农林废弃物—耐性真菌复合吸附剂重金属离子吸附特性与机制研究

发布时间：2018-02-26 23:34

  本文关键词： 重金属污染水体 农林废弃物 耐性真菌 复合生物吸附剂 等温吸附 吸附动力学 固定吸附床　出处：《中南林业科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：生物吸附法是一种利用生物质材料自身吸附性能去除污染物质的有效方法。利用农林废弃生物质材料和微生物菌体为原料制备的生物吸附剂去除重金属,具有广阔的应用前景。但是单一农林类废弃生物质材料在实际应用中存在吸附容量低、密度小、易漂浮等缺点,而单一微生物菌体在吸附应用中也存在造粒困难、固液分离困难等问题,导致两者难以大规模单独应用于重金属污染治理中。近年来,有关改进生物质材料吸附容量和性能方面的报道很多,但采用农林废弃物接种耐重金属菌体制备复合生物吸附剂方面的研究甚少。本研究针对农林废弃生物质材料与耐铅真菌,利用两类不同材料制备复合生物吸附剂,通过耐性菌株和农林废弃物材料的生化复合过程,提升材料吸附性能。采用农林废弃物花生壳(PS)、粟米糠(MC)等为原料,与铅锌矿区尾矿渣中筛选出的耐性菌株米曲霉菌(Aspergillus oryae,HA)通过复合培养方式,制备花生壳-米曲霉(PSH)、粟米糠-米曲霉(MCH)等复合吸附剂,通过静态批量试验考察pH值、吸附剂浓度、Pb~(2+)离子浓度和吸附时间对吸附效果的影响,通过动态连续流固定床吸附试验研究不同操作条件下固定床系统的吸附穿透曲线并分析其动态吸附特性,应用等温吸附模型、吸附动力学模型、穿透曲线拟合模型、扫描电镜和傅里叶红外光谱分析生物吸附剂对Pb~(2+)离子的吸附机理。主要研究结果如下:①引入HA改变了玉米秸秆、小麦秸秆、花生壳和粟米糠的吸附容量,四种复合吸附剂的吸附能力存在较大差异,吸附容量增大顺序为粟米糠花生壳小麦秸秆玉米秸秆。②静态Pb~(2+)吸附试验结果表明,与MC和PS相比,MCH和PSH具有吸附容量大,吸附速率快,pH值适用范围广的特点。③相比于Freundlich和D-R等温吸附模型,Langmuir模型可以更好的描述不同吸附剂对Pb~(2+)离子的等温吸附过程,PS、PSH、MC、MCH的理论吸附容量由qm分别为:14.62、20.92、11.89、21.79mg/g。Lagergren准二级动力学模型较准一级和颗粒内扩散模型可以更好的描述复合吸附剂对Pb~(2+)的吸附过程,说明化学吸附为该过程的主要作用和限速步骤。④FTIR和SEM分析表明,复合后吸附剂表面形态和官能团均发生显著改变,活性官能团中以羧基、胺基的变化最为明显,羟基、羧基、氨基和羰基在吸附Pb~(2+)过程中起主要作用。MCH相比PSH具有更多样的吸附活性官能团且表面形态变化更为明显。⑤ 动态连续流吸附试验结果表明,复合吸附剂PSH、MCH的穿透时间tb和饱和点时间te分别比单一吸附剂PS、MC明显推迟。复合后吸附剂PSH、MCH的动态吸附容量qexp分别由复合前的4.62、7.13 mg/g提升至6.49、8.30 mg/g。复合后吸附剂穿透曲线传质区长度缩短,系统的整体吸附能力提升。⑥动态连续流不同操作条件试验结果表明,系统的穿透时间tb随柱高的增加或者流速、初始Pb~(2+)浓度的减小而增加,传质区长度H则随柱高的减小或者流速、初始浓度的增加而增加,其中流速变化对穿透时间和传质区长度影响最大,初始浓度变化对穿透时间和传质区长度影响最小。⑦Thomas 模型较好的拟合了 PSH(R2=0.9532～0.9828)和MCH(R2=0.9410～0.9681)对Pb~(2+)的动态吸附过程,说明该过程中的内部扩散和外部扩散并非限速步骤,模型较好地预测了不同操作条件下吸附剂动态吸附性能,可以用于描述PSH为填料的吸附固定床系统。BDST模型较好的描述了 PSH和MCH系统的不同吸附柱高度与不同ct/co下的的穿透时间关系,对不同流速和初始浓度条件下的穿透时间进行了较为精确的预测,对吸附剂为PSH时的预测效果优于MCH。⑧相比单一材料,复合吸附剂对复合重金属离子的去除效果均有了明显提升,复合后PSH相比PS对Pb3~(2+)、Zn~(2+)、Cd~(2+)、Cu~(2+)离子的的除率分别提升了75.55、123.56、119.39、95.15%,MCH 相比 MC 对 Pb~(2+)、Zn~(2+)、Cd~(2+)、Cu~(2+)离子的去除率分别提升了 188.26、135.50、139.49、173.92%,MCH对不同重金属离子的吸附效果提升更为明显。
[Abstract]:Biosorption is an effective method for the utilization of biomass materials adsorption properties to remove pollutants. The removal of heavy metal biosorbent waste biomass materials and microbial as raw material prepared by agriculture and forestry, has a wide application prospect. But the single agricultural waste biomass materials in practical applications of low adsorption capacity and low density, easy to floating the disadvantages of single microbial adsorption on the application also exists in the granulation difficulty, solid-liquid separation difficulties, resulting in two difficult large-scale applied to heavy metal pollution. In recent years, the improvement of biomass materials adsorption capacity and performance of many reports, but the study of agricultural and forestry waste inoculation composite biosorbent resistant the heavy metal is very little. This study was made for the agricultural waste biomass materials and lead tolerant fungus, using two different Preparation of composite materials by composite biosorbent, biochemical process tolerance strains and agricultural and forestry