ORCID Profile
0000-0001-8381-2108
Current Organisations
University of Adelaide
,
University of South Australia
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Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1MA00859E
Abstract: This review article critically assesses materials engineering advances across blood separation technologies which addresses operating challenges such as surface fouling and material biocompatibility.
Publisher: Elsevier BV
Date: 03-2012
Publisher: Springer Science and Business Media LLC
Date: 14-06-2018
DOI: 10.1007/S10661-018-6744-X
Abstract: Trace metals occur at various concentrations in all wetlands. Their proliferation, chemical speciation, mobility and bioavailability are dependent on the redox potential (Eh), pH and the presence of organic and inorganic adsorption surfaces and co-precipitating metals. Consequently, changes in these key parameters have the potential to alter the fate of the dominant trace metal species in the sediment. An imposition of preload surcharge is a technique use in geotechnical engineering to improve in the strength and load carrying capacity of waterlogged sediments. The soil strength improvement is effected through the expulsion of porewater from the sediment. The imposition of surcharge over wetland sediments has the potential to create oxygen-deficient condition within the sediment, and cause pH, temperature, redox, EC and salinity changes in the sediment, which would impact on the mobilisation, chemical speciation, mobility and bioavailability of dominant toxic trace metals and their toxicity in the sediment. In the present work, a case study of the impact of preload surcharge on the proliferation, chemical speciation, mobilisation, mobility and bioavailability of arsenic, chromium, cobalt, copper and zinc in a naturally occurring pyrite-rich sediment is presented. The imposition of preload surcharge over the pyrite-rich sediment was accompanied by changes in the redox dynamics of the sediment, with multi-facet impact on the concentration, mobilisation and bioavailability of toxic trace metals, their redox transformation between oxidation states and on the toxicity within and outside the sediment environment.
Publisher: Elsevier BV
Date: 05-2021
Publisher: American Chemical Society (ACS)
Date: 02-10-2014
DOI: 10.1021/LA503248E
Abstract: The adsorption of carboxymethylcellulose polymers on molybdenite was studied using spectroscopic ellipsometry and atomic force microscopy imaging with two polymers of differing degrees of carboxyl group substitution and at three different electrolyte conditions: 1 × 10(-2) M KCl, 2.76 × 10(-2) M KCl, and simulated flotation process water of multicomponent electrolyte content, with an ionic strength close to 2.76 × 10(-2) M. A higher degree of carboxyl substitution in the adsorbing polymer resulted in adsorbed layers that were thinner and with more patchy coverage increasing the ionic strength of the electrolyte resulted in increased polymer layer thickness and coverage. The use of simulated process water resulted in the largest layer thickness and coverage for both polymers. The effect of the adsorbed polymer layer on bubble-particle attachment was studied with single bubble-surface collision experiments recorded with high-speed video capture and image processing and also with single mineral molybdenite flotation tests. The carboxymethylcellulose polymer with a lower degree of substitution resulted in almost complete prevention of wetting film rupture at the molybdenite surface under all electrolyte conditions. The polymer with a higher degree of substitution prevented rupture only when adsorbed from simulated process water. Molecular kinetic theory was used to quantify the effect of the polymer on the dewetting dynamics for collisions that resulted in wetting film rupture. Flotation experiments confirmed that adsorbed polymer layer properties, through their effect on the dynamics of bubble-particle attachment, are critical to predicting the effectiveness of polymers used to prevent mineral recovery in flotation.
Publisher: Elsevier BV
Date: 15-10-2009
Publisher: Elsevier BV
Date: 11-1999
Publisher: Trans Tech Publications, Ltd.
Date: 12-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.148-149.643
Abstract: Refinery crude preheat train (CPHT) is prone to fouling and ageing effects due to the complexity of processed crude feedstock preheated prior to distillation. This has serious implications on the thermal and hydraulic performance of the CPHT. As a result, efficient performance of crude preheat trains is compromised and as such, optimal scheduling cleaning operations are required to restore performance. In this paper, we attempt to review the subject of fouling/ageing control and mitigation in crude preheat train network by optimal scheduling cleaning approach. Three prominent optimisation techniques/models namely Mathematical Models (Mixed integer linear programming (MILP) and Mixed integer non-linear programming (MINLP) models) Artificial Intelligence (AI) Models and Heuristic Techniques used for achieving optimal cleaning are outlined.
