【作者】 刘洋；

【导师】 张丽芳；

【作者基本信息】 沈阳理工大学 ， 环境科学与工程， 2022， 硕士

【摘要】 近些年,工业废水中的重金属离子污染问题越来越严峻,引起了国内外的重视。本文以壳聚糖为基质,对其进行改性,制备出多种改性壳聚糖,并以Ni（Ⅱ）和Cr（Ⅵ）为目标污染物,探究改性后壳聚糖对重金属离子的吸附能力。本文采用共沉淀法制备四氧化三铁（Fe₃O₄）改性壳聚糖（以下简称Fe₃O₄-CTS）。以Cr（Ⅵ）为目标污染物,考察了Fe₃O₄用量、超声时间、戊二醛用量等制备条件对Fe₃O₄-CTS吸附能力的影响。采用三乙烯四胺（TETA）对磁性壳聚糖进一步改性制备出胺基改性磁性壳聚糖（以下简称TETA-Fe₃O₄-CTS）,以Cr（Ⅵ）为目标污染物,考察了环氧氯丙烷用量、TETA用量对TETA-Fe₃O₄-CTS吸附能力的影响。利用柠檬酸（CA）对壳聚糖进行改性制备出柠檬酸改性壳聚糖（以下简称CA-CTS）,以Ni（Ⅱ）为目标污染物,考察了CA用量、催化剂用量、反应时间、反应温度等对CA-CTS吸附能力的影响。实验对制备的Fe₃O₄-CTS、TETA-Fe₃O₄-CTS和CA-CTS采用扫描电镜、红外光谱等方法进行了表征分析。研究了其对重金属离子的吸附规律及其吸附动力学、吸附等温线和热力学特性。研究Fe₃O₄改性CTS时发现,当选用CTS投加量为0.4 g（以下实验该条件相同）、Fe₃O₄投加量为0.1 g、戊二醛用量为10 m L、超声破碎时间为5 min时制备出的Fe₃O₄-CTS在溶液p H值为4时对Cr（Ⅵ）的吸附能力较强,去除率为54.45%。根据扫描电镜分析发现,Fe₃O₄-CTS表面粗糙且表面存在Fe₃O₄颗粒。通过红外光谱分析发现,Fe₃O₄-CTS在波数为579 cm^-1处出现了与Fe₃O₄类似的Fe-O吸收峰,这说明制得的样品中存在Fe₃O₄。对Fe₃O₄-CTS吸附Cr（Ⅵ）过程进行了一级动力学和准二级动力学分析,发现吸附过程符合准二级动力学模型。等温吸附模型分析结果表明Langmuir模型能更好地描述Fe₃O₄-CTS对Cr（Ⅵ）的吸附行为,热力学分析表明该过程为自发吸热过程。研究TETA改性Fe₃O₄-CTS发现,当环氧氯丙烷用量为5 m L、三乙烯四胺用量为1m L时制备的TETA-Fe₃O₄-CTS在溶液p H值为4时对Cr（Ⅵ）的吸附能力较强,去除率为78.07%。红外光谱分析发现,在波数为1649 cm^-1处的峰为N-H面内弯曲振动;651 cm^-1处的峰为N-H面外弯曲振动,以上说明TETA分子的胺基引入到Fe₃O₄-CTS上。采用滴定法测定TETA-Fe₃O₄-CTS中胺基含量,测其胺基含量为5.56 mmol/g。吸附动力学模型分析表明TETA-Fe₃O₄-CTS对Cr（Ⅵ）的吸附过程符合准二级动力学模型。等温吸附模型分析表明Langmuir模型能更好地描述TETA-Fe₃O₄-CTS对Cr（Ⅵ）的吸附行为,热力学分析表明该过程为自发吸热过程。研究CA改性CTS发现,当改性反应时间为110 min,改性反应温度为120℃,催化剂磷酸二氢钠用量为0.075 g、柠檬酸用量为0.06 g时,制备的CA-CTS在溶液p H值为7时对Ni（Ⅱ）的吸附能力较强,去除率为83.11%。扫描电镜分析发现,CA-CTS表面凹凸不平、有孔隙。红外光谱分析发现,在1740 cm^-1处的峰为C=O伸缩振动,表明壳聚糖表面引入了羧基。分别用一级动力学和准二级动力学对CA-CTS吸附Ni（Ⅱ）的吸附过程进行分析,结果表明,吸附过程符合准二级动力学模型。考察了30、35和40℃下CA-CTS对Ni（Ⅱ）等温吸附,分别进行等温吸附模型和热力学分析,发现Langmuir模型能更好地描述吸附行为,且该过程为自发吸热过程。更多还原

