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首页> 外文期刊>Applied Geochemistry: Journal of the International Association of Geochemistry and Cosmochemistry >Effects of freshwater Synechococcus sp cyanobacteria pH buffering on CaCO3 precipitation: Implications for CO2 sequestration
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Effects of freshwater Synechococcus sp cyanobacteria pH buffering on CaCO3 precipitation: Implications for CO2 sequestration

机译：淡水Synechococcus sp蓝细菌pH缓冲对CaCO3沉淀的影响：对CO2螯合的意义

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摘要

In the present study, a mixed-flow steady-state bio-reactor was designed to biomineralize CO2 as a consequence of photosynthesis from active Synechococcus sp. Dissolved CO2, generated by constant air bubbling of inorganic and cyanobacteria stock solutions, was the only source of inorganic carbon. The release of hydroxide ion by cyanobacteria from photosynthesis maintained highly alkaline pH conditions. In the presence of Ca2+ and carbonate species, this led to calcite supersaturation under steady state conditions. Ca2+ remained constant throughout the experiments showing the presence of steady state conditions. Similarly, the Synechococcus sp. biomass concentration remained stable within uncertainty. A gradual pH decrease was observed for the highest Ca2+ condition coinciding with the formation of CaCO3. The high degree of supersaturation, under steady-state conditions, contributed to the stabilization of calcite and maintained a constant driving force for the mineral nucleation and growth. For the highest Ca2+ condition a fast crystal growth rate was consistent with rapid calcite precipitation as suggested further by affinity calculations. Although saturation state based kinetic precipitation models cannot accurately reflect the controls on crystal growth kinetics or reliably predict growth mechanisms, the relatively reaction orders obtained from modeling of calcite precipitation rates as function of decreasing carbonate concentration suggest that the precipitation occurred via surface-controlled rate determining reactions. These high reaction orders support in addition the hypothesis that crystal growth proceeded through complex surface controlled mechanisms. In conclusion, the steady state supersaturated conditions generated by a constant cyanobacteria biomass and metabolic activity strongly suggest that these microorganisms could be used for the development of efficient CO2 sequestration methods in a controlled large-scale environment. (C) 2016 Elsevier Ltd. All rights reserved.
机译：在本研究中，设计了一种混合流稳态生物反应器，以将由于活性Synechococcus sp。的光合作用而使CO2矿化。由无机和蓝细菌储备溶液不断鼓泡产生的溶解的CO2是无机碳的唯一来源。蓝细菌从光合作用中释放出氢氧根离子，从而保持了高碱性的pH条件。在存在Ca2 +和碳酸盐物质的情况下，这导致在稳态条件下方解石过饱和。在整个实验中，Ca2 +保持恒定，表明存在稳态条件。类似地，Synechococcus sp。生物量浓度在不确定性范围内保持稳定。在最高Ca2 +条件下观察到pH值逐渐降低，这与CaCO3的形成相吻合。在稳态条件下的高度过饱和度有助于方解石的稳定化，并保持了矿物成核和生长的恒定驱动力。对于最高的Ca2 +条件，如亲和力计算所进一步表明的，快速的晶体生长速率与快速的方解石沉淀相一致。尽管基于饱和状态的动力学沉淀模型无法准确反映晶体生长动力学的控制或可靠地预测生长机理，但从方解石沉淀速率建模获得的相对反应顺序是碳酸盐浓度降低的函数，这表明沉淀是通过表面控制速率确定反应。这些高反应顺序还支持了晶体生长通过复杂的表面控制机制进行的假设。总之，由恒定的蓝细菌生物量和代谢活性产生的稳态过饱和条件强烈表明，这些微生物可用于在可控的大规模环境中开发有效的CO2螯合方法。 （C）2016 Elsevier Ltd.保留所有权利。

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