三峡库区泥沙对磷的吸附解吸特性研究

发布时间：2018-03-25 10:17

本文选题：三峡库区　切入点：泥沙　出处：《中央民族大学》2017年硕士论文

【摘要】：三峡水库运行以来,库区流速降低,营养盐增加,导致生态环境系统恶化,支流河段出现富营养化现象。磷是水体富营养化的主要限制因子,与泥沙有着很强的亲和力,泥沙磷吸附解吸所产生的"源"、"汇"效应对三峡库区富营养化过程具有重要影响。因此,研究三峡库区泥沙对磷的吸附解吸规律,对于三峡富营养化的防控和治理具有重要意义。本文首先针对当前本底吸附污染物清洗所存在的不确定性问题,通过研究不同浓度盐酸对于本底吸附污染物的清洗效果及泥沙基体结构变化,确定最优的洗沙预处理盐酸浓度。在此基础上,通过单因子控制变量实验,分别研究了扰动强度、反应温度、泥沙浓度、初始pH值等因素对泥沙磷吸附解吸特性的影响。泥沙预处理实验研究结果表明,不同浓度的盐酸清洗后,泥沙对磷的平衡吸附量各不相同,微观形貌及表面特征也发生改变;天然泥沙表面有本底吸附物质聚集、架桥形成的孔隙结构,盐酸清洗后,泥沙表面孔隙中的污染物释放,比表面积增加,但浓度超过1 mol/L的盐酸对泥沙基体结构产生较大影响;泥沙颗粒上的本底吸附磷、钙及有机质在盐酸浓度为0.5 mol/L时,基本得到去除;综合分析可得,0.5 mol/L盐酸对泥沙上本底吸附物质有良好的去除效果,且对泥沙基体几乎没有影响,是吸附实验中泥沙的预处理时最佳的盐酸浓度。泥沙对磷的吸附解吸特性实验研究表明:(1)泥沙对磷的吸附过程较好的符合准二级动力学方程,反应开始时吸附的速率较大,随着时间的推移,速率逐渐减小;饱和吸附磷的污染泥沙对磷的解吸动力学过程也分为快、慢两个阶段,符合准二级动力学模型。(2)Langmuir方程能更好的描述泥沙对磷的等温吸附行为,随着扰动强度的增加、反应温度的升高以及泥沙浓度的减少,吸附方程中最大吸附量(Qm)增加;吸附过程中△G°0、△H°0以及△S°0,说明泥沙对磷的吸附为自发吸热过程,过程中熵增加。(3)水体扰动对磷的吸附有显著影响,扰动强度越大,泥沙对磷的吸附量越大,吸附达到平衡时,250 r/min扰动强度下单位质量泥沙对磷的吸附量是静置条件下的1.39倍;在中、强度的扰动下,污染泥沙对磷的解吸随着扰动强度增强而增加,但当扰动强度较小时(如100 r/min),泥沙对磷解吸量与静置时相近,说明泥沙上磷的吸附有一定的稳定性。(4)溶液温度的升高有利于吸附反应的进行,当温度由8 ℃升高至35 ℃时,泥沙对磷的最大吸附量相应地由0.142 mg/g增加至0.207 mg/g,增加了 1.45倍;升高温度更大地促进了污染泥沙对磷的解吸,当温度由8 ℃升至35 ℃时,最大解吸量分别为0.128 mg/g与0.198 mg/g,增加了 1.54倍。(5)随着泥沙浓度的增加,单位质量泥沙对磷的吸附量减少,单位污染泥沙对磷的解吸量同样减少,表现出"固体浓度效应",但泥沙对水体磷浓度的影响增强。(6)随着溶液初始pH值增加,单位质量泥沙对磷的吸附量呈"U"型变化趋势,中性时泥沙对磷的吸附量达到最小值,酸性及碱性条件均能促进泥沙对磷的吸附。污染泥沙中磷在中性条件下解吸量最少,碱性溶液中的解吸最为显著,当pH=12时,解吸量已经达到0.284 mg/g,是pH=7时的2.9倍。
[Abstract]:Since the operation of the Three Gorges Reservoir area, the flow rate decreases, nutrient increase leads to the deterioration of the ecological environment system, tributary of the river eutrophication. Phosphorus is the main limiting factor of eutrophication, has a strong affinity with sediment, sediment phosphorus adsorption desorption from the "source", "has an important influence on exchange process effect of the Three Gorges reservoir eutrophication. Therefore, study on the sediment in the Three Gorges Reservoir on the phosphorus adsorption desorption law, is of great significance for the prevention and control of the Three Gorges eutrophication. Firstly, to solve the uncertainty problem of the current background contaminants are clean through the study of different concentrations of hydrochloric acid, the cleaning effect and sediment matrix structure change the adsorption of pollutants, determine the sand washing pretreatment. The optimal concentration of hydrochloric acid on the basis of single factor experiment, the control variables are studied respectively, disturbance intensity, reaction temperature, mud Effect of sediment concentration, initial pH value and other factors on phosphorus adsorption desorption characteristics of sediment. Sediment pretreatment experiment results showed that different concentrations of hydrochloric acid cleaning, the balance of sediment phosphorus adsorption amount varies, microstructure and surface characteristics have changed; the bottom surface of the natural sediment adsorption material accumulation, pore structure bridge formation, hydrochloric acid cleaning after the release of pollutants in the surface sediment porosity, specific surface area increased but the concentration of more than 1 mol/L hydrochloric acid has great effects on the sediment matrix structure; sediment particles on the bottom of the phosphorus adsorption, calcium and organic matter in hydrochloric acid