Publisher: MDPI AG
Date: 27-08-2020
DOI: 10.3390/MIN10090759
Abstract: In our previous studies, we investigated the performance of a novel pneumatic planar magnetic separator (PMS) for the dry beneficiation of a selected magnetite ore. In the present study, we have extended the studies on the PMS with the focus on investigating how various PMS processing flowsheet configurations influence its performance. The outcomes were subsequently compared with those of a Davis tube recovery (DTR) tester. The study demonstrated that the use of PMS in the dry beneficiation of magnetite ores is feasible, and operating the PMS in different flowsheet configurations positively influences the magnetite concentrate grade and purity. Finally, the study showed that the PMS performance compares well with that of DTR and can potentially replace DTR in operations that are carried out in arid regions.
Publisher: Elsevier BV
Date: 12-2015
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.NEUBIOREV.2014.04.001
Abstract: The ability to inhibit actions, one of the hallmarks of human motor control, appears to decline with advancing age. Evidence for a link between changes in inhibitory functions and poor motor performance in healthy older adults has recently become available with transcranial magnetic stimulation (TMS). Overall, these studies indicate that the capacity to modulate intracortical (ICI) and interhemispheric (IHI) inhibition is preserved in high-performing older in iduals. In contrast, older in iduals exhibiting motor slowing and a declined ability to coordinate movement appear to show a reduced capability to modulate GABA-mediated inhibitory processes. As a decline in the integrity of the GABA-ergic inhibitory processes may emerge due to age-related loss of white and gray matter, a promising direction for future research would be to correlate in idual differences in structural and/or functional integrity of principal brain networks with observed changes in inhibitory processes within cortico-cortical, interhemispheric, and/or corticospinal pathways. Finally, we underscore the possible links between reduced inhibitory functions and age-related changes in brain activation patterns.
Publisher: Elsevier BV
Date: 03-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2CC17690D
Abstract: A multi-drug delivery system with sequential release based on titania nanotube arrays and polymer micelles as drug carriers is presented. Delivery of multiple water insoluble and soluble drugs required for combined local therapy is demonstrated.
Publisher: Elsevier BV
Date: 07-2013
Publisher: Elsevier BV
Date: 02-2005
Publisher: Elsevier BV
Date: 10-2014
Publisher: Elsevier BV
Date: 15-10-2009
Publisher: American Chemical Society (ACS)
Date: 15-02-2010
DOI: 10.1021/IE901803V
Publisher: Academy of Science of South Africa
Date: 2018
Publisher: Elsevier BV
Date: 1997
Publisher: Elsevier BV
Date: 07-2013
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 05-2015
Publisher: Elsevier BV
Date: 11-2016
Publisher: Informa UK Limited
Date: 23-05-2022
Publisher: IEEE
Date: 02-2010
Publisher: Elsevier BV
Date: 09-2003
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 06-2012
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 08-2018
Publisher: Unpublished
Date: 2014
Publisher: Elsevier BV
Date: 10-1999
Publisher: Elsevier BV
Date: 09-2016
Publisher: Springer Science and Business Media LLC
Date: 06-09-2013
Publisher: Elsevier BV
Date: 2014
Publisher: Elsevier BV
Date: 11-2005
Publisher: Wiley
Date: 20-07-2012
Abstract: A new approach to engineer a local drug delivery system with delayed release using nanostructured surface with nanotube arrays is presented. TNT arrays electrochemically generated on a titanium surface are used as a model substrate. Polymer micelles as drug carriers encapsulated with drug are loaded at the bottom of the TNT structure and their delayed release is obtained by loading blank micelles (without drug) on the top. The delayed and time-controlled drug release is successfully demonstrated by controlling the ratio of blank and drug loaded-micelles. The concept is verified using four different polymer micelles (regular and inverted) loaded with water-insoluble (indomethacin) and water-soluble drugs (gentamicin).
