Study On The Crystallination Process Of Calcium Carbonate Influenced By Sulfate Reducing Bacteria And Magnesium

With the development and utilization of the ocean,more and more marine equipment such as oil pipelines and monitoring originals are put into the ocean.The marine environment was complex and contains a large amount of inorganic salt ions and microorganisms.In this case,it was easy to make Equipment surface corrosion and crystallization,these inorganic salt crystals are usually carbonate precipitation,and the use and operation cost of the instrument are extremely large.However,there was no particularly effective method to solve the crystallization problem.There have been many scholars studying marine microorganisms with the participation of metal materials Corrosion and crystallization of inorganic salts.In view of the above problems,this article uses the marine fouling bacteria sulfate-reducing bacteria as fouling bacteria to extract the metabolite of sulfate-reducing bacteria EPS,and studied the effect of different concentrations of EPS on carbonate crystallization.Magnesium ions,study the crystallization process of inorganic salts under the action of magnesium ions.Finally,we studied the effects of organic matter and inorganic salt ions on the crystal morphology and growth rate under the EPS and magnesium-calcium composite system.The main research contents are as follows:(1)Control the calcium ion concentration by gas diffusion method,extract sulfate to reduce extracellular polymer EPS,and study the crystal morphology and crystal type distribution under different organic matter concentrations.The study found that from the concentration of EPS-C 2 mg/L to 8 mg/L,Higher concentration promotes the formation of calcite.The organic components of microorganisms can absorb calcium ions in the solution,reduce the solution saturation and promote the generation of calcite-type calcium carbonate.(2)Control the ocean concentration of calcium ion concentration to 10 mmol/L,study the crystallization process of calcium carbonate under different magnesium-calcium(Mg/Ca=0,1/2,1,2,4,6)ratio conditions,and find that the blank group crystallizes as Vaterite,calcite crystal form appears when the ratio of magnesium to calcium was 0.5,and polycrystalline products,vaterite,magnesium calcite and aragonite appear when the ratio of magnesium to calcium is 1.Increased magnesium concentration promotes aragonite formation(Mg/Ca=6)makes amorphous crystals appear.Magnesium ions compete for carbonates through their hydration and suppress the formation of calcite by occupying the crystal lattice of calcite,which promotes the production of aragonite.Ahigh concentration of magnesium helps free Stability of fixed form calcium carbonate.(3)Considering the concentration of organic carbon in seawater,the EPS-C concentration was 2 mg/L and the calcium ion concentration was 10 mmol/L.The crystallization process at different magnesium-calcium ratios(Mg/Ca=0,1/2,1,2,4).The study found that when EPS exists,the system is more prone to calcite and aragonite.This shows that the low concentration of EPS mainly shows the adsorption of calcium ions.The increase of magnesium ion concentration promotes the formation of magnesium-containing calcite.When the ratio of magnesium to calcium was 2,almost all of the crystalline products are aragonite.The combined influence of organic matter and magnesium ion produces a hemispherical aragonite morphology.One of the merits was that the amorphous calcium carbonate under this system appears in the experimental condition where the ratio of magnesium to calcium was 4.It shows that organic matter and magnesium ion affect the appearance of amorphous form.Through the monitoring of calcium ions,it was found that the increase of magnesium ion concentration helps to inhibit the crystallization of calcium carbonate.(4)By collecting seawater in different regions and studying the crystallization of inorganic salts under seawater conditions by adding carbonate ions,the study found that the concentration of magnesium ions in seawater is much higher than the concentration of calcium ions.There are large differences in ions and organic carbon in seawater in different regions.Under this condition,the crystal on the glass substrate is rod-shaped or cauliflower-shaped aragonite.