Poly (acrylic acid-co-acrylamide) hydrogel microspheres were prepared via Pickering emulsion polymerization with hydrophobic silica as emulsifiers. The functional groups and the morphology of the hydrogel microspheres were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The effect of the dosage of hydrophobic silica on Pickering emulsion polymerization was investigated, and the hydrogel microspheres with different particle sizes were used to remove copper ions in water. The results showed that the diameter (D) of the hydrogel microspheres was inversely proportional to the dosage (S) of the hydrophobic silica used. The size of the hydrogel microspheres mainly affected the adsorption equilibrium time, and the maximum adsorption capacity could reach 85 mg/g at pH = 5. The results of desorption experiment demonstrated that copper ions were adsorbed by hydrogel microspheres mainly through chemical interaction. Pickering emulsion polymerization was an efficient and environmentally friendly approach for the fabrication of granular hydrogels. Graphical Abstract The novel poly (acrylic acid-co-acrylamide) hydrogel microspheres have been fabricated by Pickering emulsion polymerization. Pickering emulsions have superiorities over conventional surfactant-stabilized emulsions, including low level in foaming, toxicity, and cost. Furthermore, the diameter of the emulsion droplets can be controlled by the dosage of solid particles, and the relationship between average particle diameter (D) of hydrogel microspheres and the dosage of hydrophobic silica (S) are consistent with the equation of D = 123 × S−0.948. Hydrogel microspheres with different particle sizes are used to adsorb copper ions in aqueous solution and exhibit excellent absorption properties. The novel poly (acrylic acid-co-acrylamide) hydrogel microspheres have been fabricated by Pickering emulsion polymerization. Pickering emulsions have superiorities over conventional surfactant-stabilized emulsions, including low level in foaming, toxicity, and cost. Furthermore, the diameter of the emulsion droplets can be controlled by the dosage of solid particles, and the relationship between average particle diameter (D) of hydrogel microspheres and the dosage of hydrophobic silica (S) are consistent with the equation of D = 123 × S−0.948. Hydrogel microspheres with different particle sizes are used to adsorb copper ions in aqueous solution and exhibit excellent absorption properties.

中文翻译：

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使用W/O Pickering乳液制备的尺寸可控的聚（丙烯酸-共-丙烯酰胺）水凝胶微球去除铜离子

以疏水性二氧化硅为乳化剂，通过 Pickering 乳液聚合制备聚（丙烯酸-共聚-丙烯酰胺）水凝胶微球。水凝胶微球的官能团和形态分别通过傅里叶变换红外光谱和扫描电子显微镜进行表征。考察了疏水二氧化硅用量对Pickering乳液聚合反应的影响，采用不同粒径的水凝胶微球去除水中的铜离子。结果表明，水凝胶微球的直径 (D) 与所用疏水性二氧化硅的剂量 (S) 成反比。水凝胶微球的大小主要影响吸附平衡时间，pH=5时最大吸附容量可达85mg/g。解吸实验结果表明，水凝胶微球主要通过化学相互作用吸附铜离子。Pickering 乳液聚合是一种高效且环保的制备颗粒水凝胶的方法。图形摘要通过Pickering乳液聚合制备了新型聚（丙烯酸-共-丙烯酰胺）水凝胶微球。Pickering 乳液比传统的表面活性剂稳定乳液具有优越性，包括低泡沫、低毒性和成本。此外，乳液液滴的直径可以通过固体颗粒的用量来控制，水凝胶微球的平均粒径（D）与疏水性二氧化硅（S）的用量之间的关系符合方程 D = 123 × S-0.948。不同粒径的水凝胶微球用于吸附水溶液中的铜离子，表现出优异的吸附性能。通过Pickering乳液聚合制备了新型聚（丙烯酸-共-丙烯酰胺）水凝胶微球。Pickering 乳液比传统的表面活性剂稳定乳液具有优越性，包括低泡沫、低毒性和成本。此外，乳液液滴的直径可以通过固体颗粒的用量来控制，水凝胶微球的平均粒径（D）与疏水性二氧化硅（S）的用量之间的关系符合方程 D = 123 × S-0.948。不同粒径的水凝胶微球用于吸附水溶液中的铜离子，表现出优异的吸附性能。