concentration was 0.5 mol/L, basically removal; comprehensive analysis 0.5, mol/L on the bottom of hydrochloric acid on sediment adsorption material has good removal effect, and has almost no effect on sediment matrix pretreatment in the adsorption experiments of sediment when the optimal concentration hydrochloric acid on phosphorus sediment. Experimental study on adsorption desorption characteristics showed that: (1) the adsorption process of phosphorus to sediment quasi two order kinetic equation with good adsorption, at the start of the reaction rate is higher, with the passage of time, the rate gradually decreases; pollution of sediment phosphorus adsorption desorption kinetics of phosphorus is also divided into fast and slow two stages. With the pseudo two order kinetics model. (2) the isothermal adsorption behavior of Langmuir equation can better describe the sediment on phosphorus, with the increase of disturbance intensity, the increase of reaction temperature and decrease of sediment concentration, the maximum adsorption quantity in the equation (Qm) increased; the adsorption process of Delta G 0 degrees, 0 degrees and delta H Delta S degrees 0, indicating that the adsorption of sediment on phosphorus is a spontaneous endothermic process, increase the entropy in the process. (3) the adsorption of phosphorus in water disturbance has significant effect, the greater the intensity of disturbance, the adsorption capacity of phosphorus to sediment larger adsorption reached equilibrium, 250 r/min single disturbance intensity The adsorption capacity of phosphorus to sediment quality is 1.39 times of static conditions; in the intensity of disturbance, pollution of sediment desorption of phosphorus increased with the disturbance intensity, but when the disturbance intensity was low (100 r/min), the sediment on phosphorus desorption and solution of similar standing, indicating that the adsorption of sediment phosphorus has certain stability. (4) the solution temperature favors the adsorption reaction, when the temperature increased from 8 to 35 DEG C, the maximum phosphorus adsorption on sediment correspondingly increased from 0.142 mg/g to 0.207 mg/g, an increase of 1.45 times; elevated temperature greatly promote desorption of sediment pollution P, when the temperature from 8 degrees to 35 degrees, the maximum desorption were 0.128 mg/g and 0.198 mg/g, increased 1.54 times. (5) with the increase of sediment concentration, the adsorption capacity per unit mass of phosphorus to sediment reduction, the amount of desorption of phosphorus in sediment pollution units also reduced, performance "Solid concentration effect", but the influence of sediment on phosphorus concentration increased. (6) with the increase of initial pH value of solution, adsorption capacity per unit mass of sediment on phosphorus showed "U" trend, the adsorption capacity of neutral sediment phosphorus reaches a minimum, acidic and alkaline conditions could promote the adsorption of sediment the phosphorus pollution of phosphorus in the sediment. Under neutral conditions desorption at least, desorption in alkaline solution was the most significant, when pH=12, the desorption amount has reached 0.284 mg/g, 2.9 times pH=7.

【学位授予单位】：中央民族大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV145;X524

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