【作者】 杨韬；

【导师】 余江； 邢智；

【作者基本信息】 四川大学 ， 环境工程（专业学位）， 2023， 硕士

【摘要】 沸石具有较好的吸附性能与离子交换性能,在重金属污染土壤修复方面潜力较大,而煤矸石是合成人工沸石的理想材料之一,以其为原料合成沸石可以实现大宗固废再利用,达到“以废治污”的目的。本研究基于煤矸石固体废物研制X型沸石,并对其进行有机官能团和负载金属修饰以提升其吸附性能和稳定性,获得巯基修饰X型沸石（SH-X）和载锰X型沸石（Mn-X）材料。通过吸附试验,研究沸石材料对重金属Pb²⁺、Cd²⁺和Cu²⁺的吸附效果,分析其动力学特性和等温吸附特性;通过土壤培养试验探究添加沸石材料后土壤理化性质、重金属有效态含量和赋存形态的变化;通过定量加速老化实验研究沸石材料对重金属污染土壤的长效固定性能,基于恒速和加速老化模型分析钝化材料对重金属Pb、Cd和Cu的可靠性。主要的研究结果如下:（1）基于煤矸石固体废物成功研制X型沸石,并对其进行有机官能团和负载金属修饰,得到SH-X和Mn-X材料。FT-IR谱图说明当物料投加比为7ml/g时,SH-X材料的-CH₂弯曲振动吸收峰在1465cm^-1～1340cm^-1处表现最为明显。通过在碱融反应前添加锰源进行负载修饰,综合考虑选取0.1M组别,且紫外漫反射图谱发现Mn-X在250nm处出现吸收带,表明Mn³⁺在沸石骨架中呈四面体配位状态,证明沸石骨架中锰原子的掺杂。（2）吸附试验发现当投加量为0.05 g时,X、SH-X、Mn-X对Pb²⁺的最大吸附容量分别为176.77 mg/g、192.06 mg/g、196.98 mg/g。SH-X和Mn-X对重金属的吸附效果相比X均有提升,其中Mn-X对重金属Cu²⁺的最大吸附容量相比X提升了16.2%。结果表明准二级动力学模型更能准确阐释X、SH-X、Mn-X对Cu²⁺、Pb²⁺和Cd²⁺的吸附动力学,吸附过程皆为化学吸附。等温吸附试验发现Freundlich模型更能准确地拟合SH-X和Mn-X对Cd²⁺的吸附,这表明其中的吸附行为是多分子层吸附。（3）将X、SH-X和Mn-X材料进行土壤培养实验后,土壤p H值呈现随添加量的增加而上升的趋势,并且Mn-X在2.0%添加量条件下可使土壤p H值提升15.15%。添加沸石后可大幅降低土壤中重金属有效态的含量,随着钝化材料添加量的增加,重金属Pb有效态的含量下降效果越明显;对比发现2%Mn-X对土壤中重金属的钝化效果最优,可使重金属Pb、Cd和Cu的有效态含量分别下降26.54%、14.72%和12.06%。Mn-X可有效促进土壤中可交换态重金属转化为较稳定的可还原态和残渣态。（4）加速老化过程中,Mn-X处理组毒性浸出液中Pb、Cd、Cu浓度均低于对照组。经过72年老化后,Mn-X沸石材料对重金属的固定性能均随老化时间的延长而逐渐减弱,经108年后,Mn-X对Pb、Cd的固定率相比对照组仍高于27%。老化模型拟合结果表明,加速老化模型能较好的呈现Mn-X钝化材料对重金属Pb、Cu的老化过程,而Mn-X钝化材料对重金属Cd的老化速率展现为恒速。随着老化循环周期的增加,Mn-X材料施加组部分固定的重金属重新释放到土壤中,表现为一种缓慢变化过程,导致可交换态占比上升。更多还原

