螯合—絮凝剂二硫代羧基化壳聚糖的制备及其捕集重金属性能研究
发布时间：2019-03-06 14:52
【摘要】：作为自然界的碱性天然高分子多糖,壳聚糖分子结构中含有大量的氨基、羟基和N-乙酰基活性功能团,特别是氨基N原子上的孤对电子可进入到重金属离子的空轨道上,通过配位键结合,形成稳定的螯合物,可去除许多种金属离子。对壳聚糖进行化学改性并将其应用于水处理领域已成为近年来研究的热点。论文以壳聚糖为母体,采用化学合成方法将含硫原子配位基团即二硫代羧基引入其分子结构中,制备出对重金属具有螯合和絮凝双重作用的新型高分子絮凝剂二硫代羧基化壳聚糖(DTCTS)。本文以壳聚糖(CTS)、二硫化碳(CS2)、氢氧化钠(NaOH)为原料,采用单因素实验法、正交实验法以及响应面法确定了DTCTS的最佳制备条件,并通过使用电镜扫描、紫外光谱分析、红外分析及元素分析等方法对DTCTS进行了表征。同时通过絮凝沉淀实验研究了DTCTS对重金属的捕集及除浊性能;并对DTCTS的溶液特性及存放稳定性,重金属螯合絮体的分形维数和絮体的稳定性及重金属回收性能进行了探讨。实验结果如下:(1)通过单因素实验确定影响DTCTS合成的主要因素有:反应物CTS、NaOH、CS2的摩尔比例、壳聚糖分子量和脱乙酰度、壳聚糖浓度、预反应时间及主反应时间、预反应温度及主反应温度等。(2)选择反应物摩尔比例、预反应温度及主反应温度、预反应时间及主反应时间进行正交实验,并分别以水样中Cu2+、Cd2+(投药量300mg/L和360mg/L)去除率为考察指标,得到四组不同的最优合成条件。表明正交实验的优化组合条件受离子种类和DTCTS投加量的影响。(3)选取正交实验对DTCTS合成影响最大的三个主要因素:反应物摩尔比例、预反应时间t1、主反应温度T2进行响应面实验,得出DTCTS的最佳制备条件为:反应物CTS、CS2、NaOH三者的摩尔比例为1:1.5:2,预反应温度T1为25℃,预反应时间t1为30min,主反应温度T2为60℃,主反应时间t2为120min。该优化组合条件不受离子种类的影响,具有通用性。避免针对不同重金属离子而制备不同的DTCTS,由此简化了合成过程。(4)DTCTS属于两性高分子絮凝剂,其在蒸馏水体系中的等电点pHiep为6.8,在自来水体系中的等电点pHiep为6.0。(5)DTCTS对含单一重金属(Cu2+、Cd2+、Pb2+)废水有很好的去除效果,且所需pH值较低。当pH值为6.0,在最佳投药量下,DTCTS对Cu2+、Cd2+、Pb2+的去除率均可达100%;对于含Ni2+废水DTCTS处理效果不佳,在DTCTS投加量为720mg/L时,去除率仅为86.18%,需进一步增大投药量才能达到较好的去除效果。DTCTS对于混合重金属离子的总体捕集顺序为Cu2+Pb2+Cd2+Ni2+。(6)EDTA、浊度对DTCTS捕集重金属离子的影响不同。EDTA对DTCTS除Cu2+和Cd2+均有明显的抑制作用,但通过增大DTCTS投加量可以使抑制作用减弱;浊度对DTCTS除Cu2+、Cd2+的促进或抑制作用不明显,但是当重金属离子存在时,DTCTS除浊效果明显增加。(7)DTCTS与重金属形成的螯合絮体分形维数越大,重金属的去除率越高;DTCTS螯合絮体稳定性和回收性能较好,这有利于DTCTS的实际应用。本文制备的新型高分子螯合絮凝剂DTCTS对重金属离子具有良好的捕集效果,在适宜的条件下可有效去除多种重金属离子,且絮体沉降性好,使重金属废水处理简单易行,对含重金属废水处理具有广阔的应用前景。
[Abstract]:As the basic natural high molecular polysaccharide of the natural world, the molecular structure of the chitosan contains a large amount of amino, hydroxyl and N-ethanediyl active functional groups, in particular, the lone pair of electrons on the amino N atom can enter an empty track of heavy metal ions, and the chitosan molecular structure can be combined by a coordination bond, A stable laminate can be formed to remove a wide variety of metal ions. The chemical modification of chitosan and its application in the field of water treatment have become the hot spot in recent years. In this paper, a novel high-molecular flocculant-based chitosan (DTCTS), which is a new kind of high-molecular flocculant, is prepared by introducing a sulfur-containing atom coordination group or a dithiocarbamate group into the molecular structure by adopting a chemical synthesis method as a mother material and adopting a chemical synthesis method. The best preparation conditions of DTCTS were determined by single factor experimental method, orthogonal experiment method and response surface method with chitosan (CTS), carbon disulfide (CS2) and sodium hydroxide (NaOH), and by using electron microscope scanning and ultraviolet spectrum analysis, The DTCTS was characterized by IR analysis and elemental analysis. The effects of DCTS on the collection and turbidity removal of heavy metals were studied by means of flocculation and precipitation, and the solution properties and storage stability of DTCTS, the fractal dimension of heavy metals and the floc and the stability of the floc and the recovery of heavy metals were discussed. The results of the experiment were as follows: (1) The main factors affecting the synthesis of DCTS were determined by single factor experiment: the molar ratio of CTS, NaOH, CS2, the molecular weight of chitosan, the deacetylation degree, the concentration of chitosan, the pre-reaction time, the main reaction time, the pre-reaction temperature and the main reaction temperature. (2) The molar ratio of the reactants, the pre-reaction temperature and the main reaction temperature, the pre-reaction time and the main reaction time were selected for the orthogonal experiment, and the removal rate of Cu2 +, Cd2 + (the dosage of 300 mg/ L and 360 mg/ L) in the water sample was taken as the study index, and four groups of different optimal synthesis