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 03-2004
DOI: 10.1016/J.JCIS.2003.09.042
Abstract: Nonionic polyethylene oxide (PEO) and anionic polyacrylamide (PAM) flocculation of kaolinite dispersions has been investigated at pH 7.5 in the temperature range 20-60 degrees C. The surface chemistry (zeta potential), particle interactions (shear yield stress), and dewatering behavior were also examined. An increase in the magnitude of zeta potential of kaolinite particles, in the absence of flocculant and at a fixed PEO and PAM concentration, with increasing temperature was observed. The zeta potential behavior of the flocculated particles indicated a decrease in the adsorbed polymer layer thickness, while at the same time, however, the adsorbed polymer density showed a significant increase with increasing temperature. These results suggest that polymer adsorption was accompanied by temperature-influenced conformation changes. The hydrodynamic diameter and supernatant solution viscosity of both polymers decreased with increasing temperature, consistent with a change in polymer-solvent interactions and conformation, prior to adsorption. The analysis of the free energy (DeltaG(ads)) of adsorption showed a strong temperature dependence and the adsorption process to be more entropically than enthalpically driven. The polymer conformation change and increased negative charge at the kaolinite particle surface with increasing temperature resulted in decreased polymer bridging and flocculation performance. Consequently, the shear yield stress and the rate and the extent of dewatering (consolidation) of the pulp decreased significantly at higher temperatures (>40 degrees C). The temperature effect was more pronounced in the presence of PEO than PAM, with 40 and 20 degrees C indicated as the optima for enhanced performance of the latter and former flocculants, respectively. The results demonstrate that a temperature-induced conformation change, together with polymer structure type, plays an important role in flocculation and dewatering behavior of kaolinite dispersions.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM16819G
Publisher: Elsevier BV
Date: 10-2007
Publisher: Elsevier BV
Date: 06-2012
Publisher: Springer Science and Business Media LLC
Date: 13-03-2019
DOI: 10.1007/S10661-019-7289-3
Abstract: Pyrite undergoes oxidation when exposed to aqueous oxygen to produce acidic leachate with high concentrations of H
Publisher: Elsevier BV
Date: 09-2018
Publisher: Elsevier BV
Date: 02-2013
Publisher: Elsevier BV
Date: 03-2013
Publisher: Elsevier BV
Date: 11-2000
Publisher: Royal Society of Chemistry (RSC)
Date: 16-10-2014
DOI: 10.1039/C4CP03161J
Abstract: The adsorption of poly(N-isopropyl acrylamide) (PNIPAM) onto talc from aqueous solutions has been studied using the in situ methodology of particle film attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. PNIPAM was observed to adsorb significantly onto the talc particle film at a temperature below its lower critical solution temperature (LCST). Peak shifts were seen in the adsorbed layer FTIR spectrum that match those observed when PNIPAM solution is heated above its LCST. This observation indicates that adsorption causes a conformational re-arrangement similar to that seen when PNIPAM undergoes a coil-to-globule transition, in this case presumably induced by hydrophobic interactions between PNIPAM and the talc basal plane surface. The kinetics of adsorption are seen to be complex, with potential influences of conformational rearrangement and differential adsorption kinetics for the two dominant surface regions of talc particles. The adsorbed PNIPAM was seen to be exceptionally resistant to removal, with no desorption occurring when a background electrolyte solution was flowed over the adsorbed layer. Spectra acquired of the adsorbed polymer layer heated above the LCST reveal that a further conformational rearrangement takes place for the adsorbed layer, finalizing the transition from coil-to-globule that was initiated by the interaction with the mineral surface.
Publisher: Elsevier BV
Date: 09-2020
Publisher: IOP Publishing
Date: 12-09-2022
Abstract: Ti 3 C 2 T x MXene is a promising active material for developing fiber-based devices due to its exceptional electrical conductivity and electrochemical capacitance. However, fabricating robust fibers with high MXene content remains challenging due to shortcomings such as low interfacial adhesion between sheets and shrinkage-induced sheet disorientation during processing, leading to diminished physical and electrochemical properties. Here, we demonstrate the fabrication of tough, conductive, and electrochemically active fibers through a sequential bridging strategy involving calcium cation (Ca 2+ ) infiltration of cellulose nanocrystal (CNC)-bridged MXene, cross-linked and dried under tension. The resulting fibers exhibited a record toughness of ∼2.05 MJ m −3 and retained high volumetric capacitance (∼985 F cm −3 ), attributed to the synergistic CNC bridging, Ca 2+ cross-linking, and tension application during fiber drying. These fibers also surpass the conductivity of their unaligned pristine MXene counterpart (∼8347 S cm −1 vs ∼5078 S cm −1 ), ascribed to the tension-induced improvement in MXene alignment within these fibers, mitigating the undesirable effects of inserting an insulating CNC bridge. We anticipate that improving the toughness and conductivity of sequentially bridged MXene fibers will pave the way for the production of robust multifunctional MXene fibers, allowing their use in practical high-performance applications like wearable electronics and energy storage devices.
