磁性羥基磷酸鹽復(fù)合材料可控合成及應(yīng)用研究
發(fā)布時(shí)間：2019-03-12 13:30
【摘要】：近年來,污水的不恰當(dāng)排放給人類生存及自然環(huán)境的保護(hù)帶來了嚴(yán)峻的考驗(yàn)。羥基磷灰石作為一種廉價(jià)高效、環(huán)境友好的吸附材料而成為研究熱點(diǎn),其本身具備的離子交換特性有利于對(duì)水體中重金屬離子的吸附,但其吸附性能仍有待進(jìn)一步提高。制備方法的改善及材料的摻雜有助于提高吸附材料的綜合性能。本文采用水熱法可控制備了摻鍶碳羥基磷灰石與磁性羥基磷酸鍶復(fù)合材料,并深入探究了它們在去除水溶液中重金屬Pb~(~(2+))的行為和機(jī)理。主要研究結(jié)果如下:1、利用水熱法合成了單分散、由納米片自組裝而成的繡球花狀Sr-CHAp,具有較大的比表面積(43.54 m2·g-1)。Sr-CHAp對(duì)重金屬鉛離子具有很強(qiáng)的吸附能力,在最佳pH值(pH=3.0)的溶液中其對(duì)Pb~(~(2+))的飽和吸附量達(dá)到985.1 mg·g-1,為獲得酸性條件下高效的Pb~(~(2+))吸附劑提供可能。其吸附Pb~(~(2+))的等溫線數(shù)據(jù)與Langmuir模型相符,動(dòng)力學(xué)數(shù)據(jù)與偽二級(jí)動(dòng)力學(xué)模型相符。在酸性溶液中SrCHAp對(duì)Pb~(~(2+))的吸附主要表現(xiàn)為溶解/沉淀機(jī)理。溶液pH值不同會(huì)導(dǎo)致處理Pb~(~(2+))后產(chǎn)物有所不同,強(qiáng)酸性有助于PbHPO4的生成,而pH值為3.0-6.0時(shí)生成的主要產(chǎn)物則是Pb10(PO4)6(OH)2。2、將Fe_3O_4/SrCO_3前驅(qū)材料作為硬模板合成了Fe_3O_4/SrHAp1磁性復(fù)合材料,該復(fù)合材料由有棱的梭形棒自組裝而成,比表面積的大小是51.68 m2·g-1。另外,利用直接水熱法合成了Fe_3O_4/SrHAp2磁性材料,該材料由Fe_3O_4納米球和羥基磷酸鍶納米棒組合而成,其中Fe_3O_4平均粒徑是~150 nm,羥基磷酸鍶納米棒平均長度是~800 nm,直徑是~90 nm。3、相比于Fe_3O_4/SrHAp1,Fe_3O_4/SrHAp2具有更強(qiáng)的飽和磁化強(qiáng)度(20.6 emu·g-1),作為吸附材料更有利于磁性分離。而且Fe_3O_4/SrHAp2復(fù)合材料吸附Pb~(~(2+))的能力更佳,最大吸附量高達(dá)291.1 mg·g-1,其吸附鉛離子的平衡時(shí)間為20 min。偽二級(jí)動(dòng)力學(xué)方程能很好地描述Fe_3O_4/SrHAp2磁性復(fù)合材料吸附Pb~(~(2+))的動(dòng)力學(xué)過程,其等溫線實(shí)驗(yàn)數(shù)據(jù)符合Langmuir模型。Fe_3O_4/SrHAp2在弱酸性溶液中吸附鉛離子的過程主要源于該材料的表面吸附以及Pb~(~(2+))與Sr~(~(2+))的離子交換反應(yīng);在強(qiáng)酸性條件下吸附機(jī)理主要表現(xiàn)為溶解/沉淀機(jī)理,其中pH值為2.5時(shí),主要生成PbHPO4沉淀,而pH值達(dá)到3.0時(shí),主要產(chǎn)物則是Pb10(PO4)6(OH)2。本研究制備的摻鍶碳羥基磷灰石與磁性羥基磷酸鍶復(fù)合材料用于去除酸性水溶液中重金屬Pb~(~(2+))時(shí)展現(xiàn)出優(yōu)良的吸附性能,具有很好的應(yīng)用前景,其性能及機(jī)理研究在重金屬污水處理領(lǐng)域具有一定的參考價(jià)值。
[Abstract]:In recent years, the improper discharge of sewage has brought a severe test to the survival of human beings and the protection of natural environment. Hydroxyapatite (HA), as a cheap, efficient and environmentally friendly adsorption material, has become a research hotspot. Its ion exchange properties are beneficial to the adsorption of heavy metal ions in water, but its adsorption performance needs to be further improved. The improvement of the preparation method and the doping of the materials are helpful to improve the comprehensive properties of the adsorptive materials. Strontium-doped carbon hydroxyapatite and magnetic strontium hydroxyphosphate composites were prepared by hydrothermal method and their removal behavior and mechanism of heavy metal Pb~ (2) in aqueous solution were investigated. The main results are as follows: 1. Monodisperse and self-assembled hydrangea-like Sr-CHAp, was synthesized by hydrothermal method. The specific surface area (43.54 m ~ 2 路g ~ (- 1) of Sr-CHAp was higher than that of Pb ~ (2 +), and the adsorption