Study On Adsorption Of Cd²⁺ By Microbial-cement Composites Materials

With the exploitation of resources and human activities,the problem of heavy metal pollution has appeared more and more in people’s vision.Among them,soil heavy metal pollution has become a major part of soil pollution.How to effectively deal with heavy metal pollution has become a hot topic in current research.In this paper,heavy metal Cd2+was adsorbed by cement-based materials and cement-based microbial composite materials.The adsorption effects of pure microbial materials,cement-based microbial composites and Ca2+-microbial cement-based materials were compared.The heavy metal ions of different experimental groups were determined.The content was observed to observe the effect of strain revitalization on the adsorption of heavy metals by enzyme catalysis.The possibility of using mineralized bacteria with porous cement-based carrier as a heavy metal pollution treatment was explored.It includes the cultivation of microorganisms and the adsorption mechanism of single cement-based materials.(1)The growth status and urease activity of Bacillus pasteurii under different pH,different urea concentration and different NaCl concentration were studied.The optimal culture conditions of Bacillus pasteurii and the growth process and mineralization of Bacillus pasteurii were studied.The relationship between the effects.The results showed that the pH was 7-9,which was the most suitable for cell growth.Urea had a certain inhibitory effect on the growth of bacteria.The NaCl concentration at 2g/L-12g/L had no obvious inhibitory effect on the growth of the cells.The optimal mineralization conditions were explored by culturing Bacillus pasteurii under conditions containing CaCl2 to study the amount of precipitation under different factors.The results showed that when the pH was 8,the urea concentration was 20g/L,the NaCl was 2g/L,and the CaCl2 concentration was<10g/L,the calcium carbonate formation rate could reach about 90%.(2)The effects of temperature,pH,dosage,Cd2+concentration and adsorption time on the adsorption of cement-based porous materials were investigated.The results showed that the adsorption effect of cement-based adsorbent increased with the increase of pH;The increase of temperature will reduce the adsorption efficiency;the increase of Cd2+concentration will increase the adsorption rate of cement material;and the excessive cement-based porous adsorption material will lead to the decrease of unit adsorption capacity;(3)The adsorption effect of pure bacterial liquid,porous cement-based material-bacterial liquid,Ca2+-porous cement-based material-bacterial liquid on Cd2+was studied.The results show that the addition of cement-based materials can improve the adsorption of Cd2+.Adsorption removal rate,and CaCO3 coating effect in the presence of Ca2+,a certain filling effect,and further improve the adsorption removal rate of Cd2+.