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0JM04307A
Publisher: MDPI AG
Date: 08-09-2022
DOI: 10.3390/MIN12091138
Abstract: This study presented the first in a series of investigations currently underway to develop efficacious, cost-effective, and benign processing opportunities to produce rare earth elements (REE)–rich concentrate from an Australian complex low–grade saprolite ore [1.14% total rare earth oxides (TREO) grade], which is primarily exploited for its gold and copper values. This work specifically presented a preliminary flotation investigation carried out on the ore using sodium oleate as a collector. The relative effects of pulp pH, desliming, and depressants were investigated to ascertain any chance of recovering and upgrading REE minerals in saprolite ore using three different processing configurations. Based on the experimental results, flotation processes carried out on raw feed allowed the recovery of the majority of REE minerals ( %), but the process was unselective, where clay and silicate gangue minerals reported into the flotation concentrate along with the REE minerals. However, desliming before flotation in the presence of depressants (starch and sodium silicate) improved REE minerals flotation selectivity, which produced concentrates assaying 5.87% and 4.22% TREO grades, with corresponding recoveries of 45% and 50% at pulp pH 9 and 10.5, respectively. Mineralogical analysis conducted on selected flotation concentrate indicated that silicate and clay gauge minerals were recovered via the synergistic act of surface activation and entrainment due to their fine to ultrafine nature. A comparison of all the test results revealed a haphazard grade–recovery relationship suggesting that there is an opportunity to further maximize both REE recovery and grade through further flotation studies where other process parameters may be investigated and optimized. The prospect of using magnetic separation has also been suggested.
Publisher: Wiley
Date: 29-01-2023
Abstract: Constructing highly porous structures using Ti 3 C 2 T x MXene provides a promising strategy toward achieving low density, high specific surface area, and shorter ion/molecule transport paths. However, the weak MXene‐MXene or MXene‐substrate interactions hinder the development of ultra‐robust and elastic MXene‐based architectures. To address this issue, a bio‐inspired strategy is developed to effectively adhere the MXene nanosheets onto melamine foam via covalent and hydrogen bonding interactions through polyethyleneimine olydopamine‐modification. The enhanced interactions contribute to high MXene loading (≈94 wt.%) and reversible compressibility even after 10 000 compression/release cycles at 80% strain. The compressible supercapacitor device assembled from this foam exhibits high energy storage capability (119 F g −1 at 2 mV s −1 ) with capacitance retention of ≈93% after 1000 compression/release cycles at 50% strain. Moreover, the presence of polydopamine and MXene enable the absorption of light in the UV–Vis and near‐IR regions, respectively, inducing photothermal conversion functionality, with an evaporation rate of ≈1.5 kg m −2 h −1 and ≈89% solar evaporation efficiency under one sun illumination. It is envisaged that this bio‐inspired chemical modification offers a versatile strategy for the assembly of MXene nanosheets onto different substrates for various applications, such as electromagnetic interference shielding, energy storage, and conversion.
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 08-1999
Publisher: Elsevier BV
Date: 12-2012
Publisher: Informa UK Limited
Date: 09-10-2020
Publisher: Elsevier BV
Date: 05-2012
Publisher: Informa UK Limited
Date: 21-01-2019
Publisher: Informa UK Limited
Date: 18-04-2016
Publisher: Elsevier BV
Date: 02-2019
Publisher: Elsevier BV
Date: 10-2007
Publisher: Elsevier BV
Date: 05-2018
Publisher: Elsevier BV
Date: 12-2014
Publisher: Wiley
Date: 21-04-2022
Abstract: Ti 3 C 2 T x MXene (or “MXene” for simplicity) has gained noteworthy attention for its metal‐like electrical conductivity and high electrochemical capacitance—a unique blend of properties attractive toward a wide range of applications such as energy storage, healthcare monitoring, and electromagnetic interference shielding. However, processing MXene architectures using conventional methods often deals with the presence of defects, voids, and isotropic flake arrangements, resulting in a trade‐off in properties. Here, a sequential bridging (SB) strategy is reported to fabricate dense, freestanding MXene films of interconnected flakes with minimal defects, significantly enhancing its mechanical properties, specifically tensile strength (≈285 MPa) and breaking energy (≈16.1 MJ m –3 ), while retaining substantial values of electrical conductivity (≈3050 S cm –1 ) and electrochemical capacitance (≈920 F cm –3 ). This SB method first involves forming a cellulose nanocrystal‐stitched MXene framework, followed by infiltration with structure‐densifying calcium cations (Ca 2+ ), resulting in tough and fatigue resistant films with anisotropic, evenly spaced, and strongly interconnected flakes — properties essential for developing high‐performance energy‐storage devices. It is anticipated that the knowledge gained in this work will be extended toward improving the robustness and retaining the electronic properties of 2D nanomaterial‐based macroarchitectures.
