Kumar Himanshu, Sinha Swapan Kumar, Goud Vaibhav V, Das Surajit
1Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, Odisha 769008 India.
2Northeastern Regional Centre, The Energy and Resources Institute, Guwahati, Assam 781036 India.
J Environ Health Sci Eng. 2019 Nov 23;17(2):1001-1016. doi: 10.1007/s40201-019-00415-5. eCollection 2019 Dec.
Extracellular polymeric substances (EPS) from Cr(VI) resistant acid-tolerant biofilm forming bacterium (CrRAtBb) RTA-01 was used for synthesis of magnetic iron oxide nanoparticles (MIONPs) in removal of Cr(VI).
MIONPs synthesized in EPS matrix were characterized by UV-Vis, DLS, ATR-FTIR, XRD, FESEM, HRTEM and VSM. Primarily, the synthesis of MIONPs was established by the formation of black-colored precipitate through surface plasmon resonance (SPR) peak in between 330 and 450 nm.
The size of the spherical MIONPs with diameter range 13.75-106 nm was confirmed by DLS, XRD and FESEM analysis. HRTEM study confirmed the size of the MIONPs in the range of 10-65 nm. Moreover, the EDX and SAED confirmed the purity and polycrystalline nature of MIONPs. The ATR-FTIR peaks below 1000 cm designated the synthesis of MIONPs. Also, the magnetic property of MIONPs was confirmed for separation from the aqueous solution. MIONPs were further checked for the adsorption of Cr(VI) with initial concentration range of 50-200 mg L. An adsorption isotherm and thermodynamic study were also carried out and the experimental data was best fitted in Langmuir isotherm model with maximum adsorption percent of 1052.63 mg g of Cr(VI). Post interaction with Cr(VI), the surface characteristic of MIONPs in EPS matrix was evaluated by zeta potential, EDX, ATR-FTIR and XRD.
This study ascertained the adsorption of Cr(VI) over EPS stabilized MIONPs whereas the zeta potential and XRD analysis confirmed the presence of reduced Cr(IV) on the adsorbent surface.
来自耐铬（VI）耐酸生物膜形成细菌（CrRAtBb）RTA - 01的胞外聚合物（EPS）用于合成磁性氧化铁纳米颗粒（MIONPs）以去除铬（VI）。
通过紫外可见光谱、动态光散射、衰减全反射傅里叶变换红外光谱、X射线衍射、场发射扫描电子显微镜、高分辨率透射电子显微镜和振动样品磁强计对在EPS基质中合成的MIONPs进行表征。首先，通过在330至450nm之间形成表面等离子体共振（SPR）峰产生黑色沉淀来确定MIONPs的合成。
通过动态光散射、X射线衍射和场发射扫描电子显微镜分析确定了直径范围为13.75 - 106nm的球形MIONPs的尺寸。高分辨率透射电子显微镜研究证实了MIONPs的尺寸在10 - 65nm范围内。此外，能量散射X射线光谱和选区电子衍射证实了MIONPs的纯度和多晶性质。低于1000cm的衰减全反射傅里叶变换红外光谱峰表明了MIONPs的合成。此外，证实了MIONPs具有从水溶液中分离的磁性。进一步检测了MIONPs对初始浓度范围为50 - 200mg/L的铬（VI）的吸附。还进行了吸附等温线和热力学研究，实验数据最符合朗缪尔等温线模型，最大吸附百分比为1052.63mg/g铬（VI）。与铬（VI）相互作用后，通过zeta电位、能量散射X射线光谱、衰减全反射傅里叶变换红外光谱和X射线衍射评估了EPS基质中MIONPs的表面特性。
本研究确定了铬（VI）在EPS稳定的MIONPs上的吸附，而zeta电位和X射线衍射分析证实了吸附剂表面存在还原态的铬（IV）。
