NiFe2O4直接分解二氧化碳成碳循环反应过程结构演变研究

用XRD Rietveld分析法,对共沉淀法制备的NiFe2O4在H2／CO2循环反应中的结构演变进行研究,发现随着循环反应次数的增加,NiFe2O4物相的含量逐渐降低,Fe2Ni1-x物相的含量及其(200)衍射的平均晶粒逐渐增大,并出现Fe3C物相,其含量增长较快．纯NiEe2O4经15次循环反应后,体系中NiFe2O4物相的含量只剩下5％左右,样品基本失去分解CO2的活性．NiFe2O4掺杂4％铬后,明显提高了NiFe2O4骨架结构的稳定性,虽经50次H2／CO2循环反应,体系中NiFe2O4物相含量仍然有20％,分解CO2的活性仍达到初始活性的40％．     

Dry reforming of methane over oil palm shell activated carbon and ZSM-5 supported cobalt catalysts

In this study, cobalt supported oil palm shell activated carbon (Co/OPS-AC) and ZSM-5 zeolite (Co/ZSM-5) catalysts have been prepared for dry reforming of methane. Cobalt ratios of 6.0 and 14.0 wt% were deposited via wet impregnation method to the OPS-AC and ZSM-5 catalysts. The catalysts were characterized by XRD, N₂ adsorption--desorption isotherms, BET surface area, SEM, FESEM-EDX, TPR-H₂, and TPD-NH₃. The dry reforming of methane was performed using a micro reactor system under the condition of 10,000 ml/h.g-cat, 3 atm, CH₄/CO₂ ratio of 1.2:1.0 and temperature range from 923 K to 1023 K. The gaseous products were analyzed by gas chromatography (GC) with thermal conductivity detector (TCD) and further quantified to determine the conversions of CH₄ and CO₂, and the yields of CO and H₂. Experimental results revealed both catalysts exhibited lower conversions of CO₂ and CH₄ with the increase in temperature from 923 K to 1023 K. The reduced conversions may be due to the formation of carboneous substance on the catalyst known as coking. Comparatively, Co/OPS-AC gave higher conversions of CO₂ and CH₄ as well as higher yields of H₂ and CO as it has a higher surface area than Co/ZSM-5 which subsequently rendered higher activity for the reforming of methane. With the increasing cobalt loadings and reaction temperature, OPS-AC(14) catalyst exhibited improved activity and H₂/CO ratio. Based on these results, cobalt supported OPS activated carbon catalyst was suggested to be more effective for CO₂ and CH₄ conversions.     

镍铁氧体@活性炭复合材料去除六价铬的表征、性能及机制

采用化学共沉淀法将镍铁氧体(NiFe₂O₄)负载到活性炭,制备出一种磁性吸附剂镍铁氧体@活性炭(NiFe₂O₄@AC),并将其用于吸附废水中的Cr(Ⅵ).研究了吸附剂吸附Cr(Ⅵ)的影响因素、吸附动力学和吸附等温线.结果表明,在温度为25℃、 pH为2、 Cr(Ⅵ)初始浓度为150 mg·L^-1、活性炭投加量为0.1 g、吸附时间为720 min时,NiFe₂O₄@AC吸附Cr(Ⅵ)的去除率达到96.92%,吸附量达到72.62 mg·g^-1.实验数据符合准二级动力学和Langmuir模型,表明其吸附过程是一个单层的化学吸附过程.热力学研究证实,温度升高有利于Cr(Ⅵ)在NiFe₂O₄@AC上的吸附,该吸附过程是自发和吸热反应.NiFe₂O₄@AC吸附机制主要是通过络合作用和静电吸引来吸附Cr(Ⅵ),同时,外加磁场可从溶液中分...     

