海水电沉积作用碳酸钙结晶与珊瑚骨骼晶体的比较

Comparison of calcium carbonate crystals of seawater electrodeposit and coral skeleton crystal

电沉积促进珊瑚生长和岸礁修复技术是国际上常采用的生态修复方法,但电沉积技术中电流条件与沉积晶体之间的关系却鲜有研究,关于其形成的电沉积物的晶体结构的报道更是少有。本文探索了在不同电流密度的条件下海水形成碳酸钙晶体的特点,并与珊瑚骨骼晶体进行了对比。本实验设置了300、600、900和1200 m A/m2四组电流密度,在海水中进行5 d电沉积反应,实验后称量了阴极上形成的电沉积物质量,用扫描电子显微镜和X-射线衍射分析了电沉积物中晶体特点并与珊瑚骨骼进行了比较。结果发现,随着电流密度增大,电沉积物质量增加,电流密度为600 m A/m2条件下电沉积物形成的速率与南海的滨珊瑚的生长速率相当。在各个电流密度梯度条件下形成的晶体均与珊瑚骨骼的晶体结构相似。较低电流密度下电沉积物中碳酸钙比例较高。其中,在电流密度为600 m A/m2的条件下,形成的沉积物碳酸钙文石比例最高,和珊瑚骨骼晶体最为接近。本研究为促珊瑚生长的电沉积技术提供了基础数据和理论。

Electrodeposition technique can be used for the restoration of the reef, but the relationship between the current conditions and the formation rate of the electrodeposit is rarely studied. Researches on the crystal structure of the electrodeposit are even less. Hence, this paper aims to explore the characteristics of calcium carbonate crystal in the electrodeposit forming at different electrical current density in seawater, and compare the crystal of the elec-trodeposit with the coral skeleton crystal. In this experiment, four groups of current density gradient （300, 600, 900 and 1200 mA/m2） were setted up. 5 days after the reaction, the electrodeposits formed on the cathode were weighed and analyzed using scanning electron microscopy and X-ray diffraction. The results showed that the weight of eletrodeposits increased with the current density. When the current density is 600 mA/m2, the formation rate of the electrodeposit is equivalent to the growth rate of the Porites andrewsi in the South China Sea. The results of scan-ning electron microscopy showed that the morphology of the crystals of the electrodeposit was found to have a similar crystal structure with the structure of the coral skeleton. The X-ray diffraction results showed that the higher proportion of calcium carbonate was present at the low current density, and reached up to the highest proportion of 84% at the current density of 600 mA/m2. This study provides basic data and theory for the electrodeposition tech-nology promoting coral growth.