Khandelwal Nitin, Singh Nisha, Tiwari Ekta, Darbha Gopala Krishna
Environmental Nanoscience Laboratory, Indian Institute of Science Education and Research Kolkata Mohanpur Kolkata West Bengal India 741246
Centre for Climate Change and Environmental Studies, Indian Institute of Science Education and Research Kolkata Mohanpur West Bengal India 741246.
RSC Adv. 2019 Apr 9;9(20):11160-11169. doi: 10.1039/c9ra00742c.
A bentonite supported amorphous aluminum (B-Al) nanocomposite was synthesized by the NaBH reduction method in an ethanol-water interfacial solution and characterized with SEM, TEM, XRD, FT-IR and XRF. Surface morphology and line scans obtained from TEM imaging suggest the successful synthesis of the nanocomposite while XRF data shows a drastic change in Al concentration in the synthesized nanocomposite with respect to raw bentonite. This synthesized nanocomposite was further utilized for the removal of hexavalent chromium (Cr(vi)) from aqueous solutions. The very high removal efficiency of the composite for Cr(vi) ( 49.5 mg g) was revealed by the Langmuir sorption isotherm. More than 90% removal of Cr(vi) in just 5 minutes of interaction suggests very fast removal kinetics. Inner sphere complexation and coprecipitation of Cr(vi) can be concluded as major removal mechanisms. No influence of ionic strength suggests inner sphere complexation dominated in Cr(vi) uptake. pH of the solution didn't influence the sorption much but comparatively the removal was higher under alkaline conditions (99.4%) than under acidic conditions (93.7%). The presence of humic acid and bicarbonate ions reduced the sorption significantly. The final product, Cr-Al(OH) results in precipitation by forming alum which indicates that clay supported amorphous aluminum nanocomposites can be considered as potential sorbents for toxic metal ions in the environment.
通过在乙醇 - 水界面溶液中采用硼氢化钠还原法合成了膨润土负载的非晶态铝（B - Al）纳米复合材料，并用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射仪（XRD）、傅里叶变换红外光谱仪（FT - IR）和X射线荧光光谱仪（XRF）对其进行了表征。从TEM成像获得的表面形态和线扫描表明纳米复合材料合成成功，而XRF数据显示合成的纳米复合材料中铝浓度相对于原始膨润土有显著变化。这种合成的纳米复合材料进一步用于从水溶液中去除六价铬（Cr(Ⅵ)）。朗缪尔吸附等温线表明该复合材料对Cr(Ⅵ)具有非常高的去除效率（49.5 mg/g）。在仅5分钟的相互作用中，Cr(Ⅵ)的去除率超过90%，表明去除动力学非常快。可以得出结论，Cr(Ⅵ)的内球络合和共沉淀是主要的去除机制。离子强度没有影响，表明内球络合在Cr(Ⅵ)的吸附中占主导地位。溶液的pH值对吸附影响不大，但相对而言，在碱性条件下（99.4%）的去除率高于酸性条件下（93.7%）。腐殖酸和碳酸氢根离子的存在显著降低了吸附。最终产物Cr - Al(OH)通过形成明矾导致沉淀，这表明粘土负载的非晶态铝纳米复合材料可被视为环境中有毒金属离子的潜在吸附剂。
