Study On Performance Of Removal Of Cd,Ni And Hg By Algae-based Adsorbent And Its Optimization Analysis

Microalgae is a miniature photosynthetic organism found in both marine and freshwater environments,with similar photosynthetic mechanisms to terrestrial plants.In terms of biomass,they constitute the world's largest group of primary producers,with photosynthesis accounting for at least 32% of the world's total.Researchers all over the world are studying the advantages of microalgae in biosorption.Its easy handling,recyclability,low cost and fast growth have become the focus of scholars.Active algae organisms can survive with minimal nutrient environment,and both algae alive and dead have the ability to remove heavy metal ions out of polymetallic solutions.Therefore,microalgae not only has more optimistic development potential in the field of energy utilization,but also has good research prospects in terms of resource utilization.On the basis of previous studies,this paper selects the algae powder of common chlorella as the research material,and explores the difference of the morphology of the algae powder,the grease residue and the modified residue.At the same time,by using the modified residue of formic acid as the adsorbent under different environmental conditions,the adsorption efficiencies of three heavy metals,Cd,Ni and Hg,were studied.Based on the response surface analysis results run by the software Design Expert,and the experimental results,the interaction effects of multiple factors were simulated.Cd was selected as an important heavy metal representative,and the most accurate experimental conditions were obtained.The results showed that the inactivated algae and the samples after the degreasing and drying did not have a good pore structure physically.The modification of the small molecular acid,represented by formic acid,can change the physical structure of the sample,so that the algae-based adsorbent has a pore structure capable of high-efficiency adsorption.On the other hand,the changes in pH and solid-liquid ratio can have a greater impact on the adsorption efficiency.By changing the different environmental conditions,the purpose of adjusting the adsorption characteristics of the adsorbent can be achieved.In addition,this paper also analyzes and compares the adsorption difference of three different heavy metals of Cd,Ni and Hg adsorbed by formic acid modified algae adsorbent.The rank of adsorption performance that one adsorbent worked for three heavy metal can be seen from the experimental results: Cd>Ni>Hg.At the same time,based on the above experiments,Design Expert was introduced to simulate the response surface analysis of the experiment.By setting the range of pH,temperature and solid-liquid ratio,together with the actual experimental operation,the optimal adsorption conditions under the interaction of three factors are accurately obtained.