P. D. Patel Institute of Applied Sciences, Charotar University of Science and Technology, CHARUSAT Campus, Changa, Gujarat, 388421, India.
Environ Sci Pollut Res Int. 2020 Aug;27(22):27330-27344. doi: 10.1007/s11356-019-05942-0. Epub 2019 Jul 22.
This study evaluated Cr(VI) biosorption by a halotolerant gram-negative bacterium Halomonas sp. DK4 isolated from chrome electroplating sludge. The bacterium could withstand high concentrations of Cr(VI) exhibiting a minimal inhibitory concentration (MIC) of 250 mg/L. Plackett-Burman design confirmed glucose, KHPO, NaCl, inoculum size, and initial Cr(VI) concentration as significant variables influencing the Cr(VI) removal ability of the bacterium. The suspended culture of Halomonas sp. DK4 was able to remove 81% (100 mg/L) of Cr(VI) in optimized MSM medium from aqueous solutions within 48 h. The bacterium also removed 59% Cr(VI) in the presence of 15% NaCl concentration within 72 h. The main mechanism involved in Cr(VI) removal by Halomonas sp. DK4 was determined to be biosorption which was best explained using the Langmuir isotherm model, wherein the maximum adsorption of 150.7 mg/g was observed under equilibrium conditions. Kinetic studies reveal that chemisorption of Cr(VI) by Halomonas sp. DK4 was a rate-limiting process which followed pseudo-second-order kinetics (R = 0.99). Bacterial biomass exhibited maximum adsorption of 70.3% Cr(VI) at an initial concentration of 100 mg/L under optimal conditions. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the presence of hydroxyl, carboxyl, amide, and phosphate groups on the bacterial surface which may be involved in Cr(VI) adsorption. Scanning electron microscopy coupled energy dispersive X-ray (SEM-EDX) analysis revealed morphological changes in the bacterial cell and accumulation of Cr(VI) on the cell surface. These results suggest the potential application of Halomonas sp. DK4 in the removal of Cr(VI) from saline chromium-containing industrial wastewaters.
本研究评估了一株耐盐革兰氏阴性菌 Halomonas sp. DK4 对六价铬（Cr(VI)）的生物吸附作用，该菌从镀铬污泥中分离得到。该菌能耐受高浓度的 Cr(VI)，最小抑制浓度（MIC）为 250 mg/L。Plackett-Burman 设计证实，葡萄糖、KHPO4、NaCl、接种量和初始 Cr(VI)浓度是影响该菌 Cr(VI)去除能力的显著变量。Halomonas sp. DK4 的悬浮培养物能够在优化后的 MSM 培养基中，在 48 小时内从水溶液中去除 81%（100 mg/L）的 Cr(VI)。在 15%NaCl 浓度存在的情况下，该菌在 72 小时内也能去除 59%的 Cr(VI)。Halomonas sp. DK4 去除 Cr(VI)的主要机制被确定为生物吸附，该机制最符合 Langmuir 等温线模型，在平衡条件下观察到最大吸附量为 150.7 mg/g。动力学研究表明，Cr(VI)的化学吸附是 Halomonas sp. DK4 的限速过程，遵循准二级动力学（R = 0.99）。在最佳条件下，当初始浓度为 100 mg/L 时，细菌生物量对 Cr(VI)的最大吸附率为 70.3%。傅里叶变换红外光谱（FTIR）分析证实，细菌表面存在羟基、羧基、酰胺和磷酸盐基团，这些基团可能参与 Cr(VI)的吸附。扫描电子显微镜结合能量色散 X 射线（SEM-EDX）分析显示，细菌细胞的形态发生了变化，Cr(VI)在细胞表面积累。这些结果表明，Halomonas sp. DK4 具有从含铬工业废水中去除 Cr(VI)的潜力。