【Abstract】 Zeolite has good adsorption and ion exchange properties,and has great potential in the remediation of heavy metal contaminated soil.Coal gangue is one of the ideal materials for synthesizing artificial zeolite.Using it as a raw material to synthesize zeolite can achieve the reuse of bulk solid waste and achieve the goal of"treating pollution with waste".In this study,X zeolite was prepared based on coal gangue solid waste,and modified with organic functional groups and loaded metal to improve its adsorption performance and stability,and sulfhydryl modified X zeolite（SH-X）and manganese loaded X zeolite（Mn-X）materials were obtained.The adsorption effects of zeolite materials on heavy metals Pb²⁺,Cd²⁺and Cu²⁺were studied through adsorption experiments,and their kinetic and isothermal adsorption characteristics were analyzed;Exploring the changes in soil physicochemical properties,available heavy metal content,and occurrence forms after adding zeolite materials through soil culture experiments;The long-term fixation performance of zeolite materials on heavy metal contaminated soil was studied through quantitative accelerated aging experiments,and the reliability of passivation materials on heavy metal Pb,Cd,and Cu was analyzed based on constant rate and accelerated aging models.The main research findings are as follows:（1）Based on the solid waste of coal gangue,X zeolite was successfully developed,and modified with organic functional groups and loaded metal to obtain SH-X and Mn-X materials.FT-IR spectrum shows that when the material dosage ratio is 7ml/g,the-CH₂bending vibration absorption peak of SH-X material is obvious at 1465cm^-1～1340cm^-1.By adding manganese source for loading modification before alkali melting reaction,the 0.1M group was selected comprehensively,and the absorption band of Mn-X was found at 250nm in the UV diffuse reflectance spectrum,indicating that Mn³⁺was in tetrahedral coordination state in the zeolite skeleton,which proved the doping of manganese atoms in the zeolite skeleton.（2）The adsorption test found that when the dosage was 0.05 g,the maximum adsorption capacity of X,SH-X and Mn-X for Pb²⁺was 176.77 mg/g,192.06 mg/g and 196.98 mg/g,respectively.Compared with X,the adsorption effect of SH-X and Mn-X on heavy metals is improved,and the maximum adsorption capacity of Mn-X on heavy metal Cu²⁺is 16.2%higher.The results show that the quasi-secondary kinetic model can more accurately explain the adsorption kinetics of X,SH-X and Mn-X for Cu²⁺,Pb²⁺and Cd²⁺,and the adsorption process is chemical adsorption.The isothermal adsorption test found that the Freundlich model can more accurately fit the adsorption of Cd²⁺by SH-X and Mn-X,which indicates that the adsorption behavior is multi-molecular layer adsorption.（3）After conducting soil culture experiments on X,SH-X,and Mn-X materials,the soil p H showed a trend of increasing with the addition amount,and Mn-X can increase the soil p H by 15.15%under the condition of 2.0%addition amount.The addition of zeolite can significantly reduce the content of available heavy metals in soil.With the increase of passivation material addition,the effect of decreasing the content of available heavy metal Pb is more obvious;By comparison,it was found that 2%Mn-X had the best passivation effect on heavy metals in soil,reducing the available content of heavy metals Pb,Cd,and Cu by 26.54%,14.72%,and 12.06%,respectively.Mn-X can effectively promote the transformation of exchangeable heavy metals in soil into more stable reducible and residual forms.（4）During the accelerated aging process,the concentrations of Pb,Cd,and Cu in the toxic leaching solution of the Mn-X treatment group were lower than those of the control group.After 72 years of aging,the fixation performance of Mn-X zeolite material for heavy metals gradually weakened with the extension of aging time.After108 years,the fixation rate of Mn-X for Pb and Cd was still higher than 27%in the control group.The fitting results of the aging model indicate that the accelerated aging model can better present the aging process of Mn-X passivation material on heavy metals Pb and Cu,while the aging rate of Mn-X passivation material on heavy metals Cd shows a constant rate.As the aging cycle increases,the heavy metals partially fixed by the applied component of Mn-X material are released back into the soil,exhibiting a slow change process,leading to an increase in the proportion of exchangeable states.更多还原