material ratio of25:1(v/w),and digestion time of15minutes. Compared with wet digestion, microwave digestion showedmore effectiveness, such as shorter time, less reagents and more completed digestion2、To determine the contents of metallic elements in Porphyra haitanensis, such as Cr, Cu, Zn,Cd, As, Pb and Al, a method of microwave digestion coupled plasma atomic emissionspectroscopy (ICP-AES) was developed. The results showed that the recovery rates of metals werebetween97.8%and104.9%, which confirmed that this method was sensitive enough to achieve thedetermination of metal contents in porphyra haitanensis. Besides, the results showed an significantincreasing trends in the metal contents of porphyra haitanensis during the past five years (P<0.05，RSD<1.89%).The contents of Cr, Cu, Zn, Cd, As, Pb increased from0.132mg/kg to1.154mg/kg,14.259mg/kg to23.258mg/kg,31.237mg/kg to45.375mg/kg,0.055mg/kg to0.735mg/k,0.574mg/kg to1.251mg/kg,0.472to1.755mg/kg,188.171to270.437mg/kg,respectively. In addition, the porphyra haitanensis with different tenderness in2012wascollected, the mental contents showed an increasing trends: the first＞the second＞the third＞thefourth.3、Using the contents of Cd, Cr, As, Pb in Porphyra haitanensis as the indexes, the effect ofultrasonic parameters were optimized by the response surface methodology.The results showed asfollowes: ultrasonic power313W, concentration of citric acid0.10mol/L, ultrasonic time21min.under thess conditions, the removal rates of Cd, Cr,As, Pb were88.47%,58.95%,61.42% and46.61%, respectively, which were all under the limits formulated in GB.4、The qualities of Porphyra haitanensis before and after the removal of heavy metals wereevaluated. It is revealed that the mount of total sugar and crude protein were changed a little. Inshort, the chang of the sensory properties was insignificant...