Article
Environmental Sciences
Diana M. Rodriguez, Natalia Mayordomo, Dieter Schild, Salim Shams Aldin Azzam, Vinzenz Brendler, Katharina Mueller, Thorsten Stumpf
Summary: The study investigated the reductive immobilization of Tc-99 using a synthetic FeS2 mixture, finding complete removal of Tc at certain pH levels and revealing the oxidation of S2- to SO42- by marcasite as a key mechanism for Tc immobilization. The research provides new insights into the redox reactions involved in Tc(VII) mobilization and highlights the potential of marcasite for natural Tc remediation by delaying re-oxidation of Tc(IV).
Article
Chemistry, Inorganic & Nuclear
Diana M. Rodriguez, Natalia Mayordomo, Andres Parra-Puerto, Dieter Schild, Vinzenz Brendler, Thorsten Stumpf, Katharina Mueller
Summary: Researchers have studied the reduction process of Tc(VII) in noncomplex media using a combination of electrochemistry, spectroscopy, and microscopy techniques. The results provide important insights into the speciation and chemistry of Tc, and bridge the gap in fundamental knowledge.
INORGANIC CHEMISTRY
(2022)
Article
Environmental Sciences
Ruiming Zhang, Rossana Napolano, Beidou Xi, Anne Millicent Salazar, Qiantao Shi, Ying Zhao, Xiaoguang Meng
Summary: Recent studies have found that the combination of zero-valent iron (ZVI) and pyrite (FeS2) can effectively remove Cr(VI) from water. This study discovered that dissolved oxygen (DO) plays a crucial role in enhancing the removal efficiency. The presence of DO led to the oxidation of pyrite, producing protons that promote ZVI corrosion and creating dissolved sulfide, which improves the removal of Cr(VI) by forming ferrous sulfide precipitates on the ZVI surface.
Article
Engineering, Chemical
Zhongxian Wu, Dongping Tao, Youjun Tao, Guangxi Ma
Summary: This study investigated the effects of cavitation nanobubbles on the oxidation characteristics and xanthate adsorption behavior of pyrite surface. The presence of cavitation nanobubbles enhanced the floatability and flotation kinetics of pyrite, as well as the adsorption capacity of sodium amyl xanthate and dixanthogen. The reactive species generated by nanobubbles were identified as dissolved oxygen and hydroxyl radicals. Zeta potential measurements demonstrated that the rapid formation of cavitation nanobubbles reduced the oxidation of pyrite surface.
MINERALS ENGINEERING
(2023)
Article
Environmental Sciences
Wenting Yu, Yuanyuan Cao, Song Yan, Huaming Guo
Summary: Nowadays, arsenic (As) pollution in aquatic environments poses a severe threat to human health. The effects of dissolved oxygen concentrations on As(V) adsorption onto siderite are not clear. This study investigated the removal of As(V) from aqueous solutions with different DO concentrations using synthesized siderite. The results showed that As(V) adsorption onto siderite was enhanced in the presence of dissolved oxygen, but excessive DO concentration did not further increase the adsorption due to the coating of Fe(III) oxides on the siderite surface.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Environmental Sciences
Liu Guo, Ziqiu Nie, Lijia Wen, Bohan Chen, Jie Tang, Man Gao, Jiajing Chen, Jingjing Liu
Summary: This study found that natural pyrite (FeS2) can effectively activate sodium percarbonate (SPC) and has good catalytic activity and stability for the removal of tetracycline. The SPC/FeS2 system achieved a tetracycline degradation efficiency of 70% within 10 minutes, with nearly half degraded in the first 5 minutes. The optimum SPC dosage was 8 mM, with FeS2 dosage of 0.5 g/L, and the tetracycline removal efficiency remained above 60% after 4 cycles.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Engineering, Environmental
Danying Xing, Shujing Shao, Yuyan Yang, Zuoming Zhou, Guohua Jing, Xiaodan Zhao
Summary: In this study, a novel advanced oxidation process called pyrite/PAA process was proposed for the efficient removal of tetracycline under neutral conditions. The pyrite/PAA process relies on the synergy of homogeneous and heterogenous Fe(II) species and generates CH3C(O)OO• radical as the main species for tetracycline degradation. The superior activation properties of pyrite can be attributed to the electron-donating ability of reducing sulfur species, which facilitate the reduction of Fe(III) to Fe(II). The study also analyzed the degradation pathways of tetracycline and the toxicity of the degradation intermediates.