Publisher: Elsevier BV
Date: 11-2005
Publisher: Elsevier BV
Date: 08-2020
Publisher: Elsevier BV
Date: 03-2006
Publisher: Informa UK Limited
Date: 06-06-2021
Publisher: Elsevier BV
Date: 06-2005
Publisher: Elsevier BV
Date: 08-2015
Publisher: Elsevier BV
Date: 07-2012
Publisher: Academy of Science of South Africa
Date: 31-01-2022
DOI: 10.17159/2411-9717/1654/2022
Abstract: Recently, coal fly ash has become a potential candidate as a secondary resource of rare earth elements (REE). In this investigation, we studied the recovery of REE from fly ash from a commercial power plant. The specific aim was to assess the technical feasibility of recovering REE from the coal fly ash using conventional preconcentration methods, including gravity separation, magnetic separation, and froth flotation. The experimental results revealed that flotation achieved major gains in REE recovery and upgrading. However, during gravity and wet magnetic separation tests, the bulk of REE reported to the tailings. The results showed significant variations in the performance of the various beneficiation methods investigated. This study has confirmed that existing physical separation methods could be used to recover REE from coal fly ash prior to hydrometallurgical and pyrometallurgical processing, although some challenges persist.
Publisher: Elsevier BV
Date: 09-2017
Publisher: Elsevier BV
Date: 08-2017
Publisher: Informa UK Limited
Date: 24-06-2021
Publisher: Elsevier BV
Date: 03-2016
Publisher: Elsevier BV
Date: 2012
Publisher: Elsevier BV
Date: 08-2010
Publisher: Elsevier BV
Date: 05-2014
Publisher: Elsevier BV
Date: 08-2012
Publisher: American Chemical Society (ACS)
Date: 17-05-2012
DOI: 10.1021/CG3003004
Publisher: American Chemical Society (ACS)
Date: 05-1990
DOI: 10.1021/IE00101A023
Publisher: Elsevier BV
Date: 08-2012
Publisher: American Chemical Society (ACS)
Date: 22-05-2013
DOI: 10.1021/CG301477E
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 09-2015
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CC01305F
Abstract: Diatom silica microcapsules prepared by purification of diatomaceous earth (DE) were functionalised by dopamine modified iron-oxide nanoparticles, in order to introduce diatoms with magnetic properties. The application of magnetised diatoms as magnetically guided drug delivery microcarriers has been demonstrated.
Publisher: Elsevier BV
Date: 08-2018
Publisher: American Chemical Society (ACS)
Date: 13-03-1998
DOI: 10.1021/JE970187I
Publisher: Elsevier BV
Date: 12-2018
Publisher: Informa UK Limited
Date: 02-2012
Publisher: Elsevier BV
Date: 08-2015
Publisher: Elsevier BV
Date: 08-2015
Publisher: Elsevier BV
Date: 08-2015
Publisher: Elsevier BV
Date: 10-2004
Publisher: Elsevier BV
Date: 06-2011
Publisher: American Chemical Society (ACS)
Date: 24-09-2004
DOI: 10.1021/JE049889F
Publisher: Elsevier BV
Date: 06-2012
Publisher: Elsevier BV
Date: 02-2014
Publisher: Wiley
Date: 23-02-2023
Abstract: Conductive fibers are needed for the development of flexible electronic and biomedical devices. MXene fibers show great promise for use in such applications because of their high conductivity. Current literature on MXene fiber development highlights the need for improving their mechanical properties and investigation of biocompatibility. Here the use of silk fibroin biopolymer as a MXene formulation additive for the production of MXene fibers is studied. It is found that the favorable silk fibroin–MXene interactions resulted in improved durability, withstanding up to 1 h of high frequency sonication in buffered solutions. Furthermore, fibers with ≈5 wt% silk fibroin displays interesting properties including high conductivity (≈3700 S cm −1 ), high volumetric capacitance (≈910 F cm −3 ), and non‐cytotoxicity toward THP‐1 monocytic cells. The results presented here provide an important insight into potential use of MXene fibers in flexible electronics and biomedical applications.
Publisher: Elsevier BV
Date: 04-2010
Publisher: Elsevier BV
Date: 06-2005
DOI: 10.1016/J.JCIS.2005.01.083
Abstract: The growth kinetics of colloidal Al(III)-containing particles (diameter 9.00), however, a marked increase in growth rate with increasing sigma was displayed. At constant DeltaC or sigma, the growth rate showed a strong variation with NaOH concentration, indicating that Na(+) and OH(-) species play a pivotal role in the Al(OH) precursor particles (nuclei) growth process. Furthermore, the kinetics of growth displayed by these nanosized particles are an order of magnitude slower than those observed for macroscopic gibbsite (gamma-Al(OH)(3)) crystals at similar supersaturations and temperature. The difference may be rationalized in terms of particle size and Al(OH)(3) dimorphic phase dependent solubility effects. An empirically adequate growth kinetics modeling was achieved when the growth rates were correlated with the Al(III) supersaturation (DeltaC or sigma) and the excess (free) NaOH concentration, rather than the former alone, as is commonly the case. A critical [NaOH]/[Al(III)] molar ratio of 1.27-1.35, below which the particle growth rate increased markedly and above which the rate was significantly reduced, was observed. This behavior is believed to be linked to solution speciation change that occurs at certain Al(III) and NaOH compositions.
