4种微生物吸附剂对低质量浓度Cr(Ⅲ)的吸附性能研究

Study on adsorption capacity of four biosorbents for Cr(Ⅲ) of low concentration

从皮革铬鞣、复鞣污泥等处分离、纯化出4株吸附Cr^(3+)菌株TP、XB、MY和TQ,采用ASS和FTIR等方法研究了其对低质量浓度Cr^(3+)的吸附特性。结果表明,4种微生物吸附剂对低质量浓度Cr^(3+)有较好的吸附作用,在实验室条件下其对Cr^(3+)的最佳吸附条件是pH值4.0,投加量0.5g/L,吸附温度30℃;TP、XB、MY和TQ的最大吸附量分别是8.66 mg/g、11.65 mg/g、11.05 mg/g和10.22 mg/g。碱处理有助于提高微生物吸附的吸附量,经过0.3 mol/L NaOH预处理后,其吸附量分别提高了17.86%～38.96%。吸附等温曲线拟合研究表明,吸附剂TP、MY和TQ更符合Langmuir等温方程,XB更符合Temkin等温方程;用Dubimim-Radushkevich(D-R)等温曲线方程拟合发现,TP、XB和TQ吸附过程属于离子交换吸附。吸附动力学研究表明,4种吸附剂对Cr^(3+)的吸附过程符合拟二级动力学模型;颗粒内扩散模型拟合表明,该过程主要分为吸附剂外表面吸附、细孔内缓慢吸附和平衡吸附3个阶段。

This article is aimed to present its author＇s investigative study of the effect of chromium-removing biosorptive conditions and its mechanic performance by using such instruments as AAS （Atomic Adsorption Spectra） and FT-IR （Fourier transform infrared spectroscopy）. For the research purpose, we have isolated four microbial adsorbents （TP, XB, MY and TQ） from the chrome-tanned leather- making section sludge and activated sludge respectively. The results of our experimental investigation show that the chromium-removing behavior of the microbial powder is effective and influenced noticeably by the solution temperature and pH, the contact time and the dosage of the adsorbents. The results of our observation also indicated that the highest adsorption capacity of the four microbial sorbents is 8.66 mg/g, 11.65 mg/g, 11.05 mg/g and 10.22 mg/g under the optimal biosorptive conditions （the pH value is 4.0, mass concentration is 0.5 g/L, and the temperature is 30 ℃ ）. It has also been proved that the alkali treatment of the microbial sorbents can improve their ad- sorptive capability by using [NaOH] = 0.3 mol/L. In so doing, the absorption capabilities can be made to increase by 34.54%, 23.21%, 17.86% and 38.96%, respectively. In addition, the four adsorption isotherm models were used to represent the experimental data, of which TP, MY and TQ prove to be well fitted with the Lang- muir isotherm model. The adsorption of Cr （ Ⅲ ） ions which were binding with the functional groups on the surface of them can be re- garded as the monolayer absorption. Whereas XB is well fitted with the Temkin isotherm model, it also reveals that its adsorption is char- aeterized by a uniform distribution of the binding energies. The result of fitting Dubimim-Radushkevich （D-R） isotherm model shows that the Cr m biosorption of TP, XB and TQ belongs to the ion exchange adsorption and the data deduced from the pseudo-second-order model turned out well fitted with the experimental value ; the fitting of intra- particular diffusion model indicates that the sorption process involves three steps, that is, the external surface adsorption, the gradual ad- sorption and the final equilibrium adsorption.