Preface

No abstract in Englis

Preface

No abstract in Englis

Study on removal of Se(IV) using Fe-Mn layered double hydroxides and Fe-Mn Dos (double oxides)

In this study, Fe-Mn-CO3 layered double hydroxide (LDHs) and Fe-Mn Double oxide (DOs) were synthesized by the co-recipitation methods for Se(IV) removal from aqueous solutions. The Se(IV) adsorption capacities and removal mechanism of Fe-Mn LDH and Fe-Mn DOs determined by batch and column experiments. The calculated Se(IV) adsorption capacities on Fe-Mn LDH and Fe-Mn DOs were 52.5 and 55.3 mg/g, respectively. Kinetic models applied to the adsorption of Se(IV) on the Fe-Mn LDH and Fe-Mn DOs calculated using pseudo-first, second-order, Elovich, and Intraparticle diffusion kinetic models and all kinetic parameters were calculated and discussed. Isotherm studies were also performed using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich equations in the temperature range of 283 - 323 K. Adsorption kinetics and isotherm experiments are well fitted pseudo-second order model and Freundlich isotherm, respectively. The production of this adsorbent is cost-effective for industrial applications

Treatment of copper-containing leaching residue by sulfation roasting followed by acid/water leaching

This research investigates the extraction of copper from copper-containing leaching residue, which includes 33.45% of copper, 14.14% of iron, 23.87% of sulfur and trace amounts of silver and other elements. Roasting the copper-containing residue under air and oxygen flow convert sulfides into sulfate, followed by water and acid leaching to extract copper. The process parameters, including leaching temperature, sulfuric acid concentration, leaching time, solid-to liquid ratio, and agitation speed, were optimized for both water and acid leaching methods. Results showed that the maximum copper dissolution efficiency was 93.12% with water leaching, and 97.16% with acid leaching. Chemical analysis revealed that the water and acid leaching residue contained 48.13% and 31.64% of iron, respectively. This study provides valuable insights into the process optimization for copper extraction from copper-containing leaching residue, which can inform the development of more efficient and sustainable methods for metal recovery

Treatment of copper-containing leaching residue by sulfation roasting followed by acid/water leaching

This research investigates the extraction of copper from copper-containing leaching residue, which includes 33.45% of copper, 14.14% of iron, 23.87% of sulfur and trace amounts of silver and other elements. Roasting the copper-containing residue under air and oxygen flow convert sulfides into sulfate, followed by water and acid leaching to extract copper. The process parameters, including leaching temperature, sulfuric acid concentration, leaching time, solid-to liquid ratio, and agitation speed, were optimized for both water and acid leaching methods. Results showed that the maximum copper dissolution efficiency was 93.12% with water leaching, and 97.16% with acid leaching. Chemical analysis revealed that the water and acid leaching residue contained 48.13% and 31.64% of iron, respectively. This study provides valuable insights into the process optimization for copper extraction from copper-containing leaching residue, which can inform the development of more efficient and sustainable methods for metal recovery