Publisher: Elsevier BV
Date: 2011
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 07-2013
Publisher: Elsevier BV
Date: 03-2013
Publisher: Elsevier BV
Date: 07-2013
Publisher: Elsevier BV
Date: 02-2019
Publisher: Future Medicine Ltd
Date: 09-2011
DOI: 10.2217/NNM.11.29
Abstract: Aim: This study explores the use of natural silica-based porous material from diatoms, known as diatomaceous earth, as a drug carrier of therapeutics for implant- and oral-delivery applications. Materials & Methods: To prove this concept, two drugs models were used and investigated: a hydrophobic (indomethacin) and hydrophilic (gentamicin). Results & Discussion: Results show the effectiveness of diatom microcapsules for drug-delivery application, showing 14–22 wt% drug loading capacity and sustained drug release over 2 weeks. Two steps in the drug release from diatom structures were observed: the first, rapid release (over 6 h is attributed to the surface deposited drug) and the second, slow and sustained release over 2 weeks with zero order kinetics. Conclusion: These results confirm that natural material based on diatom silica can be successfully applied as a drug carrier for both oral and implant drug-delivery applications, offering considerable potential to replace existing synthetic nanomaterials.
Publisher: Elsevier BV
Date: 08-2013
Publisher: SAGE Publications
Date: 28-03-2013
Abstract: Naturally available and biocompatible materials are potential substitutes for synthetic mesoporous materials as suitable drug carriers for the development of cost-effective drug delivery systems. This work investigates the application of a porous silica material derived from diatoms, also known as diatomaceous earth. The aim is to explore the surface functionalization of diatom microcapsules and their impact on the drug loading and release characteristics of water-insoluble drugs. Indomethacin was used as the model for poorly soluble drug. The surface modification on diatoms was performed with two organosilanes 3-aminopropyltriethoxy silane and N-(3-(trimethoxysilyl) propyl) ethylene diamine and phosphonic acids (2-carboxyethyl-phosphonic acid and 16-phosphono-hexadecanoic acid) providing organic surface hydrophilic and hydrophobic properties. Extensive characterizations using scanning electron microscopy, X-ray photoelectron spectroscopy and differential scanning calorimetry was performed to confirm covalent grafting of monolayer aminosilane and phosphonic acid on the diatom surfaces. Differences in loading capacity of diatoms (15–24%) and release time (6–15 days) were observed which is due to the presence of different functional groups on the surface. It was found that 2-carboxyethyl-phosphonic acid, 3-aminopropyltriethoxy silane and N-(3-(trimethoxysilyl) propyl) ethylene diamine render diatom surfaces hydrophilic, due to polar carboxyl functional group (COOH) and active amine species (NH and NH 2 ) that favor drug adsorption better encapsulation efficiency and prolonged release of drugs, over the hydrophobic surface created by 16-phosphono-hexadecanoic acid. This work demonstrates diatom porous silica as a promising drug carrier, with possibility to further improve their performances by tailoring their surface functionalities to achieve the required drug loading and release characteristics for different therapeutic conditions.