Article
Chemistry, Physical
Guangsheng Zeng, Wei Chen, Sheng Liu, Guangyi Liu
Summary: In the xanthate flotation system, the aggregation of serpentine on sulfide minerals weakens their floatability. While electrostatic attraction was assumed to be the dominant driver for serpentine slimes coating, this study proposes that the hydrophobic interaction between the talc-like cleavage plane of serpentine and the xanthate-hydrophobized surface of sulfide minerals is the dominating factor. Through experiments using optical microscopy, micro-flotation, contact angle, zeta potential, and FT-IR, the aggregation behavior and mechanism of serpentine on pyrite surface were investigated, along with the disaggregation mechanism of HEDP. The findings reveal that the hydrophobic interaction promotes the aggregation between serpentine and pyrite, while the attendance of HEDP prevents their aggregation through electrostatic repulsion.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Engineering, Environmental
Yongpeng Ma, Jiandong Wang, Wentao Gu, Xiaojing Zhang, Haomiao Xu, Wenjun Huang, Yonghui Guo, Shaobo Wang
Summary: In this study, MoS2 was used as a catalyst for the heterogeneous removal of Hg-0 from flue gas. The results showed that the dosage of MoS2 and the inlet Hg-0 concentration had significant effects on Hg-0 removal efficiency, with gas-liquid mass transfer being the limiting step. Additionally, low pH and low temperature were beneficial for Hg-0 removal, while the presence of Cl- greatly enhanced the removal efficiency.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Environmental Sciences
Kalpana Bhatt, Deep Chandra Suyal, Saurabh Kumar, Kuldeep Singh, Priya Goswami
Summary: Rapid industrialization and overutilization of organic pollutants have altered the environment, and the interaction between plants and microbes has the potential for sustainable removal of pollutants and enhancement of crop productivity.
Article
Engineering, Environmental
Yanghai Yu, Liying Feng, Junlian Qiao, Xiaohong Guan
Summary: In recent years, the UV/sulfite process has shown high superiority in removing toxic halogenated organic compounds and oxyanions. This study reinvestigated the reduction of bromate (BrO3-) in this process, finding that it is influenced by key coexisting species such as dissolved oxygen (DO) and humic acid (HA). The study also revealed that besides electron reduction, sulfite radical (SO3-) also contributes to the reduction of BrO3-. Additionally, increasing sulfite dosage enhances the energy efficiency of the process for BrO3- removal.
JOURNAL OF WATER PROCESS ENGINEERING
(2022)
Article
Chemistry, Multidisciplinary
Leila Razavi, Heidar Raissi, Farzaneh Farzad
Summary: This study investigated the adsorption behavior of glyphosate on silicene nanosheets and provided detailed information about the adsorption mechanism using molecular dynamics and well-tempered metadynamics simulations. The results showed differences in total energy among different systems, and the free energy surface of the SNS/GLY system was determined.