conditions were obtained. It is shown that the optimal combination condition of the orthogonal experiment is influenced by the ionic species and the dosage of the DTCTS. and (3) selecting three main factors which have the greatest influence on the synthesis of the DTCTS by the orthogonal experiment: the molar ratio of the reactants, the pre-reaction time t1 and the main reaction temperature T2 are subjected to response surface experiments, and the optimal preparation conditions of the DCTS are as follows: the molar ratio of the reactants CTS, CS2 and NaOH is 1: 1.5:2, The pre-reaction temperature T1 is 25 DEG C, the pre-reaction time t1 is 30 min, the main reaction temperature T2 is 60 DEG C, and the main reaction time t2 is 120 min. The optimized combination condition is not influenced by the ion species, and has the universality. Different DTCTS can be prepared for different heavy metal ions, thereby simplifying the synthesis process. (4) DTCTS is a amphoteric polymeric flocculant, which has a pH of 6.8 in the distilled water system and 6.0 in the tap water system. (5) DCTS has good removal effect on wastewater containing single heavy metal (Cu2 +, Cd2 +, Pb2 +), and the required pH value is low. When the pH value is 6.0, the removal rate of the DTCTS to Cu2 +, Cd2 + and Pb2 + can be up to 100% under the optimal dosage, and the removal rate is only 86.18% for the DCTS containing Ni2 + wastewater and the dosage of DTCTS is 720 mg/ L. The total trapping order of DTCTS for mixed heavy metal ions is Cu2 + Pb2 + Cd2 + Ni2 +. (6) The influence of EDTA and turbidity on heavy metal ions trapped by DTCTS was different. EDTA has a significant inhibitory effect on DCTS except for Cu2 + and Cd2 +, but by increasing the dosage of DCTS, the inhibition of DCTS is not obvious, but the effect of turbidity on the removal of Cu2 + and Cd2 + in DCTS is not obvious, but when heavy metal ions are present, the effect of DCTS is obviously increased. (7) The larger the fractal dimension of DCTS and heavy metals, the higher the removal rate of heavy metals, and the better stability and recovery performance of DTCTS, which is beneficial to the practical application of DTCTS. The novel high-molecular compound flocculant DTCTS prepared by the invention has good trapping effect on heavy metal ions, can effectively remove various heavy metal ions under suitable conditions, and has good floc sedimentation property, so that the waste water treatment of the heavy metal is simple and feasible, And has wide application prospect to the wastewater containing heavy metal.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ317;X703
本文编号：2435625
[Abstract]:As the basic natural high molecular polysaccharide of the natural world, the molecular structure of the chitosan contains a large amount of amino, hydroxyl and N-ethanediyl active functional groups, in particular, the lone pair of electrons on the amino N atom can enter an empty track of heavy metal ions, and the chitosan molecular structure can be combined by a coordination bond, A stable laminate can be formed to remove a wide variety of metal ions. The chemical modification of chitosan and its application in the field of water treatment have become the hot spot in recent years. In this paper, a novel high-molecular flocculant-based chitosan (DTCTS), which is a new kind of high-molecular flocculant, is prepared by introducing a sulfur-containing atom coordination group or a dithiocarbamate group into the molecular structure by adopting a chemical synthesis method as a mother material and adopting a chemical synthesis method. The best preparation conditions of DTCTS were determined by single factor experimental method, orthogonal experiment method and response surface method with chitosan (CTS), carbon disulfide (CS2) and sodium hydroxide (NaOH), and by using electron microscope scanning and ultraviolet spectrum analysis, The