Frequently, black sand from coastal deposits is a magnetic ore with a complex structure that is composed principally by iron, titanium and silica oxides, and metals such as vanadium, chromium, nickel, strontium, etc. This material could be used in oxidation/reduction processes as a photocatalyst doped naturally. However, its surface area low and the mass transfer constraints caused by the cluster formation in bulk reaction due to its magnetic character, limits the photocatalytic performance. Microspheres of black sand have been prepared by a simple associating method with alginate-Na and calcined under oxidizing atmosphere at 1100 °C. These have been characterized by XRF spectroscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller surface area analysis, XRD diffraction, N₂ adsorption/desorption measurements, FT-IR spectroscopy, differential thermal thermogravimetric analysis, and UV-Vis spectrophotometry. The catalytic activity for photocatalytic hydrogen production from EDTA solutions under UV light irradiation, using the response surface methodology in order to determine the optimum conditions of the process, has been tested. At calcination temperature, rounded microspheres with rough surface, have had apparent density different from the raw material and although the specific surface of the microspheres decreased owing to surface sintering, the chemical composition has been similar compared with the starting material. Due to their buoyancy in the suspension, the hydrogen production due to the contact between photons that entered into suspension and the as-prepared microspheres, has been favored. 

中文翻译：

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以黑砂矿物为光催化剂的微球，可在紫外线下产生光催化制氢

通常，沿海沉积物中的黑砂是一种具有复杂结构的磁性矿石，其主要成分是铁，钛和氧化硅以及诸如钒，铬，镍，锶等金属。该材料可用于氧化/还原作为自然掺杂的光催化剂进行加工。然而，其表面积低以及由于其磁性而在本体反应中由于团簇形成而引起的传质限制限制了光催化性能。用一种简单的方法将海藻酸钠与黑砂制成微球，并在1100℃的氧化气氛下煅烧。这些已通过XRF光谱，扫描电子显微镜/能量色散X射线光谱，Brunauer-Emmett-Teller表面积分析，XRD衍射，N _2进行了表征。吸附/解吸测量，FT-IR光谱，差示热重分析和UV-Vis分光光度法。为了确定工艺的最佳条件，已经使用响应表面方法测试了在紫外线照射下从EDTA溶液中光催化制氢的催化活性。在煅烧温度下，具有粗糙表面的圆形微球具有与原料不同的表观密度，并且尽管由于表面烧结而使微球的比表面积降低，但是与起始材料相比化学组成相似。由于它们在悬浮液中的浮力，由于进入悬浮液的光子与所制备的微球之间的接触而产生氢是受到青睐的。