Department of Chemistry, Birla Institute of Technology and Science, Pilani, Hyderabad campus, Jawahar Nagar, Hyderabad, 500 078, India.
Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Hyderabad campus, Jawahar Nagar, Hyderabad, 500 078, India.
Sci Rep. 2018 Jun 29;8(1):9862. doi: 10.1038/s41598-018-28067-9.
The presence of harmful contaminants in the waste stream is an important concern worldwide. The convergence of biotechnology and nanoscience offers a sustainable alternative in treating contaminated waters. Hexavalent chromium, being carcinogenic deserves effective and sustainable methods for sequestration. Here in, we report the immobilization of a prokaryote (Rhizobium) and eukaryote (Saccharomyces cerevisiae) in multiwalled carbon nanotubes (MWCNTs) for the effective adsorption of hexavalent chromium. The carboxylic groups were introduced into the MWCNTs during oxidation using potassium permanganate and were subjected to EDC-HOBT coupling to bind with microbial cell surface. FTIR, TGA, BET, FESEM-EDAX, HRTEM, XPS and confocal microscopy were the investigative techniques used to characterize the developed biosorbents. Experimental variables such as pH, adsorbent dosage, kinetics, isotherms and thermodynamics were investigated and it was observed that the system follows pseudo second order kinetics with a best fit for Langmuir isotherm. Electrostatic interactions between the functional groups in the microbial cell wall and hydrochromate anion at pH 2.0 propel the adsorption mechanism. The lab scale column studies were performed with higher volumes of the Cr(VI) contaminated water. Sodium hydroxide was used as the desorbing agent for reuse of the biosorbents. The sustainable biosorbents show prospects to treat chromium contaminated water.
废水中有害污染物的存在是全球关注的一个重要问题。生物技术和纳米科学的融合为处理受污染的水提供了一种可持续的替代方法。六价铬具有致癌性，因此需要有效的可持续方法来进行螯合。在这里，我们报告了将原核生物（根瘤菌）和真核生物（酿酒酵母）固定在多壁碳纳米管（MWCNTs）中，以有效吸附六价铬。在使用高锰酸钾氧化过程中，将羧酸基团引入 MWCNTs 中，并进行 EDC-HOBT 偶联以与微生物细胞表面结合。使用傅里叶变换红外光谱（FTIR）、热重分析（TGA）、BET、场发射扫描电子显微镜-能谱分析（FESEM-EDAX）、高分辨率透射电子显微镜（HRTEM）、X 射线光电子能谱（XPS）和共聚焦显微镜等技术对开发的生物吸附剂进行了表征。研究了 pH、吸附剂用量、动力学、等温线和热力学等实验变量，并观察到该体系遵循拟二级动力学，对 Langmuir 等温线拟合效果最佳。在 pH 2.0 时，微生物细胞壁中的官能团与重铬酸根阴离子之间的静电相互作用推动了吸附机制。在实验室规模的柱实验中，使用了更高体积的含 Cr(VI)污染水。氢氧化钠被用作生物吸附剂的解吸剂，以实现其重复使用。这种可持续的生物吸附剂有望用于处理含铬废水。