Article
Chemistry, Physical
Zhikai Liang, Xiaobing Lan, Jun Chen, Jianjian Wu, Bin Deng
Summary: Heavy metal ions in waste water can be potentially treated by hydrate formation and dissociation. This study investigated the removal of nickel chloride as a heavy metal solution using methane hydrate. Factors such as stirring speed, hydration time, temperature, and concentration were considered. The study found that adherence of heavy metal solution on the hydrate surface and accumulation of wrapped heavy metal solution were the main reasons for impurity in heavy metal removal. A flushing water method was proposed to improve the removal efficiency. The study also suggested controlling hydrate formation conditions and combining hydrate-based method with other methods to enhance heavy metal removal efficiency.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Engineering, Chemical
Jincheng Ran, Dehao Kong, Yuepeng Li, Man Jiang, Xiaobing Yu, Rongdong Deng
Summary: This study investigated the effect of particle size on the flotation performance of minerals using X-ray photoelectron spectroscopy (XPS). The results showed that fine particles were more likely to become hydrophilic under low-temperature plasma modification, but they also had a higher critical oxidation degree. Coarse particles had a lower flotation recovery due to their low adsorption density of collector.
ADVANCED POWDER TECHNOLOGY
(2022)
Article
Engineering, Environmental
Mingzhu Liu, Nannan Wu, Xiaoyu Li, ShengNan Zhang, Virender K. Sharma, Jamaan S. Ajarem, Ahmed A. Allam, Ruijuan Qu
Summary: This study investigated the oxidation reaction of benzophenones, commonly used UV filters, by the oxidant potassium permanganate (KMnO4). The addition of potassium permanganate enhanced the reaction rate and efficiency. The degradation of benzophenones involved hydroxylation, bond breaking, polymerization, and carboxylation processes. Toxicity assessments revealed that the intermediate products formed during the degradation process posed a decreasing ecological risk.
Article
Chemistry, Physical
Sumit Kumar, Joerg Rothe, Nicolas Finck, Tonya Vitova, Kathy Dardenne, Aaron Beck, Dieter Schild, Horst Geckeis
Summary: The study reveals that a nanoparticulate (NpO2)-O-IV solid is the only speciation of Np sorbed on both doped and undoped magnetites. The Mn-O sites preferentially sorb Np(V) compared to Fe-O sites, indicating the significant role of impurity atom interacting with sorbing species through redox process. The participation of Mn through Fe(II)/Mn (III) redox couple in reducing sorbed Np(V) becomes significant only when the doped-magnetite contains a critical minimum concentration of Mn (>6 wt%).
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2022)
Article
Engineering, Environmental
M. Demnitz, K. Molodtsov, S. Schymura, A. Schierz, K. Mueller, F. Jankovsky, V Havlova, T. Stumpf, M. Schmidt
Summary: The study demonstrates that the sorption behavior of curium on crystalline rock is influenced by mineralogy and surface roughness, with increased sorption uptake and strength of Cm(III) observed around surface holes or grain boundaries with growing surface roughness. In areas with high surface roughness, inner-sphere sorption complexation and surface incorporation of Cm(III) are prominent, indicating that surface roughness should be considered a key parameter in predictive radionuclide modeling simulations.
JOURNAL OF HAZARDOUS MATERIALS
(2022)
Article
Multidisciplinary Sciences
Stephan Hilpmann, Miriam Bader, Robin Steudtner, Katharina Mueller, Thorsten Stumpf, Andrea Cherkouk
Summary: The safe disposal of high-level radioactive waste in a deep geological repository is a huge challenge. This study investigates the interactions between a halophilic archaeon and uranium(VI), an important radionuclide for long-term storage. The research reveals complex combinations of different processes and highlights the importance of studying the interactions of different microorganisms with uranium(VI). This work provides new insights into microbe-uranium(VI) interactions in highly saline conditions relevant to the long-term storage of radioactive waste in rock salt.
Article
Environmental Sciences
M. Stockmann, K. Fritsch, F. Bok, M. Marques Fernandes, B. Baeyens, R. Steudtner, K. Muller, C. Nebelung, V Brendler, T. Stumpf, K. Schmeide
Summary: This study investigated the influence of ionic strength on U(VI) sorption onto montmorillonite under different conditions and found significant variations in sorption rates. A comprehensive analysis was conducted using batch sorption experiments and spectroscopic methods, resulting in the establishment of an accurate sorption model that can predict U(VI) sorption processes in complex clay rich natural environments.
