Titanium dioxide (TiO2, rutile) nanoparticles, inorganic ultraviolet absorbers, are used extensively in sunscreen cosmetics as an inorganic ultraviolet (UV) absorber to prevent skin damage; because of their nanotoxicity, use in combination with a support, such as montmorillonite (Mnt), rather than alone, is suggested. Mnt-supported TiO2 composites (Mnt-TiO2) for sunscreens are most suitable when the particles are spherical and of relatively uniform size, which are normally accomplished by spray drying, but this is difficult to achieve because of the naturally layered structure of Mnt. The objective of the present study was, therefore, to find the ideal characteristics of spray-drying nozzles to produce the desired spherical shape and size distribution of the Mnt-TiO2 composite particles. The starting Mnt was extracted from natural bentonite by particle-size separation. An ultrasonic nozzle in the spray dryer was selected for use in the synthesis of Mnt-TiO2 composites based on the particle-size distribution (PSD) of Mnt prepared using a two-fluid nozzle and an ultrasonic nozzle at 453 K. The incorporation of TiO2 in the final Mnt-TiO2 composites was examined by X-ray powder diffraction (XRD) and elemental analysis. With increasing TiO2 concentration, the TiO2 content and average particle size of the Mnt-TiO2 composites increased. Scanning electron microscopy (SEM) images showed that all samples prepared had uniform and nearly spherical shapes. Absorbance of UV by Mnt-TiO2 (5:1) composites was greater than that by either purified Mnts or pure TiO2. The present study demonstrated a simple method, using a spray dryer with an ultrasonic nozzle, to synthesize Mnt-TiO2 composites of uniform size and shape suitable for cosmetic application.

中文翻译：

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用于增强紫外吸收的蒙脱石支持的 TiO2 复合材料的合成和表征

二氧化钛（TiO2，金红石）纳米粒子，无机紫外线吸收剂，广泛用于防晒化妆品中，作为无机紫外线（UV）吸收剂，防止皮肤损伤；由于它们的纳米毒性，建议与支持物（例如蒙脱石 (Mnt)）结合使用，而不是单独使用。当颗粒呈球形且尺寸相对均匀时，Mnt 负载的 TiO2 复合材料 (Mnt-TiO2) 最适合用于防晒霜，通常通过喷雾干燥来实现，但由于 Mn 的自然层状结构，这很难实现。因此，本研究的目的是找到喷雾干燥喷嘴的理想特性，以产生所需的球形形状和尺寸分布的 Mnt-TiO2 复合颗粒。通过粒度分离从天然膨润土中提取起始Mnt。根据使用双流体喷嘴和 453 K 的超声波喷嘴制备的 Mnt 的粒度分布 (PSD)，选择喷雾干燥器中的超声波喷嘴用于合成 Mnt-TiO2 复合材料。 TiO2 的掺入通过 X 射线粉末衍射 (XRD) 和元素分析对最终的 Mnt-TiO2 复合材料进行了检查。随着TiO2浓度的增加，Mnt-TiO2复合材料的TiO2含量和平均粒径增加。扫描电子显微镜 (SEM) 图像显示制备的所有样品均具有均匀且接近球形的形状。Mnt-TiO2 (5:1) 复合材料对紫外线的吸收率大于纯 Mnts 或纯 TiO2。本研究展示了一种简单的方法，