Open Data for publication "Visible light photocatalysts from low-grade iron ore: the environmentally benign production of magnetite/carbon (Fe3O4/C) nanocomposites" by Periyasamy et al. in Environmental Science and Pollution Research (https://doi.org/10.1007/s11356-021-15972-2)

Synthetic data report the ball-milling of mined iron ore tailings (IOTs) dried at 100°C. These were milled using a laboratory ball mill (internal diameter 300 mm and length 300 mm, using 150 steel alloy balls and an ore-to-ball ratio of 0.5 with a milling time of 30 min). Conversion of the resulting ≤50 μm IOTs to aqueous (soluble) FeCl3 removed insoluble Al-, Si-, Mg- and Ca-based minerals. This was done by the described sequential heating and filtering protocol. The conversion of FeCl3 to magnetite nanoparticles (NPs) by reduction with excess dextrose is described. Conditions of pH control, heating and washing are included. Powder X-ray diffraction (PXRD) data (obtained for 20–75° 2θ using Ni-filtered Cu Kα (λ = 0.15418 nm) radiation and a data step size of 0.02° 2θ and counting time of 2 s per step) of the resulting magnetite is presented in graphical (OriginPro) and raw (Excel) formats. Scanning electron microscopy (SEM) was combined with energy dispersive X-ray spectroscopy (EDX) to evaluate morphology and size distribution of IOTs and magnetite. IOTs analysed by SEM on a Hitachi S3400N (accelerating voltage 15 kV) and magnetite analysed on a field emission (FE) TESCAN MIRA 3 SEM (accelerating voltage 30 kV) at high (scale bar 100-200 nm) and low magnification (scale bar 1-100 μm). EDX data were obtained using a Horiba EX-400 identified Fe content (at%) at the red spot indicated in the corresponding SEM image. Transmission electron microscopy (TEM) followed sample sonication in EtOH and then drop-casting onto holey carbon copper grids. Magnetite NPs only were analysed using a FEI Philips Tecnai 20 with an accelerating voltage 200 KeV and a 70 μm objective aperture. Low magnification brightfield imaging (scale bars 10-100 nm) were employed to obtain a mean size distribution based on 100 NPs. High-resolution (HR) brightfield imaging and combined High-angle annular dark-field (HAADF) scanning TEM (STEM) and EDX analysis used a Thermo Scientific Talos F200X G2 TEM fitted with a Super-X EDS detector system. EDX detected Fe content (at%) in the white square panels indicated in representative HAADF images. Selected-area electron diffraction (SAED) data for magnetite were obtained with a 40 μm aperture. X-ray photoelectron spectroscopy (XPS) is presented in processed (OriginPro) and raw (Excel) formats. XPS signals were referenced using the C1s peak at 284.6 eV. FT-Infrared spectra of magnetite NPs were measured using a JASCO FT/IR-4000 in the range 400–4000 cm–1 and raw and processed data are reported. Thermogravimetric analysis (TGA) data were obtained for magnetite coated with dextrose on a TA Instruments TGA 500. Data acquisition was in the range 25-750 °C in N2 (ramp rate 10 °C min–1). UV-vis diffuse reflectance spectroscopy (UV-vis DRS) of magnetite was collected on a Varian Cary-50 UV-vis spectrophotometer with a Harrick Video-Barrelino diffuse reflectance probe. Photoluminescence (PL) and excitation (PLE) spectra of magnetite required dispersion in ethanol (1.0 × 10–5 M concentration of magnetite). PL spectra were recorded using Perkin-Elmer LS 55 fluorescence spectrometer. Magnetization of both IOTs and magnetite NPs were Recorded on a SQUID magnetometer (Quantum DesignMPMS XL-7) at 300 K in the range +/-30 kOe. Photocatalytic activity was analysed by degrading bodactive red BNC-BS dye in aqueous H2O2 under simulated solar irradiation (100 W Xenon lamp fitted with a UV cut-off filter, Solar Simulator-Royal Enterprise, 1 sun illumination, 100 mW cm-2). For testing, 25 mg of magnetite NPs were added to 50 ml of 1.0 x 10–5 M aqueous dye. The mixture was kept in the dark for 45 mins. before a 5.0 ml aliquot was withdrawn and centrifuged. The 418 nm absorption for the dye was used to determine the dye concentration before photocatalysis. The remaining suspension was treated with H2O2 (250 µl) and then irradiated. Dye degradation was monitored in triplicated experiments over 180 mins. by UV-vis spectroscopy. The solution was kept ice-cold throughout. Reference experiments without irradiation in the presence of catalyst but without H2O2 and with light irradiation in the absence of catalyst but presence of H2O2 were also done. To show hydroxyl radical photoformation a terephthalic acid (TA) probe was used. Catalyst (25 mg) was dispersed 30 ml TA (5 × 10−4 M), NaOH (2 × 10−3 M) and 0.15 ml H2O2. During irradiation, 3.0 ml aliquots were withdrawn at 30 min. intervals, centrifuged, and the fluorescence emission of the supernatant measured (excitation at 315 nm, emission at 425 nm for hydroxylated TA).

