偏高岭土基地聚合物吸附及固化铜离子的研究

发布时间：2018-06-06 22:42

本文选题：地聚合物 + 吸附　；参考：《广东工业大学》2017年硕士论文

【摘要】：地聚合物是一种具有牢笼结构的硅铝酸盐无机聚合物,在材料领域和环境领域均得到重视。由于地聚合物具有多孔结构和良好的机械性能,本研究将地聚合物作为重金属吸附剂,并对吸附的重金属在聚合物表面进行固化。偏高岭土是高岭土高温失水后的产物,富含硅铝酸盐,由其制得的地聚合物结构统一,以此为原料制备地聚合物。偏高岭土与硅酸钠、氢氧化钠和偏铝酸钠三种激活剂进行水热反应生成地聚合物,以Cu~(2+)为重金属代表,对激活剂浓度、激活剂配比、激活时间、激活温度和固液比进行优化,制备出性能优秀的地聚合物;进一步研究了优化后地聚合物的吸附过程的影响因素,包括投加量、pH、共存离子、吸附等温线、吸附动力学和吸附热力学,并借助现代分析手段,对偏高岭土以及吸附前后的地聚合物样品进行了比对;最后以吸附Cu~(2+)后的地聚合物作为基础,研究了地聚合物吸附剂本身对Cu~(2+)的固化效果。得到的主要结论如下:(1)以偏高岭土为原料,使用水热反应制备地聚合物。其中激活剂Na_2SiO_3、NaOH、NaAlO_2的最佳激活浓度分别是0.5mol/L,0.8mol/L和0.8mol/L;最佳激活剂配比是n(Na_2SiO_3):n(NaAlO_2):n(NaOH)为6:4:6;最佳激活时间是120min;最佳激活温度是160℃;最佳激活固液比是1g(偏高岭土):20mL(激活剂);地聚合物对Cu~(2+)的吸附量最高是97.67mg/g。Na_2SiO_3、NaOH、NaAlO_2三种激活剂中,NaOH和NaAlO_2对Cu~(2+)的吸附量有较大影响,Na_2SiO_3影响则相对较小。地聚合物结构在100℃后快速形成,反应时间需要120min以上,固液比以小于1g(偏高岭土):8mL(激活剂)为佳。(2)地聚合物吸附Cu~(2+)时投加量以1g/L,pH在4-5为佳;Freundlich吸附等温线能够很好地描述地聚合物吸附Cu~(2+)的规律;反应过程满足Ho公式,是一个表观二级动力学过程;吸附反应ΔH00,ΔG00,可以判定吸附是一个自发的吸热过程;偏高岭土主要由晶体物质组成,主要有多铝红柱石(Al6Si2O13),硅线石(Al2SiO5)、铁堇青石(Fe_2Al_4Si_5O_(18))和硅铝酸钙(CaAl_4Si_2O_(11)),经过水热反应后生成地聚合物(Na-PS),地聚合物吸附前后晶态并无明显变化;激活后地聚合物比表面积是偏高岭土比表面积的三倍,且地聚合物中存在更有利于吸附的介孔(2nm-50nm)。溶液中共存的金属离子和阴离子均能够对地聚合物去除Cu~(2+)产生一定影响。(3)吸附了Cu~(2+)后的地聚合物经过水热反应再次激活(即Cu~(2+)的固化)可以恢复对Cu~(2+)的吸附能力,经过5次再生后Cu~(2+)去除率在95%左右,仍有较好的Cu~(2+)去除效果,Cu~(2+)的固化率大于99%;多次在激活剂作用下原料偏高岭土中未反应的硅铝酸盐成分逐渐转化成地聚合物,但地聚合物晶态并无明显变化,仍是以Na-PS为主;经过5次再生后,地聚合物的孔径、孔体积和比表面积均有所减小。
[Abstract]:Geopolymer is a kind of organosilicite inorganic polymer with cage structure, which has been paid much attention in the field of material and environment. Because of the porous structure and good mechanical properties of the geopolymer, the geopolymer is used as a heavy metal adsorbent, and the heavy gold of the adsorption is solidified on the surface of the polymer. The product of high temperature after water loss is rich in aluminosilicate, which is prepared by the unified structure of the geopolymer. The geopolymer is prepared by three activators of sodium silicate, sodium hydroxide and sodium aluminate, which represent the Cu~ (2+) as the heavy metal, the activator concentration, the activator ratio, and the activation. Time, activation temperature and solid-liquid ratio were optimized to prepare excellent properties of geopolymers, and further studied the factors affecting the adsorption process of the optimized ground polymer, including dosage, pH, coexistence ion, adsorption isotherm, adsorption kinetics and adsorption thermodynamics, and with the aid of modern analytical methods, to the metakaolin and before and after adsorption The sample of geopolymer was compared. Finally, based on the adsorbed Cu~ (2+) geopolymer, the curing effect of the geopolymer adsorbent itself on Cu~ (2+) was studied. The main conclusions were as follows: (1) the geopolymer was used as the raw material to prepare the geopolymer by hydrothermal reaction. The best activation concentration of activator Na_2SiO_3, NaOH and NaAlO_2 was obtained. The ratio is 0.5mol/L, 0.8mol/L and 0.8mol/L; the best activator ratio is n (Na_2SiO_3): n (NaAlO_2): n (NaOH) is 6:4:6; the best activation time is 120min; the optimum activation temperature is 160; the best activation ratio is 1g (the ridge): the highest adsorption capacity of the geopolymer is the three species. Among the activators, NaOH and NaAlO_2 have a greater effect on the adsorption of Cu~ (2+), and the effect of Na_2SiO_3 is relatively small. The structure of the geopolymer is quickly formed at 100 C, the reaction time needs to be more than 120min, the solid-liquid ratio is less than 1G (high ridge soil): 8mL (activator) is better. (2) the dosage of polymer adsorbed Cu~ (2+) is 1g/L, pH in 4-5 is better. The adsorption isotherm can well describe the law of Cu~ (2+) adsorption by geopolymer, and the reaction process satisfies the Ho formula. It is a apparent two stage kinetic process. The adsorption reaction Delta H00 and delta G00 can determine that the adsorption is a spontaneous endothermic process; the metakaolin mainly consists of crystalline substance, mainly aluminum andalusite (Al6Si2O13), and sillimanite (Al2Si). O5), ferric cordierite (Fe_2Al_4Si_5O_ (18)) and calcium aluminosilicate (CaAl_4Si_2O_ (11)) formed geopolymer (Na-PS) after hydrothermal reaction, and there was no obvious change in the crystalline state before and after the adsorption of geopolymer. The specific surface area of the polymer was three times more than the surface of the partial surface of kaolin, and the mesoporous mesopore (2nm-50nm) was more favorable for adsorption in the geopolymer. The metal ions and anions coexisted in the solution can have a certain effect on the removal of Cu~ (2+) by the geopolymer. (3) the adsorption capacity of the geopolymer after the adsorption of Cu~ (2+) after the hydrothermal reaction (i.e., Cu~ (2+)) can restore the adsorption capacity of Cu~ (2+). After 5 regeneration, the removal rate of Cu~ (2+) is about 95%, and there is still a better Cu~ (2+). In addition to the effect, the curing rate of Cu~ (2+) is greater than 99%, and the unreacted aluminosilicate composition in the raw material in metakaolin is gradually transformed into a geopolymer, but the crystalline state of the geopolymer is not obviously changed, but it is still dominated by Na-PS. After 5 regeneration, the pore size, pore volume and specific surface area of the geopolymer are reduced.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703;O647.3

【相似文献】