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题名:
生物基复合材料对稀土和金的吸附性能研究
作者: 王福春
学位类别: 博士
答辩日期: 2014-06
授予单位: 中国科学院研究生院
导师: 刘会洲
关键词: 生物质吸附剂  ;  稀土  ;  贵金属  ;  吸附  ;  离子交换
其他题名: Adsorptive Properties of Rare Earth(III) and Gold(III) on Novel Biomass-Based Adsorbent Composites
学位专业: 化学工艺
中文摘要: 从稀溶液中吸附回收金属离子是一种绿色高效的方法,尤其针对稀贵金属,如稀土和贵金属,具有重要的环保意义和经济效益。生物吸附法以生物质为吸附剂,具有原料来源广泛、种类繁多、成本低廉、生物相容的特性。合成的吸附剂无毒无害、易于生物降解。更重要的是生物质吸附剂含有丰富的羧基、氨基、羟基等活性官能团,可以络合金属离子也便于吸附剂的进一步修饰,有望成为传统吸附材料的补充或替代。本论文选择三价稀土离子 (如Nd(III)) 和贵金属离子 (如Au(III)) 作为模型金属离子,着眼于提高生物质吸附剂的稳定性、吸附容量和分离选择性,开展生物吸附回收分离溶液中金属离子的应用基础研究,进一步丰富金属离子的生物吸附机理基础理论研究 (1) 首次采用溶胶-凝胶法,一步合成了SiO2包埋O-CMCH的复合生物质吸附剂 (SiO2/CMCH)。发现O-CMCH固定化可以提高O-CMCH对Nd(III) 吸附能力,自由-NH2和-COO-对Nd(III) 的配位有明显的协同效应。 (2) 首次采用溶胶-凝胶法一步合成了包埋纳米二氧化硅的海藻酸钙复合吸附剂 (ALG-SiO2),纳米二氧化硅包埋可以显著改善海藻酸钙基吸附剂的水溶胀性和机械强度,吸附剂循环性能优良,并可简化液固分离流程;首次合成了以海藻酸钙为核以硅酸钙为壳并包埋萃取剂P507的复合吸附剂 (ALG-CaSiO3-P507),加入P507可以提高稀土的吸附容量,显著提高吸附剂对相邻稀土元素之间的分离因素以及Nd(III) 与非稀土的分离因素,硅酸钙外壳可以缓解吸附剂对P507的释放,提高吸附剂的循环性能。首次合成了包埋聚谷氨酸的海藻酸钙复合吸附剂 (ALG-PGA),包埋聚谷氨酸可以显著提高吸附剂对稀土的吸附容量,与文献比较,ALG-PGA是对Nd(III) 吸附容量最高的吸附剂,包埋PGA可以提高稀土与非稀土离子的分离因子,并且大分子PGA不会泄露,循环性能优良。首次提出ALG基吸附剂对镧系元素能表现出明显的凸型“四分组效应”。吸附机理是-COOH和-POOH起作用的阳离子交换吸附机理,同时PGA中的-HN-C=O有协同配位效应。 (3) 首次采用水热碳球对溶液中的金离子进行回收。金的吸附属于络合-还原吸附机理,生成的单质金纳米颗粒将可以直接焚烧回收也可用酸性硫脲解吸后回收,吸附剂经过碱活化后可再生。CMS-M能高选择性地将金从贱金属和其他贵金属的盐酸介质中分离出来,分离因子在1000以上。采用还原与吸附耦合的方法,可以大大提高吸附剂对金的吸附容量也可以改善还原法对金回收率不高的缺点,简化液固分离流程。 (4) 首次采用玉米秸秆、纸和棉花为原材料,分别通过碱活化、NaIO4选择性氧化以及氨基硫脲修饰成功地制备了硫脲修饰的生物质吸附剂,硫脲修饰可以显著提高金的吸附容量。Au(III) 的吸附主要属于络合-还原吸附机理。在高酸度下,AT-S能高选择性地将金从贱金属 (如Co(II)、Cu(II)、Ni(II))和Rh(III) 的盐酸介质中分离出来。添加EDTA后,可以在整个实验pH范围内实现与Co(II)、Cu(II)、Ni(II)和Rh(III) 的有效分离。在25℃下,AT-S对Au(III)的饱和吸附量为21.4 mmol/g,与文献比较,AT-S是Au(III) 吸附容量最高的吸附剂。负载了金的AT-S-Au用酸性硫脲溶液可实现Au(III) 的解吸,并可实现AT-S的循环再生。
英文摘要: It is a high efficient and green technology to recover and separate of metal ions from complicated dilute aqueous solution by solid-liquid adsorption, especially for rare and precious metals, not only for the benefit of environment protection but also with great economic value. Biosorption is considered as a potential supplementary or substitute technology for the recovery of metals from solutions. (1) novel carboxymethyl chitosan (O-CMCH) with -COOH and -NH2 adsorbents entrapped by silica gel (abbr. as SiO2/CMCH) has been prepared by one step sol-gel method. Cation exchange between Nd(III) and -COOH are the primary adsorption mechanism, at the same time -NH2 has the obvious synergistic coordination effect. Complete desorption can be reached when the concentration of HCl is more than 0.1 M. (2) Novel Ca2+ crosslinked alginate (ALG) hybrid beads including ALG doping with nano SiO2 (abbr. as ALG-SiO2), ALG core containing extractant P507 with CaSiO3 shell (ALG-CaSiO3-P507), and ALG entrapped γ-poly glutamic acid (PGA) with ultra-high molecular weight (ALG-PGA) have been prepared. For the whole lanthanides, it exhibits a distinct ‘tetrad effect’ with the increasing atomic number. The doped SiO2 can enhance the mechanical strength of the beads and reduce the