waste materials, enhance the adsorption properties of materials. The agricultural and forestry waste peanut shell (PS), corn bran (MC) as raw materials, and the resistance strain of Aspergillus oryzae were selected by lead-zinc mine tailings in (Aspergillus oryae, HA) by composite cultivation, preparation of peanut shell Aspergillus oryzae (PSH), corn bran and Aspergillus oryzae (MCH) composite adsorbent, through static batch test pH value, adsorbent concentration, Pb~ (2+) effect of ion concentration and adsorption time on the adsorption effect, through the dynamic continuous flow fixed bed adsorption adsorption experiment fixed bed system under different operating conditions of the breakthrough curve and analyze its dynamic adsorption characteristics, application of adsorption isotherm, adsorption kinetics model, through curve fitting model, analysis of adsorption of Pb scanning electron microscope and infrared spectra of Fu Li leaves ~ (2+) ion adsorption mechanism. The main results are as follows: the introduction of HA changed the corn straw, wheat straw, corn bran and peanut shell adsorption capacity, there is a big difference between the four kinds of adsorption capacity, adsorption capacity increases the order of millet rice bran peanut shell wheat straw corn straw. The static Pb~ (2+) adsorption test results show that, compared with MC and PS, MCH and PSH have high adsorption capacity, adsorption speed, pH value is applicable to a wide range of characteristics. Compared to the Freundlich and D-R isotherm model, Langmuir model can better describe the adsorption of Pb~ (2+) adsorption isotherm, ion PS, PSH, MC, the theory of the adsorption capacity of MCH by QM were 14.62,20.92,11.89,21.79mg/g.Lagergren quasi description composite adsorbent kinetic model is a quasi two level and intra particle diffusion model is better for Pb~ (2+) adsorption process, explains Study of adsorption as the main function and the rate limiting step of the process. The FTIR and SEM analysis showed that the adsorbent surface morphology and functional groups changed significantly after compound, active functional groups with carboxyl, amino change is the most obvious, hydroxyl, carboxyl, amino and carbonyl groups in the adsorption of Pb~ (2 +) in the process of the main.MCH PSH has more than the adsorption of reactive functional groups and surface morphology change is more obvious. The dynamic continuous adsorption test results show that the composite adsorbent PSH TB MCH, the breakthrough time and saturation time te respectively than single adsorbent PS, MC significantly delayed. The composite adsorbent PSH, the dynamic adsorption capacity of qexp MCH 4.62,7.13 mg/g respectively by the composite before the upgrade to 6.49,8.30 mg/g. composite adsorbent penetration length curve of mass transfer zone is shortened, enhance the overall adsorption ability of the system. The dynamic continuous different operating conditions, the results of the test show that, 绯荤粺鐨勭┛閫忔椂闂磘b闅忔煴楂樼殑澧炲姞鎴栬，

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