本文選題：三峽庫區(qū)　切入點：泥沙　出處：《中央民族大學》2017年碩士論文

【摘要】：三峽水庫運行以來,庫區(qū)流速降低,營養(yǎng)鹽增加,導致生態(tài)環(huán)境系統(tǒng)惡化,支流河段出現(xiàn)富營養(yǎng)化現(xiàn)象。磷是水體富營養(yǎng)化的主要限制因子,與泥沙有著很強的親和力,泥沙磷吸附解吸所產(chǎn)生的"源"、"匯"效應對三峽庫區(qū)富營養(yǎng)化過程具有重要影響。因此,研究三峽庫區(qū)泥沙對磷的吸附解吸規(guī)律,對于三峽富營養(yǎng)化的防控和治理具有重要意義。本文首先針對當前本底吸附污染物清洗所存在的不確定性問題,通過研究不同濃度鹽酸對于本底吸附污染物的清洗效果及泥沙基體結構變化,確定最優(yōu)的洗沙預處理鹽酸濃度。在此基礎上,通過單因子控制變量實驗,分別研究了擾動強度、反應溫度、泥沙濃度、初始pH值等因素對泥沙磷吸附解吸特性的影響。泥沙預處理實驗研究結果表明,不同濃度的鹽酸清洗后,泥沙對磷的平衡吸附量各不相同,微觀形貌及表面特征也發(fā)生改變;天然泥沙表面有本底吸附物質聚集、架橋形成的孔隙結構,鹽酸清洗后,泥沙表面孔隙中的污染物釋放,比表面積增加,但濃度超過1 mol/L的鹽酸對泥沙基體結構產(chǎn)生較大影響;泥沙顆粒上的本底吸附磷、鈣及有機質在鹽酸濃度為0.5 mol/L時,基本得到去除;綜合分析可得,0.5 mol/L鹽酸對泥沙上本底吸附物質有良好的去除效果,且對泥沙基體幾乎沒有影響,是吸附實驗中泥沙的預處理時最佳的鹽酸濃度。泥沙對磷的吸附解吸特性實驗研究表明:(1)泥沙對磷的吸附過程較好的符合準二級動力學方程,反應開始時吸附的速率較大,隨著時間的推移,速率逐漸減小;飽和吸附磷的污染泥沙對磷的解吸動力學過程也分為快、慢兩個階段,符合準二級動力學模型。(2)Langmuir方程能更好的描述泥沙對磷的等溫吸附行為,隨著擾動強度的增加、反應溫度的升高以及泥沙濃度的減少,吸附方程中最大吸附量(Qm)增加;吸附過程中△G°0、△H°0以及△S°0,說明泥沙對磷的吸附為自發(fā)吸熱過程,過程中熵增加。(3)水體擾動對磷的吸附有顯著影響,擾動強度越大,泥沙對磷的吸附量越大,吸附達到平衡時,250 r/min擾動強度下單位質量泥沙對磷的吸附量是靜置條件下的1.39倍;在中、強度的擾動下,污染泥沙對磷的解吸隨著擾動強度增強而增加,但當擾動強度較小時(如100 r/min),泥沙對磷解吸量與靜置時相近,說明泥沙上磷的吸附有一定的穩(wěn)定性。(4)溶液溫度的升高有利于吸附反應的進行,當溫度由8 ℃升高至35 ℃時,泥沙對磷的最大吸附量相應地由0.142 mg/g增加至0.207 mg/g,增加了 1.45倍;升高溫度更大地促進了污染泥沙對磷的解吸,當溫度由8 ℃升至35 ℃時,最大解吸量分別為0.128 mg/g與0.198 mg/g,增加了 1.54倍。(5)隨著泥沙濃度的增加,單位質量泥沙對磷的吸附量減少,單位污染泥沙對磷的解吸量同樣減少,表現(xiàn)出"固體濃度效應",但泥沙對水體磷濃度的影響增強。(6)隨著溶液初始pH值增加,單位質量泥沙對磷的吸附量呈"U"型變化趨勢,中性時泥沙對磷的吸附量達到最小值,酸性及堿性條件均能促進泥沙對磷的吸附。污染泥沙中磷在中性條件下解吸量最少,堿性溶液中的解吸最為顯著,當pH=12時,解吸量已經(jīng)達到0.284 mg/g,是pH=7時的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.

【學位授予單位】：中央民族大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TV145;X524

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