本报告对在100°C下干燥的采矿铁矿石尾矿（IOTs）的球磨过程进行了综合分析。采用实验室型球磨机（内径300毫米，长度300毫米，配备150颗钢合金球，矿石与球料比为0.5，球磨时间为30分钟）进行磨碎。通过将所得≤50微米IOTs转化为水溶性的氯化铁（FeCl3），移除了不可溶的基于铝、硅、镁和钙的矿物。此过程通过所述的顺序加热和过滤程序完成。通过过量的葡萄糖还原氯化铁至磁铁矿纳米颗粒（NPs）的过程亦被详细描述。实验中包含了pH控制、加热和洗涤的条件。利用镍过滤的铜Kα（λ = 0.15418纳米）辐射，以2θ为20-75°的数据步长为0.02° 2θ，每步计数时间为2秒，获得了磁铁矿的粉末X射线衍射（PXRD）数据，并以图形（OriginPro）和原始（Excel）格式呈现。扫描电子显微镜（SEM）结合能谱仪（EDX）被用于评估IOTs和磁铁矿的形貌和尺寸分布。在Hitachi S3400N（加速电压15 kV）SEM上分析了IOTs，在加速电压为30 kV的场发射（FE）TESCAN MIRA 3 SEM上分析了磁铁矿，分别在高倍（标尺100-200纳米）和低倍（标尺1-100微米）下进行。使用Horiba EX-400能谱仪获取了对应SEM图像中红点所示的红斑的Fe含量（质量百分比）。通过乙醇超声处理后，在孔状碳铜网上滴铸样品，随后采用透射电子显微镜（TEM）进行分析。仅对磁铁矿NPs进行分析，使用FEI Philips Tecnai 20，加速电压为200 KeV，物镜孔径为70微米。采用低倍明场成像（标尺10-100纳米）以获取基于100个NPs的平均尺寸分布。高分辨率（HR）明场成像以及结合高角度环形暗场（HAADF）扫描透射电子显微镜（STEM）和EDX分析使用了配备Super-X EDS检测系统的Thermo Scientific Talos F200X G2 TEM。在代表性HAADF图像中指示的白方块区域内检测到了Fe含量（质量百分比）。通过40微米孔径获取了磁铁矿的选区电子衍射（SAED）数据。X射线光电子能谱（XPS）数据以处理（OriginPro）和原始（Excel）格式呈现。XPS信号以284.6 eV的C1s峰为参考。使用JASCO FT/IR-4000对磁铁矿NPs的FT-红外光谱进行了测量，测量范围为400-4000 cm−1，并报告了原始和处理数据。在TA Instruments TGA 500上对覆盖有葡萄糖的磁铁矿进行了热重分析（TGA），数据采集范围为25-750 °C，氮气气氛下升温速率为10 °C min−1。使用Varian Cary-50 UV-vis分光光度计和Harrick Video-Barrelino漫反射探头收集了磁铁矿的紫外-可见漫反射光谱（UV-vis DRS）。磁铁矿的光致发光（PL）和激发（PLE）光谱在乙醇（磁铁矿浓度为1.0 × 10−5 M）中进行了分散。使用Perkin-Elmer LS 55荧光光谱仪记录了PL光谱。IOTs和磁铁矿NPs的磁化率在300 K下使用SQUID磁强计（Quantum Design MPMS XL-7）在±30 kOe范围内进行记录。通过在模拟太阳光照射下（配备UV截止滤光片，100 W氙灯，Solar Simulator-Royal Enterprise，1个太阳光强度，100 mW cm−2）降解水溶液中的活性红BNC-BS染料来分析光催化活性。实验中，将25 mg磁铁矿NPs加入50 ml 1.0 x 10−5 M水溶液中，在黑暗中保持45分钟后，取出5.0 ml的样品进行离心。使用染料的418 nm吸收率来确定光催化前的染料浓度。然后将剩余的悬浮液与250 µl的H2O2混合并进行照射。通过紫外-可见光谱在三重实验中监测了180分钟内的染料降解。在整个过程中，溶液保持冰冻状态。在没有催化剂但存在H2O2的情况下进行照射的参考实验，以及在存在催化剂但无H2O2的情况下进行光照的参考实验也被进行。为了显示羟基自由基的光形成，使用了苯二甲酸（TA）探针。将25 mg催化剂分散在30 ml TA（5 × 10−4 M）、2 × 10−3 M NaOH和0.15 ml H2O2中。在照射过程中，每30分钟取出3.0 ml的样品，离心后测量上清液的荧光发射（激发波长为315 nm，发射波长为425 nm以检测羟基化的TA）。