微波辅助细菌纤维素酯的制备及对Pb(Ⅱ)的高效去除(英文)

Microwave-Assisted Synthesis of Esterified Bacterial Celluloses to Effectively Remove Pb(Ⅱ)

以细菌纤维素(BC)为原料,通过微波辅助酯化改性的方法制得了两种改性细菌纤维素,细菌纤维素黄原酸酯(XMBC)和细菌纤维素硫酸酯(SMBC)。对所制备的样品进行X射线衍射(XRD)、扫描电镜-电子能谱(SEM-EDS)、傅里叶变换红外(FT-IR)光谱和BET比表面积分析,通过续批式实验考察其对Pb(Ⅱ)的去除效果。研究了p H值、反应时间、温度、污染物初始浓度、离子强度对其吸附能力的影响以及材料再生性能。结果表明,改性细菌纤维素的比表面积和孔容均有上升,其对Pb(Ⅱ)的吸附量随反应温度和离子强度的增加而降低,最优p H值为5.0。巯基的引入增强了细菌纤维素对Pb(Ⅱ)的吸附能力,改性后的吸附剂显示出比原始BC更优异的吸附性能,其中XMBC和SMBC的最大吸附量分别为144.93和126.58 mg?g^(-1),该吸附过程符合准二级速率方程和Langmuir等温吸附模型。材料对Pb(Ⅱ)的吸附是自发的放热过程,且吸附剂易于再生和重复回收。因此,SMBC和XMBC作为从水中富集分离重金属的新型材料具有及大应用前景。

Two modified bacterial celluloses, xanthate-modified bacterial cellulose（XMBC） and sulfate-modified bacterial cellulose（SMBC）, were prepared from bacterial cellulose（BC） esterified with xanthate and sulfate,respectively, using microwave irradiation. The as-prepared samples were characterized by X-ray diffraction（XRD）, scanning electron microscopy-energy-dispersive spectroscopy（SEM-EDS）, Fourier transform infrared（FT-IR） spectroscopy, and Brunauer-Emmett-Teller（BET） surface analysis. Batch experiments were carried out to determine the ability of XMBC and SMBC to remove Pb（Ⅱ） from solution. The effects of p H, contact time,temperature, initial adsorption concentration, and ionic strength on Pb（Ⅱ） removal were investigated along with regeneration performance. Both the specific surface area and total pore volume of the modified biosorbents were higher than those of unmodified bacterial cellulose. The adsorption of Pb（Ⅱ） decreased with increasing temperature and ionic strength, and the optimal p H was 5.0. The introduction of thiol groups on bacterial cellulose increased its adsorption capacity for Pb（Ⅱ）; the modified biosorbents exhibited adsorption capacities of 144.93mg？g^（-1）for XMBC and 126.58 mg？g^（-1）for SMBC. The adsorption rate closely followed a pseudo-second order model and the adsorption isotherm data were consistent with the Langmuir model. The adsorption of Pb（Ⅱ） was exothermic, and the spent adsorbents could be readily regenerated for reuse. As a result, SMBC and XMBC are promising materials for the preconcentration and separation of heavy metals from large volumes of aqueous solutions.