Enhanced solar-light-driven photocatalytic properties of novel Z-scheme binary BiPO4 nanorods anchored onto NiFe2O4 nanoplates: Efficient removal of toxic organic pollutants

Global environmental problems have been increasing with the growth of the world economy and have become a crucial issue. To replace fossil fuels, sustainable and eco-friendly catalysts are required for the removal of organic pollutants. In this study, nickel ferrite (NiFe₂O₄) was prepared using a simple wet-chemical synthesis, followed by calcination; bismuth phosphate (BiPO₄) was also prepared using a hydrothermal method. Further, NiFe₂O₄/BiPO₄ nanocomposites were prepared using a hydrothermal technique. Numerous characterization studies, such as structural, morphology, surface area, optical, photoluminescence, and photoelectrochemical investigations, were used to analyze NiFe₂O₄/BiPO₄ nanocomposites. The morphology analysis indicated a successful decoration of BiPO₄ nanorods on the surface of NiFe₂O₄ nanoplate. Further, the bandgap of the NiFe₂O₄/BiPO₄ nanocomposites was modified owing to the formation of a heterostructure. The as-prepared NiFe₂O₄/BiPO₄ nanocomposite exhibited promising properties to be used as a novel heterostructure for tetracycline (TC) and Rhodamine B (RhB) removal. The NiFe₂O₄/BiPO₄ nanocomposite degrades TC (98%) and RhB (99%) pollutants upon solar-light irradiation within 100 and 60 min, respectively. Moreover, the trapping experiments confirmed the Z-scheme approach of the prepared nanocomposites. The efficient separation and transfer of photogenerated electron-hole pairs rendered by the heterostructure were confirmed by utilizing electrochemical impedance spectroscopy, photocurrent experiments, and photoluminescence. Mott–Schottky measurements were used determine the positions of the conduction and valence bands of the samples, and the detailed mechanism of photocatalytic degradation of toxic pollutants was projected and discussed.     

碳纳米管负载的非晶态CoP合金和金属Co对高毒气体PH3的催化分解

采用沉积-沉淀法和诱导-还原沉积法制备了碳纳米管(CNTs)负载的金属Co和非晶态CoP合金,并将其应用于PH3分解反应.同时,通过XRD 、TEM、XPS、BET等一系列检测手段,对制备样品的相结构、形貌、组分和比表面积进行了表征.结果发现,反应过程中,Co/CNTs生成了高活性的金属磷化物CoP,而CoP/CNTs生成了CoP和Co2P两种金属磷化物.研究表明,Co/CNTs较CoP/CNTs显示出更高的催化活性和稳定性.高温还原预处理方式可提高Co/CNTs在PH3分解反应前期的活性,而低温还原的预处理方式有利于CoP/CNTs保持较高的催化活性,减轻样品的失活程度.     

分光光度法测定工业废水中的钴含量研究

通过试验确定了一种测定工业废水中钴含量的方法。考察入射波长、显色剂用量、干扰离子等因素对吸光度的影响;确定本法最佳测定波长为570 nm,显色剂最佳用量为1 mL;在废水中加入钴标准溶液进行测定,结果表明加标回收率在98.6%~105.60%之间,平均加标回收率为102.4%。该法灵敏度高、结果准确、检出限低、具有良好的精密度和准确度,是测定工业废水中钴含量的有效方法。     

磷基及铁基钝化剂对Pb、Cd、As复合污染土壤的修复效果及其工艺条件优化

通过DTPA和NaHC03浸提方法评价磷基、铁基钝化剂对Pb、Cd、As复合污染土壤的钝化修复效果.结果表明,磷基钝化剂中磷酸二氢钙对有效态Pb、Cd固定效果较好,35 d后其去除率分别为61％、38％;铁基钝化剂中以硫酸高铁对有效态As固定效果最好,28 d后其去除率达74.6％.工艺条件优化结果表明,随磷酸二氢钙用量增加,土壤中有效态Pb、Cd含量明显下降;随硫酸高铁用量增加,对有效态As的固定效果明显增加,当硫酸高铁添加量为土壤中As总物质的量的3.06倍时,28 d后土壤中有效态As的去除率高达74.5％.土壤水分含量在最大田间持水量的60％～80％时,对有效态Pb固定影响不大,但均略高于最大田间持水量30％ ～ 50％时的Pb去除率;土壤水分含量在最大田间持水量的60％～80％时,有效态Cd固定效果较好.当磷酸二氢钙用量为土壤中Pb、Cd总物质的量的10倍,土壤水分含量为最大田间持水量的60％时,21 d后有效态Pb、Cd去除率分别达到93％和39％.铁基与磷基钝化剂复配可以同时固定土壤中的Pb、Cd、As.当Fe3+与PO43-物质的量的比为7.2∶1时,7d后土壤有效态Pb、Cd、As去除率分别为99％、41％、69％.     

