生物吸附-浮选法去除水中Pb^(2+)的研究

Study on removing Pb^(2+) from water by means of biosorptive flotation

以苦味诺卡氏菌作为Pb2+吸附剂,研究了采用生物吸附-浮选法去除废水中Pb2+的效果及其作用机理。先通过吸附条件试验确定了试验条件:当水中Pb2+浓度为200mg/L时,培养5d的苦味诺卡氏菌用量为1g/L,试验温度为25℃,搅拌吸附时间为10min,试验pH值范围为2～7。在此基础上,考察了吸附-浮选试验中不同溶液pH值与捕收剂(DA、DB、SLS与NaOL)对Pb2+去除效果的影响。结果表明,随着pH值的升高,捕收剂中DA与DB均能保持较好的捕收效果,且其所在试验组的Pb2+吸附率均较高,因此对Pb2+的去除效果较为理想。以DA为例,当其浓度为3.3×10-4mol/L,浮选时间为10min,pH=7.2时,其所在废水组的Pb2+去除率可达80%,表明采用该方法去除废水中的Pb2+是可行的。采用SEM及X射线光散射能谱(EDS)分析了苦味诺卡氏菌对Pb2+的生物吸附-浮选机理。结果表明,生物吸附-浮选过程可能与细胞壁上羧基阴离子(—COO-)和Pb2+的静电作用以及氨基(—NH2)、乙酰氨基(—NHCOCH3)中N和Pb2+的络合作用有关,同时也与离子交换过程的协同作用有关。

The paper is concerned with its experimental study on the mechanism and effect of Nocardia amarae used as adsorbent for removing Pb^2＋ from the waste water by way of biosorption-flotation. As the first step, we have defined the experimental conditions through a series of adsorption experiments. For example, we have chosen Pb^2 ＋ concentration as 200 my/L, the bacteria cultured in 5 days with the biomass of Nocardia amarae, 1 y/L, at the temperature of 25 ℃ , the adsorption time for 10 min with pH = 2 - 7. On the basis of our experiments, we have studied the effect of collectors of DA, DB, SIS and NaOL on the removing rate of Pb^2 ＋ at different pH values in the adsorption-flotation experiments, The results of our experiments show that the collectors both of DA and DB could produce better collecting results with pH value added. In the experimental group, the adsorption rate of Pb^2 ＋ can be made higher so as to improve the removing result of Pb^2＋. For example, when the removing rate of Pb^2＋ reached 80% on the condition of DA dosage of 3.3 × 10^-4 mol/L, and pH = 7.2 for 10 min, it proves that the method is fit for removing Pb^2＋ in waste water. Furthermore, we have also studied the mechanism in biosorption-flotation process of Pb^2＋ by analyzing SEM and EDS. The results of SEM and EDS analysis indicate that the adsorption-flotation process would be likely to be electronically attractive to （-COO^-） on the cell wall with Pb^2＋ , involving N in the group （NH2） （-NHCOCH3） with Pb^2＋, while the biosorption-flotation is just involving ions interrelated exchange in the absorption process.