Publisher: Elsevier BV
Date: 05-2003
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 11-1999
Publisher: Elsevier BV
Date: 10-1999
Publisher: American Chemical Society (ACS)
Date: 1996
DOI: 10.1021/JE950188F
Publisher: Elsevier BV
Date: 03-2008
Publisher: Wiley
Date: 23-01-2008
DOI: 10.1002/APJ.110
Publisher: Elsevier BV
Date: 06-2015
Publisher: Elsevier BV
Date: 03-2013
Publisher: Elsevier BV
Date: 12-2017
Publisher: Springer Science and Business Media LLC
Date: 13-01-2017
DOI: 10.1007/S10661-017-5771-3
Abstract: Pyrite-rich sediments would, invariably, undergo redox reactions which would lead to acidic aqueous environment containing solubilized toxic metal species. When such sediments are subjected to preload, a technique employed by geotechnical engineers to improve the load-bearing capacity of highly compressible formation, transient flow of pore water, accompanied by acidity transfer, would occur as a response. Despite the concomitant environmental and socio-economic significance, to date, there has been limited interdisciplinary research on the underpinning geotechnical engineering and geo-environmental science issues for pyrite-rich sediments under preload. In this study, we investigate the effect of pyrite-rich sediment pore water transfer under preload surcharge on the receiving environment and the impact on the groundwater speciation and quality. Sediment s les were obtained at close depth intervals from boreholes established within pristine areas and those subjected to the preload application. Soil and pore water s les were subjected to solid/solution speciation, moisture contents, soil pH and the Atterberg Limits' analyses using standard analytical techniques and methods. Standpipes were also installed in the boreholes for groundwater s ling and in situ monitoring of water quality parameters. It is shown that the imposition of preload surcharge over pyritic sediment created a reducing environment rich in SO
Publisher: American Chemical Society (ACS)
Date: 23-06-2000
DOI: 10.1021/JE000025D
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1016/J.JCIS.2004.09.048
Abstract: Interfacial chemistry and rheological behavior of talc suspensions as a function of pH, talc solid content, and type and concentration of ions have been investigated using electrokinetic measurements, rheology, settling behavior, and solution analysis. Zeta potential measurements show a strong dependence on the pH history of the talc suspension that only occurs when the surface area (solid content) of the talc is high. Particle interactions measured through dispersion yield stress measurements show a similar dependence. Talc is a magnesium silicate mineral and the dependence seen in the electrokinetic properties in this study has been attributed to Mg(II) dissolution at low pH, and has been confirmed by solution analysis. At high solid content (>20 wt%), pronounced Mg(II) ion dissolution occurs at low pH values. Formation and adsorption of electropositive Mg(II) hydrolysis products occurs at high pH (>9), and these lead to zeta potential reduction and, at high solid contents, charge reversal. Particle interactions reflect the surface chemistry behavior. Consequently, for a freshly prepared suspension at high pH, the yield stress is lower compared to after the pH has been taken to 5 and subsequently increased.
Publisher: Informa UK Limited
Date: 02-2005
DOI: 10.1081/SS-200042003
Publisher: American Scientific Publishers
Date: 12-2011
Abstract: Diatom silica microparticles from natural diatomaceous earth (DE) silica have been functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) and their application for adsorption of gold (III) ions from aqueous solutions is demonstrated. Fourier transform infrared spectroscopy (FTIR) and X-ray Photoelectron spectroscopy (XPS) analyses of the MPTMS modified diatom microparticles revealed that the silane layer with functional group (-SH) was successfully introduced to the diatom surface. The adsorption study of Au(III) ions using MPTMS-DE indicated that the process depends on initial gold (III) concentration and pH showing maximum adsorption capacity at pH = 3. The Au(III) adsorption kinetics results showed that the adsorption was very fast and followed a pseudo-second-order reaction model. The Langmuir model was used to provide a sound mechanistic basis for the theoretical of the adsorption equilibrium data. Gold recovery from MPTMS-DE structures was also investigated by using acidified thiourea solution and found to be high (> 95%). These results show that chemically modified DE microparticles can be used as a new, cost effective and environmentally benign adsorbent suitable for adsorption of gold metal ions from aqueous solutions.
Publisher: Elsevier BV
Date: 11-2016
Publisher: Elsevier BV
Date: 07-2006
DOI: 10.1016/J.JCIS.2006.03.015
Abstract: The mechanisms of high-molecular-weight polyacrylamide nonionic homopolymer and 25 mol% anionic acrylate-substituted copolymer adsorption onto iron oxide particles were investigated via DRIFT and UV-vis spectroscopies at three pH values (6, 8.5, and 11). While electrostatic interactions play an important role in charged polymer adsorption, this information is not spectroscopically available. At pH values above and below pH 8.5 (the isoelectric point for the anionic polymer), bidentate chelation and hydrogen bonding were the main adsorption mechanisms. At the isoelectric point, monodentate chelation was observed to be the main mode of adsorption, along with hydrogen bonding. For the nonionic polymer, in all cases, hydrogen bonding through the carbonyl group was the main mode of adsorption. The adsorption of both polymers conformed well to the Freundlich model, suggesting that the adsorbed polymer amount increases with increasing polymer concentration up to 7500 g/t solid, rather than approaching monolayer coverage. Spectroscopic evidence was found to suggest that hydrolysis of nonionic polyacrylamide occurs at high pH.
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 04-1999
Publisher: Springer Science and Business Media LLC
Date: 10-03-2020
Publisher: Elsevier BV
Date: 07-1998
Publisher: MDPI AG
Date: 26-10-2020
DOI: 10.3390/MIN10110955
Abstract: In our previous studies, we demonstrated the performance of novel superfine crusher and pneumatic planar magnetic separator as energy-efficient technologies for dry processing of magnetite ores. The present study investigates the economic and socio-environmental benefits of applying these technologies in conceptual dry magnetite ore processing flowsheet. The outcome of the study is compared with that of a conceptual wet processing flowsheet for the same ore. The cost estimations used are based on the Brook Hunt C1 methodology whilst revenue estimations are based on the Platts Iron Ore Index specification. The demonstrated economic and socio-environmental benefits show that dry processing flowsheet offers significant energy and cost savings and improved revenue generation compared with the wet process flowsheet. These findings are vital to the magnetite industry, particularly in water- and energy-scarce regions as a benchmark for future studies aimed at deepening and expanding the knowledge base of dry beneficiation of magnetite ores.
