本文選題：層狀雙金屬氫氧化物 + 硫酸根��； 參考：《太原理工大學(xué)》2015年博士論文

【摘要】：我國(guó)高硫酸根、高氟離子地下水分布范圍較廣，，未經(jīng)處理直接飲用會(huì)引起健康問(wèn)題�！渡铒嬘盟l(wèi)生標(biāo)準(zhǔn)》（GB5749-2006）要求硫酸根濃度不超過(guò)250mg/L，氟含量應(yīng)小于1.0mg/L。常規(guī)處理方法存在去除效率低、工藝流程長(zhǎng)、運(yùn)行和維護(hù)成本高等缺陷。吸附法因具有處理工藝簡(jiǎn)單、適應(yīng)范圍廣而受人重視，其中吸附材料是吸附污染控制技術(shù)的關(guān)鍵部分和核心基礎(chǔ)。層狀金屬氫氧化物作為典型的陰離子吸附劑在處理陰離子方面具有獨(dú)特優(yōu)勢(shì)。因此本課題采用焙燒的Mg/Fe層狀金屬氫氧化物處理硫酸根離子，淀粉穩(wěn)定化的Mg/Al層狀金屬氫氧化物處理氟離子，焙燒的Mg/Fe層狀金屬氫氧化物同時(shí)處理硫酸根離子和氟離子。主要研究?jī)?nèi)容和結(jié)論如下： （1）采用共沉淀法制備了晶相單一的Mg/Fe層狀金屬氫氧化物（Mg/FeLDHs），400℃焙燒后得到產(chǎn)物Mg/Fe CLDH。Mg/Fe LDHs和Mg/Fe CLDH用ICP、元素分析、XRD、FT-IR、TG-DSC、BET和SEM進(jìn)行表征。結(jié)果表明：Mg/Fe LDHs具有典型的層狀結(jié)構(gòu)，Mg/Fe CLDH為金屬氧化物結(jié)構(gòu)。Mg/Fe CLDH比表面積和孔容都比Mg/Fe LDH有所增加，SEM顯示有微小團(tuán)聚。吸附實(shí)驗(yàn)表明Mg、Fe摩爾比為3:1，焙燒溫度為400℃的Mg/Fe CLDH表現(xiàn)出高效的吸附硫酸根離子能力。等溫吸附研究表明Mg/Fe CLDH去除水體中硫酸根滿(mǎn)足Langmuir等溫吸附模型，說(shuō)明吸附過(guò)程為單層吸附。KL值大于0，表明吸附為優(yōu)先吸附。熱力學(xué)分析表明不同溫度下吉布斯自由能△G0分別為-20.67KJ/mol、-22.02KJ/mol、-23.02KJ/mol，說(shuō)明吸附過(guò)程是自發(fā)的；標(biāo)準(zhǔn)焓變△H0為15.01KJ/mol，說(shuō)明反應(yīng)是吸熱的；標(biāo)準(zhǔn)熵變△S0為14.18J/(mol·K)，說(shuō)明吸附時(shí)固液界面是隨機(jī)的。動(dòng)力學(xué)吸附表明Mg/FeCLDH去除水體中硫酸根滿(mǎn)足擬二級(jí)動(dòng)力學(xué)模型，反應(yīng)速率常數(shù)較小，說(shuō)明反應(yīng)很快。對(duì)應(yīng)吸附階段的活化能為74.25kJ/mol，說(shuō)明主要為化學(xué)反應(yīng)控制。粒內(nèi)擴(kuò)散模型表明吸附包括從溶液相擴(kuò)散到吸附劑外表面的過(guò)程、緩慢的吸附過(guò)程和平衡過(guò)程三個(gè)階段，說(shuō)明Mg/Fe CLDH吸附模擬水中硫酸根是一復(fù)雜過(guò)程。吸附后的XRD和FT-IR表征表明Mg/Fe CLDH有效地吸附了硫酸根。在pH為3~11的變化過(guò)程中，CLDH對(duì)模擬水中硫酸根的吸附量隨pH的增大而不斷減小，但幅度不大，吸附結(jié)束后pH變?yōu)?1，表明發(fā)生了“記憶效應(yīng)”。 （2）首次將淀粉作為穩(wěn)定劑，采用共沉淀法穩(wěn)定化處理Mg/Al LDHs（S-LDH）。Mg/Al LDHs和S-LDH采用XRD、FT-IR、TG-DSC、SEM和粒度分析等表征。粒徑分析表明S-LDH粒徑較Mg/Al LDHs合成粒度尺度更小，粒徑分布范圍更窄。吸附試驗(yàn)表明淀粉含量為10mg時(shí)S-LDH吸附氟離子的能力高于沒(méi)有穩(wěn)定化的Mg/Al LDHs吸附氟離子的能力。等溫吸附研究表明，S-LDH去除模擬水中氟離子滿(mǎn)足Langmuir等溫吸附模型，去除天然水中氟離子滿(mǎn)足Freundlich等溫吸附模型，表明模擬水中氟離子和天然水中氟離子具有不同的吸附過(guò)程，這與天然水中存在的共存離子干擾有關(guān)。S-LDH去除模擬水中氟離子熱力學(xué)分析表明吸附過(guò)程是自發(fā)的，反應(yīng)是吸熱的，吸附時(shí)固液界面是隨機(jī)的。吸附動(dòng)力學(xué)滿(mǎn)足擬二級(jí)動(dòng)力學(xué)。S-LDH吸附氟離子的過(guò)程是一復(fù)雜過(guò)程，包括離子交換和表面吸附。 （3）Mg/Fe CLDH同時(shí)去除模擬水中硫酸根和氟離子的性能表明，pH值對(duì)模擬水中硫酸根去除的影響小于對(duì)氟離子的影響。等溫吸附研究表明CLDH去除模擬水中硫酸根和氟離子均滿(mǎn)足Langmuir等溫吸附模型。動(dòng)力學(xué)吸附表明CLDH去除模擬水中硫酸根和氟離子均滿(mǎn)足擬二級(jí)動(dòng)力學(xué)模型。去除硫酸根和氟離子的機(jī)理包括表面吸附、離子交換和結(jié)構(gòu)重建等。
[Abstract]:The distribution of high sulphuric acid and high fluoride ions in our country is wide, and the health problem is caused by untreated direct drinking. The hygienic standard for drinking water (GB5749-2006) requires that the concentration of sulfate is not more than 250mg/L, and the content of fluorine should be less than that of the conventional treatment method of 1.0mg/L., which has low removal efficiency, long process flow and high cost of operation and maintenance. The absorption method is the key part and core base of the adsorption pollution control technology because of its simple processing technology and wide range of adaptation. The layered metal hydroxide is a typical anion adsorbent for the treatment of anions. Because of this problem, the Mg/Fe layered metal hydrogen roasted is used in this project. The oxide treatment of sulfate radical ions, the stabilized Mg/Al layered metal hydroxide for the treatment of fluorine ions, the Mg/Fe layered metal hydroxide calcined at the same time treated the sulfate ion and fluorine ions. The main contents and conclusions are as follows:
