One pot synthesis of nano Ag in calcium alginate beads and its catalytic application in p‐Nitrophenol reduction with kinetic parameter estimation and model fitting,The Canadian Journal of Chemical Engineering

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One pot synthesis of nano Ag in calcium alginate beads and its catalytic application in p‐Nitrophenol reduction with kinetic parameter estimation and model fitting
The Canadian Journal of Chemical Engineering ( IF 1.6 ) Pub Date : 2020-06-19 , DOI: 10.1002/cjce.23831
Supriya ₁ , Chandan K. Pal ₂ , Sonali Sengupta ₁ , Jayanta K. Basu ₁

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In this work, one step process of synthesis of silver nanoparticles (Agnp) embedded in insitu formed calcium alginate (CA) beads is stated. CA, formed from the reaction between sodium alginate and calcium hydroxide, acts as reducing and stabilizing agent as well as support for nanoparticles. The reaction mechanism for the formation and stabilization of Agnp is proposed where the vicinal dihydroxy groups of alginate are assumed to act as the reducing agent for Ag⁺ to Ag°. Transmission electron microscopy (TEM), x‐ray diffraction (XRD), UV‐vis spectroscopy, field emission scanning electron microscopy (FESEM), and atomic absorption spectroscopy (AAS) were used to characterize the Agnp. The formation of spherical nanoparticles with average size range of 4‐5 nm was confirmed by TEM. Catalytic activity of this nano silver‐calcium alginate (Agnp‐CA) composite was evaluated in the reduction of p‐nitrophenol. Concentrations of sodium alginate, calcium hydroxide, and AgNO₃ are found to be the parameters that critically affect the synthesis of Agnp. The efficacy of the catalyst is expressed on the basis of suitable reaction parameters. Both pseudo‐homogeneous and heterogeneous kinetic models are proposed for the reaction to find the best model and the Eley‐Riedel model is found to fit well with the experimental data. The novelty of this work is that the tandem process of CA bead formation, Agnp formation, and Agnp entrapment in CA have been transformed into a single‐step process. Moreover, elaborations of each step of the ionic mechanisms of Agnp formation and p‐NP reduction with Agnp and the establishment of a heterogeneous kinetic model for the reaction are reported for the first time here.

中文翻译：

一锅法合成藻酸钙珠中的纳米银及其动力学参数估计和模型拟合及其在对硝基苯酚还原中的催化应用

在这项工作中，陈述了一种合成方法，即一步一步地合成嵌入在原位形成的藻酸钙（CA）珠中的银纳米颗粒（Agnp）。由藻酸钠和氢氧化钙之间的反应形成的CA充当还原剂和稳定剂以及纳米颗粒的载体。提出了形成和稳定Agnp的反应机理，其中假定藻酸盐的邻位二羟基充当Ag ⁺的还原剂到Ag°。透射电子显微镜（TEM），X射线衍射（XRD），紫外可见光谱，场发射扫描电子显微镜（FESEM）和原子吸收光谱（AAS）表征了Agnp。TEM证实了平均粒径范围为4-5 nm的球形纳米颗粒的形成。在对硝基苯酚的还原反应中评估了这种纳米藻酸银-钙银（Agnp-CA）复合材料的催化活性。海藻酸钠，氢氧化钙和AgNO _3的浓度被发现是严重影响Agnp合成的参数。催化剂的功效基于合适的反应参数来表达。提出了拟均相和异相动力学模型来寻找最佳模型，并且发现Eley-Riedel模型与实验数据非常吻合。这项工作的新颖之处在于，CA中CA珠形成，Agnp形成和Agnp截留的串联过程已转变为单步过程。此外，这里首次报道了Agnp形成和p- NP还原与Agnp的离子机理的每个步骤的详细阐述，以及该反应的异质动力学模型的建立。

更新日期：2020-06-19

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