【作者】 张恒；

【导师】 张保平；

【作者基本信息】 武汉科技大学 ， 冶金工程， 2023， 硕士

【摘要】 钨作为当代高新技术发展的战略金属,广泛应用于材料、化工和医药等领域。传统的溶剂萃取法、化学沉淀法、膜分离法和离子交换法提取钨存在化学试剂耗量大、耗时长和成本高等缺点,离子交换法所用树脂中毒后的焚烧还会产生苯和焦油等有机污染物。本课题组前期研究发现,季铵、胺和金属离子改性的木质素对阴离子具有很好的吸附性能,但存在吸附剂的改性路线、吸附行为和机制不明确等问题。针对这些问题,本研究以木质素为原料,通过季铵化、胺化和金属化改性合成了胺/季铵木质素和Zn/多胺木质素基阴离子吸附剂并用于吸附钨。采用SEM-EDS和FTIR对合成产物进行了表征。通过对W（VI）-H₂O体系的热力学分析,探明了含钨物种的存在形态及其变化规律。通过对吸附过程参数的设计和评价,明确了吸附过程的行为。通过SEM-EDS、FTIR和XPS分析揭示了吸附过程的机制。获取了以下有意义的结论。（1）木质素经酚化、交联和氯化后进行季铵化和胺化改性,合成了胺/季铵木质素,再采用Zn Cl₂对胺/季铵木质素进行金属化改性,合成了Zn/多胺木质素。SEM-EDS和FTIR分析结果表明,两种木质素基阴离子吸附剂表面疏松多孔且含有大量的酚羟基、胺基和季铵官能团,而Zn/多胺木质素还含有锌离子活性位点。（2）W（VI）-H₂O体系热力学分析表明,pH值对钨的存在形态影响较大。在pH值由大变小的过程中,体系中的含钨物种发生WO₄^2-→W₇O₂₄^6-→H₂W₁₂O₄₀^6-的转变,在pH≤4时,溶液中的钨主要以H₂W₁₂O₄₀^6-形态存在。当[W]_T>0.1 mol·L^-1时,H₂W₁₂O₄₀^6-摩尔百分数超过99%。（3）在25℃,pH值为4,钨初始浓度为800 mg·L^-1,振荡速率为400 r/min和960 min时,1.0 g·L^-1胺/季铵木质素对钨的饱和吸附容量为421.68 mg·g^-1,4.0g·L^-1的最大吸附率为75.36%。胺/季铵木质素对钨的吸附过程遵循Langmuir吸附等温模型和准二级动力学模型,表明吸附过程为单分子层均质化学吸附。SEM-EDS、FTIR和XPS分析结果表明,胺/季铵木质素通过静电吸引、离子交换和配合反应吸附钨。（4）在25℃,pH值为2,钨初始浓度为700 mg·L^-1,振荡速率为400 r/min和720 min时,0.5 g·L^-1 Zn/多胺木质素对钨的饱和吸附容量为488.28 mg·g^-1,4.0g·L^-1的最大吸附率为92.98%。Zn/多胺木质素对钨的吸附过程遵循Langmuir吸附等温模型和准二级动力学模型,表明吸附过程为单分子层均质化学吸附。SEM-EDS、FTIR和XPS分析结果显示,Zn/多胺木质素通过静电吸引、离子交换和配合反应吸附钨。（5）在25℃,振荡速率为400 r/min和振荡时间为60 min的条件下,10 m L1.5 mol·L^-1N OH+1.0 mol·L^-1NaCl混合解吸剂对10 mg负载钨胺/季铵木质素的解吸率为47.82%,3次累计解吸率为90.34%。在振荡时间为120 min时混合解吸剂对5 mg负载钨Zn/多胺木质素的解吸率为80.96%,2次累计解吸率为94.66%。更多还原

