假单胞菌菌株4-05生物质对二价锰离子的吸附与动力学表征

Adsorption and Kinetics Characterization of Divalent Manganese Ion onto Pseudomonas sp. 4-05 Biomass

以假单胞菌（Pseudomonas sp.4-05）生物质为吸附材料,设置不同生物质添加量、不同二价锰离子（manganese,Mn（Ⅱ））起始质量浓度、不同温度和时间条件,研究Mn（Ⅱ）被生物质吸附的效率.采用Langmuir和Freundlich等温吸附模型及准一级动力学、准二级动力学和颗粒内扩散模型研究生物质对Mn（Ⅱ）的吸附特性.结果表明,超过一定范围后生物质添加量的增加不利于Mn（Ⅱ）吸附;但在5 g·L-1生物质添加量条件下,随着Mn（Ⅱ）质量浓度的增加其吸附容量也随之上升,说明溶液离子强度可促进Mn（Ⅱ）向生物质的传递.菌株4-05生物质对50 mg·L-1Mn（Ⅱ）的吸附平衡时间为90~120 min,且温度的升高有利于Mn（Ⅱ）吸附量的提高,说明该吸附属于吸热反应.Langmuir模型和Freundlich模型都能较好地拟合吸附反应,表明该吸附过程可能属于非均匀生物质表面的单层吸附,其理论吸附容量可达21.8 mg·g-1.动力学拟合结果表明,Mn（Ⅱ）被菌株4-05生物质吸附是一个表面扩散和粒内扩散同时进行的过程,但反应速率取决于前者.两种动力学模型计算得到的平衡吸附容量与实验值都比较接近,但准二级动力学型拟合的可决系数高于准一级动力学模型,说明Mn（Ⅱ）的吸附以化学吸附为主且受吸附剂和吸附质质量浓度的复合影响.

Adsorption of divalent manganese ion（ Mn（ Ⅱ）） onto the Pseudomonas sp. 4-05 biomass was investigated under various conditions including biomass contents,initial Mn（ Ⅱ） concentrations,different temperature and reaction time. Mn（ Ⅱ） adsorption characteristics were evaluated by using Langmuir and Freundlich isotherm models and kinetics including pseudo-first-order,pseudo-second-order and intraparticle diffusion models. Results showed that the over-increase of Pseudomonas sp. 4-05 biomass lowered Mn（ Ⅱ） adsorption capacity,which might be due to the enhanced electrostatic repulsion from the biomass. In the addition of 5 g·L- 1dry biomass（ mass concentration）,however,the adsorption capacity was increased with the increase of Mn（ Ⅱ） concentration（ mass concentration）,indicating that ion strength in the solution promoted the mass transfer of Mn（ Ⅱ） from solution to biomass surface. Besides,our data suggested that the equilib-rium time of Mn（ Ⅱ） at 50 mg·L- 1onto the biomass of strain 4-05 was obtained within 90 ~ 120 min,while higher temperature resulted in higher removal efficiency,showing that Mn（ Ⅱ） removal by the biomass of strain 4-05 belongs to endothermic reaction. Both Langmuir and Freundlich isotherms well fitted Mn（ Ⅱ） adsorption process,indicating that the adsorption of Mn（ Ⅱ） onto the biomass of strain 4-05 might occur on a heterogeneous biomass surface by monolayer model,being up to a theoretical value at 21. 8 mg·g- 1. Kinetics fitting indicated that both surface diffusion and intrapartical diffusion led to Mn（ Ⅱ） adsorption onto the biomass of strain 4-05,while the reaction rate was dependent on the former process. Although the equilibrium adsorption capacity calculated from both pseudo-first-order and pseudo-second-order models was close to the experimental data,the latter one had higher coefficient of determination,demonstrating that Mn（ Ⅱ） adsorption onto the biomass of strain 4-05 was close related to chemical adsorption and dependent on both the concentrations of adsorbents and adsorbates.