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 11-2016
Publisher: Elsevier BV
Date: 1997
Publisher: Informa UK Limited
Date: 2015
DOI: 10.15834/CIMJ.2015.3
Publisher: Elsevier BV
Date: 06-1999
Publisher: Elsevier BV
Date: 2006
DOI: 10.1016/J.JCIS.2005.06.034
Abstract: Orthokinetic flocculation of clay dispersions at pH 7.5 and 22 degrees C has been investigated to determine the influence of interfacial chemistry and shear on dewatering and particle interactions behavior. Modification of pulp chemistry and behavior was achieved by using kaolinite and Na-exchanged (swelling) smectite clay minerals, alent metal ions (Ca(II), Mn(II)) as coagulants and anionic polyacrylamide copolymer (PAM A) and non-ionic polyacrylamide homopolymer (PAM N) as flocculants. The pivotal role of shear, provided by a two-blade paddle impeller, was probed as a function of agitation rate (100-500 rpm) and time (15/60 s). Particle zeta potential and adsorption isotherms were measured to quantify the interfacial chemistry, whilst rheology and cryogenic SEM were used to investigate particle interactions and floc structure and aggregate network, respectively. Osmotic swelling, accompanied by the formation of "honeycomb" particle network structure and high yield stress, was produced by the Na-exchanged smectite, but not kaolinite, dispersions. Dispersion of the clay particles in 0.05 M Ca(II) or Mn(II) solution led to a marked reduction in particle zeta potential, complete suppression of swelling, honeycomb network structure collapse and a concomitant reduction in shear yield stress of smectite pulps. Optimum conditions for improved, orthokinetic flocculation performance of negatively charged clay particles, reflecting faster settling flocs comprised (i) coagulation, (ii) moderate agitation rate, (iii) shorter agitation time, and (iv) anionic rather than non-ionic PAM. The optimum dewatering rates were significantly higher than those produced by standard, manual-mixing flocculation techniques (plunging and cylinder inversion) commonly used in industry for flocculant trials. The optimum flocculation conditions did not, however, have a significant impact on the final sediment solid content of 20-22 wt%. Further application of shear to pre-sedimented pulps improved consolidation by 5-7 wt% solid. Higher shear yield stresses and greater settling rates were displayed by PAM A based than PAM N based pulps and this is attributed to the former's more expanded interfacial conformation and greater clay particles bridging ability. It appears that the intrinsic clay particles' physico-chemical properties and interactions limit compact pulp consolidation.
Publisher: Elsevier BV
Date: 04-2000
Publisher: American Chemical Society (ACS)
Date: 28-07-2010
DOI: 10.1021/LA102083T
Abstract: Diatoms (unicellular algae) form porous silica walls (frustule) with intricate, hierarchically organized three-dimensional (3D) structures with micro- to nanoscale dimensions. This paper presents the fabrication of self-supporting gold microstructures with complex 3D morphologies by using electroless gold deposition onto a diatom silica substrate, followed by the substrate removal by acid dissolution. It was demonstrated that gold diatom replicas with distinct micro- to nanoscale structures can be created by a simple and scalable process based on electroless gold deposition. Excellent catalytic properties (catalytic rate constant k = 23.5 +/- 1 x 10(-2) min(-1)) of prepared gold replica catalysts were confirmed for the reduction process of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of NaBH(4) as the reductant. This synthetic approach is general and flexible, and it is envisaged that it can be applied for the preparation of a wide range of different metals (Pt, Pd, Ag, Ni, etc.) offering more efficient catalytic, optical, or magnetic properties.
Publisher: Elsevier BV
Date: 03-2004
Publisher: Elsevier
Date: 2000
Publisher: Elsevier BV
Date: 09-2013
Publisher: Elsevier BV
Date: 02-1999
Publisher: Elsevier BV
Date: 10-2005
Publisher: Wiley
Date: 28-01-2008
DOI: 10.1002/APJ.112
Publisher: IEEE
Date: 02-2010
Publisher: Elsevier BV
Date: 08-2003
Start Date: 2013
End Date: 2018
Funder: University of South Australia
View Funded ActivityStart Date: 2015
End Date: 2016
Funder: South Australian Research and Development Institute
View Funded Activity