【作者】 何园；

【导师】 王宪；

【作者基本信息】 厦门大学 ， 海洋化学， 2008， 硕士

【摘要】 本文采用处理过的海藻为生物吸附剂,以含金、银、铜、镍等贵重金属的电镀废水为吸附对象,分析了生物吸附等温线方程及吸附-解吸动力学变化规律,同时研究了吸附剂的循环利用效率,并与先前的研究结果进行了对比。通过对pH、金属离子初始浓度、吸附剂浓度等影响因子的研究确定其最佳吸附条件,进行工厂化海藻生物吸附剂吸附重金属的中试试验。在现场实验的基础上,优化最佳吸附条件。通过以上研究工作,对海藻对Au²⁺、Ag⁺、Cu²⁺、Ni²⁺离子的吸附特性可得出以下结论:1.海藻对Au²⁺、Ag⁺、Cu²⁺、Ni²⁺的吸附,pH值对吸附量有较大影响。海藻藻粉吸附Au²⁺、Ag⁺、Cu²⁺、Ni²⁺电镀废水的最适pH范围为4.0-6.0。在生物吸附剂用量一定的情况下,金属离子浓度在5-80 mg/L范围内,随着Au²⁺、Ag⁺、Cu²⁺、Ni²⁺金属离子初始浓度的升高,吸附率均有所降低,吸附量均有所升高。超过80 mg/L,吸附率降低得比较明显。海藻作为吸附剂,在低浓度时,相较于其他物理化学处理方法更可显示出其优越性。随着吸附剂浓度的增大,Au²⁺、Ag⁺、Cu²⁺、Ni²⁺的吸附率和吸附量均呈现不同的变化。综合两方面原因,实验可选择吸附剂浓度为2.50 g/L。这样即可以达到对金属离子良好的吸附效果,又可以节省藻粉的投入量。因此,选择pH=6.0、吸附剂浓度为2.50 g/L、粒径为60 mesh及金属离子初始浓度小于80 mg/L为适合的吸附条件。2.海藻吸附Au²⁺、Ag⁺、Cu²⁺、Ni²⁺在开始时均有快速的吸附过程,30分钟左右基本达到平衡,表明吸附作用是一个快速的过程。生物吸附过程符合Langumir模型,根据Langmuir吸附等温模型的计算结果表明,固定化海藻对Au²⁺、Ag⁺、Cu²⁺、Ni²⁺的最大吸附量分别为0.96、0.53、7.35、38.46 mg/g,海藻对Ni²⁺离子的亲和性比其他离子的大。与先前实验室研究结果进行对比,结果表明,共存的Zn²⁺、Cd²⁺等金属离子与Cu²⁺、Ni²⁺之间存在竞争吸附,导致Cu²⁺、Ni²⁺的吸附量下降。3.Au²⁺、Ag⁺、Cu²⁺、Ni²⁺在Laminaria japonica上第1阶段的吸附进行得很快,10 min即达平衡。随着时间的推移,Au²⁺、Ag⁺、Cu²⁺、Ni²⁺的吸附量均略微增加。Au²⁺、Ag⁺、Cu²⁺、Ni²⁺在L.japonica上的吸附可以用准二级动力学方程很好地描述（R²分别为0.977、0.995、0.999、0.999）,动力学参数k₂分别为0.1106、0.3818、0.4589、2.6912 g/（mg·min）,q_e分别为2.52、0.54、2.46、8.62 mg/g。与先前实验室研究结果进行对比,结果表明,海藻吸附Cu²⁺、Ni²⁺平衡时的吸附量q_e规律为:实验室溶液>电镀废水;准二级速率常数k₂规律为:电镀废水>实验室溶液。4.用0.1 mol/L的HCl溶液解吸吸附了重金属的L.japonica效果明显,能十分迅速的把Au²⁺、Ag⁺、Cu²⁺、Ni²⁺解吸下来,其解吸过程与吸附过程相似。Au²⁺、Ag⁺、Cu²⁺、Ni²⁺在L.japonica上的解吸同样可以用准二级动力学方程很好地描述（R²分别为0.999、0.998、0.999、0.999）,动力学参数k₂分别为10.6508、4.9264、0.6556、0.0312g/（mg·min）,q_e分别为0.20、0.07、0.84、29.41 mg/g。解吸过的藻粉依然有良好的吸附性能,经过三次吸附.解吸过程藻粉依然保持着很好的吸附能力。5.从对三个公司重金属废水的处理情况来看,对于含重金属的废水,藻粉吸附剂表现出了良好的吸附能力,对各种重金属的吸附率都维持在一个较高的水平,平均吸附总量在120-180 mg/g,处理过废水中重金属的浓度基本上可达到国家二级排放标准。藻粉吸附剂的再生特性可同时实现电镀废水中贵重金属的回收以及吸附剂的循环使用。从福建新文行灯饰有限公司电镀废水的循环利用实验结果来看,贵重金属的回收率都能维持在一个较高水平,Ni²⁺、Au²⁺均达到了80%以上,Cu²⁺也在50%左右,为贵重金属的回收提供了一个新的途径,具有良好的发展潜力和应用前景。更多还原

