【作者】 祝春水；

【导师】 王丽萍；

【作者基本信息】 中国矿业大学 ， 环境工程， 2012， 博士

【摘要】 重金属污染事故频发，使其成为全社会持续高度关注的环境热点问题之一。吸附法具有投资少、操作简单、选择性好、不产生二次污染等优点，是中低浓度重金属废水处理的常用方法。但在高盐废水中，吸附过程往往受到共存干扰离子的影响，传统吸附剂的吸附容量较低。针对这一矛盾，本论文开展磷酸氢锡系列无机新型高效吸附材料的开发和应用研究。关于磷酸氢锡吸附特性及机理研究，目前开展的很少。关于磷酸氢锡的固定化理论及应用等方面的研究也未见报道。本论文以模拟水热合成法和液相沉淀法分别合成得到晶体磷酸氢锡、无定形磷酸氢锡，采用平衡吸附法分别研究了单离子、双离子和三离子体系中对水溶液中Pb（II）、Cu（II）和Zn（II）的吸附性能，考察了高盐介质对吸附性能的影响，综合运用XRD、SEM、TEM、FT-IR、TG、比表面积和孔隙率测定、电位滴定等技术手段研究了两种材料的结构和表面化学特征，揭示了磷酸氢锡材料吸附重金属离子的机理。另分别采用三种主要成分均为SiO₂的材料负载无定形磷酸氢锡，考察了这些固定化材料在模拟海水中的吸附性能。取得了以下主要结果：晶体磷酸氢锡和无定形磷酸氢锡对三种离子的选择性吸附顺序为Pb（II）>Cu（II）>Zn（II），这主要与金属离子的水化热有关。通过FT-IR、XRD、电位滴定分析，结合热力学参数计算，揭示了吸附机理为化学吸附，主要是磷酸氢锡中的H+与重金属离子进行离子交换。由于无定形磷酸氢锡的比表面积大，是晶体磷酸氢锡的5.13倍，而且氢原子不受相邻层间原子之间的作用力、自由度较大，因而无定形磷酸氢锡的吸附性能显著优于晶体磷酸氢锡。硅藻土中无定形磷酸氢锡的负载量为170mg/g，负载后的总孔容与比表面积均大大下降。吸附Pb（II）、Cu（II）和Zn（II）的等温吸附数据符合Freundlich模型，吸附Pb（II）时孔内扩散是速控步骤，吸附Cu（II）和Zn（II）时由液膜扩散和孔内扩散共同控制。在接近海水浓度的0.6mol/L NaCl溶液中，Pb（II）、Cu（II）和Zn（II）的吸附量分别达到13.9mg/g、3.95mg/g和3.74mg/g（初始浓度50mg/L,50mL），且吸附后的材料可以用0.5mol/L的HCl溶液再生，表明该材料具有去除高盐介质中重金属离子的潜能。粗孔微球硅胶中无定形磷酸氢锡的负载量为92.6mg/g，负载后材料的孔径以中孔为主，比表面积急剧下降，只有1.163m²/g。材料用量为2.0g （对应高度5.3cm）时吸附50mg/L的Pb（II）、Cu（II）和Zn（II）溶液，穿透时间分别达到30.55h、6.17h、4.9h，对应吸附量分别为10.4mg/g，2.88mg/g和2.47mg/g。溶胶-凝胶法原位合成的SiO₂负载无定形磷酸氢锡材料孔隙率高，孔径分布窄（主要集中在2-10nm范围），比表面积达到513m²/g，无定形磷酸氢锡在SiO₂网络上负载均匀，负载量为96.4mg/g。在淡水介质中，对Pb（II）、Cu（II）和Zn（II）的饱和吸附量分别为30.02mg/g、27.59mg/g、25.12mg/g；材料用量为1.0g （对应高度2.7cm）、吸附浓度为4.5mg/L时吸附Pb（II）、Cu（II）和Zn（II）离子溶液，穿透时间分别达到39.85h、10.07h、5.45h。在接近海水浓度的0.6mol/L NaCl溶液中表现出较好的吸附性能，对Pb（II）、Cu（II）和Zn（II）的吸附量分别达到12.82mg/g、4.39mg/g和3.37mg/g。人工海水介质下的试验中，吸附三种离子的穿透时间分别为5533min、8330min和22min，性能优异，在去除养殖海水中的重金属离子方面具有较好的应用潜力。该论文有图115幅，表41个，参考文献246篇。更多还原