【Abstract】 In recent years,the pollution of heavy metal ions in industrial wastewater has become more and more serious,which has attracted attention at home and abroad.In this paper,chitosan was used as the matrix to prepare a variety of modified chitosan,and Ni（Ⅱ）and Cr（Ⅵ）were used as the target pollutants to explore the adsorption capacity of modified chitosan to heavy metal ions.In this paper,chitosan modified by Fe₃O₄（Fe₃O₄-CTS）was prepared by coprecipitation method.Taking Cr（Ⅵ）as the target pollutant,the effects of preparation conditions such as Fe₃O₄ dosage,ultrasonic time and glutaraldehyde dosage on the adsorption capacity of Fe₃O₄-CTS were investigated.Using triethylene tetramine（TETA）preparation of magnetic chitosan further modified amino modified magnetic chitosan（hereinafter referred to as the TETA-Fe₃O₄-CTS）.Taking Cr（Ⅵ）as the target pollutant,the effects of epichlorohydrin dosage and TETA dosage on the adsorption capacity of TETA-Fe₃O₄-CTS were investigated.Citric acid modified chitosan（CA-CTS）was prepared by using citric acid（CA）to modify chitosan.With Ni（Ⅱ）as the target pollutant,the effects of CA dosage,catalyst dosage,reaction time and reaction temperature on the adsorption capacity of CA-CTS were investigated.The Fe₃O₄-CTS,TETA-Fe₃O₄-CTS and CA-CTS were characterized and analyzed by SEM and IR.The adsorption kinetics,isotherms and thermodynamic characteristics of heavy metal ions were studied.When the modification of CTS by Fe₃O₄ was studied,it was found that when the selected CTS dosage is 0.4g（same condition in the following experiments）,the dosage of Fe₃O₄ was 0.1 g,the dosage of glutaraldehyde was 10 m L,and the ultrasonic crushing time was 5 min,the Fe₃O₄-CTS prepared had a strong adsorption capacity for Cr（Ⅵ）at the p H value of 4,and the removal rate was 54.45%.The surface of Fe₃O₄-CTS was rough and Fe₃O₄ particles existed on the surface.It was found by infrared spectrum analysis that Fe₃O₄-CTS had a Fe-O similar Fe₃O₄ absorption peak at wave number579 cm^-1,which indicated the presence of Fe₃O₄ in the prepared sample.The adsorption process of Cr（Ⅵ）by Fe₃O₄-CTS was analyzed by first-order kinetics and quasi-second-order kinetics,and it was found that the adsorption process accords with the quasi-second-order kinetics model.The results of isothermal adsorption model analysis showed that Langmuir model could better describe the adsorption behavior of Cr（Ⅵ）on Fe₃O₄-CTS,and thermodynamic analysis showed that the process was spontaneous endothermic.The study of TETA modified Fe₃O₄-CTS showed that TETA-Fe₃O₄-CTS prepared with epichlorohydrin dosage of 5 m L and triethylenetetramine dosage of 1m L had a strong adsorption capacity for Cr（Ⅵ）at p H value of 4,and the removal rate was78.07%.The peak at wave number 1649 cm^-1 is N-H bending vibration.The peak at651 cm^-1 was N-H out-of-plane bending vibration,which indicated that the amine group of TETA molecule was introduced into Fe₃O₄-CTS.The amine group content in TETA-Fe₃O₄-CTS was determined by titration.The amine group content was 5.56 mmol/g.The analysis of adsorption kinetic model shows that the adsorption process of Cr（Ⅵ）by TETA-Fe₃O₄-CTS conforms to the quasi-second-order kinetic model.The Langmuir model can better describe the adsorption behavior of Cr（Ⅵ）on TETA-Fe₃O₄-CTS,and the thermodynamic analysis shows that the process is spontaneous endothermic.It was found that when the reaction time was 110 min,the reaction temperature was120℃,the amount of sodium dihydrogen phosphate was 0.075 g,the amount of citric acid was 0.06 g,the prepared CA-CTS had a strong adsorption capacity for Ni（Ⅱ）at the solution p H value of 7,and the removal rate was 83.11%.Scanning electron microscopy showed that the surface of CA-CTS was uneven and porous.The peak at 1740 cm^-1 was C=O stretching vibration,indicating that carboxyl group was introduced into the surface of chitosan.The adsorption process of Ni（Ⅱ）by CA-CTS was analyzed by first-order kinetics and quasi-second-order kinetics,respectively.The results show that the adsorption process accords with the quasi-second-order kinetics model.The isothermal adsorption of Ni（Ⅱ）by CA-CTS at 30℃,35℃and 40℃was investigated.The isothermal adsorption model and thermodynamic analysis were carried out respectively.It was found that Langmuir model could better describe the adsorption behavior,and the process was spontaneous endothermic.更多还原