swelling properties of the hybrid adsorbents. The adsorption capacity can be improved by adding P507 and PGA, especially PGA. The selectivity among rare earths and selectivities between Nd(III) and non rare earths can be increased by adding P507 and PGA, especially P507. The leaking rate of P507 can be delayed and reusability have been improved owing to the introduction of CaSiO3 crust. ALG-SiO2 and ALG-PGA show no observable loss and leaking of ionophores during the adsorption process. Fast desorption of Nd(III) can be reached when the concentration of HCl is more than 0.1 M within 20 min. Cation exchange between Nd(III) and -COOH in ALG and PGA and -POOH in P507 is proposed as the main adsorption mechanism, and besides -NH-C=O in PGA is believed to have the synergistic coordination effect. (3) Adsorption behaviors and mechanism of Au(III) from aqueous acidic chloride media with the hydrothermal carbon microspheres (CMS), which are prepared from saccharides by hydrothermal method, have been investigated. Highly selective adsorption tawards Au(III) over Pt(IV), Pd(II), Rh(III) and part of base metals including Fe(III), Co(II), Cu(II), Ni(II) from aqueous acidic chloride media can be achieved via monodisperse CMS. Taking glycine as an assistant reductant, the adsorption efficiency with carbon microspheres can be improved effectively compared with the system of single carbon microspheres or single glycine. Such as, the adsorption capacities of Au(III) by CMS can increase up to 11.2 from 2.13 mmol/g at 25℃ in the presence of 0.06 M glycine. The maximum recovery efficiency of Au(III) can increase from ~ 87% to ~ 99% by adding 10 mg CMS into glycine system. Besides, the solid-liquid seperation process can be facilitated a lot by adding CMS. Crystalline structure, XRD, FTIR and SEM images of the CMS and CMS-Au were analyzed, which demonstrates that Au(III) is reduced to elementary gold and fixed on the surface of the CMS. The loaded gold on the surface of CMS can be desorbed by acidic thiourea solution and the sorbents can reused after reactivation by NaOH solution. (4) Novel biomass gels with aminothiourea groups synthesized from corn stalk, paper and cotton abbreviated as AT-S, AT-P, and AT-C, have been prepared for the first time. The maximum loading capacities are evaluated as up to 21.4, 19.0, and 3.28 mmol/g at 25℃ for AT-S, AT-P, and AT-C, respectively. At pH < 2, the gel was found to be highly selective for Au(III) over other metals (e.g. Rh, Cu, Co and Ni), especially, the addition of EDTA into the aqueous phase can greatly enhance the separation effect during the whole pH range. The adsorption process belongs to typical chelation-reduction reaction, where Au(III) ha
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ipe.ac.cn/handle/122111/15557
Appears in Collections:研究所(批量导入)_学位论文

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Recommended Citation:
王福春. 生物基复合材料对稀土和金的吸附性能研究[D]. 中国科学院研究生院. 2014.
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