【Abstract】 Freuquent heavy metal pollution events have made it a major environmental problem inthe whole society. Owing to the merits of smaller investments, easy to operation, high selectiveadsorption, no secondary pollution, adsorption has become a common method for the removalof heavy metal in waste water with moderate and low concentration. However, the adsorptionprocess is affected by coexisted ions in high salinity waste water and traditional adsorbentshave poor adsorption capacity. Aiming to this problem, study to explore new inorganic andefficient material was conducted in this dissertation. Study on the adsorption property andmechanism with tin(IV) hydrogen phosphate (abbr. SnP) is rather incomplete and study on thefixation and its application has never been reported.In this dissertation, crystalline and amorphous SnP were synthesized by modifiedhydrothermal method and liquid-phase precipitation method, respectively. Batch experimentswere used to examine the adsorption property for Pb(II), Cu(II), and Zn(II) at single ion system,binary ions system, and ternary ions system, respectively. Multiple detection techniques, XRD,SEM, TEM, FT-IR, TG, and specific surface area, were employed to characterize the sampleand understand the surface chemistry. Mechanism of heavy metal removal by SnP wasinvestigated by thermodynamics analysis and potentiometric titration along withabove-mentioned methods. The immobilization of amorphous SnP was conducted andexperiments were carried out in salinity water to investigate the adsorption property. Mainresults were given as follow:The selective adsorption sequence is Pb(II)>Cu(II)>Zn(II), either by crystalline SnP oramorphous SnP, which is relative to hydratation heat of heavy metal ions. The main adsorptionmechanism is ion exchange. These two materials all exhibited favorable behavior in highsalinity media. The material used can be regenerated by dilute HCl solution. However,amorphous SnP presented much better adsorption property than crystalline one, activatedcarbon, and several ion exchange resins. The reason for this phenomenon may lie in the largespecific surface area (four times larger than crystalline SnP), less acting force of hydrogen atom,and larger free degree.The amorphous SnP loaded on the diatomite is170mg/g. The total pore volume andspecific surface area of diatomite both decreases greatly after the loading. The equilibrium datafollows Freundlich model well. The main adsorption mechanism is chemical sorption.Intra-particle diffusion is the reaction rate control step when adsorbing Pb(II). The adsorptionamount is13.9mg/g,3.75mg/g, and3.74mg/g under the conditions of initial concentration50 mg/L and volume50mL in the media of0.6mol/L NaCl solutions. The composite material canbe regenerated with HCl solution and so has the potential for the practice of heavy metalsequestration in high salinity media.The amorphous SnP loaded on the macro-porous silica gel is92.6mg/g. In the columnadsorption, the breakthrough time is30.55h,6.17h,4.9h, and corresponding adsorptioncapacity was10.4mg/g,2.88mg/g,2.47mg/g, for Pb(II), Cu(II), and Zn(II), respectively underthe conditions of initial concentration50mg/L, adsorbent mass2.0g (corresponding bed height5.3cm). The material after column adsorption can also be regenerated, while the adsorptionproperty will be subjected to declination by a small margin. The breakthrough time predictedwith Yoon-Nelson and BDST model can serve as a reference in actual operation.Amorphous SnP-SiO2composite prepared by gel-sol method in-situ possesses large specificsurface area (513m2/g) and abundant pore. The load amount is96.4mg/g, slightly larger thanthat of amorphous SnP loaded on the macro-porous silica gel. Adsorption behavior followsFreundlich model well. The main adsorption mechanism is chemical sorption. In the fresh watermedia, the breakthrough time is39.85h,10.07h,5.45h for Pb(II), Cu(II), and Zn(II),respectively under the conditions of initial concentration4.5mg/L, adsorbent mass1.0g(corresponding bed height2.7cm). In the media of artificial sea water, the breakthrough time is5533min,8330min, and22min. These results demonstrate a new material with excellentadsorption property and bright future for the potential application in sequestering heavy metalsin high salinity waste water.*There are115figures,41tables, and246references.更多还原