Manipulation von monodispersen Emulsionen in Mikrokanälen

Die Frage wie räumlich auf mikrofluide Kanalnetzwerke begrenzte monodisperse Gelemulsionen auf verschiedene Manipulationen reagieren, wurde in der vorliegenden Arbeit bearbeitet. In verschiedenen Kanalgeometrien wurde die Tropfenanordnung in Abhängigkeit von der Volumenfraktion der dispergierten Phase untersucht, wobei sowohl statische ("passive") als auch schaltbare ("aktive") Kanalgeometrien genutzt wurden. Weiterhin wurden quasi-zweidimensionale Strukturübergänge an statischen Tropfenanordnungen in Abhängigkeit von der lateral aufgeprägten Kraft betrachtet. Schließlich wurden mehrere Methoden, insbesondere die kontrollierte Tropfenerzeugung, die gezielte Elektrokoaleszenz von Tropfenpaaren und die Manipulation von Tropfen in verschiedenen Kanalgeometrien, angewendet, um die Bildung und Manipulation von Fibrinnetzwerken innerhalb von Tropfen zu studieren.Übergänge zwischen bestimmten Tropfenanordnungen in einer durch einen Kanal fließen-den Emulsion können beispielsweise induziert werden, indem die Kanalgeometrie im Verlauf des Kanals verändert wird. Aufgrund der endlichen Energie, die benötigt wird, um eine bestimmte Tropfenanordnung umzuorganisieren, sind diese Übergänge inhärent hysteretisch und hängen nicht nur von der Tropfengröße, sondern auch vom Volumenanteil der dispergierten Phase ab. Es wurden die Tropfenumordnungen für verschiedene Kanalgeometrien, wie Einengungen und Ecken, abhängig vom Volumenanteil und Tropfengröße studiert. Des Weiteren war auch der Einfluss der Volumenfraktion und der Tropfengröße auf Übergänge in der Tropfenanordnung bei Einwirkung einer lateralen Kraft Gegenstand der Arbeit.Um die Emulsionsanordnungen in einem Mikrokanal aktiv manipulieren zu können wurden Ferrofluide als kontinuierliche Phase der Emulsion verwendet. Durch das Anlegen von externen Magnetfeldern an die geschlossene Anordnung konnten Übergänge zwischen zwei Tropfenanordnungen beobachtet werden. Dabei wurden vorübergehend ferrofluidische An-sammlungen hergestellt, die die Kanalgeometrie so veränderten, dass Strukturübergänge zu beobachten waren.In Kombination mit einer Technik, bei der gezielt Paare von Tropfen fusioniert werden, wurde die Bildung und Manipulation in situ sowie die Struktur von in Tropfen eingeschlossenen Fibrinnetzwerken untersucht. Im dynamischen Fall, bei dem sich Tropfen kontinuierlich durch die Kanäle bewegen, wurde die Aggregation von Fibrinnetzwerken in Abhängigkeit von der Geschwindigkeitsverteilung im Strömungsfeld innerhalb des Tropfens beobachtet. Wurde der Tropfen aber in der Reaktionskammer bis zur vollständigen Entwicklung des Fibrinnetz-werkes "geparkt" und dann kontrolliert deformiert, wurde anders als im dynamischen Fall eine elastische Wiederherstellung der ursprünglichen Form des Fibrinnetzwerkes beobachtet

Supercritical hydrothermal synthesis of silver nanoparticles, composites, and their characterizations

Silver nanoparticles (AgNPs) and silver nanoparticles doped activated carbon (AC-Ag) composite materials were synthesized by hydrothermal processes in supercritical water conditions (29 MPa and 400 °C) using batch reactor. We studied the influence of the precursor solution concentration, reaction temperature under the hydrothermal conditions, and synthesis time on the properties of synthesized materials. The properties of plain AgNPs and AC-Ag composite materials synthesized in supercritical water, including crystallinity, particle size, and molecular interactions between AC and Ag were investigated, comprehensively. Compared to the plain AgNPs, the activated carbon-supported Ag nanocomposite was synthesized faster due to the active functional groups of activated carbon. Furthermore, the FTIR results reveal that the silver nanoparticles are attached to the activated carbon surface in the presence of oxygen bonded carbonyl and carboxyl groups. The nano-sized metal silver particles were observed on the AC surface when analyzed by TEM and XRD. All results imply that the supercritical water condition allows the formation of silver particles less than 100 nm either in the form of plain particles or deposited on the activated carbon surface using the silver acetate precursor solution. This environmentally benign supercritical hydrothermal process can replace the conventional method and become a novel synthesis method for preparing various new materials

Removal of Chromium from Aqueous Solution by Thermally Treated Mgal Layered Double Hydroxide

MgAl based layered double hydroxide (MgAl-LDH) was used as adsorbent for the removal of chromium oxyanion from an aqueous solution. MgAl-LDH was synthesized successfully using co-precipitation method, and was characterized by X-Ray Diffractometer (XRD), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). MgAl-LDH was thermally treated for improving the chromium adsorption. Samples were treated at 220°C and 450°C. A negligible difference of total chromium adsorption capacities was observed between MgAl-LDH000 and MgAl-LDH220 as 12.56 mg/g and 11.01 mg/g. The maximum chromium adsorption capacity of MgAl-LDH was 88.07 mg/g at 500g/l chromium concentration for MgAl-LDH which has been thermally treated at 450°C (MgAl-LDH450). The results indicated that memory effects of thermally treated MgAl-LDH at certain temperatures were retained and enhanced chromium removal efficiency