@article{GranathLoebmannMandel2021,
  author    = {Granath, Tim and L{\"o}bmann, Peer and Mandel, Karl},
  title     = {Oxidative Precipitation as a Versatile Method to Obtain Ferromagnetic Fe\(_{3}\)O\(_{4}\) Nano- and Mesocrystals Adjustable in Morphology and Magnetic Properties},
  series = {Particle \& Particle Systems Characterization},
  volume    = {38},
  journal   = {Particle \& Particle Systems Characterization},
  number    = {3},
  doi       = {10.1002/ppsc.202000307},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224419},
  year      = {2021},
  abstract  = {Oxidative precipitation is a facile synthesis method to obtain ferromagnetic iron oxide nanoparticles from ferrous salts—with unexplored potential. The concentration of base and oxidant alone strongly affects the particle's structure and thus their magnetic properties despite the same material, magnetite (Fe\(_{3}\)O\(_{4}\)), is obtained when precipitated with potassium hydroxide (KOH) from ferrous sulfate (FeSO\(_{4}\)) and treated with potassium nitrate (KNO\(_{3}\)) at appropriate temperature. Depending on the potassium hydroxide and potassium nitrate concentrations, it is possible to obtain a series of different types of either single crystals or mesocrystals. The time-dependent mesocrystal evolution can be revealed via electron microscopy and provides insights into the process of oriented attachment, yielding faceted particles, showing a facet-dependent reactivity. It is found that it is the nitrate and hydroxide concentration that influences the ligand exchange process and thus the crystallization pathways. The presence of sulfate ions contributes to the mesocrystal evolution as well, as sulfate apparently hinders further crystal fusion, as revealed via infrared spectroscopy. Finally, it is found that nitrite, as one possible and ecologically highly relevant reduction product occurring in nature in context with iron, only evolves if the reaction is quantitative.},
  language  = {en}
}
@article{SchneiderTschoepeHanselmannetal.2020,
  author    = {Schneider, Michael and Tsch{\"o}pe, Andr{\´e} and Hanselmann, Doris and Ballweg, Thomas and Gellermann, Carsten and Franzreb, Matthias and Mandel, Karl},
  title     = {Adsorber Particles with Magnetically-Supported Improved Electrochemical Conversion Behavior for Waste Water Treatment Processes},
  series = {Particle \& Particle Systems Characterization},
  volume    = {37},
  journal   = {Particle \& Particle Systems Characterization},
  number    = {2},
  doi       = {10.1002/ppsc.201900487},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-214738},
  year      = {2020},
  abstract  = {Micron-sized supraparticles, consisting of a plurality of discrete nano- and microscale functional units, are assembled and fused by means of a droplet extrusion process. By combining nano magnetite, activated carbon, and conductive carbon with a polymeric binder matrix, particles are obtained which unite good magnetic properties, electrical conductivity, and adsorber activity through the high accessible surface area of the incorporated activated carbon of about 570 m\(^{2}\) g\(^{-1}\), thereby enabling a new approach toward sustainable water treatment processes. Due to the interplay of the components, it is possible to adsorb target substances, dissolved in the water which is demonstrated by the adsorption of the model dye methylene blue. A very fast adsorption kinetic and an adsorption capacity of about 400 mg g\(^{-1}\) is determined. By using the developed composite particles, it is also possible to electrochemically alter substances flowing through a magnetically-stabilized fluidized-bed reactor by electrochemically charging/discharging, significantly supported by the magnetic field enabling alternatingly optimum mobility/adsorption phases with contact/charging intervals. The electrochemical conversion can be increased up to 151\% depending on the applied flow-rate and electrical voltage. By applying an external magnetic field, a further increase of electrochemical conversion of up to 70\% can be observed.},
  language  = {en}
}
@article{WintzheimerOppmannDoldetal.2019,
  author    = {Wintzheimer, Susanne and Oppmann, Maximilian and Dold, Martin and Pannek, Carolin and Bauersfeld, Marie-Luise and Henfling, Michael and Trupp, Sabine and Schug, Benedikt and Mandel, Karl},
  title     = {Indicator Supraparticles for Smart Gasochromic Sensor Surfaces Reacting Ultrafast and Highly Sensitive},
  series = {Particle \& Particle Systems Characterization},
  volume    = {36},
  journal   = {Particle \& Particle Systems Characterization},
  number    = {10},
  doi       = {10.1002/ppsc.201900254},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213671},
  year      = {2019},
