Ordered mesoporous alumina (MA) was successfully modified with three amino organosilanes including 3-aminopropyltriethoxysilane (1N), N-(β-aminoethyl)-γ-aminopropylmethylbimethoxysilane (2N) and N-3-trimethoxysilylpropyldiethylenetriamine (3N) via a facile grafting method, and the as-prepared amino organosilane grafted MA–1N, MA–2N and MA–3N show enhanced adsorption performance towards Cr(VI) removal from wastewater. Their physicochemical properties and the MA before modification were comparatively characterized by FT-IR, TEM, XRD, N2 adsorption–desorption, CHNS elemental analysis, zeta potential measurements and XPS. Their adsorption performance was also comparatively studied along with the effect of contact time, adsorption isotherms, multi-metal ion adsorption, interference of co-existing anions and regeneration ability in batch experiments. It was found that their adsorption kinetics data were better fitted by the pseudo-second order model; adsorption isotherms were better described by the Langmuir isotherm for MA–1N, the Freundlich isotherm for MA–2N and the Temkin isotherm for MA–3N. Among them, MA–2N shows the maximum adsorption capacity of 137.9 mg g?1 which is more than twice the 59.4 mg g?1 of MA. The residual concentration of Cr(VI) with a concentration of 50 mg L?1 when treated with MA–2N meets the emission standard of the World Health Organization (WHO). Moreover, MA–2N shows better selectivity toward Cr(VI), and can reduce relatively more Cr(VI) to low toxicity Cr(III). More results were found that Cr(VI) is adsorbed on the surface through a monodentate ligand or bidentate ligand, and then Cr(VI) is reduced to Cr(III) by an adjacent electron donor, after which Cr(III) is co-precipitated with the adsorbents. All the amine-grafted samples show good reusability for 5 cycles. These results indicated that the amino organosilane grafted ordered MA with high adsorption capacity, good selectivity and favourable reusability is a promising candidate for Cr(VI) removal, in combination with its low cost and energy saving preparation process.
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机译：用三种氨基有机硅烷成功地改性了有序介孔氧化铝（MA），包括3-氨丙基三乙氧基硅烷（1N）， N -（β-氨乙基）-γ-氨丙基甲基二甲氧基硅烷（2N）和 N -3-三甲氧基甲硅烷基丙基二亚乙基三胺（3N）通过简便的接枝方法，制备的氨基有机硅烷接枝的MA–1N，MA–2N和MA–3N表现出增强的对Cr的吸附性能（ VI ）从废水中去除。通过FT-IR，TEM，XRD，N 2 吸附-解吸，CHNS元素分析，ζ电位测量和XPS对它们的理化性质和改性前的MA进行了比较表征。在批处理实验中，还对它们的吸附性能以及接触时间，吸附等温线，多金属离子吸附，共存阴离子的干扰和再生能力的影响进行了比较研究。发现它们的吸附动力学数据更适合拟二阶模型。 MA-1N的Langmuir等温线，MA-2N的Freundlich等温线和MA-3N的Temkin等温线更好地描述了吸附等温线。其中，MA–2N的最大吸附量为137.9 mg g ？1 ，是59.4 mg g ？1的两倍以上 MA的sup> 。用MA–2N处理时，残留浓度为50 mg L ？1 的Cr（ VI ）符合标准的排放标准。世界卫生组织（世卫组织）。此外，MA–2N对Cr（ VI ）有更好的选择性，并且可以将相对更多的Cr（ VI ）还原为低毒的Cr（ III ）。结果表明，Cr（ VI ）通过单齿配体或二齿配体吸附在表面，然后Cr（ VI ）被还原为Cr（ III ）通过相邻的电子给体，然后Cr（ III ）与吸附剂共沉淀。所有的胺接枝样品在5个循环中均显示出良好的可重复使用性。这些结果表明，氨基有机硅烷接枝有序MA具有高吸附能力，良好的选择性和良好的可重复使用性，结合其低成本和节能的制备方法，是去除Cr（ VI ）的有希望的候选者。
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