Adsorption And Tolerance Of Heavy Metal Chromium By Oocystis Borgei

As the pollution of heavy metals increasingly intensified,water resources Security is deteriorating.Chromium seriously threats to the Earth's biological health as one of the most serious heavy metal pollutants.As we know,hexavalent chromium especially have the strongest toxicity among the chromium compounds.Scholars and professionals have pay more attention to the issue of reducing the toxicity and the pollution of chromium(?)to study the adsorption of chromium by bioabsorbent materials in recent years,and many academic research have confirmed that algae has the characteristics of adsorption heavy metals.Researchers and experts prefer to study the bioabsorbent materials algae as they have many applicable values and potential characteristics,such as widely material sources,convenience in applications,high economic and enviro nmentally protection advantages.This paper use algae Oocystis borgei as research object to study its tolerance and adsorption to heavy metal chromium,and to provide theoretical method and application guidance for reducing chromium pollution in water conta mination protection.We study Oocystis borgei from the angle of two aspacts in this paper,the effects of chromium on the growth and its tolerance of Oocystis borgei and study the adsorption effects.1 The tolerance of Oocystis borgei to chromium(?)We set a serious of chromium concentrations 2.5,5.0,7.5,10.0,12.5 and 15.0 mg/L,observe the growth of Oocystis borgei by deter mining the concentration of algal cell concentration,Chlorophyll a and protein content,the results showed that when the chromium concentration was less than 5.0mg/L,the content of chlorophyll a and algin protein increased with the increase of chromium content.When the chromium concentration increased to 7.5mg/L,(P>0.05),which was lower than that of the control group,but the difference was not significant.The content of algal protein continued to increase to the maximum.When the chromium content was more than 10.0mg/L,thealgal cell concentration and chlorophyll a content And the content of algin protein decreased with the increase of chromium.When the concentration of chromium reached15mg/L,the number of algal cells was smaller than that of the initial value.From the above experimental results,it can be concluded that the optimum concentration of Oocystis borgei on heavy metal chromium(?)is 7.5mg/L and 15.0mg/L is the growth critical value of the Oocystis borgei.2 The adsorption of Oocystis borgei to chromium(?)We research the adsorption of Oocystis borgei to chromium(?)by the following points :the adsorption time,the adsorption conditions(pH),the adsorbent content,the adsorbed matter content and the adsorbent activity.The experimental conclusion is as follows :When the adsorption time is 10 min,the adsorption process of fresh algae and inactivated algae are 87.8% and 81.0% respectively.During 10 min to 120 min,the adsorption process of Oocystis borgei on chromium(?)are completed,which are indicated that the activity of Oocystis borgei have not affect on the adsorption rate of chromium.Next we have studied the effect of different initial chromium concentration on the inactivation of inactivated algae and fresh algae.The experimental results show that when the concentration of chromium was 1.0~100.0mg/L,the increase of chromium concentration was beneficial to the increase of the adsorption efficiency.When the chromium concentration was 100.0~200.0mg/L,the adsorption efficiency And the maximum adsorption efficiency was 91.2% and 93.1% at 100.0 mg/L.The experimental results show that the increase of initial biomass of Oocystis borgei(adsorbent)was beneficial to the increase of adsorption efficiency.But the increase rate of adsorption efficiency varied with the biomass of Oocystis borgei algae,and the adsorption efficiency increase to the highest when the amount of algae 1.0g.Besides,we studied the factors affecting to the pH experiment,the adsorption efficiency of algae was significantly different in pH value of 1~7,which was mainly due to the decrease of pH and the sensitivity of fresh algae to pH change.The experimental results show that the inactivated algae were in the range of 1~4(P<0.05).However,the adsorption efficiency of 69.4% is still affected.The effect of pH acts upon the adsorbability by interference the surface functional groups of biological adsorbent and adsorbate ions.The adsorption process is complex.In general,the inactivated algae has a good adsorption effect in above overall comparison.3 The adsorption process of Oocystis borgei to chromium(?)conforms to the quasi first order kinetics model and the secondary dynamic model(Inactivated algal).