【Abstract】 As a strategic metal for the development of contemporary high and new technology,tungsten is widely used in the fields of materials,chemical industry and medicine.The traditional methods such as solvent extraction,chemical precipitation,membrane separation and ion exchange to extract tungsten have the disadvantages of high consumption of chemical reagents,time-consuming and high cost.The incineration of the poisoned resin used for the ion exchange method will produce organic pollutants such as benzene and tar.The earlier period research discovered that quaternary ammonium,amine and metal ions had great adsorption performance for anions.However,the modification route of adsorbent,adsorption behavior and mechanism are undefined.To solve these problems,amine/quaternary ammonium lignin and Zn/polyamine lignin were synthesized by quaternization,amination and metalization of lignin and were used to adsorb tungsten in this study.The synthetic products were characterized by SEM-EDS and FTIR.The existing forms and change rules of tungsten species had been ascertained according to the thermodynamic analysis of the system of W（VI）-H₂O.The adsorption behavior was cleared through the design and evaluation of adsorption parameters.The adsorption mechanism was revealed by SEM-EDS,FTIR and XPS.The following meaningful conclusions were obtained.（1）Amine/quaternary ammonium lignin was synthesized by quaternization and amination of lignin after phenolation,crosslinking and chlorination,and then the Zn/polyamine lignin was synthesized by ZnCl₂ from amine/quaternary ammonium lignin.The results of SEM-EDS and FTIR analysis showed that the surface of the two kinds of lignin-based anion adsorbents were loose and porous and contained a large number of phenolic hydroxyl,amino and quaternary ammonium functional groups.Moreover,Zn/polyamine lignin also contained zinc ion active sites.（2）The results of the thermodynamic analysis of W（VI）-H₂O showed that the value of pH had a great influence on the existing forms of tungsten.The tungsten species in the system changed from WO₄^2-to W₇O₂₄^6-and H₂W₁₂O₄₀^6-with the decreasing of the value of pH.H₂W₁₂O₄₀^6-was the main existing form when the value of pH was less than4.The molar percentage of H₂W₁₂O₄₀^6-was greater than 99%when[W]_T was more than 0.1 mol·L^-1.（3）Under the optimum conditions of 25℃,the pH of 4,the initial tungsten concentration of 800 mg·L^-1,oscillation rate of 400 r/min and 960 min,the saturated adsorption capacity of 1.0 g·L^-1 amine/quaternary ammonium lignin for tungsten reached 421.68 mg·g^-1 and the maximum adsorption rate of 4.0 g·L^-1 amine/quaternary ammonium lignin was 75.36%.The adsorption followed Langmuir adsorption isothermal model and quasi-second-order kinetic model,which indicated that the adsorption was monolayer homogeneous chemical adsorption.The results of SEM-EDS,FTIR and XPS analysis showed that tungsten was adsorbed by electrostatic attraction,ion exchange and coordination reaction.（4）Under the optimum conditions of 25℃,the pH of 2,the initial tungsten concentration of 700 mg·L^-1,oscillation rate of 400 r/min and 720 min,the saturated adsorption capacity of 0.5 g·L^-1 Zn/polyamine lignin for tungsten was 488.28 mg·g^-1and the maximum adsorption rate of 4.0 g·L^-1 Zn/polyamine lignin reached 92.98%.The adsorption of tungsten on Zn/polyamine lignin followed the Langmuir adsorption isothermal model and quasi-second-order kinetic model,indicating that the adsorption was monolayer homogeneous chemical adsorption.The results of SEM-EDS,FTIR and XPS analysis showed that tungsten was adsorbed by electrostatic attraction,ion exchange and coordination reaction.（5）Under the optimum conditions of 25℃,oscillation rate of 400 r/min and 60 min,the desorption rate of 10 m L 1.5 mol·L^-1 NaOH+1.0 mol·L^-1 NaCl mixed desorption agent for 10 mg loaded tungstate amine/quaternary ammonium lignin reached 47.82%and the cumulative desorption rate of 3 times was 90.34%.While the desorption rate of 120 min for 5 mg loaded tungsten Zn/polyamine lignin was 80.96%and the cumulative desorption rate of 2 times was 94.66%.更多还原