DTCTS was characterized by IR analysis and elemental analysis. The effects of DCTS on the collection and turbidity removal of heavy metals were studied by means of flocculation and precipitation, and the solution properties and storage stability of DTCTS, the fractal dimension of heavy metals and the floc and the stability of the floc and the recovery of heavy metals were discussed. The results of the experiment were as follows: (1) The main factors affecting the synthesis of DCTS were determined by single factor experiment: the molar ratio of CTS, NaOH, CS2, the molecular weight of chitosan, the deacetylation degree, the concentration of chitosan, the pre-reaction time, the main reaction time, the pre-reaction temperature and the main reaction temperature. (2) The molar ratio of the reactants, the pre-reaction temperature and the main reaction temperature, the pre-reaction time and the main reaction time were selected for the orthogonal experiment, and the removal rate of Cu2 +, Cd2 + (the dosage of 300 mg/ L and 360 mg/ L) in the water sample was taken as the study index, and four groups of different optimal synthesis conditions were obtained. It is shown that the optimal combination condition of the orthogonal experiment is influenced by the ionic species and the dosage of the DTCTS. and (3) selecting three main factors which have the greatest influence on the synthesis of the DTCTS by the orthogonal experiment: the molar ratio of the reactants, the pre-reaction time t1 and the main reaction temperature T2 are subjected to response surface experiments, and the optimal preparation conditions of the DCTS are as follows: the molar ratio of the reactants CTS, CS2 and NaOH is 1: 1.5:2, The pre-reaction temperature T1 is 25 DEG C, the pre-reaction time t1 is 30 min, the main reaction temperature T2 is 60 DEG C, and the main reaction time t2 is 120 min. The optimized combination condition is not influenced by the ion species, and has the universality. Different DTCTS can be prepared for different heavy metal ions, thereby simplifying the synthesis process. (4) DTCTS is a amphoteric polymeric flocculant, which has a pH of 6.8 in the distilled water system and 6.0 in the tap water system. (5) DCTS has good removal effect on wastewater containing single heavy metal (Cu2 +, Cd2 +, Pb2 +), and the required pH value is low. When the pH value is 6.0, the removal rate of the DTCTS to Cu2 +, Cd2 + and Pb2 + can be up to 100% under the optimal dosage, and the removal rate is only 86.18% for the DCTS containing Ni2 + wastewater and the dosage of DTCTS is 720 mg/ L. The total trapping order of DTCTS for mixed heavy metal ions is Cu2 + Pb2 + Cd2 + Ni2 +. (6) The influence of EDTA and turbidity on heavy metal ions trapped by DTCTS was different. EDTA has a significant inhibitory effect on DCTS except for Cu2 + and Cd2 +, but by increasing the dosage of DCTS, the inhibition of DCTS is not obvious, but the effect of turbidity on the removal of Cu2 + and Cd2 + in DCTS is not obvious, but when heavy metal ions are present, the effect of DCTS is obviously increased. (7) The larger the fractal dimension of DCTS and heavy metals, the higher the removal rate of heavy metals, and the better stability and recovery performance of DTCTS, which is beneficial to the practical application of DTCTS. The novel high-molecular compound flocculant DTCTS prepared by the invention has good trapping effect on heavy metal ions, can effectively remove various heavy metal ions under suitable conditions, and has good floc sedimentation property, so that the waste water treatment of the heavy metal is simple and feasible, And has wide application prospect to the wastewater containing heavy metal.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ317;X703
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相关期刊论文 前3条
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