  abstract  = {The detection of toxic gases, such as NH\(_{3}\) and CO, in the environment is of high interest in chemical, electronic, and automotive industry as even small amounts can display a health risk for workers. Sensors for the real-time monitoring of these gases should be simple, robust, reversible, highly sensitive, inexpensive and show a fast response. The indicator supraparticles presented herein can fulfill all of these requirements. They consist of silica nanoparticles, which are assembled to supraparticles upon spray-drying. Sensing molecules such as Reichardt's dye and a binuclear rhodium complex are loaded onto the microparticles to target NH\(_{3}\) and CO detection, respectively. The spray-drying technique affords high flexibility in primary nanoparticle size selection and thus, easy adjustment of the porosity and specific surface area of the obtained micrometer-sized supraparticles. This ultimately enables the fine-tuning of the sensor sensitivity and response. For the application of the indicator supraparticles in a gas detection device, they can be immobilized on a coating. Due to their microscale size, they are large enough to poke out of thin coating layers, thus guaranteeing their gas accessibility, while being small enough to be applicable to flexible substrates.},
  language  = {en}
}
@article{FleglerSchneiderPrieschletal.2016,
  author    = {Flegler, Andreas and Schneider, Michael and Prieschl, Johannes and Stevens, Ralph and Vinnay, Thomas and Mandel, Karl},
  title     = {Continuous flow synthesis and cleaning of nano layered double hydroxides and the potential of the route to adjust round or platelet nanoparticle morphology},
  series = {RSC Advances},
  volume    = {6},
  journal   = {RSC Advances},
  number    = {62},
  doi       = {10.1039/c6ra09553d},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191305},
  pages     = {57236-57244},
  year      = {2016},
  abstract  = {Here, we report a continuous flow synthesis of nano LDH, comprising a continuous precipitation process using static mixers and followed by an immediate cleaning process via a semi-continuous centrifuge to obtain the final product in one-go. Via this synthesis setup, it is possible to independently vary the concentrations of the reactants during precipitation and at the same time ensure constant reaction conditions and an immediate "quenching" of the precipitate due to "on the flow"-washing. We found that this paves the way to adjust the synthesis parameters in a way that the final morphology of the nano-LDH particles can be controlled to be either round or platelet-like.},
  language  = {en}
}
@article{SzczerbaZukrowskiPrzybylskietal.2016,
  author    = {Szczerba, Wojciech and Zukrowski, Jan and Przybylski, Marek and Sikora, Marcin and Safonova, Olga and Shmeliov, Aleksey and Nicolosi, Valeria and Schneider, Michael and Granath, Tim and Oppmann, Maximilian and Straßer, Marion and Mandel, Karl},
  title     = {Pushing up the magnetisation values for iron oxide nanoparticles via zinc doping: X-ray studies on the particle's sub-nano structure of different synthesis routes},
  series = {Physical Chemistry Chemical Physics},
  volume    = {18},
  journal   = {Physical Chemistry Chemical Physics},
  number    = {36},
  doi       = {10.1039/c6cp04221j},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-187390},
  pages     = {25221-25229},
  year      = {2016},
  abstract  = {The maximum magnetisation (saturation magnetisation) obtainable for iron oxide nanoparticles can be increased by doping the nanocrystals with non-magnetic elements such as zinc. Herein, we closely study how only slightly different synthesis approaches towards such doped nanoparticles strongly influence the resulting sub-nano/atomic structure. We compare two co-precipitation approaches, where we only vary the base (NaOH versus NH\(_3\)), and a thermal decomposition route. These methods are the most commonly applied ones for synthesising doped iron oxide nanoparticles. The measurable magnetisation change upon zinc doping is about the same for all systems. However, the sub-nano structure, which we studied with Mossbauer and X-ray absorption near edge spectroscopy, differs tremendously. We found evidence that a much more complex picture has to be drawn regarding what happens upon Zn doping compared to what textbooks tell us about the mechanism. Our work demonstrates that it is crucial to study the obtained structures very precisely when "playing'' with the atomic order in iron oxide nanocrystals.},
  language  = {en}
}
@phdthesis{Mandel2013,
  author    = {Mandel, Karl},
  title     = {Synthesis and Characterisation of Superparamagnetic Nanocomposite Particles for Water Purification and Resources Recovery},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-81208},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2013},
  abstract  = {Superparamagnetic nanocomposite microparticles, compromised of magnetite nanoparticles in a silica matrix, have been synthesised and surface-modified to act as adsorbers for substances (e.g. toxic heavy metals or valuable resources) dissolved in fluids like water. The particles can be used for a magnetic-extraction-assisted separation process of these target substances which thereby can be recovered from the fluid.},
  subject      = {Magnetisches Trennverfahren},
  language  = {en}
}