水环境中营养盐磷在生物膜上吸附热力学研究

Thermodynamics study of nutrient phosphorus adsorption on surface coatings in aquatic environment

营养盐磷是浮游藻类生长繁殖乃至水体发生富营养化的最重要的限制性元素之一，受到水环境中生物膜的强烈吸附作用，探究生物膜对磷的吸附特性对水环境治理有着重要意义．采集天然水体中的生物膜吸附不同初始浓度的正磷酸盐溶液，并分析了多种环境因素对吸附作用的影响，研究了天然水体生物膜吸附磷的热力学特征，获得了多种环境因素影响下的吸附等温线．研究结果表明，天然水体生物膜吸附磷的热力学特征符合Langmuir模型；温度和振荡速率能显著影响生物膜对磷的吸附作用，25～30℃为最佳吸附温度，振荡速率越大，饱和平衡吸附量越大；pH对吸附的影响主要表现为在碱性条件下天然水体中生成的絮状体的间接作用；磷负荷是影响平衡吸附率和单位干质量生物膜平衡吸附量的主要因素，磷的总质量和生物膜的总用量是影响总吸附量的主要因素．

Nutrient phosphorus is one of key factors which restrict phytoplankton growth and reproduction, and even the occurrence of water eutrophication. Surface coatings in aquatic environment possess a strong adsorption to phosphorus. It is of great significance for water environment treatment to study the adsorption characteristics of phosphorus on surface coatings. Surface coatings sampled from several natural waters are used to absorb orthophosphate solution with different initial concentrations and the influence of several environmental factors is analyzed. Thus, the thermodynamic features are studied and the conditions are obtained. The results show that adsorption isotherms under different environmental the adsorption thermodynamics are fitted with the Langmuir model very well. Temperature and oscillation possess great impact on the adsorption process. The best adsorption temperature is 25-30℃. The maximum equilibrium adsorption capacity increases as oscillation rate increases, pH hardly affects the thermodynamic features itself, but pH has an indirect impact on phosphorus adsorption by the floe generated in an alkaline environment. Meanwhile, it is found that adsorption rate and the amount of phosphate adsorbed per unit mass of surface coatings at equilibrium are mainly affected by and the total adsorbent dosage are key factors which phosphorus load. The gross mass of phosphorus influence the total adsorption capacity.