(1) a single crystalline Mg/Fe layered metal hydroxide (Mg/FeLDHs) was prepared by coprecipitation method. After calcination at 400 C, the products Mg/Fe CLDH.Mg/Fe LDHs and Mg/Fe CLDH were obtained with ICP, elemental analysis, XRD, FT-IR, TG-DSC, BET, and CLDH.Mg/Fe. The specific surface area and pore volume of CLDH are higher than that of Mg/Fe LDH, and SEM shows a small agglomeration. The adsorption experiment shows that the molar ratio of Mg to Fe is 3:1 and the Mg/Fe CLDH at the calcination temperature of 400 C shows the ability to adsorb the sulfate ion efficiently. The isothermal adsorption study shows that Mg/Fe CLDH removes sulphate from the water body to satisfy the Langmuir isothermal adsorption model, indicating the absorption of the adsorption model. The adsorption.KL value is greater than 0, indicating that adsorption is preferential adsorption. Thermodynamic analysis shows that the Gibbs free energy is -20.67KJ/mol, -22.02KJ/mol, -23.02KJ/mol respectively at different temperatures, indicating that the adsorption process is spontaneous; the standard enthalpy Delta H0 is 15.01KJ/mol, indicating that the reaction is endothermic; the standard entropy change Delta S0 is 14.18J/ (mol. K). It shows that the solid-liquid interface is random when adsorption. Kinetic adsorption shows that Mg/FeCLDH can meet the quasi two order kinetic model in the water removal. The reaction rate constant is small and the reaction is very fast. The activation energy of the corresponding adsorption stage is 74.25kJ/mol, which is mainly chemical reaction control. The intragranular diffusion model shows that the adsorption includes from solution phase. The process of diffusion to the external surface of the adsorbent, the slow adsorption process and the three phases of the equilibrium process, indicate that Mg/Fe CLDH is a complex process for the adsorption of sulfate roots in water. The adsorption of XRD and FT-IR shows that Mg/Fe CLDH adsorbed sulfate radical effectively. In the process of pH 3~11, the adsorption amount of CLDH to the simulated water is with pH. The pH decreased to 11 after the adsorption, indicating a "memory effect".
(2) starch was used as a stabilizer for the first time. Mg/Al LDHs (S-LDH).Mg/Al LDHs and S-LDH were stabilized by co precipitation method. XRD, FT-IR, TG-DSC, SEM and particle size analysis were used to characterize the starch. The particle size analysis showed that the size of S-LDH particle size was smaller than that of Mg/Al, and the size distribution was narrower. The ability of fluorine ion is higher than that of Mg/Al LDHs without stabilization. The isothermal adsorption study shows that S-LDH removal of fluorine ions in simulated water satisfies the Langmuir isothermal adsorption model, and the removal of fluorine ions in natural water satisfies the Freundlich isothermal adsorption model, which shows that fluorine ions in the simulated water and the natural water fluorine ions have different absorption. The thermodynamic analysis of.S-LDH removal of fluorine ions in the simulated water shows that the adsorption process is spontaneous, the reaction is endothermic and the adsorption of the solid-liquid interface is random. The adsorption kinetics satisfies the pseudo two kinetics.S-LDH adsorption process as a complex process, including ion exchange. And surface adsorption.
(3) the performance of Mg/Fe CLDH at the same time removal of sulphate and fluorine in simulated water shows that the effect of pH on the removal of sulfate radical in simulated water is less than that of the fluoride ion. The isothermal adsorption study shows that the removal of sulphate and fluorine ions in simulated water satisfies the Langmuir isothermal adsorption model. Kinetic adsorption shows that CLDH can remove sulfuric acid in simulated water. Both the root and the fluorine ions satisfy the pseudo two stage kinetic model. The mechanisms of removing sulfate and fluoride include surface adsorption, ion exchange and structural reconstruction.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TQ424.2;TU991.2

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