capacity of Pb ~ (2 +) was very strong. The saturated adsorption capacity of Pb~ (2) reached 985.1 mg 路g-1 in the solution of optimum pH value (pH=3.0), which provided a possibility for obtaining efficient Pb~ (2) adsorbent under acidic conditions. The isotherm data of the adsorption Pb~ (2) are consistent with the Langmuir model and the kinetic data are in agreement with the pseudo-second order kinetic model. The adsorption of Pb~ (2) by SrCHAp in acidic solution is mainly due to the mechanism of dissolution / precipitation. Different solution pH values lead to different products after treatment of Pb~ (2), strong acidity contributes to the formation of PbHPO4, while Pb10 (PO4) 6 (OH) 2.2 is the main product when pH value is 3.0-6.0. Fe_3O_4/SrHAp1 magnetic composite was synthesized by using Fe_3O_4/SrCO_3 precursor as a hard template. The composite was self-assembled with ribbed fusiform rods with a specific surface area of 51.68 m2 路g-1.The surface area of the composite was 51.68 m ~ 2 路g ~ (- 1). In addition, Fe_3O_4/SrHAp2 magnetic material was synthesized by direct hydrothermal method. The material was composed of Fe_3O_4 nanospheres and strontium hydroxyphosphate nanorods, in which the average diameter of Fe_3O_4 was ~ 150 nm,. The average length of strontium hydroxyphosphate nanorods is ~ 800 nm, diameter is ~ 90 nm.3, and has stronger saturation magnetization than that of Fe_3O_4/SrHAp1,Fe_3O_4/SrHAp2 (20.6 emu 路g-1). As a adsorptive material, magnetic separation is more favorable. Moreover, the adsorption capacity of Pb~ (2) on Fe_3O_4/SrHAp2 composites is better, the maximum adsorption capacity is up to 291.1 mg 路g-1, and the equilibrium time of lead ion adsorption is 20 min.. The pseudo-second order kinetic equation can well describe the dynamic process of Pb~ (2) adsorption on Fe_3O_4/SrHAp2 magnetic composites. The isotherm experimental data are in accordance with the Langmuir model. The adsorption of lead ions by Fe _ 3O_4/SrHAp2 in weak acid solution is mainly due to the surface adsorption of the material and the ion exchange reaction between Pb~ (2) and Sr~ (2). In the strong acid condition, the adsorption mechanism is mainly the dissolution / precipitation mechanism, in which the pH value is 2.5, the main formation of PbHPO4 precipitation, and when the pH value is 3.0, the main product is Pb10 (PO4) 6 (OH) 路2. In this study, strontium-doped carbon hydroxyapatite and magnetic strontium hydroxyphosphate composites show excellent adsorption properties for removing heavy metal Pb~ (2) in acidic aqueous solution, and have good application prospects. The study of its performance and mechanism has certain reference value in the field of heavy metal wastewater treatment.