高铁锌焙砂还原焙烧-酸性浸出选择性分离铁锌研究

传统湿法炼锌中的氧化焙烧阶段产生大量铁酸锌,在常规条件下铁酸锌难以溶出,不利于铁锌的分离和回收.铁酸锌的生成导致后续沉铁工序复杂,渣量大,既浪费了锌铁资源又污染环境.提出了一种新的还原焙烧方法,使高铁锌焙砂中的铁酸锌选择性分解为氧化锌和磁性氧化铁.以北京某锌冶炼厂的锌焙砂为研究对象,研究铁酸锌选择性分解为氧化锌和磁性氧化铁过程中的变化规律,寻找最佳还原焙烧条件.采用化学分析法和XRD检测技术研究了锌焙砂还原焙烧过程中焙烧温度、焙烧时间、CO体积分数和CO/CO2配比等网素对亚铁生成量、可溶锌率及锌浸出率的影响.结果表明,在750℃、CO体积分数为4％、CO/(CO+ CO2)体积比为20％、焙烧60 min的焙烧条件,以及浸出酸度为150 g/L H2SO4、液固比为15∶1、转速为500 r/min、30℃的浸出条件下,锌的浸出率为93.24％,实现了铁锌的有效分离.     

Total cobalt determination in human blood and synovial fluid using inductively coupled plasma-mass spectrometry: method validation and evaluation of performance variables affecting metal hip implant patient samples

Inductively coupled plasma with mass spectrometric detection (ICP-MS) has been used for clinical analysis of cobalt (Co) due to its sensitivity and specificity; however, media-specific validation studies are lacking. This study provides data on performance variables affecting differences between selected analytical platforms (Perkin Elmer and Agilent), tissue sample preparation, storage, and interferences affecting measurements in whole blood, serum, and synovial fluid. The limits of detection (LOD) range from 0.2–0.5 µg/L in serum and synovial fluid, and 0.6–1.7 µg Co/L in whole blood. The Agilent platform with collision reaction cell is more sensitive, while the Perkin Elmer platform with dynamic reaction cell demonstrates more polyatomic interferences near the LOD for serum and whole blood. Split sample analysis showed good accuracy, precision, and reproducibility between serum Co measurements using acid digestion or detergent dilution preparations for persons with metal hip implants or following supplement intake. The results demonstrated reliability of the ICP-MS methodology across the two analytical platforms and between two commercial laboratories for Co concentrations above 5 µg Co/L, but digestion procedures and polyatomic interferences may affect measurements in some media at lower concentrations. These studies validate the described ICP-MS methodology for clinical purposes with precautions at low cobalt concentrations (<5 µg Co/L).     

氧化石墨烯电催化高效降解有机染料RBk5

电化学高级氧化技术是处理有机染料废水的有效技术方法之一，但其应用受传统贵金属电极成本高、易毒化失活等缺陷的限制.本研究采用廉价易得的石墨粉材料，制备氧化石墨烯（GO）催化剂，用于活性黑5（RBk5）染料废水的电催化氧化降解研究.利用透射电子显微镜、X射线光电子能谱、红外光谱、拉曼光谱、循环伏安法和电化学阻抗谱分析材料的结构特性及电化学性能.结果显示，氧化石墨烯具有较高的电子迁移速率，良好的亲水性和电催化活性.不同的RBk5浓度、外加电流、电解质、初始pH值等条件对RBk5的降解效率也有一定程度的影响.其中，电解质因素对材料性能影响最为显著.在RBk5浓度为10mg/L、外加电流为20mA、反应时间为35min、电解质为NaCl的条件下，电催化降解效率可以达到100%.