SCIENCE OF THE TOTAL ENVIRONMENT
(2022)
Article
Geochemistry & Geophysics
Mostafa Abdollahpour, Frank Heberling, Dieter Schild, Rasoul Rahnemaie
Summary: The concentrations of magnesium and calcium in natural aqueous environments are controlled by sorption and dissolution-precipitation reactions. Magnesium can bind in precipitating calcite, but at high magnesium to calcium ratios, aragonite is preferentially formed. Thermodynamic and kinetic controls may be at play at low magnesium to calcium ratios.
Article
Environmental Sciences
Tiziana Missana, Ursula Alonso, Natalia Mayordomo, Miguel Garcia-Gutierrez
Summary: Cadmium is a highly toxic heavy metal pollutant with strict exposure limits. This study investigated the immobilization of cadmium by smectite clay through batch sorption tests and utilized a thermodynamic model to interpret the experimental data. The results showed that the precipitation of otavite (CdCO3) has a limited contribution to the immobilization of cadmium under the studied conditions.
Article
Engineering, Environmental
Nitin Khandelwal, Nisha Singh, Ekta Tiwari, Remi Marsac, Dieter Schild, Thorsten Schaefer, Gopala Krishna Darbha
Summary: In this study, the growth behavior of redox sensitive Fe0 nanoparticles (nZVI) was found to vary on different clay surfaces. The non-swelling kaolinite (K-nZVI) showed dominant surface growth characteristics, forming larger nZVI particles (>24.8 +/- 7.4 nm) with positive zeta potential. On the other hand, the swelling bentonite (B-nZVI) exhibited negative zeta potential, mainly due to the surface charge of bentonite clay. This surface-dependent variation resulted in higher and faster removal of oxy-anions with K-nZVI, while B-nZVI showed higher sorption of cations. XPS and pXRD analysis confirmed the major removal mechanisms of reductive sorption, co-precipitation/complexation, electrostatic attraction, and complexation. The findings highlight the potential applications of K-nZVI and B-nZVI in removing specific contaminants from different types of water sources.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Materials Science, Multidisciplinary
Andres G. Munoz, T. Meyer, D. Schild, W. Calvet
Summary: The chemical transformations of native oxide on stainless steel 309 S prior to pitting in anoxic near saturated geological Q3-brine were studied using synchrotron radiation photoelectron spectroscopy (SRPES). A Cr-rich hydrated mixed iron-chromium oxide, exhibiting n-type semiconducting behavior, is formed after wet polishing. Surface accumulation of holes in the metastable pitting potential region leads to hydroxylation of oxide bonds and subsequent selective dissolution of iron. The open structure of remaining surface chromium hydroxide facilitates the inward access of chloride and water. The inhibiting effect of sulfate is attributed to the formation of stabilizing O-S-O bridges blocking chloride access.
Article
Materials Science, Multidisciplinary
Sudipta Chakraborty, Dipanjan Banerjee, Andreas C. Scheinost, Jean-Marc Greneche, Fabienne Favre, Antoine Gehin, Laurent Charlet
Summary: The reactivity of Fe(II) sorbed on different types of clay towards U(VI) reduction was investigated. U(VI) reduction only occurred on Fe-free synthetic montmorillonite (MONT), and a hydrated uranyl silicate (soddyite)-like phase was formed. The lack of reactivity on Fe-poor natural montmorillonite (Fe-MONT) and Fe-rich natural nontronite (NAu-2) is likely due to inter-valence charge transfer (IVCT) between surface Fe(II) and structural Fe(III). This study highlights the dependence of clay sorbed Fe2+ reactivity on the nature of clay and the oxidation state of sorbed Fe.