【學(xué)位授予單位】：寧波大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB33
本文編號(hào)：2438826
[Abstract]:In recent years, the improper discharge of sewage has brought a severe test to the survival of human beings and the protection of natural environment. Hydroxyapatite (HA), as a cheap, efficient and environmentally friendly adsorption material, has become a research hotspot. Its ion exchange properties are beneficial to the adsorption of heavy metal ions in water, but its adsorption performance needs to be further improved. The improvement of the preparation method and the doping of the materials are helpful to improve the comprehensive properties of the adsorptive materials. Strontium-doped carbon hydroxyapatite and magnetic strontium hydroxyphosphate composites were prepared by hydrothermal method and their removal behavior and mechanism of heavy metal Pb~ (2) in aqueous solution were investigated. The main results are as follows: 1. Monodisperse and self-assembled hydrangea-like Sr-CHAp, was synthesized by hydrothermal method. The specific surface area (43.54 m ~ 2 路g ~ (- 1) of Sr-CHAp was higher than that of Pb ~ (2 +), and the adsorption capacity of Pb ~ (2 +) was very strong. The saturated adsorption capacity of Pb~ (2) reached 985.1 mg 路g-1 in the solution of optimum pH value (pH=3.0), which provided a possibility for obtaining efficient Pb~ (2) adsorbent under acidic conditions. The isotherm data of the adsorption Pb~ (2) are consistent with the Langmuir model and the kinetic data are in agreement with the pseudo-second order kinetic model. The adsorption of Pb~ (2) by SrCHAp in acidic solution is mainly due to the mechanism of dissolution / precipitation. Different solution pH values lead to different products after treatment of Pb~ (2), strong acidity contributes to the formation of PbHPO4, while Pb10 (PO4) 6 (OH) 2.2 is the main product when pH value is 3.0-6.0. Fe_3O_4/SrHAp1 magnetic composite was synthesized by using Fe_3O_4/SrCO_3 precursor as a hard template. The composite was self-assembled with ribbed fusiform rods with a specific surface area of 51.68 m2 路g-1.The surface area of the composite was 51.68 m ~ 2 路g ~ (- 1). In addition, Fe_3O_4/SrHAp2 magnetic material was synthesized by direct hydrothermal method. The material was composed of Fe_3O_4 nanospheres and strontium hydroxyphosphate nanorods, in which the average diameter of Fe_3O_4 was ~ 150 nm,. The average length of strontium hydroxyphosphate nanorods is ~ 800 nm, diameter is ~ 90 nm.3, and has stronger saturation magnetization than that of Fe_3O_4/SrHAp1,Fe_3O_4/SrHAp2 (20.6 emu 路g-1). As a adsorptive material, magnetic separation is more favorable. Moreover, the adsorption capacity of Pb~ (2) on Fe_3O_4/SrHAp2 composites is better, the maximum adsorption capacity is up to 291.1 mg 路g-1, and the equilibrium time of lead ion adsorption is 20 min.. The pseudo-second order kinetic equation can well describe the dynamic process of Pb~ (2) adsorption on Fe_3O_4/SrHAp2 magnetic composites. The isotherm experimental data are in accordance with the Langmuir model. The adsorption of lead ions by Fe _ 3O_4/SrHAp2 in weak acid solution is mainly due to the surface adsorption of the material and the ion exchange reaction between Pb~ (2) and Sr~ (2). In the strong acid condition, the adsorption mechanism is mainly the dissolution / precipitation mechanism, in which the pH value is 2.5, the main formation of PbHPO4 precipitation, and when the pH value is 3.0, the main product is Pb10 (PO4) 6 (OH) 路2. In this study, strontium-doped carbon hydroxyapatite and magnetic strontium hydroxyphosphate composites show excellent adsorption properties for removing heavy metal Pb~ (2) in acidic aqueous solution, and have good application prospects. The study of its performance and mechanism has certain reference value in the field of heavy metal wastewater treatment.
【學(xué)位授予單位】：寧波大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB33
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