不同海域沉积物对尿素吸附的实验模拟研究

Experimental simulation of urea adsorption on sediments in different sea areas,China

本文对采自渤海、黄海和东海3个典型海域的沉积物进行了尿素吸附/解吸的实验室模拟研究,用Freundlich吸附模型和Henry吸附模型分析了不同沉积物对尿素吸附的热力学特性,并研究了温度、沉积物粒径、有机质含量等因素对尿素在沉积物表面吸附的影响。结果表明,沉积物对尿素的吸附/解吸过程总体呈现3个阶段:快速吸附阶段(0~5h)—慢速吸附阶段(5~12h)—平衡阶段(12h之后)。当水体中的尿素浓度较低时,沉积物解吸释放尿素,随着上覆水中尿素浓度逐渐增加,沉积物对上覆水中的尿素产生吸附行为,各海区沉积物对尿素的吸附能力由强至弱依次为渤海、东海、黄海,这可能与沉积物的类型有关。Freundlich方程和Henry方程均可模拟沉积物对尿素的吸附,温度、粒径以及沉积物中有机质含量等因素均对尿素在沉积物上的吸附产生影响,随着温度升高,尿素在沉积物上的吸附量变小,沉积物粒径越小,有机质含量越高,吸附尿素的能力越强,因此,揭示尿素在沉积物表面的环境行为时,必须考虑以上因素的影响。

Typical sea areas of Bohai Sea,Yellow Sea and East China Sea were selected,and the sediments were collected to simulate experiment on adsorption and desorption of urea.The Freundlich adsorption model and the Henry adsorption model were used to analyze the thermodynamic properties of urea adsorption on different sediment surfaces.The effect of temperature,particle size and organic matter content on the adsorption of urea on the surface of sediments was studied.The results showed that three typical stages,which were quick adsorption stage(0-5 h),slow adsorption stage(5-12 h)and equilibrium stage(after 12 h),were obviously showed in adsorption and desorption curves of urea on sediments.When the urea concentration is low,the sediment desorbs and releases urea,and the sediment adsorbs the urea in the overlying water when the urea concentration gradually increases.The adsorption capacity of urea from strong to weak is the Bohai Sea,East China Sea and Yellow Sea,which may be related to the types of sediments.The Freundlich equation and the Henry equation can accurately simulate the adsorption of urea by sediments.Temperature,particle size and organic matter content all affect the adsorption of urea on the sediments.With the increase of temperature,the adsorption of urea on the sediments becomes smaller.The smaller the particle size of sediments and the higher the organic matter content,the stronger the adsorption capacity.Therefore,when revealing the environmental behavior of urea on the sediment surface,it is necessary to fully consider the influence of the above factors.