生物吸附剂选择性吸附贵金属研究

发布时间：2018-04-19 09:06

  本文选题：蚕丝丝胶 + 柿单宁　； 参考：《西安建筑科技大学》2016年硕士论文

【摘要】：生物吸附法因效率高,成本低,不产生二次污染等优点,在贵金属回收研究中日渐受到青睐。本文分别以丝胶(SS)和柿皮粉(PP)为原料,通过接枝官能团制备了改性生物吸附剂2,5-二硫二脲改性丝胶(BTU-SS)和2,5-二巯基噻二唑改性柿皮(DMTD-PP),并采用红外光谱、Zeta电位、元素分析等分析手段对生物吸附剂进行了表征。实验对比研究了改性前后生物吸附剂对贵金属酸浸液中Au(Ⅲ)和Ag(Ⅰ)的吸附行为,并通过静态实验考察了吸附时间、吸附剂投加量、p H值、温度等因素对吸附行为的影响,吸附剂的再生利用性能及其在多组分体系中对Au(Ⅲ)和Ag(Ⅰ)的选择性吸附性能,通过动态吸附实验研究了生物吸附剂从五组分酸浸液中选择性分离Au(Ⅲ)和Ag(Ⅰ)的可能性,并对吸附动力学和热力学进行了分析,对生物吸附机理也进行了初步探讨。主要结果如下:(1)在p H1.0-6.0范围,BTU-SS和SS对Ag(Ⅰ)吸附率随着p H升高而增大。在单组分Ag(Ⅰ)溶液中,p H5.0时,BTU-SS和SS对Ag(Ⅰ)的平衡吸附率分别为98.3%和58.5%,吸附容量分别为30.3 mg?g-1和18.0 mg?g-1。在Ag(Ⅰ)-Cu(Ⅱ)-Zn(Ⅱ)及Ag(Ⅰ)-Cu(Ⅱ)-Zn(Ⅱ)-Ni(Ⅱ)-Pb(Ⅱ)溶液中,p H5.0时,BTU-SS对Ag(Ⅰ)的吸附率分别高达96.9%和94.0%,而对其它贱金属离子则很少吸附,显示出对Ag(Ⅰ)良好的吸附选择性。SS尽管对其它贱金属离子吸附率也较低,但在上述两种溶液中,SS对Ag(Ⅰ)的吸附率仅为38.7%和32.0%。吸附动力学表明,吸附剂对Ag(Ⅰ)的吸附符合准二级动力学模型,吸附过程为化学吸附,吸附过程活化能Ea(BTU-SS)=47.67 k J?mol-1,Ea(SS)=53.27 k J?mol-1。吸附热力学表明吸附过程为放热的自发过程。25℃吸附平衡时,Ag(Ⅰ)在固液两相的分配系数为ΘDK(BTU-SS)=16634.6,ΘDK(SS)=403.3。(2)25℃,p H3.0时,PP和DMTD-PP对Au(Ⅲ)的吸附率分别为37.3%和98.2%,吸附容量分别为11.9 mg?g-1和31.4 mg?g-1。DMTD-PP可高效选择吸附Au(Ⅲ)-Cu(Ⅱ)-Zn(Ⅱ)-Ni(Ⅱ)-Pb(Ⅱ)酸浸液中的Au(Ⅲ),p H3.0时,Au(Ⅲ)的吸附率为97.7%,而对其它贱金属离子吸附率均不足5%。DMTD-PP对Au(Ⅲ)的吸附符合准二级动力学模型,吸附过程为化学吸附,吸附过程活化能Ea(DMTD-PP)=101.1 k J?mol-1。吸附热力学表明吸附过程为吸热的自发过程。25℃吸附平衡时,Au(Ⅲ)在固液两相的分配系数为ΘDK( DMTD-PP)= 17580.9。(3)动态吸附实验表明,BTU-SS和DMTD-PP对Ag(Ⅰ)和Au(Ⅲ)具有较强的亲合力。BTU-SS吸附Ag(Ⅰ)在130 B.V.(13 h)发生穿透,250 B.V.(25 h)达到饱和,而Ag(Ⅰ)以外的贱金属离子迅速到达穿透点。硝酸-硫脲混合液洗脱2 h,Ag(Ⅰ)的浓缩因子为4.9,8 h内解吸率达92.2%;DMTD-PP吸附Au(Ⅲ)在255.6 B.V.(23h)发生穿透,444.4 B.V.(40 h)达到饱和,盐酸-硫脲混合液洗脱2 h,Au(Ⅲ)的浓缩因子为10.22,10 h内解吸率达93.4%。因此,以BTU-SS和DMTD-PP作为吸附剂,通过吸附柱可实现Au(Ⅲ)和Ag(Ⅰ)的选择性富集以及吸附剂的再生利用。(4)生物吸附剂BTU-SS和DMTD-PP对Ag(Ⅰ)和Au(Ⅲ)的吸附机理主要表现为离子交换、静电作用和配位作用,粒子内扩散为吸附过程的速控步骤。
[Abstract]:The biological adsorption method with high efficiency, low cost, does not have two pollution and other advantages, in the study of recovering precious metals is increasingly favored. In this paper, the sericin (SS) and persimmon peel powder (PP) as raw materials, was prepared by grafting functional groups of modified biosorbent 2,5- two sulphur urea modified sericin (two BTU-SS and 2,5- two) two triazole modified mercapto thiadiazole persimmon peel (DMTD-PP), and the use of infrared spectroscopy, Zeta potential of biological adsorbent were characterized by elemental analysis and other analysis methods. Experimental study of modified adsorbent for noble metal acid leaching solution of Au (III) and Ag (I). Adsorption behavior and adsorption time were investigated through static experiments, adsorbent dosage, P value of H, temperature and other factors on the adsorption behavior, adsorption properties and recycling in the multicomponent system of Au (III) and Ag (I) the selective adsorption performance by dynamic adsorption experiment the biological 鍚搁檮鍓備粠浜旂粍鍒嗛吀娴告恫涓�椋�

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