JOURNAL OF MATERIALS RESEARCH
(2023)
Article
Chemistry, Physical
Enrico Bianchetti, Augusto F. Oliveira, Andreas C. Scheinost, Cristiana Di Valentin, Gotthard Seifert
Summary: This study investigates the chemistry of TcVIIO4- and TcIV species at the Fe3O4(001) surface using a hybrid DFT functional (HSE06) method. The results indicate that the interaction between TcVIIO4- and the magnetite surface leads to the formation of reduced TcVI species without any change in the Tc coordination sphere. Additionally, several model structures for the immobilized TcIV final products are explored, showing that TcIV can be incorporated into a subsurface octahedral site or adsorbed on the surface as TcIVO2 center dot xH2O chains.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Multidisciplinary Sciences
Sanduni Ratnayake, Johannes Luetzenkirchen, Nicolas Finck, Dieter Schild, Frank Heberling, Teba Gil-Diaz, Kathy Dardenne, Joerg Rothe, Horst Geckeis
Summary: The speciation of thorium in soil samples from Sri Lanka was investigated using X-ray Absorption Spectroscopy (XAS). The results showed that thorium predominantly exists as thorium phosphate (76%) and thorium oxide (24%), with minor amounts of thorium silicate also detected. This study provides quantitative and qualitative information on thorium mineral phases in soil samples from Sri Lanka using XAS for the first time.
SCIENTIFIC REPORTS
(2023)
Article
Instruments & Instrumentation
Erik V. Johnstone, Natalia Mayordomo, Edward J. Mausolf
Summary: New methods of producing Tc-99m and Tc-101 using a compact accelerator neutron source were investigated in this study. Neutrons generated from a 16.5 MeV cyclotron were utilized for irradiation, and natural molybdenum targets were used for the (n, gamma) reactions to produce Tc isotopes. The production and potential applications of Tc-99m and Tc-101 under these conditions were discussed.
EPJ TECHNIQUES AND INSTRUMENTATION
(2023)
Article
Geochemistry & Geophysics
Jenna Kasko, Xiaodong Li, Katharina Mueller, Yanling Ge, Gianni F. Vettese, Gareth T. W. Law, Marja Siitari-Kauppi, Nina Huittinen, Johannes Raff, Malin Bomberg, Merja Herzig
Summary: This study investigated the uranium bioassociation by Pseudomonas sp. isolated from a boreal bog. The strains were able to remove uranium from the solution, and the efficiency of uranium bioassociation was influenced by nutrient source, incubation temperature, time, and pH. Infrared spectroscopy and transmission electron microscopy with energy dispersive X-ray spectroscopy revealed that carboxyl groups on the cell surface and phosphate groups inside the cells were responsible for uranium binding. The removal efficiency of uranium depended on the U(VI) speciation under different pH conditions.
APPLIED GEOCHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
Nicolas Finck, Nikoleta Morelova, Michel L. Schlegel, Dieter Schild, Solenn Reguer, Kathy Dardenne, Horst Geckeis
Summary: The stainless steel AISI 309 S, used for containers of vitrified high-level radioactive waste, was subjected to 90 degrees C under highly saline and anoxic conditions for different exposure times up to 294 days. The surface damage was minimal, and no pitting was observed. The corrosion layer consisted of an inner layer comprising mostly chromium (hydr)oxides and an outer layer composed of Fe- and Ni-based spinel compounds with admixed nickel (hydr)oxides. Minor amounts of magnetite and layered double hydroxide were also identified. Dissolved metal ion concentrations were very low, with only a slight increase in pH and limited decrease in redox potential.
Article
Chemistry, Multidisciplinary
Si Chen, Xiaohui Huang, Dieter Schild, Di Wang, Christian Kuebel, Silke Behrens
Summary: Intermetallic Pd-In nanoparticles were synthesized in ionic liquids using a novel and facile approach. The structure of the nanoparticles obtained under different reaction conditions was confirmed. These stabilized nanoparticles showed high activity and selectivity as catalysts. This research provides insights for the synthesis of intermetallic nanoparticles and the design of bimetallic catalysts.