Dolatkhah Asghar, Dewani Chandni, Kazem-Rostami Masoud, Wilson Lee D
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada.
Department of Chemical Engineering, Malaviya National Institute of Technology Jaipur, Jawahar Lal Nehru Marg, Jhalana Gram, Malviya Nagar, Jaipur 302017, Rajasthan, India.
Polymers (Basel). 2024 Sep 2;16(17):2500. doi: 10.3390/polym16172500.
Stimuli-responsive catalysts with exceptional kinetics and complete recoverability for efficient recyclability are essential in, for example, converting pollutants and hazardous organic compounds into less harmful chemicals. Here, we used a novel approach to stabilize silver nanoparticles (NPs) through magneto/hydro-responsive anionic polymer brushes that consist of poly (acrylic acid) (PAA) moieties at the amine functional groups of chitosan. Two types of responsive catalyst systems with variable silver loading (wt.%) of high and low (PAAgCHI/FeO/Ag (H, L)) were prepared. The catalytic activity was evaluated by monitoring the reduction of organic dye compounds, 4-nitrophenol and methyl orange in the presence of NaBH. The high dispersity and hydrophilic nature of the catalyst provided exceptional kinetics for dye reduction that surpassed previously reported nanocatalysts for organic dye reduction. Dynamic light scattering (DLS) measurements were carried out to study the colloidal stability of the nanocatalysts. The hybrid materials not only showed enhanced colloidal stability due to electrostatic repulsion among adjacent polymer brushes but also offered more rapid kinetics when compared with as-prepared Ag nanoparticles (AgNPs), which results from super-hydrophilicity and easy accumulation/diffusion of dye species within polymer brushes. Such remarkable kinetics, biodegradability, biocompatibility, low cost and facile magnetic recoverability of the Ag nanocatalysts reported here contribute to their ranking among the top catalyst systems reported in the literature. It was observed that the apparent catalytic rate constant for the reduction of methyl orange dye was enhanced, PAAgCHI/FeO/Ag (H) ca. 35-fold and PAAgCHI/FeO/Ag (L) ca. 23-fold, when compared against the as prepared AgNPs. Finally, the regeneration and recyclability of the nanocatalyst systems were studied over 15 consecutive cycles. It was demonstrated that the nanomaterials display excellent recyclability without a notable loss in catalytic activity.
具有卓越动力学性能和完全可回收性以实现高效循环利用的刺激响应型催化剂，对于将污染物和有害有机化合物转化为危害较小的化学物质等应用至关重要。在此，我们采用了一种新颖的方法，通过磁/水响应性阴离子聚合物刷来稳定银纳米颗粒（NPs），该聚合物刷由壳聚糖胺官能团上的聚（丙烯酸）（PAA）部分组成。制备了两种银负载量（重量%）高低不同的响应型催化剂体系（PAAgCHI/FeO/Ag（高，低））。通过监测在NaBH存在下有机染料化合物4-硝基苯酚和甲基橙的还原反应来评估催化活性。催化剂的高分散性和亲水性为染料还原提供了卓越的动力学性能，超过了先前报道的用于有机染料还原的纳米催化剂。进行动态光散射（DLS）测量以研究纳米催化剂的胶体稳定性。这种杂化材料不仅由于相邻聚合物刷之间的静电排斥而表现出增强的胶体稳定性，而且与制备的银纳米颗粒（AgNPs）相比，还具有更快的动力学性能，这是由于其超亲水性以及染料物种在聚合物刷内易于积累/扩散。本文报道的银纳米催化剂具有如此显著的动力学性能、生物降解性、生物相容性、低成本和易于磁回收性，使其跻身文献报道的顶级催化剂体系之列。据观察，与制备的AgNPs相比，甲基橙染料还原的表观催化速率常数提高了，PAAgCHI/FeO/Ag（高）约35倍，PAAgCHI/FeO/Ag（低）约23倍。最后，对纳米催化剂体系进行了连续15个循环的再生和循环利用研究。结果表明，纳米材料表现出优异的循环利用性，催化活性没有明显损失。