【Abstract】 The pretreated algae biosorbent was used to treat Au²⁺,Ag⁺,Cu²⁺ and Ni²⁺ ions of electroplating wastewater in this paper. Biosorption isotherm equation, biosorption-desorption kinetics and the reuse efficiency of biosorbent were studied, and compared with previous study. In this work, adsorption features of algae were investigated as a function of initial pH, initial concentration of ions and algal dose, and then the optimal biosorption features were obtained. Based on pilot test experiment of factory treatment of heavy metals by marine algae, the optimal biosorption features was optimized. The major conclusions are summarized as follows:1.pH of solution influences greatly on biosorption capacity of Au²⁺,Ag⁺,Cu²⁺ and Ni²⁺ ions in the water. The optimal adsorption effect of metal ions on algae was observed at pH 4.0-6.0. The percent removal of metal ions was decreased, and biosorption capacity of algae was increased with increasing initial concentration of Au²⁺,Ag⁺,Cu²⁺ and Ni²⁺ ions, while the certain algal dose and metal ions concentration 5-80 mg/L. The biosorption capacity of algae decreased quickly as metal ions concentration beyond 80 mg/L. The algal biosorption is more efficient than the traditional physicochemical methods at low ions concentration. The biosorption efficiencies and capacities of ions showed different variation with increasing biomass concentration. Considering the two aspects: good biosorption effect and saving algal dose, we chose the biomass concentration was 2.50 g/L. So the optimal sorption condition is pH of 6.0, algal dose of 2.50 g/L, particle size of 60 mesh and metal ions concentration being less than 80 mg/L.2.The adsorption process is fast, reaching equilibrium state in less than 30 min. The biosorption process followed Langmuir isotherm model, then the calculated result showed: maximum biosorption capacity of immobilized algae was observed 0.96, 0.53, 7.35 and 38.46 mg/g for Au²⁺,Ag⁺,Cu²⁺ and Ni²⁺,respectively, and the affinity of Ni²⁺ ion with algae was stronger than the other ions. Compared with previous studies, the result indicated: competitive adsorption of Cu²⁺,Ni²⁺ and coexisting Zn²⁺, Cd²⁺ ions lead to the decrease of biosorption capacity of Cu²⁺,Ni²⁺. 3. The first stage adsorption process of Au²⁺,Ag⁺,Cu²⁺ and Ni²⁺ on Laminaria japonica is fast, reaching equilibrium state in 10 min. The biosorption capacities increased a little as the time going. The adsorption process of Au²⁺,Ag⁺,Cu²⁺ and Ni²⁺ on L. japonica followed the pseudo-second order model well （R² was 0.977, 0.995, 0.999 and 0.999, respectively）, and the kinetics parameter k₂ was 0.1106, 0.3818, 0.4589 and 2.6912 g/（mg·min）, respectively, biosorption capacities （q_e） was 2.52, 0.54, 2.46, 8.62 mg/g, respectively. Compared with previous studies, the result indicated: the order for q_e of algae biosorption on Cu²⁺,Ni²⁺ at equilibrium state was experiment solution > electroplating wastewater, but the order for rate constant of the pseudo-second order model was electroplating wastewater > experiment solution.4. Desorption experiments showed 0.1 mol/L HC1 was an efficient desorption, metal ions Au²⁺,Ag⁺,Cu²⁺ and Ni²⁺ can be desorbed quickly, and the desorption process was similar to adsorption process. The desorption process followed the the pseudo-second order model well （R² was 0.999, 0.998, 0.999 and 0.999, respectively）, and the kinetics parameter k₂ was 10.6508, 4.9264, 0.6556 and 0.0312 g/（mg·min）, respectively, biosorption capacities （q_e） was 0.20, 0.07, 0.84 and 29.41 mg/g, respectively. The adsorption capacity of desorbed algae was very good, which allowed the reuse of the biomass in three biosorption-desorption cycles without any considerable loss of biosorption capacity.5. The experiments of heavy metal wastewater treatment in three companies indicated that algae biosorbent was a good biosorbent. The mean sorption capacity of algae was 120-180 mg/g, and the concentration of heavy metal ions in the treated wastewater was lower than the nation second grade quality standards. The adsorption features of regenerative allowed the recovery of precious metal from the electroplating wastewater and the reuse of biosorbent simultaneously. Experiment of Wenton Group（Hong Kong） Limited of Fujian showed there was a good recovery rate of precious metal as Ni²⁺,Au²⁺higher than 80 % and Cu²⁺ higher than 50 %. The biosorption-desorption provide a new approach to recover precious metal, and there will be a very good development potential and application prospect.更多还原